static import - Page 162

Slick2d/Nifty-gui input

- by eerongal

I'm trying to get input from slick2d into nifty gui. Ive searched online, and I've seen a few examples, but I can't seem to get it working right. i've tried the example on here but I can't seem to get everything working. I'm not entirely sure what I'm doing wrong. I've also looked at examples using the JMonkeyEngine to help point me in the right direction, but still having issues with input. I can get everything else working like i need. Here's the code for my element controller: package gui; import java.util.Properties; import de.lessvoid.nifty.Nifty; import de.lessvoid.nifty.controls.Controller; import de.lessvoid.nifty.elements.Element; import de.lessvoid.nifty.input.NiftyInputEvent; import de.lessvoid.nifty.screen.Screen; import de.lessvoid.xml.xpp3.Attributes; public class BaseElementController implements Controller { private Element element; public void bind(Nifty arg0, Screen arg1, Element arg2, Properties arg3, Attributes arg4) { this.element = element; } public void init(Properties arg0, Attributes arg1) { // TODO Auto-generated method stub } public boolean inputEvent(NiftyInputEvent arg0) { // TODO Auto-generated method stub return false; } public void onFocus(boolean arg0) { // TODO Auto-generated method stub } public void onStartScreen() { // TODO Auto-generated method stub } public void test() { System.out.println("test"); } public void bam() { System.out.println("bam"); } } Here's my XML file: <?xml version="1.0" encoding="UTF-8" standalone="no"?> <nifty> <useStyles filename="nifty-default-styles.xml"/> <useControls filename="nifty-default-controls.xml"/> <screen id="screen2" controller="gui.BaseScreenController"> <layer backgroundColor="#fff0" childLayout="absolute" id="layer4" controller="gui.BaseElementController"> <panel childLayout="center" height="30%" id="panel1" style="nifty-panel-simple" width="50%" x="282" y="334" controller="gui.BaseElementController"> <control id="checkbox1" name="checkbox"/> <control childLayout="center" id="button2" label="button2" name="button" x="381" y="224" visibleToMouse="true" controller="gui.BaseElementController"> <interact onClick="bam()"/> </control> </panel> <text text="${CALL.getPlayerName()}" style="nifty-label" width="100%" height="100%" x="0" y="10" /> </layer> </screen> </nifty> Here's how I'm trying to bind the controller: public void init(GameContainer gc) throws SlickException { Input input = gc.getInput(); inputSystem = new PlainSlickInputSystem(); inputSystem.setInput(input); gui = new Gui(); gui.init(gc, inputSystem, "gui/tset.xml", "screen2"); input.removeListener(this); input.removeListener(inputSystem); input.addListener(inputSystem); } Essentially, all that happens right now is the screen loads up and displays, and it grabs the variable correctly in the label, but none of the input seems to be getting forwarded to Nifty from slick. I assume there's something I'm missing, but I can't seem to figure out what that is. In so far as what I have tried, I attempted to define a custom input listener to pick up events and assign that to my game in order to pick up input, which did not work, so i dropped that implementation, at current i'm trying to take the default inputs and bind then with a PlainSlickInputSystem and assigning that to the input (as shown in the first example link). On code execution, all the code is hit, and i've put several system.out.println's to get ouput of what is happening (the code above has been cleaned for presentation), and i even see the elements getting bound to the controller, yet it doesn't pick up controller events. As far as EXACTLY what's wrong, that I don't know, because I've followed all implementations i can find of this, and none of them seem to do anything it's like the input is just getting thrown out. None of the objects from niftyGui appear to be recognizing any input. Here is the binding from my objects at run time: ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: button2 (de.lessvoid.nifty.elements.Element@1e8c1be9) ******INITIALIZED ELEMENT: focusable => true, width => 100px {nifty-button#panel}, backgroundImage => button/button.png {nifty-button#panel}, label => button2, paddingLeft => 7px {nifty-button#panel}, imageMode => sprite-resize:100,23,0,2,96,2,2,2,96,2,19,2,96,2,2 {nifty-button#panel}, paddingRight => 7px {nifty-button#panel}, id => button2, visibleToMouse => true, height => 23px {nifty-button#panel}, style => nifty-button, name => button, inputMapping => de.lessvoid.nifty.input.mapping.MenuInputMapping, childLayout => center, controller => gui.BaseElementController, y => 224, x => 381 ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: panel1 (de.lessvoid.nifty.elements.Element@373ec894) ******INITIALIZED ELEMENT: id => panel1, height => 30%, style => nifty-panel-simple, width => 50%, backgroundImage => panel/nifty-panel-simple.png {nifty-panel-simple}, controller => gui.BaseElementController, childLayout => center, padding => 5px {nifty-panel-simple}, imageMode => resize:9,2,9,9,9,2,9,2,9,2,9,9 {nifty-panel-simple}, y => 334, x => 282 ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: layer4 (de.lessvoid.nifty.elements.Element@6427d489) ******INITIALIZED ELEMENT: id => layer4, backgroundColor => #fff0, controller => gui.BaseElementController, childLayout => absolute the button2 object is getting bound to my BaseElementController, but i can't seem to get it into the defined "onClick" call.

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Make a lives display in HUD, Flash AS3 (not text!)

- by user40404

I've been searching the internet all day and I can't find the answer I'm looking for. In my HUD I want to use orange dots to represent lives. The user starts off with 5 lives and every time they die, I want a dot to be removed. Pretty straight forward. So far my idea is to make a movie clip that has the five dots in a line. There would be 5 frames on the timeline (because after the last life it goes to a game over screen right away). I would have a variable set up to store the number of lives and a function to keep track of lives. So every hit of an obstacle would result in livesCounter--;. Then I would set up something like this: switch(livesCounter){ case 5: livesDisplay.gotoAndPlay(1); break; case 4: livesDisplay.gotoAndPlay(2); break; case 3: livesDisplay.gotoAndPlay(3); break; case 2: livesDisplay.gotoAndPlay(4); break; case 1: livesDisplay.gotoAndPlay(5); break; } I feel like there has to be an easier way to do this where I could just have a movie clip of a single orange dot that I could replicate across an x value based on the number of lives. Maybe the dots would be stored in an array? When the user loses a life, a dot on the right end of the line is removed. So in the end the counter would look like this: * * * * * * * * * * * * * * * (last life lost results in the end game screen) EDIT: code based on suggestions by Zhafur and Arthur Wolf White package { import flash.display.MovieClip; import flash.events.*; import flash.ui.Multitouch; import flash.ui.MultitouchInputMode; import flash.display.Sprite; import flash.text.*; import flash.utils.getTimer; public class CollisionMouse extends MovieClip{ public var mySprite:Sprite = new Sprite(); Multitouch.inputMode = MultitouchInputMode.TOUCH_POINT; public var replacement:newSprite = new newSprite; public var score:int = 0; public var obstScore:int = -50; public var targetScore:int = 200; public var startTime:uint = 0; public var gameTime:uint; public var pauseScreen:PauseScreen = new PauseScreen(); public var hitTarget:Boolean = false; public var hitObj:Boolean = false; public var currLevel:Number = 1; public var heroLives:int = 5; public var life:Sprite; public function CollisionMouse() { mySprite.graphics.beginFill(0xff0000); mySprite.graphics.drawRect(0,0,40,40); addChild(mySprite); mySprite.x = 200; mySprite.y = 200; pauseScreen.x = stage.width/2; pauseScreen.y = stage.height/2; life = new Sprite(); life.x = 210; stage.addEventListener(MouseEvent.MOUSE_MOVE,followMouse); /*mySprite.addEventListener(TouchEvent.TOUCH_END, onTouchEnd);*/ //checkLevel(); timeCheck(); trackLives(); } public function timeCheck(){ addEventListener(Event.ENTER_FRAME, showTime); } public function showTime(e:Event) { gameTime = getTimer()-startTime; rm1_mc.timeDisplay.text = clockTime(gameTime); rm1_mc.livesDisplay.text = String(heroLives); } public function clockTime(ms:int) { var seconds:int = Math.floor(ms/1000); var minutes:int = Math.floor(seconds/60); seconds -= minutes*60; var timeString:String = minutes+":"+String(seconds+100).substr(1,2); return timeString; } public function trackLives(){ for(var i:int=0; i<heroLives; i++){ life.graphics.lineStyle(1, 0xff9900); life.graphics.beginFill(0xff9900, 1); life.graphics.drawCircle(i*15, 45, 6); life.graphics.endFill(); addChild(life); } } function followMouse(e:MouseEvent){ mySprite.x=mouseX; mySprite.y=mouseY; trackCollisions(); } function trackCollisions(){ if(mySprite.hitTestObject(rm1_mc.obst1) || mySprite.hitTestObject(rm1_mc.obst2)){ hitObjects(); } else if(mySprite.hitTestObject(rm1_mc.target_mc)){ hitTarg(); } } function hitObjects(){ addChild(replacement); mySprite.x ^= replacement.x; replacement.x ^= mySprite.x; mySprite.x ^= replacement.x; mySprite.y ^= replacement.y; replacement.y ^= mySprite.y; mySprite.y ^= replacement.y; stage.removeEventListener(MouseEvent.MOUSE_MOVE, followMouse); removeChild(mySprite); hitObj = true; checkScore(); } function hitTarg(){ addChild(replacement); mySprite.x ^= replacement.x; replacement.x ^= mySprite.x; mySprite.x ^= replacement.x; mySprite.y ^= replacement.y; replacement.y ^= mySprite.y; mySprite.y ^= replacement.y; stage.removeEventListener(MouseEvent.MOUSE_MOVE, followMouse); removeEventListener(Event.ENTER_FRAME, showTime); removeChild(mySprite); hitTarget = true; currLevel++; checkScore(); } function checkScore(){ if(hitObj){ score += obstScore; heroLives--; removeChild(life); } else if(hitTarget){ score += targetScore; } rm1_mc.scoreDisplay.text = String(score); rm1_mc.livesDisplay.text = String(heroLives); trackLives(); } } }

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Any way to turn off quips in OOWeb?

- by Misha Koshelev

http://ooweb.sourceforge.net/tutorial.html Not really a question, but I can't seem to stop writing stuff like this. Maybe someone will find it useful. I know rewriting an HTTP server is not the way to turn off the quips ;) /* Copyright 2010 Misha Koshelev. All Rights Reserved. */ package com.mksoft.common; import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.net.URLDecoder; import java.text.SimpleDateFormat; import java.util.Date; import java.util.LinkedHashMap; import java.net.ServerSocket; import java.net.Socket; /** * Simple HTTP Server. * * @author Misha Koshelev */ public class HttpServer extends Thread { /* * Constants */ /** * 404 Not Found Result */ protected final static String result404NotFound="<html><head><title>404 Not Found</title></head><body bgcolor='#ffffff'><h1>404 Not Found</h1></body></html>"; /* * Variables */ /** * Port on which HTTP server handles requests. */ protected int port; public int getPort() { return port; } public void setPort(int _port) { port=_port; } /* * Constructors */ public HttpServer(int _port) { setPort(_port); } /* * Helpers */ /** * Errors */ protected void error(String message) { System.err.println(message); System.err.flush(); } /** * Debugging */ protected boolean debugOutput=true; protected void debug(String message) { if (debugOutput) { error(message); } } /** * Lock object */ private Object lock=new Object(); /** * Should we quit? */ protected boolean doQuit=false; /** * Are we done? */ protected boolean areWeDone=false; /** * Process POST request headers */ protected String processPostRequest(String url,LinkedHashMap<String,String> headers,String inputLine) { debug("HttpServer.processPostRequest: url=\""+url); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.processPostRequest: headers."+key+"=\""+headers.get(key)+"\""); } } debug("HttpServer.processPostRequest: inputLine=\""+inputLine+"\""); try { inputLine=new URLDecoder().decode(inputLine,"UTF-8"); } catch (UnsupportedEncodingException uee) { uee.printStackTrace(); } String[] keyValues=inputLine.split("&"); LinkedHashMap<String,String> post=new LinkedHashMap<String,String>(); for (int i=0;i<keyValues.length;i++) { String keyValue=keyValues[i]; int equals=keyValue.indexOf('='); String key=keyValue.substring(0,equals); String value=keyValue.substring(equals+1); post.put(key,value); } return post(url,headers,post); } /** * Server loop (here for exception handling purposes) */ protected void serverLoop() throws IOException { /* Start server socket */ ServerSocket serverSocket=null; try { serverSocket=new ServerSocket(getPort()); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } Socket clientSocket=null; while (true) { /* Quit if necessary */ if (doQuit) { break; } /* Accept incoming connections */ try { clientSocket=serverSocket.accept(); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } /* Read request */ BufferedReader in=null; String inputLine=null; String firstLine=null; String blankLine=null; LinkedHashMap<String,String> headers=new LinkedHashMap<String,String>(); try { in=new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); while (true) { if (blankLine==null) { inputLine=in.readLine(); } else { /* POST request, read Content-length bytes */ int contentLength=new Integer(headers.get("Content-Length")).intValue(); StringBuilder sb=new StringBuilder(contentLength); for (int i=0;i<contentLength;i++) { sb.append((char)in.read()); } inputLine=sb.toString(); break; } if (firstLine==null) { firstLine=inputLine; } else if (blankLine==null) { if (inputLine.equals("")) { if (firstLine.startsWith("GET ")) { break; } blankLine=inputLine; } else { int colon=inputLine.indexOf(": "); String key=inputLine.substring(0,colon); String value=inputLine.substring(colon+2); headers.put(key,value); } } } } catch (IOException ioe) { ioe.printStackTrace(); } /* Process request */ String result=null; firstLine=firstLine.replaceAll(" HTTP/.*",""); if (firstLine.startsWith("GET ")) { result=get(firstLine.replaceFirst("GET ",""),headers); } else if (firstLine.startsWith("POST ")) { result=processPostRequest(firstLine.replaceFirst("POST ",""),headers,inputLine); } else { error("HttpServer.ServerLoop: Unhandled request \""+firstLine+"\""); } debug("HttpServer.ServerLoop: result=\""+result+"\""); /* Send response */ PrintWriter out=null; try { out=new PrintWriter(clientSocket.getOutputStream(),true); } catch (IOException ioe) { ioe.printStackTrace(); } if (result!=null) { out.println("HTTP/1.1 200 OK"); } else { out.println("HTTP/1.0 404 Not Found"); result=result404NotFound; } Date now=new Date(); out.println("Date: "+new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss z").format(now)); out.println("Content-Type: text/html; charset=UTF-8"); out.println("Content-Length: "+result.length()); out.println(""); out.print(result); /* Clean up */ out.close(); if (in!=null) { in.close(); } clientSocket.close(); } serverSocket.close(); areWeDone=true; synchronized(lock) { lock.notifyAll(); } } /* * Methods */ /** * Run server on port specified in constructor. */ public void run() { try { serverLoop(); } catch (IOException ioe) { ioe.printStackTrace(); System.exit(1); } } /** * Process GET request (should be overwritten). */ public String get(String url,LinkedHashMap<String,String> headers) { debug("HttpServer.get: url=\""+url+"\""); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.get: headers."+key+"=\""+headers.get(key)+"\""); } } if (url.equals("/")) { return "<html><head><title>HttpServer GET Test Page</title></head>\r\n"+ "<body bgcolor='#ffffff'>\r\n"+ "<center><h1>HttpServer GET Test Page</h1></center>\r\n"+ "<hr />\r\n"+ "<center><table>\r\n"+ "<form method='post' action='/'>\r\n"+ "<tr><td align=right>Test 1:</td>\r\n"+ " <td><input type='text' name='text 1' value='test me !!! !@#$'></td></tr>\r\n"+ "<tr><td align=right>Test 2:</td>\r\n"+ " <td><input type='text' name='text 2' value='type smthng'></td></tr>\r\n"+ "<tr><td> </td>\r\n"+ " <td align=right><input type='submit' value='Submit'></td></tr>\r\n"+ "</form>\r\n"+ "</table></center>\r\n"+ "<hr />\r\n"+ "<center><a href='/quit'>Shutdown Server</a></center>\r\n"+ "</html>"; } else if (url.equals("/quit")) { quit(); return ""; } else { return null; } } /** * Process POST request (should be overwritten). */ public String post(String url,LinkedHashMap<String,String> headers,LinkedHashMap<String,String> post) { debug("HttpServer.post: url=\""+url+"\""); if (debugOutput) { for (String key: headers.keySet()) { debug("HttpServer.post: headers."+key+"=\""+headers.get(key)+"\""); } } if (url.equals("/")) { String result="<html><head><title>HttpServer Post Test Page</title></head>\r\n"+ "<body bgcolor='#ffffff'>\r\n"+ "<center><h1>HttpServer Post Test Page</h1></center>\r\n"+ "<hr />\r\n"+ "<center><table>\r\n"+ "<tr><th>Key</th><th>Value</th></tr>\r\n"; for (String key: post.keySet()) { result+="<tr><td align=right>"+key+"</td><td align=left>"+post.get(key)+"</td></tr>\r\n"; } result+="</table></center>\r\n"+ "</html>"; return result; } else { return null; } } /** * Wait for server to quit. */ public void waitForCompletion() { while (areWeDone==false) { synchronized(lock) { try { lock.wait(); } catch (InterruptedException ie) { } } } } /** * Shutdown server. */ public void quit() { doQuit=true; } }

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New features of C# 4.0

This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p => p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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Using the ASP.NET Cache to cache data in a Model or Business Object layer, without a dependency on System.Web in the layer - Part One.

