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• DDD and Client/Server apps

  - by Christophe Herreman

  I was wondering if any of you had successfully implemented DDD in a Client/Server app and would like to share some experiences. We are currently working on a smart client in Flex and a backend in Java. On the server we have a service layer exposed to the client that offers CRUD operations amongst some other service methods. I understand that in DDD these services should be repositories and services should be used to handle use cases that do not fit inside a repository. Right now, we mimic these services on the client behind an interface and inject implementations (Webservices, RMI, etc) via an IoC container. So some questions arise: should the server expose repositories to the client or do we need to have some sort of a facade (that is able to handle security for instance) should the client implement repositories (and DDD in general?) knowing that in the client, most of the logic is view related and real business logic lives on the server. All communication with the server happens asynchronously and we have a single threaded programming model on the client. how about mapping client to server objects and vice versa? We tried DTO's but reverted back to exposing the state of our objects and mapping directly to them. I know this is considered bad practice, but it saves us an incredible amount of time) In general I think a new generation of applications is coming with the growth of Flex, Silverlight, JavaFX and I'm curious how DDD fits into this.

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• PostgreSQL: Rolling back a transaction within a plpgsql function?

  - by jamieb

  Coming from the MS SQL world, I tend to make heavy use of stored procedures. I'm currently writing an application uses a lot of PostgreSQL plpgsql functions. What I'd like to do is rollback all INSERTS/UPDATES contained within a particular function if I get an exception at any point within it. I was originally under the impression that each function is wrapped in it's own transaction and that an exception would automatically rollback everything. However, that doesn't seem to be the case. I'm wondering if I ought to be using savepoints in combination with exception handling instead? But I don't really understand the difference between a transaction and a savepoint to know if this is the best approach. Any advice please? CREATE OR REPLACE FUNCTION do_something( _an_input_var int ) RETURNS bool AS $$ DECLARE _a_variable int; BEGIN INSERT INTO tableA (col1, col2, col3) VALUES (0, 1, 2); INSERT INTO tableB (col1, col2, col3); VALUES (0, 1, 'whoops! not an integer'); -- The exception will cause the function to bomb, but the values -- inserted into "tableA" are not rolled back. RETURN True; END; $$ LANGUAGE plpgsql;

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• Developmnet process for an embedded project with significant Hardware change

  - by pierr

  Hi, I have a good idea about Agile