- by Rhames

ASP.NET applications can make use of the System.Web.Caching.Cache object to cache data and prevent repeated expensive calls to a database or other store. However, ideally an application should make use of caching at the point where data is retrieved from the database, which typically is inside a Business Objects or Model layer. One of the key features of using a UI pattern such as Model-View-Presenter (MVP) or Model-View-Controller (MVC) is that the Model and Presenter (or Controller) layers are developed without any knowledge of the UI layer. Introducing a dependency on System.Web into the Model layer would break this independence of the Model from the View. This article gives a solution to this problem, using dependency injection to inject the caching implementation into the Model layer at runtime. This allows caching to be used within the Model layer, without any knowledge of the actual caching mechanism that will be used. Create a sample application to use the caching solution Create a test SQL Server database This solution uses a SQL Server database with the same Sales data used in my previous post on calculating running totals. The advantage of using this data is that it gives nice slow queries that will exaggerate the effect of using caching! To create the data, first create a new SQL database called CacheSample. Next run the following script to create the Sale table and populate it: USE CacheSample GO CREATE TABLE Sale(DayCount smallint, Sales money) CREATE CLUSTERED INDEX ndx_DayCount ON Sale(DayCount) go INSERT Sale VALUES (1,120) INSERT Sale VALUES (2,60) INSERT Sale VALUES (3,125) INSERT Sale VALUES (4,40) DECLARE @DayCount smallint, @Sales money SET @DayCount = 5 SET @Sales = 10 WHILE @DayCount < 5000 BEGIN INSERT Sale VALUES (@DayCount,@Sales) SET @DayCount = @DayCount + 1 SET @Sales = @Sales + 15 END Next create a stored procedure to calculate the running total, and return a specified number of rows from the Sale table, using the following script: USE [CacheSample] GO SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: Robin -- Create date: -- Description: -- ============================================= CREATE PROCEDURE [dbo].[spGetRunningTotals] -- Add the parameters for the stored procedure here @HighestDayCount smallint = null AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; IF @HighestDayCount IS NULL SELECT @HighestDayCount = MAX(DayCount) FROM dbo.Sale DECLARE @SaleTbl TABLE (DayCount smallint, Sales money, RunningTotal money) DECLARE @DayCount smallint, @Sales money, @RunningTotal money SET @RunningTotal = 0 SET @DayCount = 0 DECLARE rt_cursor CURSOR FOR SELECT DayCount, Sales FROM Sale ORDER BY DayCount OPEN rt_cursor FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales WHILE @@FETCH_STATUS = 0 AND @DayCount <= @HighestDayCount BEGIN SET @RunningTotal = @RunningTotal + @Sales INSERT @SaleTbl VALUES (@DayCount,@Sales,@RunningTotal) FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales END CLOSE rt_cursor DEALLOCATE rt_cursor SELECT DayCount, Sales, RunningTotal FROM @SaleTbl END GO Create the Sample ASP.NET application In Visual Studio create a new solution and add a class library project called CacheSample.BusinessObjects and an ASP.NET web application called CacheSample.UI. The CacheSample.BusinessObjects project will contain a single class to represent a Sale data item, with all the code to retrieve the sales from the database included in it for simplicity (normally I would at least have a separate Repository or other object that is responsible for retrieving data, and probably a data access layer as well, but for this sample I want to keep it simple). The C# code for the Sale class is shown below: using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient; namespace CacheSample.BusinessObjects { public class Sale { public Int16 DayCount { get; set; } public decimal Sales { get; set; } public decimal RunningTotal { get; set; } public static IEnumerable<Sale> GetSales(int? highestDayCount) { List<Sale> sales = new List<Sale>(); SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt); if (highestDayCount.HasValue) highestDayCountParameter.Value = highestDayCount; else highestDayCountParameter.Value = DBNull.Value; string connectionStr = System.Configuration.ConfigurationManager .ConnectionStrings["CacheSample"].ConnectionString; using(SqlConnection sqlConn = new SqlConnection(connectionStr)) using (SqlCommand sqlCmd = sqlConn.CreateCommand()) { sqlCmd.CommandText = "spGetRunningTotals"; sqlCmd.CommandType = CommandType.StoredProcedure; sqlCmd.Parameters.Add(highestDayCountParameter); sqlConn.Open(); using (SqlDataReader dr = sqlCmd.ExecuteReader()) { while (dr.Read()) { Sale newSale = new Sale(); newSale.DayCount = dr.GetInt16(0); newSale.Sales = dr.GetDecimal(1); newSale.RunningTotal = dr.GetDecimal(2); sales.Add(newSale); } } } return sales; } } } The static GetSale() method makes a call to the spGetRunningTotals stored procedure and then reads each row from the returned SqlDataReader into an instance of the Sale class, it then returns a List of the Sale objects, as IEnnumerable<Sale>. A reference to System.Configuration needs to be added to the CacheSample.BusinessObjects project so that the connection string can be read from the web.config file. In the CacheSample.UI ASP.NET project, create a single web page called ShowSales.aspx, and make this the default start up page. This page will contain a single button to call the GetSales() method and a label to display the results. The html mark up and the C# code behind are shown below: ShowSales.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ShowSales.aspx.cs" Inherits="CacheSample.UI.ShowSales" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Cache Sample - Show All Sales</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Button ID="btnTest1" runat="server" onclick="btnTest1_Click" Text="Get All Sales" />     <asp:Label ID="lblResults" runat="server"></asp:Label> </div> </form> </body> </html> ShowSales.aspx.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using CacheSample.BusinessObjects; namespace CacheSample.UI { public partial class ShowSales : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void btnTest1_Click(object sender, EventArgs e) { System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch(); stopWatch.Start(); var sales = Sale.GetSales(null); var lastSales = sales.Last(); stopWatch.Stop(); lblResults.Text = string.Format( "Count of Sales: {0}, Last DayCount: {1}, Total Sales: {2}. Query took {3} ms", sales.Count(), lastSales.DayCount, lastSales.RunningTotal, stopWatch.ElapsedMilliseconds); } } } Finally we need to add a connection string to the CacheSample SQL Server database, called CacheSample, to the web.config file: <?xmlversion="1.0"?> <configuration> <connectionStrings> <addname="CacheSample" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample" providerName="System.Data.SqlClient" /> </connectionStrings> <system.web> <compilationdebug="true"targetFramework="4.0" /> </system.web> </configuration> Run the application and click the button a few times to see how long each call to the database takes. On my system, each query takes about 450ms. Next I shall look at a solution to use the ASP.NET caching to cache the data returned by the query, so that subsequent requests to the GetSales() method are much faster. Adding Data Caching Support I am going to create my caching support in a separate project called CacheSample.Caching, so the next step is to add a class library to the solution. We shall be using the application configuration to define the implementation of our caching system, so we need a reference to System.Configuration adding to the project. ICacheProvider<T> Interface The first step in adding caching to our application is to define an interface, called ICacheProvider, in the CacheSample.Caching project, with methods to retrieve any data from the cache or to retrieve the data from the data source if it is not present in the cache. Dependency Injection will then be used to inject an implementation of this interface at runtime, allowing the users of the interface (i.e. the CacheSample.BusinessObjects project) to be completely unaware of how the caching is actually implemented. As data of any type maybe retrieved from the data source, it makes sense to use generics in the interface, with a generic type parameter defining the data type associated with a particular instance of the cache interface implementation. The C# code for the ICacheProvider interface is shown below: using System; using System.Collections.Generic; namespace CacheSample.Caching { public interface ICacheProvider { } public interface ICacheProvider<T> : ICacheProvider { T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry); } } The empty non-generic interface will be used as a type in a Dictionary generic collection later to store instances of the ICacheProvider<T> implementation for reuse, I prefer to use a base interface when doing this, as I think the alternative of using object makes for less clear code. The ICacheProvider<T> interface defines two overloaded Fetch methods, the difference between these is that one will return a single instance of the type T and the other will return an IEnumerable<T>, providing support for easy caching of collections of data items. Both methods will take a key parameter, which will uniquely identify the cached data, a delegate of type Func<T> or Func<IEnumerable<T>> which will provide the code to retrieve the data from the store if it is not present in the cache, and absolute or relative expiry policies to define when a cached item should expire. Note that at present there is no support for cache dependencies, but I shall be showing a method of adding this in part two of this article. CacheProviderFactory Class We need a mechanism of creating instances of our ICacheProvider<T> interface, using Dependency Injection to get the implementation of the interface. To do this we shall create a CacheProviderFactory static class in the CacheSample.Caching project. This factory will provide a generic static method called GetCacheProvider<T>(), which shall return instances of ICacheProvider<T>. We can then call this factory method with the relevant data type (for example the Sale class in the CacheSample.BusinessObject project) to get a instance of ICacheProvider for that type (e.g. call CacheProviderFactory.GetCacheProvider<Sale>() to get the ICacheProvider<Sale> implementation). The C# code for the CacheProviderFactory is shown below: using System; using System.Collections.Generic; using CacheSample.Caching.Configuration; namespace CacheSample.Caching { public static class CacheProviderFactory { private static Dictionary<Type, ICacheProvider> cacheProviders = new Dictionary<Type, ICacheProvider>(); private static object syncRoot = new object(); ///<summary> /// Factory method to create or retrieve an implementation of the /// ICacheProvider interface for type <typeparamref name="T"/>. ///</summary> ///<typeparam name="T"> /// The type that this cache provider instance will work with ///</typeparam> ///<returns>An instance of the implementation of ICacheProvider for type ///<typeparamref name="T"/>, as specified by the application /// configuration</returns> public static ICacheProvider<T> GetCacheProvider<T>() { ICacheProvider<T> cacheProvider = null; // Get the Type reference for the type parameter T Type typeOfT = typeof(T); // Lock the access to the cacheProviders dictionary // so multiple threads can work with it lock (syncRoot) { // First check if an instance of the ICacheProvider implementation // already exists in the cacheProviders dictionary for the type T if (cacheProviders.ContainsKey(typeOfT)) cacheProvider = (ICacheProvider<T>)cacheProviders[typeOfT]; else { // There is not already an instance of the ICacheProvider in // cacheProviders for the type T // so we need to create one // Get the Type reference for the application's implementation of // ICacheProvider from the configuration Type cacheProviderType = Type.GetType(CacheProviderConfigurationSection.Current. CacheProviderType); if (cacheProviderType != null) { // Now get a Type reference for the Cache Provider with the // type T generic parameter Type typeOfCacheProviderTypeForT = cacheProviderType.MakeGenericType(new Type[] { typeOfT }); if (typeOfCacheProviderTypeForT != null) { // Create the instance of the Cache Provider and add it to // the cacheProviders dictionary for future use cacheProvider = (ICacheProvider<T>)Activator. CreateInstance(typeOfCacheProviderTypeForT); cacheProviders.Add(typeOfT, cacheProvider); } } } } return cacheProvider; } } } As this code uses Activator.CreateInstance() to create instances of the ICacheProvider<T> implementation, which is a slow process, the factory class maintains a Dictionary of the previously created instances so that a cache provider needs to be created only once for each type. The type of the implementation of ICacheProvider<T> is read from a custom configuration section in the application configuration file, via the CacheProviderConfigurationSection class, which is described below. CacheProviderConfigurationSection Class The implementation of ICacheProvider<T> will be specified in a custom configuration section in the application’s configuration. To handle this create a folder in the CacheSample.Caching project called Configuration, and add a class called CacheProviderConfigurationSection to this folder. This class will extend the System.Configuration.ConfigurationSection class, and will contain a single string property called CacheProviderType. The C# code for this class is shown below: using System; using System.Configuration; namespace CacheSample.Caching.Configuration { internal class CacheProviderConfigurationSection : ConfigurationSection { public static CacheProviderConfigurationSection Current { get { return (CacheProviderConfigurationSection) ConfigurationManager.GetSection("cacheProvider"); } } [ConfigurationProperty("type", IsRequired=true)] public string CacheProviderType { get { return (string)this["type"]; } } } } Adding Data Caching to the Sales Class We now have enough code in place to add caching to the GetSales() method in the CacheSample.BusinessObjects.Sale class, even though we do not yet have an implementation of the ICacheProvider<T> interface. We need to add a reference to the CacheSample.Caching project to CacheSample.BusinessObjects so that we can use the ICacheProvider<T> interface within the GetSales() method. Once the reference is added, we can first create a unique string key based on the method name and the parameter value, so that the same cache key is used for repeated calls to the method with the same parameter values. Then we get an instance of the cache provider for the Sales type, using the CacheProviderFactory, and pass the existing code to retrieve the data from the database as the retrievalMethod delegate in a call to the Cache Provider Fetch() method. The C# code for the modified GetSales() method is shown below: public static IEnumerable<Sale> GetSales(int? highestDayCount) { string cacheKey = string.Format("CacheSample.BusinessObjects.GetSalesWithCache({0})", highestDayCount); return CacheSample.Caching.CacheProviderFactory. GetCacheProvider<Sale>().Fetch(cacheKey, delegate() { List<Sale> sales = new List<Sale>(); SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt); if (highestDayCount.HasValue) highestDayCountParameter.Value = highestDayCount; else highestDayCountParameter.Value = DBNull.Value; string connectionStr = System.Configuration.ConfigurationManager. ConnectionStrings["CacheSample"].ConnectionString; using (SqlConnection sqlConn = new SqlConnection(connectionStr)) using (SqlCommand sqlCmd = sqlConn.CreateCommand()) { sqlCmd.CommandText = "spGetRunningTotals"; sqlCmd.CommandType = CommandType.StoredProcedure; sqlCmd.Parameters.Add(highestDayCountParameter); sqlConn.Open(); using (SqlDataReader dr = sqlCmd.ExecuteReader()) { while (dr.Read()) { Sale newSale = new Sale(); newSale.DayCount = dr.GetInt16(0); newSale.Sales = dr.GetDecimal(1); newSale.RunningTotal = dr.GetDecimal(2); sales.Add(newSale); } } } return sales; }, null, new TimeSpan(0, 10, 0)); } This example passes the code to retrieve the Sales data from the database to the Cache Provider as an anonymous method, however it could also be written as a lambda. The main advantage of using an anonymous function (method or lambda) is that the code inside the anonymous function can access the parameters passed to the GetSales() method. Finally the absolute expiry is set to null, and the relative expiry set to 10 minutes, to indicate that the cache entry should be removed 10 minutes after the last request for the data. As the ICacheProvider<T> has a Fetch() method that returns IEnumerable<T>, we can simply return the results of the Fetch() method to the caller of the GetSales() method. This should be all that is needed for the GetSales() method to now retrieve data from a cache after the first time the data has be retrieved from the database. Implementing a ASP.NET Cache Provider The final step is to actually implement the ICacheProvider<T> interface, and add the implementation details to the web.config file for the dependency injection. The cache provider implementation needs to have access to System.Web. Therefore it could be placed in the CacheSample.UI project, or in its own project that has a reference to System.Web. Implementing the Cache Provider in a separate project is my favoured approach. Create a new project inside the solution called CacheSample.CacheProvider, and add references to System.Web and CacheSample.Caching to this project. Add a class to the project called AspNetCacheProvider. Make the class a generic class by adding the generic parameter <T> and indicate that the class implements ICacheProvider<T>. The C# code for the AspNetCacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching; using CacheSample.Caching; namespace CacheSample.CacheProvider { public class AspNetCacheProvider<T> : ICacheProvider<T> { #region ICacheProvider<T> Members public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry); } public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry); } #endregion #region Helper Methods private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry) { U value; if (!TryGetValue<U>(key, out value)) { value = retrieveData(); if (!absoluteExpiry.HasValue) absoluteExpiry = Cache.NoAbsoluteExpiration; if (!relativeExpiry.HasValue) relativeExpiry = Cache.NoSlidingExpiration; HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value); } return value; } private bool TryGetValue<U>(string key, out U value) { object cachedValue = HttpContext.Current.Cache.Get(key); if (cachedValue == null) { value = default(U); return false; } else { try { value = (U)cachedValue; return true; } catch { value = default(U); return false; } } } #endregion } } The two interface Fetch() methods call a private method called FetchAndCache(). This method first checks for a element in the HttpContext.Current.Cache with the specified cache key, and if so tries to cast this to the specified type (either T or IEnumerable<T>). If the cached element is found, the FetchAndCache() method simply returns it. If it is not found in the cache, the method calls the retrievalMethod delegate to get the data from the data source, and then adds this to the HttpContext.Current.Cache. The final step is to add the AspNetCacheProvider class to the relevant custom configuration section in the CacheSample.UI.Web.Config file. To do this there needs to be a <configSections> element added as the first element in <configuration>. This will match a custom section called <cacheProvider> with the CacheProviderConfigurationSection. Then we add a <cacheProvider> element, with a type property set to the fully qualified assembly name of the AspNetCacheProvider class, as shown below: <?xmlversion="1.0"?> <configuration> <configSections> <sectionname="cacheProvider" type="CacheSample.Base.Configuration.CacheProviderConfigurationSection, CacheSample.Base" /> </configSections> <connectionStrings> <addname="CacheSample" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample" providerName="System.Data.SqlClient" /> </connectionStrings> <cacheProvidertype="CacheSample.CacheProvider.AspNetCacheProvider`1, CacheSample.CacheProvider, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"> </cacheProvider> <system.web> <compilationdebug="true"targetFramework="4.0" /> </system.web> </configuration> One point to note is that the fully qualified assembly name of the AspNetCacheProvider class includes the notation `1 after the class name, which indicates that it is a generic class with a single generic type parameter. The CacheSample.UI project needs to have references added to CacheSample.Caching and CacheSample.CacheProvider so that the actual application is aware of the relevant cache provider implementation. Conclusion After implementing this solution, you should have a working cache provider mechanism, that will allow the middle and data access layers to implement caching support when retrieving data, without any knowledge of the actually caching implementation. If the UI is not ASP.NET based, if for example it is Winforms or WPF, the implementation of ICacheProvider<T> would be written around whatever technology is available. It could even be a standalone caching system that takes full responsibility for adding and removing items from a global store. The next part of this article will show how this caching mechanism may be extended to provide support for cache dependencies, such as the System.Web.Caching.SqlCacheDependency. Another possible extension would be to cache the cache provider implementations instead of storing them in a static Dictionary in the CacheProviderFactory. This would prevent a build up of seldom used cache providers in the application memory, as they could be removed from the cache if not used often enough, although in reality there are probably unlikely to be vast numbers of cache provider implementation instances, as most applications do not have a massive number of business object or model types.

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C#/.NET Little Wonders: The Generic Func Delegates

- by James Michael Hare

Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET. Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates. For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method. They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression. They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3: 4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6: 7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9: 10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET. These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic. Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results. Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void. You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result. Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…). To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total. A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5: 6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8: 9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13: 14: _aggregationMethod = aggregationMethod; 15: } 16: 17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3: 4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5: 6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10: 11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them. So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2: 3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6: 7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain. Thus, this aggregator would always result in the Math.Max() result. The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4: 5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8: 9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments. In addition, it is co-variant on its return type. To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders. As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived. However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object. In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals. On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived. Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result. In other words, pay attention to the direction the item travels (parameters go in, results come out). Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5: 6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11: 12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3: 4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate. Predicates are used to examine an item and determine whether that item satisfies a particular condition. Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2: 3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine. Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4: 5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types! Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4: 5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8: 9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day. We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day. This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing. Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds. Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6: 7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13: 14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16: 17: // the item cached 18: public T Value { get; private set; } 19: 20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25: 26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2: 3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5: 6: var target = new CacheItem<int>(13); 7: 8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10: 11: Assert.IsFalse(target.IsExpired); 12: 13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15: 16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc. Func delegates can be a handy tool for this type of value generation to support more testable code. Summary Generic delegates give us a lot of power to make truly generic algorithms and classes. The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments. Stay tuned in the weeks that follow for other generic delegates in the .NET Framework! Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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What are good design practices when working with Entity Framework

- by AD

This will apply mostly for an asp.net application where the data is not accessed via soa. Meaning that you get access to the objects loaded from the framework, not Transfer Objects, although some recommendation still apply. This is a community post, so please add to it as you see fit. Applies to: Entity Framework 1.0 shipped with Visual Studio 2008 sp1. Why pick EF in the first place? Considering it is a young technology with plenty of problems (see below), it may be a hard sell to get on the EF bandwagon for your project. However, it is the technology Microsoft is pushing (at the expense of Linq2Sql, which is a subset of EF). In addition, you may not be satisfied with NHibernate or other solutions out there. Whatever the reasons, there are people out there (including me) working with EF and life is not bad.make you think. EF and inheritance The first big subject is inheritance. EF does support mapping for inherited classes that are persisted in 2 ways: table per class and table the hierarchy. The modeling is easy and there are no programming issues with that part. (The following applies to table per class model as I don't have experience with table per hierarchy, which is, anyway, limited.) The real problem comes when you are trying to run queries that include one or many objects that are part of an inheritance tree: the generated sql is incredibly awful, takes a long time to get parsed by the EF and takes a long time to execute as well. This is a real show stopper. Enough that EF should probably not be used with inheritance or as little as possible. Here is an example of how bad it was. My EF model had ~30 classes, ~10 of which were part of an inheritance tree. On running a query to get one item from the Base class, something as simple as Base.Get(id), the generated SQL was over 50,000 characters. Then when you are trying to return some Associations, it degenerates even more, going as far as throwing SQL exceptions about not being able to query more than 256 tables at once. Ok, this is bad, EF concept is to allow you to create your object structure without (or with as little as possible) consideration on the actual database implementation of your table. It completely fails at this. So, recommendations? Avoid inheritance if you can, the performance will be so much better. Use it sparingly where you have to. In my opinion, this makes EF a glorified sql-generation tool for querying, but there are still advantages to using it. And ways to implement mechanism that are similar to inheritance. Bypassing inheritance with Interfaces First thing to know with trying to get some kind of inheritance going with EF is that you cannot assign a non-EF-modeled class a base class. Don't even try it, it will get overwritten by the modeler. So what to do? You can use interfaces to enforce that classes implement some functionality. For example here is a IEntity interface that allow you to define Associations between EF entities where you don't know at design time what the type of the entity would be. public enum EntityTypes{ Unknown = -1, Dog = 0, Cat } public interface IEntity { int EntityID { get; } string Name { get; } Type EntityType { get; } } public partial class Dog : IEntity { // implement EntityID and Name which could actually be fields // from your EF model Type EntityType{ get{ return EntityTypes.Dog; } } } Using this IEntity, you can then work with undefined associations in other classes // lets take a class that you defined in your model. // that class has a mapping to the columns: PetID, PetType public partial class Person { public IEntity GetPet() { return IEntityController.Get(PetID,PetType); } } which makes use of some extension functions: public class IEntityController { static public IEntity Get(int id, EntityTypes type) { switch (type) { case EntityTypes.Dog: return Dog.Get(id); case EntityTypes.Cat: return Cat.Get(id); default: throw new Exception("Invalid EntityType"); } } } Not as neat as having plain inheritance, particularly considering you have to store the PetType in an extra database field, but considering the performance gains, I would not look back. It also cannot model one-to-many, many-to-many relationship, but with creative uses of 'Union' it could be made to work. Finally, it creates the side effet of loading data in a property/function of the object, which you need to be careful about. Using a clear naming convention like GetXYZ() helps in that regards. Compiled Queries Entity Framework performance is not as good as direct database access with ADO (obviously) or Linq2SQL. There are ways to improve it however, one of which is compiling your queries. The performance of a compiled query is similar to Linq2Sql. What is a compiled query? It is simply a query for which you tell the framework to keep the parsed tree in memory so it doesn't need to be regenerated the next time you run it. So the next run, you will save the time it takes to parse the tree. Do not discount that as it is a very costly operation that gets even worse with more complex queries. There are 2 ways to compile a query: creating an ObjectQuery with EntitySQL and using CompiledQuery.Compile() function. (Note that by using an EntityDataSource in your page, you will in fact be using ObjectQuery with EntitySQL, so that gets compiled and cached). An aside here in case you don't know what EntitySQL is. It is a string-based way of writing queries against the EF. Here is an example: "select value dog from Entities.DogSet as dog where dog.ID = @ID". The syntax is pretty similar to SQL syntax. You can also do pretty complex object manipulation, which is well explained [here][1]. Ok, so here is how to do it using ObjectQuery< string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); The first time you run this query, the framework will generate the expression tree and keep it in memory. So the next time it gets executed, you will save on that costly step. In that example EnablePlanCaching = true, which is unnecessary since that is the default option. The other way to compile a query for later use is the CompiledQuery.Compile method. This uses a delegate: static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => ctx.DogSet.FirstOrDefault(it => it.ID == id)); or using linq static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet where dog.ID == id select dog).FirstOrDefault()); to call the query: query_GetDog.Invoke( YourContext, id ); The advantage of CompiledQuery is that the syntax of your query is checked at compile time, where as EntitySQL is not. However, there are other consideration... Includes Lets say you want to have the data for the dog owner to be returned by the query to avoid making 2 calls to the database. Easy to do, right? EntitySQL string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)).Include("Owner"); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); CompiledQuery static readonly Func<Entities, int, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, Dog>((ctx, id) => (from dog in ctx.DogSet.Include("Owner") where dog.ID == id select dog).FirstOrDefault()); Now, what if you want to have the Include parametrized? What I mean is that you want to have a single Get() function that is called from different pages that care about different relationships for the dog. One cares about the Owner, another about his FavoriteFood, another about his FavotireToy and so on. Basicly, you want to tell the query which associations to load. It is easy to do with EntitySQL public Dog Get(int id, string include) { string query = "select value dog " + "from Entities.DogSet as dog " + "where dog.ID = @ID"; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>(query, EntityContext.Instance)) .IncludeMany(include); oQuery.Parameters.Add(new ObjectParameter("ID", id)); oQuery.EnablePlanCaching = true; return oQuery.FirstOrDefault(); } The include simply uses the passed string. Easy enough. Note that it is possible to improve on the Include(string) function (that accepts only a single path) with an IncludeMany(string) that will let you pass a string of comma-separated associations to load. Look further in the extension section for this function. If we try to do it with CompiledQuery however, we run into numerous problems: The obvious static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.Include(include) where dog.ID == id select dog).FirstOrDefault()); will choke when called with: query_GetDog.Invoke( YourContext, id, "Owner,FavoriteFood" ); Because, as mentionned above, Include() only wants to see a single path in the string and here we are giving it 2: "Owner" and "FavoriteFood" (which is not to be confused with "Owner.FavoriteFood"!). Then, let's use IncludeMany(), which is an extension function static readonly Func<Entities, int, string, Dog> query_GetDog = CompiledQuery.Compile<Entities, int, string, Dog>((ctx, id, include) => (from dog in ctx.DogSet.IncludeMany(include) where dog.ID == id select dog).FirstOrDefault()); Wrong again, this time it is because the EF cannot parse IncludeMany because it is not part of the functions that is recognizes: it is an extension. Ok, so you want to pass an arbitrary number of paths to your function and Includes() only takes a single one. What to do? You could decide that you will never ever need more than, say 20 Includes, and pass each separated strings in a struct to CompiledQuery. But now the query looks like this: from dog in ctx.DogSet.Include(include1).Include(include2).Include(include3) .Include(include4).Include(include5).Include(include6) .[...].Include(include19).Include(include20) where dog.ID == id select dog which is awful as well. Ok, then, but wait a minute. Can't we return an ObjectQuery< with CompiledQuery? Then set the includes on that? Well, that what I would have thought so as well: static readonly Func<Entities, int, ObjectQuery<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, ObjectQuery<Dog>>((ctx, id) => (ObjectQuery<Dog>)(from dog in ctx.DogSet where dog.ID == id select dog)); public Dog GetDog( int id, string include ) { ObjectQuery<Dog> oQuery = query_GetDog(id); oQuery = oQuery.IncludeMany(include); return oQuery.FirstOrDefault; } That should have worked, except that when you call IncludeMany (or Include, Where, OrderBy...) you invalidate the cached compiled query because it is an entirely new one now! So, the expression tree needs to be reparsed and you get that performance hit again. So what is the solution? You simply cannot use CompiledQueries with parametrized Includes. Use EntitySQL instead. This doesn't mean that there aren't uses for CompiledQueries. It is great for localized queries that will always be called in the same context. Ideally CompiledQuery should always be used because the syntax is checked at compile time, but due to limitation, that's not possible. An example of use would be: you may want to have a page that queries which two dogs have the same favorite food, which is a bit narrow for a BusinessLayer function, so you put it in your page and know exactly what type of includes are required. Passing more than 3 parameters to a CompiledQuery Func is limited to 5 parameters, of which the last one is the return type and the first one is your Entities object from the model. So that leaves you with 3 parameters. A pitance, but it can be improved on very easily. public struct MyParams { public string param1; public int param2; public DateTime param3; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where dog.Age == myParams.param2 && dog.Name == myParams.param1 and dog.BirthDate > myParams.param3 select dog); public List<Dog> GetSomeDogs( int age, string Name, DateTime birthDate ) { MyParams myParams = new MyParams(); myParams.param1 = name; myParams.param2 = age; myParams.param3 = birthDate; return query_GetDog(YourContext,myParams).ToList(); } Return Types (this does not apply to EntitySQL queries as they aren't compiled at the same time during execution as the CompiledQuery method) Working with Linq, you usually don't force the execution of the query until the very last moment, in case some other functions downstream wants to change the query in some way: static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public IEnumerable<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name); } public void DataBindStuff() { IEnumerable<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } What is going to happen here? By still playing with the original ObjectQuery (that is the actual return type of the Linq statement, which implements IEnumerable), it will invalidate the compiled query and be force to re-parse. So, the rule of thumb is to return a List< of objects instead. static readonly Func<Entities, int, string, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, int, string, IEnumerable<Dog>>((ctx, age, name) => from dog in ctx.DogSet where dog.Age == age && dog.Name == name select dog); public List<Dog> GetSomeDogs( int age, string name ) { return query_GetDog(YourContext,age,name).ToList(); //<== change here } public void DataBindStuff() { List<Dog> dogs = GetSomeDogs(4,"Bud"); // but I want the dogs ordered by BirthDate gridView.DataSource = dogs.OrderBy( it => it.BirthDate ); } When you call ToList(), the query gets executed as per the compiled query and then, later, the OrderBy is executed against the objects in memory. It may be a little bit slower, but I'm not even sure. One sure thing is that you have no worries about mis-handling the ObjectQuery and invalidating the compiled query plan. Once again, that is not a blanket statement. ToList() is a defensive programming trick, but if you have a valid reason not to use ToList(), go ahead. There are many cases in which you would want to refine the query before executing it. Performance What is the performance impact of compiling a query? It can actually be fairly large. A rule of thumb is that compiling and caching the query for reuse takes at least double the time of simply executing it without caching. For complex queries (read inherirante), I have seen upwards to 10 seconds. So, the first time a pre-compiled query gets called, you get a performance hit. After that first hit, performance is noticeably better than the same non-pre-compiled query. Practically the same as Linq2Sql When you load a page with pre-compiled queries the first time you will get a hit. It will load in maybe 5-15 seconds (obviously more than one pre-compiled queries will end up being called), while subsequent loads will take less than 300ms. Dramatic difference, and it is up to you to decide if it is ok for your first user to take a hit or you want a script to call your pages to force a compilation of the queries. Can this query be cached? { Dog dog = from dog in YourContext.DogSet where dog.ID == id select dog; } No, ad-hoc Linq queries are not cached and you will incur the cost of generating the tree every single time you call it. Parametrized Queries Most search capabilities involve heavily parametrized queries. There are even libraries available that will let you build a parametrized query out of lamba expressions. The problem is that you cannot use pre-compiled queries with those. One way around that is to map out all the possible criteria in the query and flag which one you want to use: public struct MyParams { public string name; public bool checkName; public int age; public bool checkAge; } static readonly Func<Entities, MyParams, IEnumerable<Dog>> query_GetDog = CompiledQuery.Compile<Entities, MyParams, IEnumerable<Dog>>((ctx, myParams) => from dog in ctx.DogSet where (myParams.checkAge == true && dog.Age == myParams.age) && (myParams.checkName == true && dog.Name == myParams.name ) select dog); protected List<Dog> GetSomeDogs() { MyParams myParams = new MyParams(); myParams.name = "Bud"; myParams.checkName = true; myParams.age = 0; myParams.checkAge = false; return query_GetDog(YourContext,myParams).ToList(); } The advantage here is that you get all the benifits of a pre-compiled quert. The disadvantages are that you most likely will end up with a where clause that is pretty difficult to maintain, that you will incur a bigger penalty for pre-compiling the query and that each query you run is not as efficient as it could be (particularly with joins thrown in). Another way is to build an EntitySQL query piece by piece, like we all did with SQL. protected List<Dod> GetSomeDogs( string name, int age) { string query = "select value dog from Entities.DogSet where 1 = 1 "; if( !String.IsNullOrEmpty(name) ) query = query + " and dog.Name == @Name "; if( age > 0 ) query = query + " and dog.Age == @Age "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); if( !String.IsNullOrEmpty(name) ) oQuery.Parameters.Add( new ObjectParameter( "Name", name ) ); if( age > 0 ) oQuery.Parameters.Add( new ObjectParameter( "Age", age ) ); return oQuery.ToList(); } Here the problems are: - there is no syntax checking during compilation - each different combination of parameters generate a different query which will need to be pre-compiled when it is first run. In this case, there are only 4 different possible queries (no params, age-only, name-only and both params), but you can see that there can be way more with a normal world search. - Noone likes to concatenate strings! Another option is to query a large subset of the data and then narrow it down in memory. This is particularly useful if you are working with a definite subset of the data, like all the dogs in a city. You know there are a lot but you also know there aren't that many... so your CityDog search page can load all the dogs for the city in memory, which is a single pre-compiled query and then refine the results protected List<Dod> GetSomeDogs( string name, int age, string city) { string query = "select value dog from Entities.DogSet where dog.Owner.Address.City == @City "; ObjectQuery<Dog> oQuery = new ObjectQuery<Dog>( query, YourContext ); oQuery.Parameters.Add( new ObjectParameter( "City", city ) ); List<Dog> dogs = oQuery.ToList(); if( !String.IsNullOrEmpty(name) ) dogs = dogs.Where( it => it.Name == name ); if( age > 0 ) dogs = dogs.Where( it => it.Age == age ); return dogs; } It is particularly useful when you start displaying all the data then allow for filtering. Problems: - Could lead to serious data transfer if you are not careful about your subset. - You can only filter on the data that you returned. It means that if you don't return the Dog.Owner association, you will not be able to filter on the Dog.Owner.Name So what is the best solution? There isn't any. You need to pick the solution that works best for you and your problem: - Use lambda-based query building when you don't care about pre-compiling your queries. - Use fully-defined pre-compiled Linq query when your object structure is not too complex. - Use EntitySQL/string concatenation when the structure could be complex and when the possible number of different resulting queries are small (which means fewer pre-compilation hits). - Use in-memory filtering when you are working with a smallish subset of the data or when you had to fetch all of the data on the data at first anyway (if the performance is fine with all the data, then filtering in memory will not cause any time to be spent in the db). Singleton access The best way to deal with your context and entities accross all your pages is to use the singleton pattern: public sealed class YourContext { private const string instanceKey = "On3GoModelKey"; YourContext(){} public static YourEntities Instance { get { HttpContext context = HttpContext.Current; if( context == null ) return Nested.instance; if (context.Items[instanceKey] == null) { On3GoEntities entity = new On3GoEntities(); context.Items[instanceKey] = entity; } return (YourEntities)context.Items[instanceKey]; } } class Nested { // Explicit static constructor to tell C# compiler // not to mark type as beforefieldinit static Nested() { } internal static readonly YourEntities instance = new YourEntities(); } } NoTracking, is it worth it? When executing a query, you can tell the framework to track the objects it will return or not. What does it mean? With tracking enabled (the default option), the framework will track what is going on with the object (has it been modified? Created? Deleted?) and will also link objects together, when further queries are made from the database, which is what is of interest here. For example, lets assume that Dog with ID == 2 has an owner which ID == 10. Dog dog = (from dog in YourContext.DogSet where dog.ID == 2 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Person owner = (from o in YourContext.PersonSet where o.ID == 10 select dog).FirstOrDefault(); //dog.OwnerReference.IsLoaded == true; If we were to do the same with no tracking, the result would be different. ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog = oDogQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>) (from o in YourContext.PersonSet where o.ID == 10 select o); oPersonQuery.MergeOption = MergeOption.NoTracking; Owner owner = oPersonQuery.FirstOrDefault(); //dog.OwnerReference.IsLoaded == false; Tracking is very useful and in a perfect world without performance issue, it would always be on. But in this world, there is a price for it, in terms of performance. So, should you use NoTracking to speed things up? It depends on what you are planning to use the data for. Is there any chance that the data your query with NoTracking can be used to make update/insert/delete in the database? If so, don't use NoTracking because associations are not tracked and will causes exceptions to be thrown. In a page where there are absolutly no updates to the database, you can use NoTracking. Mixing tracking and NoTracking is possible, but it requires you to be extra careful with updates/inserts/deletes. The problem is that if you mix then you risk having the framework trying to Attach() a NoTracking object to the context where another copy of the same object exist with tracking on. Basicly, what I am saying is that Dog dog1 = (from dog in YourContext.DogSet where dog.ID == 2).FirstOrDefault(); ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>) (from dog in YourContext.DogSet where dog.ID == 2 select dog); oDogQuery.MergeOption = MergeOption.NoTracking; Dog dog2 = oDogQuery.FirstOrDefault(); dog1 and dog2 are 2 different objects, one tracked and one not. Using the detached object in an update/insert will force an Attach() that will say "Wait a minute, I do already have an object here with the same database key. Fail". And when you Attach() one object, all of its hierarchy gets attached as well, causing problems everywhere. Be extra careful. How much faster is it with NoTracking It depends on the queries. Some are much more succeptible to tracking than other. I don't have a fast an easy rule for it, but it helps. So I should use NoTracking everywhere then? Not exactly. There are some advantages to tracking object. The first one is that the object is cached, so subsequent call for that object will not hit the database. That cache is only valid for the lifetime of the YourEntities object, which, if you use the singleton code above, is the same as the page lifetime. One page request == one YourEntity object. So for multiple calls for the same object, it will load only once per page request. (Other caching mechanism could extend that). What happens when you are using NoTracking and try to load the same object multiple times? The database will be queried each time, so there is an impact there. How often do/should you call for the same object during a single page request? As little as possible of course, but it does happens. Also remember the piece above about having the associations connected automatically for your? You don't have that with NoTracking, so if you load your data in multiple batches, you will not have a link to between them: ObjectQuery<Dog> oDogQuery = (ObjectQuery<Dog>)(from dog in YourContext.DogSet select dog); oDogQuery.MergeOption = MergeOption.NoTracking; List<Dog> dogs = oDogQuery.ToList(); ObjectQuery<Person> oPersonQuery = (ObjectQuery<Person>)(from o in YourContext.PersonSet select o); oPersonQuery.MergeOption = MergeOption.NoTracking; List<Person> owners = oPersonQuery.ToList(); In this case, no dog will have its .Owner property set. Some things to keep in mind when you are trying to optimize the performance. No lazy loading, what am I to do? This can be seen as a blessing in disguise. Of course it is annoying to load everything manually. However, it decreases the number of calls to the db and forces you to think about when you should load data. The more you can load in one database call the better. That was always true, but it is enforced now with this 'feature' of EF. Of course, you can call if( !ObjectReference.IsLoaded ) ObjectReference.Load(); if you want to, but a better practice is to force the framework to load the objects you know you will need in one shot. This is where the discussion about parametrized Includes begins to make sense. Lets say you have you Dog object public class Dog { public Dog Get(int id) { return YourContext.DogSet.FirstOrDefault(it => it.ID == id ); } } This is the type of function you work with all the time. It gets called from all over the place and once you have that Dog object, you will do very different things to it in different functions. First, it should be pre-compiled, because you will call that very often. Second, each different pages will want to have access to a different subset of the Dog data. Some will want the Owner, some the FavoriteToy, etc. Of course, you could call Load() for each reference you need anytime you need one. But that will generate a call to the database each time. Bad idea. So instead, each page will ask for the data it wants to see when it first request for the Dog object: static public Dog Get(int id) { return GetDog(entity,"");} static public Dog Get(int id, string includePath) { string query = "select value o " + " from YourEntities.DogSet as o " +

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JAVA image transfer problem

- by user579098

Hi, I have a school assignment, to send a jpg image,split it into groups of 100 bytes, corrupt it, use a CRC check to locate the errors and re-transmit until it eventually is built back into its original form. It's practically ready, however when I check out the new images, they appear with errors.. I would really appreciate if someone could look at my code below and maybe locate this logical mistake as I can't understand what the problem is because everything looks ok :S For the file with all the data needed including photos and error patterns one could download it from this link:http://rapidshare.com/#!download|932tl2|443122762|Data.zip|739 Thanks in advance, Stefan p.s dont forget to change the paths in the code for the image and error files package networks; import java.io.*; // for file reader import java.util.zip.CRC32; // CRC32 IEEE (Ethernet) public class Main { /** * Reads a whole file into an array of bytes. * @param file The file in question. * @return Array of bytes containing file data. * @throws IOException Message contains why it failed. */ public static byte[] readFileArray(File file) throws IOException { InputStream is = new FileInputStream(file); byte[] data=new byte[(int)file.length()]; is.read(data); is.close(); return data; } /** * Writes (or overwrites if exists) a file with data from an array of bytes. * @param file The file in question. * @param data Array of bytes containing the new file data. * @throws IOException Message contains why it failed. */ public static void writeFileArray(File file, byte[] data) throws IOException { OutputStream os = new FileOutputStream(file,false); os.write(data); os.close(); } /** * Converts a long value to an array of bytes. * @param data The target variable. * @return Byte array conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static byte[] toByta(long data) { return new byte[] { (byte)((data >> 56) & 0xff), (byte)((data >> 48) & 0xff), (byte)((data >> 40) & 0xff), (byte)((data >> 32) & 0xff), (byte)((data >> 24) & 0xff), (byte)((data >> 16) & 0xff), (byte)((data >> 8) & 0xff), (byte)((data >> 0) & 0xff), }; } /** * Converts a an array of bytes to long value. * @param data The target variable. * @return Long value conversion of data. * @see http://www.daniweb.com/code/snippet216874.html */ public static long toLong(byte[] data) { if (data == null || data.length != 8) return 0x0; return (long)( // (Below) convert to longs before shift because digits // are lost with ints beyond the 32-bit limit (long)(0xff & data[0]) << 56 | (long)(0xff & data[1]) << 48 | (long)(0xff & data[2]) << 40 | (long)(0xff & data[3]) << 32 | (long)(0xff & data[4]) << 24 | (long)(0xff & data[5]) << 16 | (long)(0xff & data[6]) << 8 | (long)(0xff & data[7]) << 0 ); } public static byte[] nextNoise(){ byte[] result=new byte[100]; // copy a frame's worth of data (or remaining data if it is less than frame length) int read=Math.min(err_data.length-err_pstn, 100); System.arraycopy(err_data, err_pstn, result, 0, read); // if read data is less than frame length, reset position and add remaining data if(read<100){ err_pstn=100-read; System.arraycopy(err_data, 0, result, read, err_pstn); }else // otherwise, increase position err_pstn+=100; // return noise segment return result; } /** * Given some original data, it is purposefully corrupted according to a * second data array (which is read from a file). In pseudocode: * corrupt = original xor corruptor * @param data The original data. * @return The new (corrupted) data. */ public static byte[] corruptData(byte[] data){ // get the next noise sequence byte[] noise = nextNoise(); // finally, xor data with noise and return result for(int i=0; i<100; i++)data[i]^=noise[i]; return data; } /** * Given an array of data, a packet is created. In pseudocode: * frame = corrupt(data) + crc(data) * @param data The original frame data. * @return The resulting frame data. */ public static byte[] buildFrame(byte[] data){ // pack = [data]+crc32([data]) byte[] hash = new byte[8]; // calculate crc32 of data and copy it to byte array CRC32 crc = new CRC32(); crc.update(data); hash=toByta(crc.getValue()); // create a byte array holding the final packet byte[] pack = new byte[data.length+hash.length]; // create the corrupted data byte[] crpt = new byte[data.length]; crpt = corruptData(data); // copy corrupted data into pack System.arraycopy(crpt, 0, pack, 0, crpt.length); // copy hash into pack System.arraycopy(hash, 0, pack, data.length, hash.length); // return pack return pack; } /** * Verifies frame contents. * @param frame The frame data (data+crc32). * @return True if frame is valid, false otherwise. */ public static boolean verifyFrame(byte[] frame){ // allocate hash and data variables byte[] hash=new byte[8]; byte[] data=new byte[frame.length-hash.length]; // read frame into hash and data variables System.arraycopy(frame, frame.length-hash.length, hash, 0, hash.length); System.arraycopy(frame, 0, data, 0, frame.length-hash.length); // get crc32 of data CRC32 crc = new CRC32(); crc.update(data); // compare crc32 of data with crc32 of frame return crc.getValue()==toLong(hash); } /** * Transfers a file through a channel in frames and reconstructs it into a new file. * @param jpg_file File name of target file to transfer. * @param err_file The channel noise file used to simulate corruption. * @param out_file The name of the newly-created file. * @throws IOException */ public static void transferFile(String jpg_file, String err_file, String out_file) throws IOException { // read file data into global variables jpg_data = readFileArray(new File(jpg_file)); err_data = readFileArray(new File(err_file)); err_pstn = 0; // variable that will hold the final (transfered) data byte[] out_data = new byte[jpg_data.length]; // holds the current frame data byte[] frame_orig = new byte[100]; byte[] frame_sent = new byte[100]; // send file in chunks (frames) of 100 bytes for(int i=0; i<Math.ceil(jpg_data.length/100); i++){ // copy jpg data into frame and init first-time switch System.arraycopy(jpg_data, i*100, frame_orig, 0, 100); boolean not_first=false; System.out.print("Packet #"+i+": "); // repeat getting same frame until frame crc matches with frame content do { if(not_first)System.out.print("F"); frame_sent=buildFrame(frame_orig); not_first=true; }while(!verifyFrame(frame_sent)); // usually, you'd constrain this by time to prevent infinite loops (in // case the channel is so wacked up it doesn't get a single packet right) // copy frame to image file System.out.println("S"); System.arraycopy(frame_sent, 0, out_data, i*100, 100); } System.out.println("\nDone."); writeFileArray(new File(out_file),out_data); } // global variables for file data and pointer public static byte[] jpg_data; public static byte[] err_data; public static int err_pstn=0; public static void main(String[] args) throws IOException { // list of jpg files String[] jpg_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo1.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo2.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo3.jpg", "C:\\Users\\Stefan\\Desktop\\Data\\Images\\photo4.jpg" }; // list of error patterns String[] err_file={ "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 1.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 2.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 3.DAT", "C:\\Users\\Stefan\\Desktop\\Data\\Error Pattern\\Error Pattern 4.DAT" }; // loop through all jpg/channel combinations and run tests for(int x=0; x<jpg_file.length; x++){ for(int y=0; y<err_file.length; y++){ System.out.println("Transfering photo"+(x+1)+".jpg using Pattern "+(y+1)+"..."); transferFile(jpg_file[x],err_file[y],jpg_file[x].replace("photo","CH#"+y+"_photo")); } } } }

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Null reading in stream images? Unable to start activity ComponentInfo

- by lasmith

I have reviewed a lot of similar questions regarding not being able to launch an activity but they don't seem to quite match my problem. I am working on a simple black jack game but its force quitting. I suspect there is a problem with loading up the card png images I have. Stepping through the debugger it crashes right while in the resetGame() function. I'm sure I am doing something dumb. My Logcat: 10-15 20:21:43.309: E/AndroidRuntime(2863): FATAL EXCEPTION: main 10-15 20:21:43.309: E/AndroidRuntime(2863): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smith.blackjack/com.smith.blackjack.Main}: java.lang.NullPointerException 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.access$600(ActivityThread.java:130) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Handler.dispatchMessage(Handler.java:99) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.os.Looper.loop(Looper.java:137) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.main(ActivityThread.java:4745) 10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invokeNative(Native Method) 10-15 20:21:43.309: E/AndroidRuntime(2863): at java.lang.reflect.Method.invoke(Method.java:511) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-15 20:21:43.309: E/AndroidRuntime(2863): at dalvik.system.NativeStart.main(Native Method) 10-15 20:21:43.309: E/AndroidRuntime(2863): Caused by: java.lang.NullPointerException 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.DeckOfCards.<init>(DeckOfCards.java:17) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.Main.resetGame(Main.java:98) 10-15 20:21:43.309: E/AndroidRuntime(2863): at com.smith.blackjack.Main.onCreate(Main.java:67) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Activity.performCreate(Activity.java:5008) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 10-15 20:21:43.309: E/AndroidRuntime(2863): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 10-15 20:21:43.309: E/AndroidRuntime(2863): ... 11 more My androidmanifest: <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.smith.blackjack" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="11" android:targetSdkVersion="15" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".Main" android:label="@string/title_activity_main" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> Here is my Main.java package com.smith.blackjack; import android.os.Bundle; import android.app.Activity; import android.content.res.AssetManager; import android.graphics.drawable.Drawable; import java.io.IOException; import java.io.InputStream; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.ImageView; public class Main extends Activity { private ImageView dealerCard0; private ImageView dealerCard1; private ImageView dealerCard2; private ImageView dealerCard3; private ImageView playerCard0; private ImageView playerCard1; private ImageView playerCard2; private ImageView playerCard3; private ImageView imgResult; private Button btnDeal; private Button btnDraw; private Button btnHold; private DeckOfCards deckOfCards; private int[] dealerValues; private int dealerSum; private int dealerCardNumber; private int[] playerValues; private int playerSum; private int playerCardNumber; private InputStream dealerHiddenCard; private Card dealerCard; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); dealerCard0 = (ImageView) findViewById(R.id.dealerCard0); dealerCard1 = (ImageView) findViewById(R.id.dealerCard1); dealerCard2 = (ImageView) findViewById(R.id.dealerCard2); dealerCard3 = (ImageView) findViewById(R.id.dealerCard3); playerCard0 = (ImageView) findViewById(R.id.playerCard0); playerCard1 = (ImageView) findViewById(R.id.playerCard1); playerCard2 = (ImageView) findViewById(R.id.playerCard2); playerCard3 = (ImageView) findViewById(R.id.playerCard3); imgResult = (ImageView) findViewById(R.id.imgResult); btnDeal = (Button) findViewById(R.id.deal); btnDraw = (Button) findViewById(R.id.draw); btnHold = (Button) findViewById(R.id.hold); btnDeal.setOnClickListener(btnDealListener); btnDraw.setOnClickListener(btnDrawListener); btnHold.setOnClickListener(btnHoldListener); resetGame(); } private void resetGame(){ AssetManager assets = getAssets(); dealerValues = new int[4]; playerValues = new int[4]; dealerSum = 0; playerSum = 0; dealerCardNumber = 0; playerCardNumber = 0; for (int i = 0; i < 4; i++) { dealerValues[i] = 0; playerValues[i] = 0; } try { InputStream stream = assets.open("cardback.png"); // stream = assets.open("cardback.png"); Drawable cardImage = Drawable.createFromStream(stream, null); dealerCard0.setImageDrawable(cardImage); dealerCard1.setImageDrawable(cardImage); dealerCard2.setImageDrawable(cardImage); dealerCard3.setImageDrawable(cardImage); playerCard0.setImageDrawable(cardImage); playerCard1.setImageDrawable(cardImage); playerCard2.setImageDrawable(cardImage); playerCard3.setImageDrawable(cardImage); imgResult.setImageDrawable(cardImage); deckOfCards = new DeckOfCards(); deckOfCards.shuffle(); assets.close(); } catch (IOException e){ Log.e("Reset Game", "Error Loading", e); } } public OnClickListener btnDealListener = new OnClickListener() { // @Override public void onClick(View v) { try { AssetManager assets = getAssets(); InputStream stream; // first player card Card newCard; newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); Drawable cardImage = Drawable.createFromStream(stream, newCard.File); playerCard0.setImageDrawable(cardImage); assets.close(); // second player card newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); playerCard1.setImageDrawable(cardImage); assets.close(); // first dealer card hidden newCard = deckOfCards.dealCard(); dealerCard = newCard; dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; dealerHiddenCard = assets.open(newCard.File); stream = assets.open("cardback.png"); cardImage = Drawable.createFromStream(stream, "cardback"); dealerCard0.setImageDrawable(cardImage); assets.close(); // second dealer card open newCard = deckOfCards.dealCard(); dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); dealerCard1.setImageDrawable(cardImage); assets.close(); } catch (IOException e){ Log.e("Deal", "Error Loading", e); } }; }; public OnClickListener btnDrawListener = new OnClickListener() { // @Override public void onClick(View v) { try { AssetManager assets = getAssets(); InputStream stream; // get next player card Card newCard; newCard = deckOfCards.dealCard(); playerValues[playerCardNumber] = newCard.faceValue; playerCardNumber++; stream = assets.open(newCard.File); Drawable cardImage = Drawable.createFromStream(stream, newCard.File); switch (playerCardNumber){ case 3: playerCard2.setImageDrawable(cardImage); case 4: playerCard3.setImageDrawable(cardImage); } assets.close(); } catch (IOException e){ Log.e("Draw", "Error Loading", e); } }; }; public OnClickListener btnHoldListener = new OnClickListener() { // @Override public void onClick(View v) { Drawable cardImage; // evaluate player hand playerSum = evaluate(playerValues); if (playerSum > 21){ // player losses } // flip over the dealer hidden card cardImage = Drawable.createFromStream(dealerHiddenCard, dealerCard.File); Card newCard; InputStream stream; AssetManager assets = getAssets(); for (int i=2; i<4; i++){ dealerSum = evaluate(dealerValues); if (dealerSum < 16 ) { newCard = deckOfCards.dealCard(); dealerValues[dealerCardNumber] = newCard.faceValue; dealerCardNumber++; try { stream = assets.open(newCard.File); cardImage = Drawable.createFromStream(stream, newCard.File); switch (dealerCardNumber){ case 3: dealerCard2.setImageDrawable(cardImage); case 4: dealerCard3.setImageDrawable(cardImage); } assets.close(); } catch (IOException e){ Log.e("Draw", "Error Loading", e); } if (dealerSum < playerSum) { // player wins } if (dealerSum > playerSum){ // dealer wins } if (dealerSum == playerSum){ // it is a draw } } } }; }; public int evaluate (int[]values) { int sumCards = 0; for (int i = 0; i < 4; i++){ sumCards += values[i]; } if (sumCards > 21) { for (int i = 0; i < 4; i++){ if (values[i] == 11) { values[i] = 1; sumCards -= 10; continue; } } } return sumCards; } } My DeckOfCards class: package com.smith.blackjack; import java.util.Random; public class DeckOfCards { private Card [] deck; private int currentCard; private static final int NUMBER_OF_CARDS = 52; private static final Random randomNumbers = new Random(); public DeckOfCards () { deck = new Card[NUMBER_OF_CARDS]; currentCard = 0 ; for(int count = 0; count < deck.length; count++) { deck[count].faceValue = count + 1; } } public void shuffle () { currentCard = 0; for (int first = 0; first < deck.length; first ++){ int second = randomNumbers.nextInt(NUMBER_OF_CARDS); int temp = deck[first].faceValue; deck[first].faceValue=deck[second].faceValue; deck[second].faceValue = temp; } } public Card dealCard(){ Card temp = new Card(); temp.faceValue = 0; temp.File = ""; if(currentCard < deck.length) { temp.faceValue = deck[currentCard].faceValue / 4; int suit = deck[currentCard].faceValue % 4; String suitString = ""; switch (suit){ case 0: suitString = "c"; case 1: suitString = "d"; case 2: suitString = "h"; case 3: suitString = "s"; } Integer face = temp.faceValue / 4 ; String faceString = face.toString(); temp.File = faceString + suitString + ".png"; switch (temp.faceValue){ case 11: temp.faceValue = 10; case 12: temp.faceValue = 10; case 13: temp.faceValue = 10; } return temp; } else return temp; } }

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Optimise Apache for EC2 micro instance

- by Shiyu Sekam

I'm running apache2 on a EC2 micro instance with ~600 mb RAM. The instance was running for almost a year without problems, but in the last weeks it just keeps crashing, because the server reached MaxClients. The server basically runs few websites, one wordpress blog(not often used), company website(most used) and 2 small sites, which are just internal. The database for the blog runs on RDS, so there's no Mysql running on this web server. When I came to the company, the server already was setup and is running apache + mod_php + prefork. We want to migrate that in the future to a nginx + php-fpm, but it still needs further testing. So for now I have to stick with the old setup. I also use CloudFlare DDOS protection in front of the server, because it was attacked a couple of the times in the last weeks. My company don't want to pay money for a better web server at this point, so I have to stick with the micro instance also. Additionally the code for the website we run is really bad and slow and sometimes a single page load can take up to 15 seconds. The whole website is dynamic and written in PHP, so caching isn't really an option here. It's a customized search for users. I've already turned off KeepAlive, which improved the performance a little bit. My prefork config looks like the following: StartServers 2 MinSpareServers 2 MaxSpareServers 5 ServerLimit 10 MaxClients 10 MaxRequestsPerChild 100 The server just becomes unresponsive after a while running and I've run the following command to see how many connections there are: netstat | grep http | wc -l 75 Trying to restart apache helps for a short moment, but after that a while the apache process(es) become unresponsive again. I've the following modules enabled(output of apache2ctl -M) Loaded Modules: core_module (static) log_config_module (static) logio_module (static) version_module (static) mpm_prefork_module (static) http_module (static) so_module (static) alias_module (shared) authz_host_module (shared) deflate_module (shared) dir_module (shared) expires_module (shared) mime_module (shared) negotiation_module (shared) php5_module (shared) rewrite_module (shared) setenvif_module (shared) ssl_module (shared) status_module (shared) Syntax OK apache2.conf # Security ServerTokens OS ServerSignature On TraceEnable On ServerName "web.example.com" ServerRoot "/etc/apache2" PidFile ${APACHE_PID_FILE} Timeout 30 KeepAlive off User www-data Group www-data AccessFileName .htaccess <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> <Directory /> Options FollowSymLinks AllowOverride None </Directory> DefaultType none HostnameLookups Off ErrorLog /var/log/apache2/error.log LogLevel warn EnableSendfile On #Listen 80 Include /etc/apache2/mods-enabled/*.load Include /etc/apache2/mods-enabled/*.conf Include /etc/apache2/ports.conf LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent Include /etc/apache2/conf.d/*.conf Include /etc/apache2/sites-enabled/*.conf Vhost of main site <VirtualHost *:80> ServerName www.example.com ## Vhost docroot DocumentRoot /srv/www/jenkins/Web ## Directories, there should at least be a declaration for /srv/www/jenkins/Web <Directory /srv/www/jenkins/Web> AllowOverride All Order allow,deny Allow from all </Directory> ## Load additional static includes ## Logging ErrorLog /var/log/apache2/www.example.com.error.log LogLevel warn ServerSignature Off CustomLog /var/log/apache2/www.example.com.access.log combined ## Rewrite rules RewriteEngine On RewriteCond %{HTTP_HOST} !^www.example.com$ RewriteRule ^.*$ http://www.example.com%{REQUEST_URI} [R=301,L] ## Server aliases ServerAlias www.example.invalid ServerAlias example.com ## Custom fragment <Location /srv/www/jenkins/Web/library> Order Deny,Allow Deny from all </Location> <Files ~ "^\.(.+)"> Order deny,allow deny from all </Files> </VirtualHost>

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opengl problem works on droid but not droid eris and others.

- by nathan

This GlRenderer works fine on the moto droid, but does not work well at all on droid eris or other android phones does anyone know why? package com.ntu.way2fungames.spacehockeybase; import java.io.DataInputStream; import java.io.IOException; import java.nio.Buffer; import java.nio.FloatBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import com.ntu.way2fungames.LoadFloatArray; import com.ntu.way2fungames.OGLTriReader; import android.content.res.AssetManager; import android.content.res.Resources; import android.opengl.GLU; import android.opengl.GLSurfaceView.Renderer; import android.os.Handler; import android.os.Message; public class GlRenderer extends Thread implements Renderer { private float drawArray[]; private float yoff; private float yoff2; private long lastRenderTime; private float[] yoffs= new float[10]; int Width; int Height; private float[] pixelVerts = new float[] { +.0f,+.0f,2, +.5f,+.5f,0, +.5f,-.5f,0, +.0f,+.0f,2, +.5f,-.5f,0, -.5f,-.5f,0, +.0f,+.0f,2, -.5f,-.5f,0, -.5f,+.5f,0, +.0f,+.0f,2, -.5f,+.5f,0, +.5f,+.5f,0, }; @Override public void run() { } private float[] arenaWalls = new float[] { 8.00f,2.00f,1f,2f,2f,1f,2.00f,8.00f,1f,8.00f,2.00f,1f,2.00f,8.00f,1f,8.00f,8.00f,1f, 2.00f,8.00f,1f,2f,2f,1f,0.00f,0.00f,0f,2.00f,8.00f,1f,0.00f,0.00f,0f,0.00f,10.00f,0f, 8.00f,8.00f,1f,2.00f,8.00f,1f,0.00f,10.00f,0f,8.00f,8.00f,1f,0.00f,10.00f,0f,10.00f,10.00f,0f, 2f,2f,1f,8.00f,2.00f,1f,10.00f,0.00f,0f,2f,2f,1f,10.00f,0.00f,0f,0.00f,0.00f,0f, 8.00f,2.00f,1f,8.00f,8.00f,1f,10.00f,10.00f,0f,8.00f,2.00f,1f,10.00f,10.00f,0f,10.00f,0.00f,0f, 10.00f,10.00f,0f,0.00f,10.00f,0f,0.00f,0.00f,0f,10.00f,10.00f,0f,0.00f,0.00f,0f,10.00f,0.00f,0f, 8.00f,6.00f,1f,8.00f,4.00f,1f,122f,4.00f,1f,8.00f,6.00f,1f,122f,4.00f,1f,122f,6.00f,1f, 8.00f,6.00f,1f,122f,6.00f,1f,120f,7.00f,0f,8.00f,6.00f,1f,120f,7.00f,0f,10.00f,7.00f,0f, 122f,4.00f,1f,8.00f,4.00f,1f,10.00f,3.00f,0f,122f,4.00f,1f,10.00f,3.00f,0f,120f,3.00f,0f, 480f,10.00f,0f,470f,10.00f,0f,470f,0.00f,0f,480f,10.00f,0f,470f,0.00f,0f,480f,0.00f,0f, 478f,2.00f,1f,478f,8.00f,1f,480f,10.00f,0f,478f,2.00f,1f,480f,10.00f,0f,480f,0.00f,0f, 472f,2f,1f,478f,2.00f,1f,480f,0.00f,0f,472f,2f,1f,480f,0.00f,0f,470f,0.00f,0f, 478f,8.00f,1f,472f,8.00f,1f,470f,10.00f,0f,478f,8.00f,1f,470f,10.00f,0f,480f,10.00f,0f, 472f,8.00f,1f,472f,2f,1f,470f,0.00f,0f,472f,8.00f,1f,470f,0.00f,0f,470f,10.00f,0f, 478f,2.00f,1f,472f,2f,1f,472f,8.00f,1f,478f,2.00f,1f,472f,8.00f,1f,478f,8.00f,1f, 478f,846f,1f,472f,846f,1f,472f,852f,1f,478f,846f,1f,472f,852f,1f,478f,852f,1f, 472f,852f,1f,472f,846f,1f,470f,844f,0f,472f,852f,1f,470f,844f,0f,470f,854f,0f, 478f,852f,1f,472f,852f,1f,470f,854f,0f,478f,852f,1f,470f,854f,0f,480f,854f,0f, 472f,846f,1f,478f,846f,1f,480f,844f,0f,472f,846f,1f,480f,844f,0f,470f,844f,0f, 478f,846f,1f,478f,852f,1f,480f,854f,0f,478f,846f,1f,480f,854f,0f,480f,844f,0f, 480f,854f,0f,470f,854f,0f,470f,844f,0f,480f,854f,0f,470f,844f,0f,480f,844f,0f, 10.00f,854f,0f,0.00f,854f,0f,0.00f,844f,0f,10.00f,854f,0f,0.00f,844f,0f,10.00f,844f,0f, 8.00f,846f,1f,8.00f,852f,1f,10.00f,854f,0f,8.00f,846f,1f,10.00f,854f,0f,10.00f,844f,0f, 2f,846f,1f,8.00f,846f,1f,10.00f,844f,0f,2f,846f,1f,10.00f,844f,0f,0.00f,844f,0f, 8.00f,852f,1f,2.00f,852f,1f,0.00f,854f,0f,8.00f,852f,1f,0.00f,854f,0f,10.00f,854f,0f, 2.00f,852f,1f,2f,846f,1f,0.00f,844f,0f,2.00f,852f,1f,0.00f,844f,0f,0.00f,854f,0f, 8.00f,846f,1f,2f,846f,1f,2.00f,852f,1f,8.00f,846f,1f,2.00f,852f,1f,8.00f,852f,1f, 6f,846f,1f,4f,846f,1f,4f,8f,1f,6f,846f,1f,4f,8f,1f,6f,8f,1f, 6f,846f,1f,6f,8f,1f,7f,10f,0f,6f,846f,1f,7f,10f,0f,7f,844f,0f, 4f,8f,1f,4f,846f,1f,3f,844f,0f,4f,8f,1f,3f,844f,0f,3f,10f,0f, 474f,8f,1f,474f,846f,1f,473f,844f,0f,474f,8f,1f,473f,844f,0f,473f,10f,0f, 476f,846f,1f,476f,8f,1f,477f,10f,0f,476f,846f,1f,477f,10f,0f,477f,844f,0f, 476f,846f,1f,474f,846f,1f,474f,8f,1f,476f,846f,1f,474f,8f,1f,476f,8f,1f, 130f,10.00f,0f,120f,10.00f,0f,120f,0.00f,0f,130f,10.00f,0f,120f,0.00f,0f,130f,0.00f,0f, 128f,2.00f,1f,128f,8.00f,1f,130f,10.00f,0f,128f,2.00f,1f,130f,10.00f,0f,130f,0.00f,0f, 122f,2f,1f,128f,2.00f,1f,130f,0.00f,0f,122f,2f,1f,130f,0.00f,0f,120f,0.00f,0f, 128f,8.00f,1f,122f,8.00f,1f,120f,10.00f,0f,128f,8.00f,1f,120f,10.00f,0f,130f,10.00f,0f, 122f,8.00f,1f,122f,2f,1f,120f,0.00f,0f,122f,8.00f,1f,120f,0.00f,0f,120f,10.00f,0f, 128f,2.00f,1f,122f,2f,1f,122f,8.00f,1f,128f,2.00f,1f,122f,8.00f,1f,128f,8.00f,1f, 352f,8.00f,1f,358f,8.00f,1f,358f,2.00f,1f,352f,8.00f,1f,358f,2.00f,1f,352f,2.00f,1f, 358f,2.00f,1f,358f,8.00f,1f,360f,10.00f,0f,358f,2.00f,1f,360f,10.00f,0f,360f,0.00f,0f, 352f,2.00f,1f,358f,2.00f,1f,360f,0.00f,0f,352f,2.00f,1f,360f,0.00f,0f,350f,0.00f,0f, 358f,8.00f,1f,352f,8.00f,1f,350f,10.00f,0f,358f,8.00f,1f,350f,10.00f,0f,360f,10.00f,0f, 352f,8.00f,1f,352f,2.00f,1f,350f,0.00f,0f,352f,8.00f,1f,350f,0.00f,0f,350f,10.00f,0f, 350f,0.00f,0f,360f,0.00f,0f,360f,10.00f,0f,350f,0.00f,0f,360f,10.00f,0f,350f,10.00f,0f, 358f,6.00f,1f,472f,6.00f,1f,470f,7.00f,0f,358f,6.00f,1f,470f,7.00f,0f,360f,7.00f,0f, 472f,4.00f,1f,358f,4.00f,1f,360f,3.00f,0f,472f,4.00f,1f,360f,3.00f,0f,470f,3.00f,0f, 472f,4.00f,1f,472f,6.00f,1f,358f,6.00f,1f,472f,4.00f,1f,358f,6.00f,1f,358f,4.00f,1f, 472f,848f,1f,472f,850f,1f,358f,850f,1f,472f,848f,1f,358f,850f,1f,358f,848f,1f, 472f,848f,1f,358f,848f,1f,360f,847f,0f,472f,848f,1f,360f,847f,0f,470f,847f,0f, 358f,850f,1f,472f,850f,1f,470f,851f,0f,358f,850f,1f,470f,851f,0f,360f,851f,0f, 350f,844f,0f,360f,844f,0f,360f,854f,0f,350f,844f,0f,360f,854f,0f,350f,854f,0f, 352f,852f,1f,352f,846f,1f,350f,844f,0f,352f,852f,1f,350f,844f,0f,350f,854f,0f, 358f,852f,1f,352f,852f,1f,350f,854f,0f,358f,852f,1f,350f,854f,0f,360f,854f,0f, 352f,846f,1f,358f,846f,1f,360f,844f,0f,352f,846f,1f,360f,844f,0f,350f,844f,0f, 358f,846f,1f,358f,852f,1f,360f,854f,0f,358f,846f,1f,360f,854f,0f,360f,844f,0f, 352f,852f,1f,358f,852f,1f,358f,846f,1f,352f,852f,1f,358f,846f,1f,352f,846f,1f, 128f,846f,1f,122f,846f,1f,122f,852f,1f,128f,846f,1f,122f,852f,1f,128f,852f,1f, 122f,852f,1f,122f,846f,1f,120f,844f,0f,122f,852f,1f,120f,844f,0f,120f,854f,0f, 128f,852f,1f,122f,852f,1f,120f,854f,0f,128f,852f,1f,120f,854f,0f,130f,854f,0f, 122f,846f,1f,128f,846f,1f,130f,844f,0f,122f,846f,1f,130f,844f,0f,120f,844f,0f, 128f,846f,1f,128f,852f,1f,130f,854f,0f,128f,846f,1f,130f,854f,0f,130f,844f,0f, 130f,854f,0f,120f,854f,0f,120f,844f,0f,130f,854f,0f,120f,844f,0f,130f,844f,0f, 122f,848f,1f,8f,848f,1f,10f,847f,0f,122f,848f,1f,10f,847f,0f,120f,847f,0f, 8f,850f,1f,122f,850f,1f,120f,851f,0f,8f,850f,1f,120f,851f,0f,10f,851f,0f, 8f,850f,1f,8f,848f,1f,122f,848f,1f,8f,850f,1f,122f,848f,1f,122f,850f,1f, 10f,847f,0f,120f,847f,0f,124.96f,829.63f,-0.50f,10f,847f,0f,124.96f,829.63f,-0.50f,19.51f,829.63f,-0.50f, 130f,844f,0f,130f,854f,0f,134.55f,836.34f,-0.50f,130f,844f,0f,134.55f,836.34f,-0.50f,134.55f,826.76f,-0.50f, 350f,844f,0f,350f,854f,0f,345.45f,836.34f,-0.50f,350f,844f,0f,345.45f,836.34f,-0.50f,345.45f,826.76f,-0.50f, 360f,847f,0f,470f,847f,0f,460.49f,829.63f,-0.50f,360f,847f,0f,460.49f,829.63f,-0.50f,355.04f,829.63f,-0.50f, 470f,7.00f,0f,360f,7.00f,0f,355.04f,24.37f,-0.50f,470f,7.00f,0f,355.04f,24.37f,-0.50f,460.49f,24.37f,-0.50f, 350f,10.00f,0f,350f,0.00f,0f,345.45f,17.66f,-0.50f,350f,10.00f,0f,345.45f,17.66f,-0.50f,345.45f,27.24f,-0.50f, 130f,10.00f,0f,130f,0.00f,0f,134.55f,17.66f,-0.50f,130f,10.00f,0f,134.55f,17.66f,-0.50f,134.55f,27.24f,-0.50f, 473f,844f,0f,473f,10f,0f,463.36f,27.24f,-0.50f,473f,844f,0f,463.36f,27.24f,-0.50f,463.36f,826.76f,-0.50f, 7f,10f,0f,7f,844f,0f,16.64f,826.76f,-0.50f,7f,10f,0f,16.64f,826.76f,-0.50f,16.64f,27.24f,-0.50f, 120f,7.00f,0f,10.00f,7.00f,0f,19.51f,24.37f,-0.50f,120f,7.00f,0f,19.51f,24.37f,-0.50f,124.96f,24.37f,-0.50f, 120f,7.00f,0f,130f,10.00f,0f,134.55f,27.24f,-0.50f,120f,7.00f,0f,134.55f,27.24f,-0.50f,124.96f,24.37f,-0.50f, 10.00f,7.00f,0f,7f,10f,0f,16.64f,27.24f,-0.50f,10.00f,7.00f,0f,16.64f,27.24f,-0.50f,19.51f,24.37f,-0.50f, 350f,10.00f,0f,360f,7.00f,0f,355.04f,24.37f,-0.50f,350f,10.00f,0f,355.04f,24.37f,-0.50f,345.45f,27.24f,-0.50f, 473f,10f,0f,470f,7.00f,0f,460.49f,24.37f,-0.50f,473f,10f,0f,460.49f,24.37f,-0.50f,463.36f,27.24f,-0.50f, 473f,844f,0f,470f,847f,0f,460.49f,829.63f,-0.50f,473f,844f,0f,460.49f,829.63f,-0.50f,463.36f,826.76f,-0.50f, 360f,847f,0f,350f,844f,0f,345.45f,826.76f,-0.50f,360f,847f,0f,345.45f,826.76f,-0.50f,355.04f,829.63f,-0.50f, 130f,844f,0f,120f,847f,0f,124.96f,829.63f,-0.50f,130f,844f,0f,124.96f,829.63f,-0.50f,134.55f,826.76f,-0.50f, 7f,844f,0f,10f,847f,0f,19.51f,829.63f,-0.50f,7f,844f,0f,19.51f,829.63f,-0.50f,16.64f,826.76f,-0.50f, 19.51f,829.63f,-0.50f,124.96f,829.63f,-0.50f,136.47f,789.37f,-2f,19.51f,829.63f,-0.50f,136.47f,789.37f,-2f,41.56f,789.37f,-2f, 134.55f,826.76f,-0.50f,134.55f,836.34f,-0.50f,145.09f,795.41f,-2f,134.55f,826.76f,-0.50f,145.09f,795.41f,-2f,145.09f,786.78f,-2f, 345.45f,826.76f,-0.50f,345.45f,836.34f,-0.50f,334.91f,795.41f,-2f,345.45f,826.76f,-0.50f,334.91f,795.41f,-2f,334.91f,786.78f,-2f, 355.04f,829.63f,-0.50f,460.49f,829.63f,-0.50f,438.44f,789.37f,-2f,355.04f,829.63f,-0.50f,438.44f,789.37f,-2f,343.53f,789.37f,-2f, 460.49f,24.37f,-0.50f,355.04f,24.37f,-0.50f,343.53f,64.63f,-2f,460.49f,24.37f,-0.50f,343.53f,64.63f,-2f,438.44f,64.63f,-2f, 345.45f,27.24f,-0.50f,345.45f,17.66f,-0.50f,334.91f,58.59f,-2f,345.45f,27.24f,-0.50f,334.91f,58.59f,-2f,334.91f,67.22f,-2f, 134.55f,27.24f,-0.50f,134.55f,17.66f,-0.50f,145.09f,58.59f,-2f,134.55f,27.24f,-0.50f,145.09f,58.59f,-2f,145.09f,67.22f,-2f, 463.36f,826.76f,-0.50f,463.36f,27.24f,-0.50f,441.03f,67.22f,-2f,463.36f,826.76f,-0.50f,441.03f,67.22f,-2f,441.03f,786.78f,-2f, 16.64f,27.24f,-0.50f,16.64f,826.76f,-0.50f,38.97f,786.78f,-2f,16.64f,27.24f,-0.50f,38.97f,786.78f,-2f,38.97f,67.22f,-2f, 124.96f,24.37f,-0.50f,19.51f,24.37f,-0.50f,41.56f,64.63f,-2f,124.96f,24.37f,-0.50f,41.56f,64.63f,-2f,136.47f,64.63f,-2f, 124.96f,24.37f,-0.50f,134.55f,27.24f,-0.50f,145.09f,67.22f,-2f,124.96f,24.37f,-0.50f,145.09f,67.22f,-2f,136.47f,64.63f,-2f, 19.51f,24.37f,-0.50f,16.64f,27.24f,-0.50f,38.97f,67.22f,-2f,19.51f,24.37f,-0.50f,38.97f,67.22f,-2f,41.56f,64.63f,-2f, 345.45f,27.24f,-0.50f,355.04f,24.37f,-0.50f,343.53f,64.63f,-2f,345.45f,27.24f,-0.50f,343.53f,64.63f,-2f,334.91f,67.22f,-2f, 463.36f,27.24f,-0.50f,460.49f,24.37f,-0.50f,438.44f,64.63f,-2f,463.36f,27.24f,-0.50f,438.44f,64.63f,-2f,441.03f,67.22f,-2f, 463.36f,826.76f,-0.50f,460.49f,829.63f,-0.50f,438.44f,789.37f,-2f,463.36f,826.76f,-0.50f,438.44f,789.37f,-2f,441.03f,786.78f,-2f, 355.04f,829.63f,-0.50f,345.45f,826.76f,-0.50f,334.91f,786.78f,-2f,355.04f,829.63f,-0.50f,334.91f,786.78f,-2f,343.53f,789.37f,-2f, 134.55f,826.76f,-0.50f,124.96f,829.63f,-0.50f,136.47f,789.37f,-2f,134.55f,826.76f,-0.50f,136.47f,789.37f,-2f,145.09f,786.78f,-2f, 16.64f,826.76f,-0.50f,19.51f,829.63f,-0.50f,41.56f,789.37f,-2f,16.64f,826.76f,-0.50f,41.56f,789.37f,-2f,38.97f,786.78f,-2f, }; private float[] backgroundData = new float[] { // # ,Scale, Speed, 300 , 1.05f, .001f, 150 , 1.07f, .002f, 075 , 1.10f, .003f, 040 , 1.12f, .006f, 20 , 1.15f, .012f, 10 , 1.25f, .025f, 05 , 1.50f, .050f, 3 , 2.00f, .100f, 2 , 3.00f, .200f, }; private float[] triangleCoords = new float[] { 0, -25, 0, -.75f, -1, 0, +.75f, -1, 0, 0, +2, 0, -.99f, -1, 0, .99f, -1, 0, }; private float[] triangleColors = new float[] { 1.0f, 1.0f, 1.0f, 0.05f, 1.0f, 1.0f, 1.0f, 0.5f, 1.0f, 1.0f, 1.0f, 0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.5f, 1.0f, 1.0f, 1.0f, 0.5f, }; private float[] drawArray2; private FloatBuffer drawBuffer2; private float[] colorArray2; private static FloatBuffer colorBuffer; private static FloatBuffer triangleBuffer; private static FloatBuffer quadBuffer; private static FloatBuffer drawBuffer; private float[] backgroundVerts; private FloatBuffer backgroundVertsWrapped; private float[] backgroundColors; private Buffer backgroundColorsWraped; private FloatBuffer backgroundColorsWrapped; private FloatBuffer arenaWallsWrapped; private FloatBuffer arenaColorsWrapped; private FloatBuffer arena2VertsWrapped; private FloatBuffer arena2ColorsWrapped; private long wallHitStartTime; private int wallHitDrawTime; private FloatBuffer pixelVertsWrapped; private float[] wallHit; private FloatBuffer pixelColorsWrapped; //private float[] pitVerts; private Resources lResources; private FloatBuffer pitVertsWrapped; private FloatBuffer pitColorsWrapped; private boolean arena2; private long lastStartTime; private long startTime; private int state=1; private long introEndTime; protected long introTotalTime =8000; protected long introStartTime; private boolean initDone= false; private static int stateIntro = 0; private static int stateGame = 1; public GlRenderer(spacehockey nspacehockey) { lResources = nspacehockey.getResources(); nspacehockey.SetHandlerToGLRenderer(new Handler() { @Override public void handleMessage(Message m) { if (m.what ==0){ wallHit = m.getData().getFloatArray("wall hit"); wallHitStartTime =System.currentTimeMillis(); wallHitDrawTime = 1000; }else if (m.what ==1){ //state = stateIntro; introEndTime= System.currentTimeMillis()+introTotalTime ; introStartTime = System.currentTimeMillis(); } }}); } public void onSurfaceCreated(GL10 gl, EGLConfig config) { gl.glShadeModel(GL10.GL_SMOOTH); gl.glClearColor(.01f, .01f, .01f, .1f); gl.glClearDepthf(1.0f); gl.glEnable(GL10.GL_DEPTH_TEST); gl.glDepthFunc(GL10.GL_LEQUAL); gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); } private float SumOfStrideI(float[] data, int offset, int stride) { int sum= 0; for (int i=offset;i<data.length-1;i=i+stride){ sum = (int) (data[i]+sum); } return sum; } public void onDrawFrame(GL10 gl) { if (state== stateIntro){DrawIntro(gl);} if (state== stateGame){DrawGame(gl);} } private void DrawIntro(GL10 gl) { startTime = System.currentTimeMillis(); if (startTime< introEndTime){ float ptd = (float)(startTime- introStartTime)/(float)introTotalTime; float ptl = 1-ptd; gl.glClear(GL10.GL_COLOR_BUFFER_BIT);//dont move gl.glMatrixMode(GL10.GL_MODELVIEW); int setVertOff = 0; gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_COLOR_ARRAY); gl.glColorPointer(4, GL10.GL_FLOAT, 0, backgroundColorsWrapped); for (int i = 0; i < backgroundData.length / 3; i = i + 1) { int setoff = i * 3; int setVertLen = (int) backgroundData[setoff]; yoffs[i] = (backgroundData[setoff + 2]*(90+(ptl*250))) + yoffs[i]; if (yoffs[i] > Height) {yoffs[i] = 0;} gl.glPushMatrix(); //gl.glTranslatef(0, -(Height/2), 0); //gl.glScalef(1f, 1f+(ptl*2), 1f); //gl.glTranslatef(0, +(Height/2), 0); gl.glTranslatef(0, yoffs[i], i+60); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, backgroundVertsWrapped); gl.glDrawArrays(GL10.GL_TRIANGLES, (setVertOff * 2 * 3) - 0, (setVertLen * 2 * 3) - 1); gl.glTranslatef(0, -Height, 0); gl.glDrawArrays(GL10.GL_TRIANGLES, (setVertOff * 2 * 3) - 0, (setVertLen * 2 * 3) - 1); setVertOff = (int) (setVertOff + setVertLen); gl.glPopMatrix(); } gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_COLOR_ARRAY); }else{state = stateGame;} } private void DrawGame(GL10 gl) { lastStartTime = startTime; startTime = System.currentTimeMillis(); long moveTime = startTime-lastStartTime; gl.glClear(GL10.GL_COLOR_BUFFER_BIT);//dont move gl.glMatrixMode(GL10.GL_MODELVIEW); int setVertOff = 0; gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_COLOR_ARRAY); gl.glColorPointer(4, GL10.GL_FLOAT, 0, backgroundColorsWrapped); for (int i = 0; i < backgroundData.length / 3; i = i + 1) { int setoff = i * 3; int setVertLen = (int) backgroundData[setoff]; yoffs[i] = (backgroundData[setoff + 2]*moveTime) + yoffs[i]; if (yoffs[i] > Height) {yoffs[i] = 0;} gl.glPushMatrix(); gl.glTranslatef(0, yoffs[i], i+60); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, backgroundVertsWrapped); gl.glDrawArrays(GL10.GL_TRIANGLES, (setVertOff * 6) - 0, (setVertLen *6) - 1); gl.glTranslatef(0, -Height, 0); gl.glDrawArrays(GL10.GL_TRIANGLES, (setVertOff * 6) - 0, (setVertLen *6) - 1); setVertOff = (int) (setVertOff + setVertLen); gl.glPopMatrix(); } //arena frame gl.glPushMatrix(); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, arenaWallsWrapped); gl.glColorPointer(4, GL10.GL_FLOAT, 0, arenaColorsWrapped); gl.glColor4f(.1f, .5f, 1f, 1f); gl.glTranslatef(0, 0, 50); gl.glDrawArrays(GL10.GL_TRIANGLES, 0, (int)(arenaWalls.length / 3)); gl.glPopMatrix(); //arena2 frame if (arena2 == true){ gl.glLoadIdentity(); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, pitVertsWrapped); gl.glColorPointer(4, GL10.GL_FLOAT, 0, pitColorsWrapped); gl.glTranslatef(0, -Height, 40); gl.glDrawArrays(GL10.GL_TRIANGLES, 0, (int)(pitVertsWrapped.capacity() / 3)); } if (wallHitStartTime != 0) { float timeRemaining = (wallHitStartTime + wallHitDrawTime)-System.currentTimeMillis(); if (timeRemaining>0) { gl.glPushMatrix(); float percentDone = 1-(timeRemaining/wallHitDrawTime); gl.glLoadIdentity(); gl.glVertexPointer(3, GL10.GL_FLOAT, 0, pixelVertsWrapped); gl.glColorPointer(4, GL10.GL_FLOAT, 0, pixelColorsWrapped); gl.glTranslatef(wallHit[0], wallHit[1], 0); gl.glScalef(8, Height*percentDone, 0); gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 12); gl.glPopMatrix(); } else { wallHitStartTime = 0; } } gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_COLOR_ARRAY); } public void init(GL10 gl) { if (arena2 == true) { AssetManager assetManager = lResources.getAssets(); try { // byte[] ba = {111,111}; DataInputStream Dis = new DataInputStream(assetManager .open("arena2.ogl")); pitVertsWrapped = LoadFloatArray.FromDataInputStream(Dis); pitColorsWrapped = MakeFakeLighting(pitVertsWrapped.array(), .25f, .50f, 1f, 200, .5f); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if ((Height != 854) || (Width != 480)) { arenaWalls = ScaleFloats(arenaWalls, Width / 480f, Height / 854f); } arenaWallsWrapped = FloatBuffer.wrap(arenaWalls); arenaColorsWrapped = MakeFakeLighting(arenaWalls, .03f, .16f, .33f, .33f, 3); pixelVertsWrapped = FloatBuffer.wrap(pixelVerts); pixelColorsWrapped = MakeFakeLighting(pixelVerts, .03f, .16f, .33f, .10f, 20); initDone=true; } public void onSurfaceChanged(GL10 gl, int nwidth, int nheight) { Width= nwidth; Height = nheight; // avoid division by zero if (Height == 0) Height = 1; // draw on the entire screen gl.glViewport(0, 0, Width, Height); // setup projection matrix gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); gl.glOrthof(0, Width, Height, 0, 100, -100); // gl.glOrthof(-nwidth*2, nwidth*2, nheight*2,-nheight*2, 100, -100); // GLU.gluPerspective(gl, 180.0f, (float)nwidth / (float)nheight, // 1000.0f, -1000.0f); gl.glEnable(GL10.GL_BLEND); gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); System.gc(); if (initDone == false){ SetupStars(); init(gl); } } public void SetupStars(){ backgroundVerts = new float[(int) SumOfStrideI(backgroundData,0,3)*triangleCoords.length]; backgroundColors = new float[(int) SumOfStrideI(backgroundData,0,3)*triangleColors.length]; int iii=0; int vc=0; float ascale=1; for (int i=0;i<backgroundColors.length-1;i=i+1){ if (iii==0){ascale = (float) Math.random();} if (vc==3){ backgroundColors[i]= (float) (triangleColors[iii]*(ascale)); }else if(vc==2){ backgroundColors[i]= (float) (triangleColors[iii]-(Math.random()*.2)); }else{ backgroundColors[i]= (float) (triangleColors[iii]-(Math.random()*.3)); } iii=iii+1;if (iii> triangleColors.length-1){iii=0;} vc=vc+1; if (vc>3){vc=0;} } int ii=0; int i =0; int set =0; while(ii<backgroundVerts.length-1){ float scale = (float) backgroundData[(set*3)+1]; int length= (int) backgroundData[(set*3)]; for (i=0;i<length;i=i+1){ if (set ==0){ AddVertsToArray(ScaleFloats(triangleCoords, scale,scale*.25f), backgroundVerts, (float)(Math.random()*Width),(float) (Math.random()*Height), ii); }else{ AddVertsToArray(ScaleFloats(triangleCoords, scale), backgroundVerts, (float)(Math.random()*Width),(float) (Math.random()*Height), ii);} ii=ii+triangleCoords.length; } set=set+1; } backgroundVertsWrapped = FloatBuffer.wrap(backgroundVerts); backgroundColorsWrapped = FloatBuffer.wrap(backgroundColors); } public void AddVertsToArray(float[] sva,float[]dva,float ox,float oy,int start){ //x for (int i=0;i<sva.length;i=i+3){ if((start+i)<dva.length){dva[start+i]= sva[i]+ox;} } //y for (int i=1;i<sva.length;i=i+3){ if((start+i)<dva.length){dva[start+i]= sva[i]+oy;} } //z for (int i=2;i<sva.length;i=i+3){ if((start+i)<dva.length){dva[start+i]= sva[i];} } } public FloatBuffer MakeFakeLighting(float[] sa,float r, float g,float b,float a,float multby){ float[] da = new float[((sa.length/3)*4)]; int vertex=0; for (int i=0;i<sa.length;i=i+3){ if (sa[i+2]>=1){ da[(vertex*4)+0]= r*multby*sa[i+2]; da[(vertex*4)+1]= g*multby*sa[i+2]; da[(vertex*4)+2]= b*multby*sa[i+2]; da[(vertex*4)+3]= a*multby*sa[i+2]; }else if (sa[i+2]<=-1){ float divisor = (multby*(-sa[i+2])); da[(vertex*4)+0]= r / divisor; da[(vertex*4)+1]= g / divisor; da[(vertex*4)+2]= b / divisor; da[(vertex*4)+3]= a / divisor; }else{ da[(vertex*4)+0]= r; da[(vertex*4)+1]= g; da[(vertex*4)+2]= b; da[(vertex*4)+3]= a; } vertex = vertex+1; } return FloatBuffer.wrap(da); } public float[] ScaleFloats(float[] va,float s){ float[] reta= new float[va.length]; for (int i=0;i<va.length;i=i+1){ reta[i]=va[i]*s; } return reta; } public float[] ScaleFloats(float[] va,float sx,float sy){ float[] reta= new float[va.length]; int cnt = 0; for (int i=0;i<va.length;i=i+1){ if (cnt==0){reta[i]=va[i]*sx;} else if (cnt==1){reta[i]=va[i]*sy;} else if (cnt==2){reta[i]=va[i];} cnt = cnt +1;if (cnt>2){cnt=0;} } return reta; } }

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MAAS not working

- by Zimika

I'm trying a whole week to make MASS to work, but no results. This is the procedure: maas createsuperuser sudo apt-get install maas-dhcp maas-import-isos apt-get install maas-enlist tftpd-hpa maas-import-isos After this I start node machine with PXE as default first boot device, and select option maas-enlist. Sistem start to installing some things, and after that on MAAS WebUI stand 1 node. But when I click on Node button on WebUI or refresh page, it show 0 node. Command cobbler system list showing: root@maas-serv:~# cobbler system list default node-3ee116ea-a8b2-11e1-a735-50e549e38206 Also, sometime this procedure register one node, but when registering second one, same problem like I described up. root@maas-serv:/var/lib/tftpboot/pxelinux.cfg# is empty, only default is there. On command maas-import-isos there is a one warning. ftpboot/images/precise-x86_64-maas-ephemeral/initrd copying images generating GPXE/PXE configuration files generating PXE menu structure warning: kernel option length exceeds 255 warning: kernel option length exceeds 255 warning: kernel option length exceeds 255 warning: kernel option length exceeds 255 copying files for distro: precise-x86_64

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ASP.NET MVC Validation Complete

- by Ricardo Peres

OK, so let’s talk about validation. Most people are probably familiar with the out of the box validation attributes that MVC knows about, from the System.ComponentModel.DataAnnotations namespace, such as EnumDataTypeAttribute, RequiredAttribute, StringLengthAttribute, RangeAttribute, RegularExpressionAttribute and CompareAttribute from the System.Web.Mvc namespace. All of these validators inherit from ValidationAttribute and perform server as well as client-side validation. In order to use them, you must include the JavaScript files MicrosoftMvcValidation.js, jquery.validate.js or jquery.validate.unobtrusive.js, depending on whether you want to use Microsoft’s own library or jQuery. No significant difference exists, but jQuery is more extensible. You can also create your own attribute by inheriting from ValidationAttribute, but, if you want to have client-side behavior, you must also implement IClientValidatable (all of the out of the box validation attributes implement it) and supply your own JavaScript validation function that mimics its server-side counterpart. Of course, you must reference the JavaScript file where the declaration function is. Let’s see an example, validating even numbers. First, the validation attribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public class IsEvenAttribute : ValidationAttribute, IClientValidatable 4: { 5: protected override ValidationResult IsValid(Object value, ValidationContext validationContext) 6: { 7: Int32 v = Convert.ToInt32(value); 8: 9: if (v % 2 == 0) 10: { 11: return (ValidationResult.Success); 12: } 13: else 14: { 15: return (new ValidationResult("Value is not even")); 16: } 17: } 18: 19: #region IClientValidatable Members 20: 21: public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) 22: { 23: yield return (new ModelClientValidationRule() { ValidationType = "iseven", ErrorMessage = "Value is not even" }); 24: } 25: 26: #endregion 27: } The iseven validation function is declared like this in JavaScript, using jQuery validation: 1: jQuery.validator.addMethod('iseven', function (value, element, params) 2: { 3: return (true); 4: return ((parseInt(value) % 2) == 0); 5: }); 6: 7: jQuery.validator.unobtrusive.adapters.add('iseven', [], function (options) 8: { 9: options.rules['iseven'] = options.params; 10: options.messages['iseven'] = options.message; 11: }); Do keep in mind that this is a simple example, for example, we are not using parameters, which may be required for some more advanced scenarios. As a side note, if you implement a custom validator that also requires a JavaScript function, you’ll probably want them together. One way to achieve this is by including the JavaScript file as an embedded resource on the same assembly where the custom attribute is declared. You do this by having its Build Action set as Embedded Resource inside Visual Studio: Then you have to declare an attribute at assembly level, perhaps in the AssemblyInfo.cs file: 1: [assembly: WebResource("SomeNamespace.IsEven.js", "text/javascript")] In your views, if you want to include a JavaScript file from an embedded resource you can use this code: 1: public static class UrlExtensions 2: { 3: private static readonly MethodInfo getResourceUrlMethod = typeof(AssemblyResourceLoader).GetMethod("GetWebResourceUrlInternal", BindingFlags.NonPublic | BindingFlags.Static); 4: 5: public static IHtmlString Resource<TType>(this UrlHelper url, String resourceName) 6: { 7: return (Resource(url, typeof(TType).Assembly.FullName, resourceName)); 8: } 9: 10: public static IHtmlString Resource(this UrlHelper url, String assemblyName, String resourceName) 11: { 12: String resourceUrl = getResourceUrlMethod.Invoke(null, new Object[] { Assembly.Load(assemblyName), resourceName, false, false, null }).ToString(); 13: return (new HtmlString(resourceUrl)); 14: } 15: } And on the view: 1: <script src="<%: this.Url.Resource("SomeAssembly", "SomeNamespace.IsEven.js") %>" type="text/javascript"></script> Then there’s the CustomValidationAttribute. It allows externalizing your validation logic to another class, so you have to tell which type and method to use. The method can be static as well as instance, if it is instance, the class cannot be abstract and must have a public parameterless constructor. It can be applied to a property as well as a class. It does not, however, support client-side validation. Let’s see an example declaration: 1: [CustomValidation(typeof(ProductValidator), "OnValidateName")] 2: public String Name 3: { 4: get; 5: set; 6: } The validation method needs this signature: 1: public static ValidationResult OnValidateName(String name) 2: { 3: if ((String.IsNullOrWhiteSpace(name) == false) && (name.Length <= 50)) 4: { 5: return (ValidationResult.Success); 6: } 7: else 8: { 9: return (new ValidationResult(String.Format("The name has an invalid value: {0}", name), new String[] { "Name" })); 10: } 11: } Note that it can be either static or instance and it must return a ValidationResult-derived class. ValidationResult.Success is null, so any non-null value is considered a validation error. The single method argument must match the property type to which the attribute is attached to or the class, in case it is applied to a class: 1: [CustomValidation(typeof(ProductValidator), "OnValidateProduct")] 2: public class Product 3: { 4: } The signature must thus be: 1: public static ValidationResult OnValidateProduct(Product product) 2: { 3: } Continuing with attribute-based validation, another possibility is RemoteAttribute. This allows specifying a controller and an action method just for performing the validation of a property or set of properties. This works in a client-side AJAX way and it can be very useful. Let’s see an example, starting with the attribute declaration and proceeding to the action method implementation: 1: [Remote("Validate", "Validation")] 2: public String Username 3: { 4: get; 5: set; 6: } The controller action method must contain an argument that can be bound to the property: 1: public ActionResult Validate(String username) 2: { 3: return (this.Json(true, JsonRequestBehavior.AllowGet)); 4: } If in your result JSON object you include a string instead of the true value, it will consider it as an error, and the validation will fail. This string will be displayed as the error message, if you have included it in your view. You can also use the remote validation approach for validating your entire entity, by including all of its properties as included fields in the attribute and having an action method that receives an entity instead of a single property: 1: [Remote("Validate", "Validation", AdditionalFields = "Price")] 2: public String Name 3: { 4: get; 5: set; 6: } 7: 8: public Decimal Price 9: { 10: get; 11: set; 12: } The action method will then be: 1: public ActionResult Validate(Product product) 2: { 3: return (this.Json("Product is not valid", JsonRequestBehavior.AllowGet)); 4: } Only the property to which the attribute is applied and the additional properties referenced by the AdditionalFields will be populated in the entity instance received by the validation method. The same rule previously stated applies, if you return anything other than true, it will be used as the validation error message for the entity. The remote validation is triggered automatically, but you can also call it explicitly. In the next example, I am causing the full entity validation, see the call to serialize(): 1: function validate() 2: { 3: var form = $('form'); 4: var data = form.serialize(); 5: var url = '<%: this.Url.Action("Validation", "Validate") %>'; 6: 7: var result = $.ajax 8: ( 9: { 10: type: 'POST', 11: url: url, 12: data: data, 13: async: false 14: } 15: ).responseText; 16: 17: if (result) 18: { 19: //error 20: } 21: } Finally, by implementing IValidatableObject, you can implement your validation logic on the object itself, that is, you make it self-validatable. This will only work server-side, that is, the ModelState.IsValid property will be set to false on the controller’s action method if the validation in unsuccessful. Let’s see how to implement it: 1: public class Product : IValidatableObject 2: { 3: public String Name 4: { 5: get; 6: set; 7: } 8: 9: public Decimal Price 10: { 11: get; 12: set; 13: } 14: 15: #region IValidatableObject Members 16: 17: public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 18: { 19: if ((String.IsNullOrWhiteSpace(this.Name) == true) || (this.Name.Length > 50)) 20: { 21: yield return (new ValidationResult(String.Format("The name has an invalid value: {0}", this.Name), new String[] { "Name" })); 22: } 23: 24: if ((this.Price <= 0) || (this.Price > 100)) 25: { 26: yield return (new ValidationResult(String.Format("The price has an invalid value: {0}", this.Price), new String[] { "Price" })); 27: } 28: } 29: 30: #endregion 31: } The errors returned will be matched against the model properties through the MemberNames property of the ValidationResult class and will be displayed in their proper labels, if present on the view. On the controller action method you can check for model validity by looking at ModelState.IsValid and you can get actual error messages and related properties by examining all of the entries in the ModelState dictionary: 1: Dictionary<String, String> errors = new Dictionary<String, String>(); 2: 3: foreach (KeyValuePair<String, ModelState> keyValue in this.ModelState) 4: { 5: String key = keyValue.Key; 6: ModelState modelState = keyValue.Value; 7: 8: foreach (ModelError error in modelState.Errors) 9: { 10: errors[key] = error.ErrorMessage; 11: } 12: } And these are the ways to perform date validation in ASP.NET MVC. Don’t forget to use them!

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update-manager crashes Ubuntu 12.04

- by user205450

The update-manager crashes with the following error frank@darkstar2:~$ update-manager Traceback (most recent call last): File "/usr/bin/update-manager", line 33, in <module> from UpdateManager.UpdateManager import UpdateManager File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 72, in <module> from Core.MyCache import MyCache File "/usr/lib/python2.7/dist-packages/UpdateManager/Core/MyCache.py", line 34, in <module> import DistUpgrade.DistUpgradeCache File "/usr/lib/python2.7/dist-packages/DistUpgrade/DistUpgradeCache.py", line 60, in <module> KERNEL_INITRD_SIZE = _set_kernel_initrd_size() File "/usr/lib/python2.7/dist-packages/DistUpgrade/DistUpgradeCache.py", line 53, in _set_kernel_initrd_size size = estimate_kernel_size_in_boot() File "/usr/lib/python2.7/dist-packages/DistUpgrade/utils.py", line 74, in estimate_kernel_size_in_boot size += os.path.getsize(f) File "/usr/lib/python2.7/genericpath.py", line 49, in getsize return os.stat(filename).st_size OSError: [Errno 5] Input/output error: '/boot/abi-3.2.0-54-generic' I am not sure how to read the error but it seems there is some error in file size. How do I fix it.

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MVC Automatic Menu

- by Nuri Halperin

An ex-colleague of mine used to call his SQL script generator "Super-Scriptmatic 2000". It impressed our then boss little, but was fun to say and use. We called every batch job and script "something 2000" from that day on. I'm tempted to call this one Menu-Matic 2000, except it's waaaay past 2000. Oh well. The problem: I'm developing a bunch of stuff in MVC. There's no PM to generate mounds of requirements and there's no Ux Architect to create wireframe. During development, things change. Specifically, actions get renamed, moved from controller x to y etc. Well, as the site grows, it becomes a major pain to keep a static menu up to date, because the links change. The HtmlHelper doesn't live up to it's name and provides little help. How do I keep this growing list of pesky little forgotten actions reigned in? The general plan is: Decorate every action you want as a menu item with a custom attribute Reflect out all menu items into a structure at load time Render the menu using as CSS friendly <ul><li> HTML. The MvcMenuItemAttribute decorates an action, designating it to be included as a menu item: [AttributeUsage(AttributeTargets.Method, AllowMultiple = true)] public class MvcMenuItemAttribute : Attribute { public string MenuText { get; set; } public int Order { get; set; } public string ParentLink { get; set; } internal string Controller { get; set; } internal string Action { get; set; } #region ctor public MvcMenuItemAttribute(string menuText) : this(menuText, 0) { } public MvcMenuItemAttribute(string menuText, int order) { MenuText = menuText; Order = order; } internal string Link { get { return string.Format("/{0}/{1}", Controller, this.Action); } } internal MvcMenuItemAttribute ParentItem { get; set; } #endregion } The MenuText allows overriding the text displayed on the menu. The Order allows the items to be ordered. The ParentLink allows you to make this item a child of another menu item. An example action could then be decorated thusly: [MvcMenuItem("Tracks", Order = 20, ParentLink = "/Session/Index")] . All pretty straightforward methinks. The challenge with menu hierarchy becomes fairly apparent when you try to render a menu and highlight the "current" item or render a breadcrumb control. Both encounter an ambiguity if you allow a data source to have more than one menu item with the same URL link. The issue is that there is no great way to tell which link a person click. Using referring URL will fail if a user bookmarked the page. Using some extra query string to disambiguate duplicate URLs essentially changes the links, and also ads a chance of collision with other query parameters. Besides, that smells. The stock ASP.Net sitemap provider simply disallows duplicate URLS. I decided not to, and simply pick the first one encountered as the "current". Although it doesn't solve the issue completely – one might say they wanted the second of the 2 links to be "current"- it allows one to include a link twice (home->deals and products->deals etc), and the logic of deciding "current" is easy enough to explain to the customer. Now that we got that out of the way, let's build the menu data structure: public static List<MvcMenuItemAttribute> ListMenuItems(Assembly assembly) { var result = new List<MvcMenuItemAttribute>(); foreach (var type in assembly.GetTypes()) { if (!type.IsSubclassOf(typeof(Controller))) { continue; } foreach (var method in type.GetMethods()) { var items = method.GetCustomAttributes(typeof(MvcMenuItemAttribute), false) as MvcMenuItemAttribute[]; if (items == null) { continue; } foreach (var item in items) { if (String.IsNullOrEmpty(item.Controller)) { item.Controller = type.Name.Substring(0, type.Name.Length - "Controller".Length); } if (String.IsNullOrEmpty(item.Action)) { item.Action = method.Name; } result.Add(item); } } } return result.OrderBy(i => i.Order).ToList(); } Using reflection, the ListMenuItems method takes an assembly (you will hand it your MVC web assembly) and generates a list of menu items. It digs up all the types, and for each one that is an MVC Controller, digs up the methods. Methods decorated with the MvcMenuItemAttribute get plucked and added to the output list. Again, pretty simple. To make the structure hierarchical, a LINQ expression matches up all the items to their parent: public static void RegisterMenuItems(List<MvcMenuItemAttribute> items) { _MenuItems = items; _MenuItems.ForEach(i => i.ParentItem = items.FirstOrDefault(p => String.Equals(p.Link, i.ParentLink, StringComparison.InvariantCultureIgnoreCase))); } The _MenuItems is simply an internal list to keep things around for later rendering. Finally, to package the menu building for easy consumption: public static void RegisterMenuItems(Type mvcApplicationType) { RegisterMenuItems(ListMenuItems(Assembly.GetAssembly(mvcApplicationType))); } To bring this puppy home, a call in Global.asax.cs Application_Start() registers the menu. Notice the ugliness of reflection is tucked away from the innocent developer. All they have to do is call the RegisterMenuItems() and pass in the type of the application. When you use the new project template, global.asax declares a class public class MvcApplication : HttpApplication and that is why the Register call passes in that type. protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); MvcMenu.RegisterMenuItems(typeof(MvcApplication)); } What else is left to do? Oh, right, render! public static void ShowMenu(this TextWriter output) { var writer = new HtmlTextWriter(output); renderHierarchy(writer, _MenuItems, null); } public static void ShowBreadCrumb(this TextWriter output, Uri currentUri) { var writer = new HtmlTextWriter(output); string currentLink = "/" + currentUri.GetComponents(UriComponents.Path, UriFormat.Unescaped); var menuItem = _MenuItems.FirstOrDefault(m => m.Link.Equals(currentLink, StringComparison.CurrentCultureIgnoreCase)); if (menuItem != null) { renderBreadCrumb(writer, _MenuItems, menuItem); } } private static void renderBreadCrumb(HtmlTextWriter writer, List<MvcMenuItemAttribute> menuItems, MvcMenuItemAttribute current) { if (current == null) { return; } var parent = current.ParentItem; renderBreadCrumb(writer, menuItems, parent); writer.Write(current.MenuText); writer.Write(" / "); } static void renderHierarchy(HtmlTextWriter writer, List<MvcMenuItemAttribute> hierarchy, MvcMenuItemAttribute root) { if (!hierarchy.Any(i => i.ParentItem == root)) return; writer.RenderBeginTag(HtmlTextWriterTag.Ul); foreach (var current in hierarchy.Where(element => element.ParentItem == root).OrderBy(i => i.Order)) { if (ItemFilter == null || ItemFilter(current)) { writer.RenderBeginTag(HtmlTextWriterTag.Li); writer.AddAttribute(HtmlTextWriterAttribute.Href, current.Link); writer.AddAttribute(HtmlTextWriterAttribute.Alt, current.MenuText); writer.RenderBeginTag(HtmlTextWriterTag.A); writer.WriteEncodedText(current.MenuText); writer.RenderEndTag(); // link renderHierarchy(writer, hierarchy, current); writer.RenderEndTag(); // li } } writer.RenderEndTag(); // ul } The ShowMenu method renders the menu out to the provided TextWriter. In previous posts I've discussed my partiality to using well debugged, time test HtmlTextWriter to render HTML rather than writing out angled brackets by hand. In addition, writing out using the actual writer on the actual stream rather than generating string and byte intermediaries (yes, StringBuilder being no exception) disturbs me. To carry out the rendering of an hierarchical menu, the recursive renderHierarchy() is used. You may notice that an ItemFilter is called before rendering each item. I figured that at some point one might want to exclude certain items from the menu based on security role or context or something. That delegate is the hook for such future feature. To carry out rendering of a breadcrumb recursion is used again, this time simply to unwind the parent hierarchy from the leaf node, then rendering on the return from the recursion rather than as we go along deeper. I guess I was stuck in LISP that day.. recursion is fun though. Now all that is left is some usage! Open your Site.Master or wherever you'd like to place a menu or breadcrumb, and plant one of these calls: <% MvcMenu.ShowBreadCrumb(this.Writer, Request.Url); %> to show a breadcrumb trail (notice lack of "=" after <% and the semicolon). <% MvcMenu.ShowMenu(Writer); %> to show the menu. As mentioned before, the HTML output is nested <UL> <LI> tags, which should make it easy to style using abundant CSS to produce anything from static horizontal or vertical to dynamic drop-downs. This has been quite a fun little implementation and I was pleased that the code size remained low. The main crux was figuring out how to pass parent information from the attribute to the hierarchy builder because attributes have restricted parameter types. Once I settled on that implementation, the rest falls into place quite easily.

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Adding an Admin user to an ASP.NET MVC 4 application using a single drop-in file

- by Jon Galloway

I'm working on an ASP.NET MVC 4 tutorial and wanted to set it up so just dropping a file in App_Start would create a user named "Owner" and assign them to the "Administrator" role (more explanation at the end if you're interested). There are reasons why this wouldn't fit into most application scenarios: It's not efficient, as it checks for (and creates, if necessary) the user every time the app starts up The username, password, and role name are hardcoded in the app (although they could be pulled from config) Automatically creating an administrative account in code (without user interaction) could lead to obvious security issues if the user isn't informed However, with some modifications it might be more broadly useful - e.g. creating a test user with limited privileges, ensuring a required account isn't accidentally deleted, or - as in my case - setting up an account for demonstration or tutorial purposes. Challenge #1: Running on startup without requiring the user to install or configure anything I wanted to see if this could be done just by having the user drop a file into the App_Start folder and go. No copying code into Global.asax.cs, no installing addition NuGet packages, etc. That may not be the best approach - perhaps a NuGet package with a dependency on WebActivator would be better - but I wanted to see if this was possible and see if it offered the best experience. Fortunately ASP.NET 4 and later provide a PreApplicationStartMethod attribute which allows you to register a method which will run when the application starts up. You drop this attribute in your application and give it two parameters: a method name and the type that contains it. I created a static class named PreApplicationTasks with a static method named, then dropped this attribute in it: [assembly: PreApplicationStartMethod(typeof(PreApplicationTasks), "Initializer")] That's it. One small gotcha: the namespace can be a problem with assembly attributes. I decided my class didn't need a namespace. Challenge #2: Only one PreApplicationStartMethod per assembly In .NET 4, the PreApplicationStartMethod is marked as AllMultiple=false, so you can only have one PreApplicationStartMethod per assembly. This was fixed in .NET 4.5, as noted by Jon Skeet, so you can have as many PreApplicationStartMethods as you want (allowing you to keep your users waiting for the application to start indefinitely!). The WebActivator NuGet package solves the multiple instance problem if you're in .NET 4 - it registers as a PreApplicationStartMethod, then calls any methods you've indicated using [assembly: WebActivator.PreApplicationStartMethod(type, method)]. David Ebbo blogged about that here: Light up your NuGets with startup code and WebActivator. In my scenario (bootstrapping a beginner level tutorial) I decided not to worry about this and stick with PreApplicationStartMethod. Challenge #3: PreApplicationStartMethod kicks in before configuration has been read This is by design, as Phil explains. It allows you to make changes that need to happen very early in the pipeline, well before Application_Start. That's fine in some cases, but it caused me problems when trying to add users, since the Membership Provider configuration hadn't yet been read - I got an exception stating that "Default Membership Provider could not be found." The solution here is to run code that requires configuration in a PostApplicationStart method. But how to do that? Challenge #4: Getting PostApplicationStartMethod without requiring WebActivator The WebActivator NuGet package, among other things, provides a PostApplicationStartMethod attribute. That's generally how I'd recommend running code that needs to happen after Application_Start: [assembly: WebActivator.PostApplicationStartMethod(typeof(TestLibrary.MyStartupCode), "CallMeAfterAppStart")] This works well, but I wanted to see if this would be possible without WebActivator. Hmm. Well, wait a minute - WebActivator works in .NET 4, so clearly it's registering and calling PostApplicationStartup tasks somehow. Off to the source code! Sure enough, there's even a handy comment in ActivationManager.cs which shows where PostApplicationStartup tasks are being registered: public static void Run() { if (!_hasInited) { RunPreStartMethods(); // Register our module to handle any Post Start methods. But outside of ASP.NET, just run them now if (HostingEnvironment.IsHosted) { Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility.RegisterModule(typeof(StartMethodCallingModule)); } else { RunPostStartMethods(); } _hasInited = true; } } Excellent. Hey, that DynamicModuleUtility seems familiar... Sure enough, K. Scott Allen mentioned it on his blog last year. This is really slick - a PreApplicationStartMethod can register a new HttpModule in code. Modules are run right after application startup, so that's a perfect time to do any startup stuff that requires configuration to be read. As K. Scott says, it's this easy: using System; using System.Web; using Microsoft.Web.Infrastructure.DynamicModuleHelper; [assembly:PreApplicationStartMethod(typeof(MyAppStart), "Start")] public class CoolModule : IHttpModule { // implementation not important // imagine something cool here } public static class MyAppStart { public static void Start() { DynamicModuleUtility.RegisterModule(typeof(CoolModule)); } } Challenge #5: Cooperating with SimpleMembership The ASP.NET MVC Internet template includes SimpleMembership. SimpleMembership is a big improvement over traditional ASP.NET Membership. For one thing, rather than forcing a database schema, it can work with your database schema. In the MVC 4 Internet template case, it uses Entity Framework Code First to define the user model. SimpleMembership bootstrap includes a call to InitializeDatabaseConnection, and I want to play nice with that. There's a new [InitializeSimpleMembership] attribute on the AccountController, which calls \Filters\InitializeSimpleMembershipAttribute.cs::OnActionExecuting(). That comment in that method that says "Ensure ASP.NET Simple Membership is initialized only once per app start" which sounds like good advice. I figured the best thing would be to call that directly: new Mvc4SampleApplication.Filters.InitializeSimpleMembershipAttribute().OnActionExecuting(null); I'm not 100% happy with this - in fact, it's my least favorite part of this solution. There are two problems - first, directly calling a method on a filter, while legal, seems odd. Worse, though, the Filter lives in the application's namespace, which means that this code no longer works well as a generic drop-in. The simplest workaround would be to duplicate the relevant SimpleMembership initialization code into my startup code, but I'd rather not. I'm interested in your suggestions here. Challenge #6: Module Init methods are called more than once When debugging, I noticed (and remembered) that the Init method may be called more than once per page request - it's run once per instance in the app pool, and an individual page request can cause multiple resource requests to the server. While SimpleMembership does have internal checks to prevent duplicate user or role entries, I'd rather not cause or handle those exceptions. So here's the standard single-use lock in the Module's init method: void IHttpModule.Init(HttpApplication context) { lock (lockObject) { if (!initialized) { //Do stuff } initialized = true; } } Putting it all together With all of that out of the way, here's the code I came up with: using Mvc4SampleApplication.Filters; using System.Web; using System.Web.Security; using WebMatrix.WebData; [assembly: PreApplicationStartMethod(typeof(PreApplicationTasks), "Initializer")] public static class PreApplicationTasks { public static void Initializer() { Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleUtility .RegisterModule(typeof(UserInitializationModule)); } } public class UserInitializationModule : IHttpModule { private static bool initialized; private static object lockObject = new object(); private const string _username = "Owner"; private const string _password = "p@ssword123"; private const string _role = "Administrator"; void IHttpModule.Init(HttpApplication context) { lock (lockObject) { if (!initialized) { new InitializeSimpleMembershipAttribute().OnActionExecuting(null); if (!WebSecurity.UserExists(_username)) WebSecurity.CreateUserAndAccount(_username, _password); if (!Roles.RoleExists(_role)) Roles.CreateRole(_role); if (!Roles.IsUserInRole(_username, _role)) Roles.AddUserToRole(_username, _role); } initialized = true; } } void IHttpModule.Dispose() { } } The Verdict: Is this a good thing? Maybe. I think you'll agree that the journey was undoubtedly worthwhile, as it took us through some of the finer points of hooking into application startup, integrating with membership, and understanding why the WebActivator NuGet package is so useful Will I use this in the tutorial? I'm leaning towards no - I think a NuGet package with a dependency on WebActivator might work better: It's a little more clear what's going on Installing a NuGet package might be a little less error prone than copying a file A novice user could uninstall the package when complete It's a good introduction to NuGet, which is a good thing for beginners to see This code either requires either duplicating a little code from that filter or modifying the file to use the namespace Honestly I'm undecided at this point, but I'm glad that I can weigh the options. If you're interested: Why are you doing this? I'm updating the MVC Music Store tutorial to ASP.NET MVC 4, taking advantage of a lot of new ASP.NET MVC 4 features and trying to simplify areas that are giving people trouble. One change that addresses both needs us using the new OAuth support for membership as much as possible - it's a great new feature from an application perspective, and we get a fair amount of beginners struggling with setting up membership on a variety of database and development setups, which is a distraction from the focus of the tutorial - learning ASP.NET MVC. Side note: Thanks to some great help from Rick Anderson, we had a draft of the tutorial that was looking pretty good earlier this summer, but there were enough changes in ASP.NET MVC 4 all the way up to RTM that there's still some work to be done. It's high priority and should be out very soon. The one issue I ran into with OAuth is that we still need an Administrative user who can edit the store's inventory. I thought about a number of solutions for that - making the first user to register the admin, or the first user to use the username "Administrator" is assigned to the Administrator role - but they both ended up requiring extra code; also, I worried that people would use that code without understanding it or thinking about whether it was a good fit.

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A Simple Approach For Presenting With Code Samples

- by Jesse Taber

Originally posted on: http://geekswithblogs.net/GruffCode/archive/2013/07/31/a-simple-approach-for-presenting-with-code-samples.aspxI’ve been getting ready for a presentation and have been struggling a bit with the best way to show and execute code samples. I don’t present often (hardly ever), but when I do I like the presentation to have a lot of succinct and executable code snippets to help illustrate the points that I’m making. Depending on what the presentation is about, I might just want to build an entire sample application that I would run during the presentation. In other cases, however, building a full-blown application might not really be the best way to present the code. The presentation I’m working on now is for an open source utility library for dealing with dates and times. I could have probably cooked up a sample app for accepting date and time input and then contrived ways in which it could put the library through its paces, but I had trouble coming up with one app that would illustrate all of the various features of the library that I wanted to highlight. I finally decided that what I really needed was an approach that met the following criteria: Simple: I didn’t want the user interface or overall architecture of a sample application to serve as a distraction from the demonstration of the syntax of the library that the presentation is about. I want to be able to present small bits of code that are focused on accomplishing a single task. Several of these examples will look similar, and that’s OK. I want each sample to “stand on its own” and not rely much on external classes or methods (other than the library that is being presented, of course). “Debuggable” (not really a word, I know): I want to be able to easily run the sample with the debugger attached in Visual Studio should I want to step through any bits of code and show what certain values might be at run time. As far as I know this rules out something like LinqPad, though using LinqPad to present code samples like this is actually a very interesting idea that I might explore another time. Flexible and Selectable: I’m going to have lots of code samples to show, and I want to be able to just package them all up into a single project or module and have an easy way to just run the sample that I want on-demand. Since I’m presenting on a .NET framework library, one of the simplest ways in which I could execute some code samples would be to just create a Console application and use Console.WriteLine to output the pertinent info at run time. This gives me a “no frills” harness from which to run my code samples, and I just hit ‘F5’ to run it with the debugger. This satisfies numbers 1 and 2 from my list of criteria above, but item 3 is a little harder. By default, just running a console application is going to execute the ‘main’ method, and then terminate the program after all code is executed. If I want to have several different code samples and run them one at a time, it would be cumbersome to keep swapping the code I want in and out of the ‘main’ method of the console application. What I really want is an easy way to keep the console app running throughout the whole presentation and just have it run the samples I want when I want. I could setup a simple Windows Forms or WPF desktop application with buttons for the different samples, but then I’m getting away from my first criteria of keeping things as simple as possible. Infinite Loops To The Rescue I found a way to have a simple console application satisfy all three of my requirements above, and it involves using an infinite loop and some Console.ReadLine calls that will give the user an opportunity to break out and exit the program. (All programs that need to run until they are closed explicitly (or crash!) likely use similar constructs behind the scenes. Create a new Windows Forms project, look in the ‘Program.cs’ that gets generated, and then check out the docs for the Application.Run method that it calls.). Here’s how the main method might look: 1: static void Main(string[] args) 2: { 3: do 4: { 5: Console.Write("Enter command or 'exit' to quit: > "); 6: var command = Console.ReadLine(); 7: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 8: { 9: Console.WriteLine("Quitting."); 10: break; 11: } 12: 13: } while (true); 14: } The idea here is the app prompts me for the command I want to run, or I can type in ‘exit’ to break out of the loop and let the application close. The only trick now is to create a set of commands that map to each of the code samples that I’m going to want to run. Each sample is already encapsulated in a single public method in a separate class, so I could just write a big switch statement or create a hashtable/dictionary that maps command text to an Action that will invoke the proper method, but why re-invent the wheel? CLAP For Your Own Presentation I’ve blogged about the CLAP library before, and it turns out that it’s a great fit for satisfying criteria #3 from my list above. CLAP lets you decorate methods in a class with an attribute and then easily invoke those methods from within a console application. CLAP was designed to take the arguments passed into the console app from the command line and parse them to determine which method to run and what arguments to pass to that method, but there’s no reason you can’t re-purpose it to accept command input from within the infinite loop defined above and invoke the corresponding method. Here’s how you might define a couple of different methods to contain two different code samples that you want to run during your presentation: 1: public static class CodeSamples 2: { 3: [Verb(Aliases="one")] 4: public static void SampleOne() 5: { 6: Console.WriteLine("This is sample 1"); 7: } 8: 9: [Verb(Aliases="two")] 10: public static void SampleTwo() 11: { 12: Console.WriteLine("This is sample 2"); 13: } 14: } A couple of things to note about the sample above: I’m using static methods. You don’t actually need to use static methods with CLAP, but the syntax ends up being a bit simpler and static methods happen to lend themselves well to the “one self-contained method per code sample” approach that I want to use. The methods are decorated with a ‘Verb’ attribute. This tells CLAP that they are eligible targets for commands. The “Aliases” argument lets me give them short and easy-to-remember aliases that can be used to invoke them. By default, CLAP just uses the full method name as the command name, but with aliases you can simply the usage a bit. I’m not using any parameters. CLAP’s main feature is its ability to parse out arguments from a command line invocation of a console application and automatically pass them in as parameters to the target methods. My code samples don’t need parameters ,and honestly having them would complicate giving the presentation, so this is a good thing. You could use this same approach to invoke methods with parameters, but you’d have a couple of things to figure out. When you invoke a .NET application from the command line, Windows will parse the arguments and pass them in as a string array (called ‘args’ in the boilerplate console project Program.cs). The parsing that gets done here is smart enough to deal with things like treating strings in double quotes as one argument, and you’d have to re-create that within your infinite loop if you wanted to use parameters. I plan on either submitting a pull request to CLAP to add this capability or maybe just making a small utility class/extension method to do it and posting that here in the future. So I now have a simple class with static methods to contain my code samples, and an infinite loop in my ‘main’ method that can accept text commands. Wiring this all up together is pretty easy: 1: static void Main(string[] args) 2: { 3: do 4: { 5: try 6: { 7: Console.Write("Enter command or 'exit' to quit: > "); 8: var command = Console.ReadLine(); 9: if ((command ?? string.Empty).Equals("exit", StringComparison.OrdinalIgnoreCase)) 10: { 11: Console.WriteLine("Quitting."); 12: break; 13: } 14: 15: Parser.Run<CodeSamples>(new[] { command }); 16: Console.WriteLine("---------------------------------------------------------"); 17: } 18: catch (Exception ex) 19: { 20: Console.Error.WriteLine("Error: " + ex.Message); 21: } 22: 23: } while (true); 24: } Note that I’m now passing the ‘CodeSamples’ class into the CLAP ‘Parser.Run’ as a type argument. This tells CLAP to inspect that class for methods that might be able to handle the commands passed in. I’m also throwing in a little “----“ style line separator and some basic error handling (because I happen to know that some of the samples are going to throw exceptions for demonstration purposes) and I’m good to go. Now during my presentation I can just have the console application running the whole time with the debugger attached and just type in the alias of the code sample method that I want to run when I want to run it.

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JMS Step 2 - Using the QueueSend.java Sample Program to Send a Message to a JMS Queue

- by John-Brown.Evans

JMS Step 2 - Using the QueueSend.java Sample Program to Send a Message to a JMS Queue .c21_2{vertical-align:top;width:487.3pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c15_2{vertical-align:top;width:487.3pt;border-style:solid;border-color:#ffffff;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c0_2{padding-left:0pt;direction:ltr;margin-left:36pt} .c20_2{list-style-type:circle;margin:0;padding:0} .c10_2{list-style-type:disc;margin:0;padding:0} .c6_2{background-color:#ffffff} .c17_2{padding-left:0pt;margin-left:72pt} .c3_2{line-height:1.0;direction:ltr} .c1_2{font-size:10pt;font-family:"Courier New"} .c16_2{color:#1155cc;text-decoration:underline} .c13_2{color:inherit;text-decoration:inherit} .c7_2{background-color:#ffff00} .c9_2{border-collapse:collapse} .c2_2{font-family:"Courier New"} .c18_2{font-size:18pt} .c5_2{font-weight:bold} .c19_2{color:#ff0000} .c12_2{background-color:#f3f3f3;border-style:solid;border-color:#000000;border-width:1pt;} .c14_2{font-size:24pt} .c8_2{direction:ltr;background-color:#ffffff} .c11_2{font-style:italic} .c4_2{height:11pt} .title{padding-top:24pt;line-height:1.15;text-align:left;color:#000000;font-size:36pt;font-family:"Arial";font-weight:bold;padding-bottom:6pt}.subtitle{padding-top:18pt;line-height:1.15;text-align:left;color:#666666;font-style:italic;font-size:24pt;font-family:"Georgia";padding-bottom:4pt} li{color:#000000;font-size:10pt;font-family:"Arial"} p{color:#000000;font-size:10pt;margin:0;font-family:"Arial"} h1{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:24pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h2{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:18pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h3{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:14pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h4{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:12pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h5{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:11pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} h6{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:10pt;font-family:"Arial";font-weight:normal;padding-bottom:0pt} This post is the second in a series of JMS articles which demonstrate how to use JMS queues in a SOA context. In the previous post JMS Step 1 - How to Create a Simple JMS Queue in Weblogic Server 11g I showed you how to create a JMS queue and its dependent objects in WebLogic Server. In this article, we will use a sample program to write a message to that queue. Please review the previous post if you have not created those objects yet, as they will be required later in this example. The previous post also includes useful background information and links to the Oracle documentation for addional research. The following post in this series will show how to read the message from the queue again. 1. Source code The following java code will be used to write a message to the JMS queue. It is based on a sample program provided with the WebLogic Server installation. The sample is not installed by default, but needs to be installed manually using the WebLogic Server Custom Installation option, together with many, other useful samples. You can either copy-paste the following code into your editor, or install all the samples. The knowledge base article in My Oracle Support: How To Install WebLogic Server and JMS Samples in WLS 10.3.x (Doc ID 1499719.1) describes how to install the samples. QueueSend.java package examples.jms.queue; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Hashtable; import javax.jms.*; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; /** This example shows how to establish a connection * and send messages to the JMS queue. The classes in this * package operate on the same JMS queue. Run the classes together to * witness messages being sent and received, and to browse the queue * for messages. The class is used to send messages to the queue. * * @author Copyright (c) 1999-2005 by BEA Systems, Inc. All Rights Reserved. */ public class QueueSend { // Defines the JNDI context factory. public final static String JNDI_FACTORY="weblogic.jndi.WLInitialContextFactory"; // Defines the JMS context factory. public final static String JMS_FACTORY="jms/TestConnectionFactory"; // Defines the queue. public final static String QUEUE="jms/TestJMSQueue"; private QueueConnectionFactory qconFactory; private QueueConnection qcon; private QueueSession qsession; private QueueSender qsender; private Queue queue; private TextMessage msg; /** * Creates all the necessary objects for sending * messages to a JMS queue. * * @param ctx JNDI initial context * @param queueName name of queue * @exception NamingException if operation cannot be performed * @exception JMSException if JMS fails to initialize due to internal error */ public void init(Context ctx, String queueName) throws NamingException, JMSException { qconFactory = (QueueConnectionFactory) ctx.lookup(JMS_FACTORY); qcon = qconFactory.createQueueConnection(); qsession = qcon.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); queue = (Queue) ctx.lookup(queueName); qsender = qsession.createSender(queue); msg = qsession.createTextMessage(); qcon.start(); } /** * Sends a message to a JMS queue. * * @param message message to be sent * @exception JMSException if JMS fails to send message due to internal error */ public void send(String message) throws JMSException { msg.setText(message); qsender.send(msg); } /** * Closes JMS objects. * @exception JMSException if JMS fails to close objects due to internal error */ public void close() throws JMSException { qsender.close(); qsession.close(); qcon.close(); } /** main() method. * * @param args WebLogic Server URL * @exception Exception if operation fails */ public static void main(String[] args) throws Exception { if (args.length != 1) { System.out.println("Usage: java examples.jms.queue.QueueSend WebLogicURL"); return; } InitialContext ic = getInitialContext(args[0]); QueueSend qs = new QueueSend(); qs.init(ic, QUEUE); readAndSend(qs); qs.close(); } private static void readAndSend(QueueSend qs) throws IOException, JMSException { BufferedReader msgStream = new BufferedReader(new InputStreamReader(System.in)); String line=null; boolean quitNow = false; do { System.out.print("Enter message (\"quit\" to quit): \n"); line = msgStream.readLine(); if (line != null && line.trim().length() != 0) { qs.send(line); System.out.println("JMS Message Sent: "+line+"\n"); quitNow = line.equalsIgnoreCase("quit"); } } while (! quitNow); } private static InitialContext getInitialContext(String url) throws NamingException { Hashtable env = new Hashtable(); env.put(Context.INITIAL_CONTEXT_FACTORY, JNDI_FACTORY); env.put(Context.PROVIDER_URL, url); return new InitialContext(env); } } 2. How to Use This Class 2.1 From the file system on UNIX/Linux Log in to a machine with a WebLogic installation and create a directory to contain the source and code matching the package name, e.g. $HOME/examples/jms/queue. Copy the above QueueSend.java file to this directory. Set the CLASSPATH and environment to match the WebLogic server environment. Go to $MIDDLEWARE_HOME/user_projects/domains/base_domain/bin and execute . ./setDomainEnv.sh Collect the following information required to run the script: The JNDI name of a JMS queue to use In the Weblogic server console > Services > Messaging > JMS Modules > (Module name, e.g. TestJMSModule) > (JMS queue name, e.g. TestJMSQueue)Select the queue and note its JNDI name, e.g. jms/TestJMSQueue The JNDI name of a connection factory to connect to the queue Follow the same path as above to get the connection factory for the above queue, e.g. TestConnectionFactory and its JNDI namee.g. jms/TestConnectionFactory The URL and port of the WebLogic server running the above queue Check the JMS server for the above queue and the managed server it is targeted to, for example soa_server1. Now find the port this managed server is listening on, by looking at its entry under Environment > Servers in the WLS console, e.g. 8001 The URL for the server to be given to the QueueSend program in this example will therefore be t3://host.domain:8001 e.g. t3://jbevans-lx.de.oracle.com:8001 Edit QueueSend.java and enter the above queue name and connection factory respectively under ...public final static String JMS_FACTORY=" jms/TestConnectionFactory "; ... public final static String QUEUE=" jms/TestJMSQueue "; ... Compile QueueSend.java using javac QueueSend.java Go to the source’s top-level directory and execute it using java examples.jms.queue.QueueSend t3://jbevans-lx.de.oracle.com:8001 This will prompt for a text input or “quit” to end. In the WLS console, go to the queue and select Monitoring to confirm that a new message was written to the queue. 2.2 From JDeveloper Create a new application in JDeveloper, called, for example JMSTests. When prompted for a project name, enter QueueSend and select Java as the technology Default Package = examples.jms.queue (but you can enter anything here as you will overwrite it in the code later). Leave the other values at their defaults. Press Finish Create a new Java class called QueueSend and use the default values This will create a file called QueueSend.java. Open QueueSend.java, if it is not already open and replace all its contents with the QueueSend java code listed above Some lines might have warnings due to unfound objects. These are due to missing libraries in the JDeveloper project. Add the following libraries to the JDeveloper project: right-click the QueueSend project in the navigation menu and select Libraries and Classpath , then Add JAR/Directory Go to the folder containing the JDeveloper installation and find/choose the file javax.jms_1.1.1.jar , e.g. at D:\oracle\jdev11116\modules\javax.jms_1.1.1.jar Do the same for the weblogic.jar file located, for example in D:\oracle\jdev11116\wlserver_10.3\server\lib\weblogic.jar Now you should be able to compile the project, for example by selecting the Make or Rebuild icons If you try to execute the project, you will get a usage message, as it requires a parameter pointing to the WLS installation containing the JMS queue, for example t3://jbevans-lx.de.oracle.com:8001 . You can automatically pass this parameter to the program from JDeveloper by editing the project’s Run/Debug/Profile. Select the project properties, select Run/Debug/Profile and edit the Default run configuration and add the connection parameter to the Program Arguments field If you execute it again, you will see that it has passed the parameter to the start command If you get a ClassNotFoundException for the class weblogic.jndi.WLInitialContextFactory , then check that the weblogic.jar file was correctly added to the project in one of the earlier steps above. Set the values of JMS_FACTORY and QUEUE the same way as described above in the description of how to use this from a Linux file system, i.e. ...public final static String JMS_FACTORY=" jms/TestConnectionFactory "; ... public final static String QUEUE=" jms/TestJMSQueue "; ... You need to make one more change to the project. If you execute it now, it will prompt for the payload for the JMS message, but you won’t be able to enter it by default in JDeveloper. You need to enable program input for the project first. Select the project’s properties, then Tool Settings, then check the Allow Program Input checkbox at the bottom and Save. Now when you execute the project, you will get a text entry field at the bottom into which you can enter the payload. You can enter multiple messages until you enter “quit”, which will cause the program to stop. The following screen shot shows the TestJMSQueue’s Monitoring page, after a message was sent to the queue: This concludes the sample. In the following post I will show you how to read the message from the queue again.

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Responsible BI for Excel, Even for Older Versions

- by andrewbrust

On Wednesday, I will have the honor of co-presenting, for both The Data Warehouse Institute (TDWI) and the New York Technology Council. on the subject of Excel and BI. My co-presenter will be none other than Bill Baker, who was a Microsoft Distinguished Engineer and, essentially, the father of BI at that company. Details on the events are here and here. We'll be talking about PowerPivot, of course, but that's not all. Probably even more important than any one product, will be our discussion of whether the usual characterization of Excel as the nemesis of IT, the guilty pleasure of business users and the antithesis of formal BI is really valid and/or hopelessly intractable. Without giving away our punchline, I'll tell you that we are much more optimistic than that. There are huge upsides to Excel and while there are real dangers to using it in the BI space, there are standards and practices you can employ to ensure Excel is used responsibly. And when those practices are followed, Excel becomes quite powerful indeed. One of the keys to this is using Excel as a data consumer rather than data storage mechanism. Caching data in Excel is OK, but only if that data is (a) not modified and (b) configured for automated periodic refresh. PowerPivot meets both criteria -- it stores a read-only copy of your data in the form of a model, and once workbook containing a PowerPivot model is published to SharePoint, it can be configured for scheduled data refresh, on the server, requiring no user intervention whatsoever. Data refresh is a bit like hard drive backup: it will only happen reliably if it's automated, and super-easy to configure. PowerPivot hits a real home run here (as does Windows Home Server for PC backup, but I digress). The thing about PowerPivot is that it's an add-in for Excel 2010. What if you're not planning to go to that new version for quite a while? What if you’ve just deployed Office 2007 in your organization? What if you're still on Office 2003, or an even earlier version? What can you do immediately to share data responsibly and easily? As it turns out, there's a feature in Excel that's been around for quite a while, that can help: Web Queries. The Web Query feature was introduced, ostensibly, to allow Excel to pull data in from Internet Web pages…for example, data in a stock quote history table will come in nicely, as will any data in a Web page that is displayed in an HTML table. To use the feature In Excel 2007 or 2010, click the Data Tab or the ribbon and click the “From Web” button towards the left; in older versions use the corresponding option in the menu or toolbars. Next, paste a URL into the resulting dialog box and tap Enter or click the Go button. A preview of the Web page will come up, and the dialog will allow you to select the specific table within the page whose data you’d like to import. Here’s an example: Now just click the table, click the Import button, and the Import Data dialog appears. You can simply click OK to bring in your data or you can first click the Properties… button and configure the data import to be refreshed at an interval in minutes that you select. Now your data’s in the spreadsheet and ready to worked with: Your data may be vulnerable to modification, but if you’ve set up the data refresh, any accidental or malicious changes will be corrected in time anyway. The thing about this feature is that it’s most useful not for public Web pages, but for pages behind the firewall. In effect, the Web Query feature provides an incredibly easy way to consume data in Excel that’s “published” from an application. Users just need a URL. They don’t need to know server and database names and since the data is read-only, providing credentials may be unnecessary, or can be handled using integrated security. If that’s not good enough, the Web Query can be saved to a special .iqy file, which can be edited to provide POST parameter data. The only requirement is that the data must be provided in an HTML table, with the first row providing the column names. From an ASP.NET project, it couldn’t be easier: a simple bound GridView control is totally compatible. Use a data source control with it, and you don’t even have to write any code. Users can link to pages that are part of an application’s UI, or developers can create pages that are specially designed for the purpose of providing an interface to the Web Query import feature. And none of this is Microsoft- or .NET-specific. You can create pages in any language you want (PHP comes to mind) that output the result set of a query in HTML table format, and then consume that data in a Web Query. Then build PivotTables and charts on the data, and in Excel 2007 or 2010 you can use conditional formatting to create scorecards and dashboards. This strategy allows you to create pages that function quite similarly to the OData XML feeds rendered when .NET developers create an “Astoria” WCF Data Service. And while it’s cool that PowerPivot and Excel 2010 can import such OData feeds, it’s good to know that older versions of Excel can function in a similar fashion, and can consume data produced by virtually any Web development platform. As a final matter, instead of just telling you that “older versions” of Excel support this feature, I’ll be more specific. To discover what the first version of Excel was to support Web queries, go to http://bit.ly/OldSchoolXL.

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Problem with Python3 picking Python2 package

- by zetah

I installed python3-numpy package, but trying to import it in Python3 interpreter I get this: $ python3 Python 3.2.3 (default, May 3 2012, 15:54:42) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import numpy Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/zetah/.local/lib/python2.7/site-packages/numpy/__init__.py", line 128, in <module> from version import git_revision as __git_revision__ ImportError: No module named version >>> Looking in Synaptic I see python3-numpy is installed in /usr/lib/python3/dist-packages/numpy/ Why is it picking wrong package and what can I do to remedy this? Update: OK, in my ~/.profile I have this line: PYTHONPATH=$PYTHONPATH:$HOME/.local/lib/python2.7/site-packages but if I remove this line then my Python 2.7 local packages (which I build from source) wont work Update 2: Everything seems to work perfect without $PYTHONPATH. I guess it was in my .profile file for nothing Please close this question

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Reduce HTTP Requests method for js and css

- by Giberno

Is these way can Reduce HTTP Requests? multiple javascript files with & symbol <script type="text/javascript" src="http://yui.yahooapis.com/combo?2.5.2/build/yahoo-dom-event/yahoo-dom-event.js &http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"> </script> multiple css files with @ import <style type="text/css"> @import url(css/style.css); @import url(css/custom.css); </style>

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MSSQL: Copying data from one database to another

- by DigiMortal

I have database that has data imported from another server using import and export wizard of SQL Server Management Studio. There is also empty database with same tables but it also has primary keys, foreign keys and indexes. How to get data from first database to another? Here is the description of my crusade. And believe me – it is not nice one. Bugs in import and export wizard There is some awful bugs in import and export wizard that makes data imports and exports possible only on very limited manner: wizard is not able to analyze foreign keys, wizard wants to create tables always, whatever you say in settings. The result is faulty and useless package. Now let’s go step by step and make things work in our scenario. Database There are two databases. Let’s name them like this: PLAIN – contains data imported from remote server (no indexes, no keys, no nothing, just plain dumb data) CORRECT – empty database with same structure as remote database (indexes, keys and everything else but no data) Our goal is to get data from PLAIN to CORRECT. 1. Create import and export package In this point we will create faulty SSIS package using SQL Server Management Studio. Run import and export wizard and let it create SSIS package that reads data from CORRECT and writes it to, let’s say, CORRECT-2. Make sure you enable identity insert. Make sure there are no views selected. Make sure you don’t let package to create tables (you can miss this step because it wants to create tables anyway). Save package to SSIS. 2. Modify import and export package Now let’s clean up the package and remove all faulty crap. Connect SQL Server Management Studio to SSIS instance. Select the package you just saved and export it to your hard disc. Run Business Intelligence Studio. Create new SSIS project (DON’T MISS THIS STEP). Add package from disc as existing item to project and open it. Move to Control Flow page do one of following: Remove all preparation SQL-tasks and connect Data Flow tasks. Modify all preparation SQL-tasks so the existence of tables is checked before table is created (yes, you have to do it manually). Add new Execute-SQL task as first task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command: EXEC sp_MSForEachTable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL' GO EXEC sp_MSForEachTable 'DELETE FROM ?' GO Save task. Add new Execute-SQL task as last task in control flow: Open task properties. Assign destination connection as connection to use. Insert the following SQL as command: EXEC sp_MSForEachTable 'ALTER TABLE ? CHECK CONSTRAINT ALL' GO Save task Now connect first Execute-SQL task with first Data Flow task and last Data Flow task with second Execute-SQL task. Now move to Package Explorer tab and change connections under Connection Managers folder. Make source connection to use database PLAIN. Make destination connection to use database CORRECT. Save package and rebuilt the project. Update package using SQL Server Management Studio. Some hints: Make sure you take the package from solution folder because it is saved there now. Don’t overwrite existing package. Use numeric suffix and let Management Studio to create a new version of package. Now you are done with your package. Run it to test it and clean out all the errors you find. TRUNCATE vs DELETE You can see that I used DELETE FROM instead of TRUNCATE. Why? Because TRUNCATE has some nasty limits (taken from MSDN): “You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint; instead, use DELETE statement without a WHERE clause. Because TRUNCATE TABLE is not logged, it cannot activate a trigger. TRUNCATE TABLE may not be used on tables participating in an indexed view.” As I am not sure what tables you have and how they are used I provided here the solution that should work for all scenarios. If you need better performance then in some cases you can use TRUNCATE table instead of DELETE. Conclusion My conclusion is bitter this time although I am very positive guy. It is A.D. 2010 and still we have to write stupid hacks for simple things. Simple tools that existed before are long gone and we have to live mysterious bloatware that is our only choice when using default tools. If you take a look at the length of this posting and the count of steps I had to do for one easy thing you should treat it as a signal that something has went wrong in last years. Although I got my job done I would be still more happy if out of box tools are more intelligent one day. References T-SQL Trick for Deleting All Data in Your Database (Mauro Cardarelli) TRUNCATE TABLE (MSDN Library) Error Handling in SQL 2000 – a Background (Erland Sommarskog) Disable/Enable Foreign Key and Check constraints in SQL Server (Decipher)

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Vertex buffer acting strange? [on hold]

- by Ryan Capote

I'm having a strange problem, and I don't know what could be causing it. My current code is identical to how I've done this before. I'm trying to render a rectangle using VBO and orthographic projection. My results: What I expect: 3x3 rectangle in the top left corner #include <stdio.h> #include <GL\glew.h> #include <GLFW\glfw3.h> #include "lodepng.h" static const int FALSE = 0; static const int TRUE = 1; static const char* VERT_SHADER = "#version 330\n" "layout(location=0) in vec4 VertexPosition; " "layout(location=1) in vec2 UV;" "uniform mat4 uProjectionMatrix;" /*"out vec2 TexCoords;"*/ "void main(void) {" " gl_Position = uProjectionMatrix*VertexPosition;" /*" TexCoords = UV;"*/ "}"; static const char* FRAG_SHADER = "#version 330\n" /*"uniform sampler2D uDiffuseTexture;" "uniform vec4 uColor;" "in vec2 TexCoords;"*/ "out vec4 FragColor;" "void main(void) {" /* " vec4 texel = texture2D(uDiffuseTexture, TexCoords);" " if(texel.a <= 0) {" " discard;" " }" " FragColor = texel;"*/ " FragColor = vec4(1.f);" "}"; static int g_running; static GLFWwindow *gl_window; static float gl_projectionMatrix[16]; /* Structures */ typedef struct _Vertex { float x, y, z, w; float u, v; } Vertex; typedef struct _Position { float x, y; } Position; typedef struct _Bitmap { unsigned char *pixels; unsigned int width, height; } Bitmap; typedef struct _Texture { GLuint id; unsigned int width, height; } Texture; typedef struct _VertexBuffer { GLuint bufferObj, vertexArray; } VertexBuffer; typedef struct _ShaderProgram { GLuint vertexShader, fragmentShader, program; } ShaderProgram; /* http://en.wikipedia.org/wiki/Orthographic_projection */ void createOrthoProjection(float *projection, float width, float height, float far, float near) { const float left = 0; const float right = width; const float top = 0; const float bottom = height; projection[0] = 2.f / (right - left); projection[1] = 0.f; projection[2] = 0.f; projection[3] = -(right+left) / (right-left); projection[4] = 0.f; projection[5] = 2.f / (top - bottom); projection[6] = 0.f; projection[7] = -(top + bottom) / (top - bottom); projection[8] = 0.f; projection[9] = 0.f; projection[10] = -2.f / (far-near); projection[11] = (far+near)/(far-near); projection[12] = 0.f; projection[13] = 0.f; projection[14] = 0.f; projection[15] = 1.f; } /* Textures */ void loadBitmap(const char *filename, Bitmap *bitmap, int *success) { int error = lodepng_decode32_file(&bitmap->pixels, &bitmap->width, &bitmap->height, filename); if (error != 0) { printf("Failed to load bitmap. "); printf(lodepng_error_text(error)); success = FALSE; return; } } void destroyBitmap(Bitmap *bitmap) { free(bitmap->pixels); } void createTexture(Texture *texture, const Bitmap *bitmap) { texture->id = 0; glGenTextures(1, &texture->id); glBindTexture(GL_TEXTURE_2D, texture); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bitmap->width, bitmap->height, 0, GL_RGBA, GL_UNSIGNED_BYTE, bitmap->pixels); glBindTexture(GL_TEXTURE_2D, 0); } void destroyTexture(Texture *texture) { glDeleteTextures(1, &texture->id); texture->id = 0; } /* Vertex Buffer */ void createVertexBuffer(VertexBuffer *vertexBuffer, Vertex *vertices) { glGenBuffers(1, &vertexBuffer->bufferObj); glGenVertexArrays(1, &vertexBuffer->vertexArray); glBindVertexArray(vertexBuffer->vertexArray); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 6, (const GLvoid*)vertices, GL_STATIC_DRAW); const unsigned int uvOffset = sizeof(float) * 4; glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0); glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)uvOffset); glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindVertexArray(0); } void destroyVertexBuffer(VertexBuffer *vertexBuffer) { glDeleteBuffers(1, &vertexBuffer->bufferObj); glDeleteVertexArrays(1, &vertexBuffer->vertexArray); } void bindVertexBuffer(VertexBuffer *vertexBuffer) { glBindVertexArray(vertexBuffer->vertexArray); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); } void drawVertexBufferMode(GLenum mode) { glDrawArrays(mode, 0, 6); } void drawVertexBuffer() { drawVertexBufferMode(GL_TRIANGLES); } void unbindVertexBuffer() { glBindVertexArray(0); glBindBuffer(GL_ARRAY_BUFFER, 0); } /* Shaders */ void compileShader(ShaderProgram *shaderProgram, const char *vertexSrc, const char *fragSrc) { GLenum err; shaderProgram->vertexShader = glCreateShader(GL_VERTEX_SHADER); shaderProgram->fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); if (shaderProgram->vertexShader == 0) { printf("Failed to create vertex shader."); return; } if (shaderProgram->fragmentShader == 0) { printf("Failed to create fragment shader."); return; } glShaderSource(shaderProgram->vertexShader, 1, &vertexSrc, NULL); glCompileShader(shaderProgram->vertexShader); glGetShaderiv(shaderProgram->vertexShader, GL_COMPILE_STATUS, &err); if (err != GL_TRUE) { printf("Failed to compile vertex shader."); return; } glShaderSource(shaderProgram->fragmentShader, 1, &fragSrc, NULL); glCompileShader(shaderProgram->fragmentShader); glGetShaderiv(shaderProgram->fragmentShader, GL_COMPILE_STATUS, &err); if (err != GL_TRUE) { printf("Failed to compile fragment shader."); return; } shaderProgram->program = glCreateProgram(); glAttachShader(shaderProgram->program, shaderProgram->vertexShader); glAttachShader(shaderProgram->program, shaderProgram->fragmentShader); glLinkProgram(shaderProgram->program); glGetProgramiv(shaderProgram->program, GL_LINK_STATUS, &err); if (err != GL_TRUE) { printf("Failed to link shader."); return; } } void destroyShader(ShaderProgram *shaderProgram) { glDetachShader(shaderProgram->program, shaderProgram->vertexShader); glDetachShader(shaderProgram->program, shaderProgram->fragmentShader); glDeleteShader(shaderProgram->vertexShader); glDeleteShader(shaderProgram->fragmentShader); glDeleteProgram(shaderProgram->program); } GLuint getUniformLocation(const char *name, ShaderProgram *program) { GLuint result = 0; result = glGetUniformLocation(program->program, name); return result; } void setUniformMatrix(float *matrix, const char *name, ShaderProgram *program) { GLuint loc = getUniformLocation(name, program); if (loc == -1) { printf("Failed to get uniform location in setUniformMatrix.\n"); return; } glUniformMatrix4fv(loc, 1, GL_FALSE, matrix); } /* General functions */ static int isRunning() { return g_running && !glfwWindowShouldClose(gl_window); } static void initializeGLFW(GLFWwindow **window, int width, int height, int *success) { if (!glfwInit()) { printf("Failed it inialize GLFW."); *success = FALSE; return; } glfwWindowHint(GLFW_RESIZABLE, 0); *window = glfwCreateWindow(width, height, "Alignments", NULL, NULL); if (!*window) { printf("Failed to create window."); glfwTerminate(); *success = FALSE; return; } glfwMakeContextCurrent(*window); GLenum glewErr = glewInit(); if (glewErr != GLEW_OK) { printf("Failed to initialize GLEW."); printf(glewGetErrorString(glewErr)); *success = FALSE; return; } glClearColor(0.f, 0.f, 0.f, 1.f); glViewport(0, 0, width, height); *success = TRUE; } int main(int argc, char **argv) { int err = FALSE; initializeGLFW(&gl_window, 480, 320, &err); glDisable(GL_DEPTH_TEST); if (err == FALSE) { return 1; } createOrthoProjection(gl_projectionMatrix, 480.f, 320.f, 0.f, 1.f); g_running = TRUE; ShaderProgram shader; compileShader(&shader, VERT_SHADER, FRAG_SHADER); glUseProgram(shader.program); setUniformMatrix(&gl_projectionMatrix, "uProjectionMatrix", &shader); Vertex rectangle[6]; VertexBuffer vbo; rectangle[0] = (Vertex){0.f, 0.f, 0.f, 1.f, 0.f, 0.f}; // Top left rectangle[1] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top right rectangle[2] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left rectangle[3] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top left rectangle[4] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left rectangle[5] = (Vertex){3.f, 3.f, 0.f, 1.f, 1.f, 1.f}; // Bottom right createVertexBuffer(&vbo, &rectangle); bindVertexBuffer(&vbo); while (isRunning()) { glClear(GL_COLOR_BUFFER_BIT); glfwPollEvents(); drawVertexBuffer(); glfwSwapBuffers(gl_window); } unbindVertexBuffer(&vbo); glUseProgram(0); destroyShader(&shader); destroyVertexBuffer(&vbo); glfwTerminate(); return 0; }

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What is the exception in java code? [closed]

- by Karandeep Singh

This java code is for reverse the string but it returning concat null with returned string. import java.util.*; import java.util.logging.Level; import java.util.logging.Logger; public class Practice { public static void main(String[] args) { String str = ""; try { str = reverse("Singh"); } catch (Exception ex) { Logger.getLogger(Practice.class.getName()).log(Level.SEVERE, null, ex); System.out.print(ex.getMessage()); }finally{ System.out.println(str); } } public static String reverse(String str) throws Exception{ String temp = null; if(str.length()<=0){ throw new Exception("empty"); }else{ for(int i=str.length()-1;i>=0;i--){ temp+=str.charAt(i); } } return temp.trim(); } } Output: nullhgniS

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A Look Inside JSR 360 - CLDC 8

- by Roger Brinkley

If you didn't notice during JavaOne the Java Micro Edition took a major step forward in its consolidation with Java Standard Edition when JSR 360 was proposed to the JCP community. Over the last couple of years there has been a focus to move Java ME back in line with it's big brother Java SE. We see evidence of this in JCP itself which just recently merged the ME and SE/EE Executive Committees into a single Java Executive Committee. But just before that occurred JSR 360 was proposed and approved for development on October 29. So let's take a look at what changes are now being proposed. In a way JSR 360 is returning back to the original roots of Java ME when it was first introduced. It was indeed a subset of the JDK 4 language, but as Java progressed many of the language changes were not implemented in the Java ME. Back then the tradeoff was still a functionality, footprint trade off but the major market was feature phones. Today the market has changed and CLDC, while it will still target feature phones, will have it primary emphasis on embedded devices like wireless modules, smart meters, health care monitoring and other M2M devices. The major changes will come in three areas: language feature changes, library changes, and consolidating the Generic Connection Framework. There have been three Java SE versions that have been implemented since JavaME was first developed so the language feature changes can be divided into changes that came in JDK 5 and those in JDK 7, which mostly consist of the project Coin changes. There were no language changes in JDK 6 but the changes from JDK 5 are: Assertions - Assertions enable you to test your assumptions about your program. For example, if you write a method that calculates the speed of a particle, you might assert that the calculated speed is less than the speed of light. In the example code below if the interval isn't between 0 and and 1,00 the an error of "Invalid value?" would be thrown. private void setInterval(int interval) { assert interval > 0 && interval <= 1000 : "Invalid value?" } Generics - Generics add stability to your code by making more of your bugs detectable at compile time. Code that uses generics has many benefits over non-generic code with: Stronger type checks at compile time. Elimination of casts. Enabling programming to implement generic algorithms. Enhanced for Loop - the enhanced for loop allows you to iterate through a collection without having to create an Iterator or without having to calculate beginning and end conditions for a counter variable. The enhanced for loop is the easiest of the new features to immediately incorporate in your code. In this tip you will see how the enhanced for loop replaces more traditional ways of sequentially accessing elements in a collection. void processList(Vector<string> list) { for (String item : list) { ... Autoboxing/Unboxing - This facility eliminates the drudgery of manual conversion between primitive types, such as int and wrapper types, such as Integer. Hashtable<Integer, string=""> data = new Hashtable<>(); void add(int id, String value) { data.put(id, value); } Enumeration - Prior to JDK 5 enumerations were not typesafe, had no namespace, were brittle because they were compile time constants, and provided no informative print values. JDK 5 added support for enumerated types as a full-fledged class (dubbed an enum type). In addition to solving all the problems mentioned above, it allows you to add arbitrary methods and fields to an enum type, to implement arbitrary interfaces, and more. Enum types provide high-quality implementations of all the Object methods. They are Comparable and Serializable, and the serial form is designed to withstand arbitrary changes in the enum type. enum Season {WINTER, SPRING, SUMMER, FALL}; } private Season season; void setSeason(Season newSeason) { season = newSeason; } Varargs - Varargs eliminates the need for manually boxing up argument lists into an array when invoking methods that accept variable-length argument lists. The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments. Varargs can be used only in the final argument position. void warning(String format, String... parameters) { .. for(String p : parameters) { ...process(p);... } ... } Static Imports -The static import construct allows unqualified access to static members without inheriting from the type containing the static members. Instead, the program imports the members either individually or en masse. Once the static members have been imported, they may be used without qualification. The static import declaration is analogous to the normal import declaration. Where the normal import declaration imports classes from packages, allowing them to be used without package qualification, the static import declaration imports static members from classes, allowing them to be used without class qualification. import static data.Constants.RATIO; ... double r = Math.cos(RATIO * theta); Annotations - Annotations provide data about a program that is not part of the program itself. They have no direct effect on the operation of the code they annotate. There are a number of uses for annotations including information for the compiler, compiler-time and deployment-time processing, and run-time processing. They can be applied to a program's declarations of classes, fields, methods, and other program elements. @Deprecated public void clear(); The language changes from JDK 7 are little more familiar as they are mostly the changes from Project Coin: String in switch - Hey it only took us 18 years but the String class can be used in the expression of a switch statement. Fortunately for us it won't take that long for JavaME to adopt it. switch (arg) { case "-data": ... case "-out": ... Binary integral literals and underscores in numeric literals - Largely for readability, the integral types (byte, short, int, and long) can also be expressed using the binary number system. and any number of underscore characters (_) can appear anywhere between digits in a numerical literal. byte flags = 0b01001111; long mask = 0xfff0_ff08_4fff_0fffl; Multi-catch and more precise rethrow - A single catch block can handle more than one type of exception. In addition, the compiler performs more precise analysis of rethrown exceptions than earlier releases of Java SE. This enables you to specify more specific exception types in the throws clause of a method declaration. catch (IOException | InterruptedException ex) { logger.log(ex); throw ex; } Type Inference for Generic Instance Creation - Otherwise known as the diamond operator, the type arguments required to invoke the constructor of a generic class can be replaced with an empty set of type parameters (<>) as long as the compiler can infer the type arguments from the context. map = new Hashtable<>(); Try-with-resource statement - The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement. try (DataInputStream is = new DataInputStream(...)) { return is.readDouble(); } Simplified varargs method invocation - The Java compiler generates a warning at the declaration site of a varargs method or constructor with a non-reifiable varargs formal parameter. Java SE 7 introduced a compiler option -Xlint:varargs and the annotations @SafeVarargs and @SuppressWarnings({"unchecked", "varargs"}) to supress these warnings. On the library side there are new features that will be added to satisfy the language requirements above and some to improve the currently available set of APIs. The library changes include: Collections update - New Collection, List, Set and Map, Iterable and Iteratator as well as implementations including Hashtable and Vector. Most of the work is too support generics String - New StringBuilder and CharSequence as well as a Stirng formatter. The javac compiler now uses the the StringBuilder instead of String Buffer. Since StringBuilder is synchronized there is a performance increase which has necessitated the wahat String constructor works. Comparable interface - The comparable interface works with Collections, making it easier to reuse. Try with resources - Closeable and AutoCloseable Annotations - While support for Annotations is provided it will only be a compile time support. SuppressWarnings, Deprecated, Override NIO - There is a subset of NIO Buffer that have been in use on the of the graphics packages and needs to be pulled in and also support for NIO File IO subset. Platform extensibility via Service Providers (ServiceLoader) - ServiceLoader interface dos late bindings of interface to existing implementations. It helpe to package an interface and behavior of the implementation at a later point in time.Provider classes must have a zero-argument constructor so that they can be instantiated during loading. They are located and instantiated on demand and are identified via a provider-configuration file in the METAINF/services resource directory. This is a mechansim from Java SE. import com.XYZ.ServiceA; ServiceLoader<ServiceA> sl1= new ServiceLoader(ServiceA.class); Resources: META-INF/services/com.XYZ.ServiceA: ServiceAProvider1 ServiceAProvider2 ServiceAProvider3 META-INF/services/ServiceB: ServiceBProvider1 ServiceBProvider2 From JSR - I would rather use this list I think The Generic Connection Framework (GCF) was previously specified in a number of different JSRs including CLDC, MIDP, CDC 1.2, and JSR 197. JSR 360 represents a rare opportunity to consolidated and reintegrate parts that were duplicated in other specifications into a single specification, upgrade the APIs as well provide new functionality. The proposal is to specify a combined GCF specification that can be used with Java ME or Java SE and be backwards compatible with previous implementations. Because of size limitations as well as the complexity of the some features like InvokeDynamic and Unicode 6 will not be included. Additionally, any language or library changes in JDK 8 will be not be included. On the upside, with all the changes being made, backwards compatibility will still be maintained. JSR 360 is a major step forward for Java ME in terms of platform modernization, language alignment, and embedded support. If you're interested in following the progress of this JSR see the JSR's java.net project for details of the email lists, discussions groups.

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- by Karandeep Singh

- by Roger Brinkley

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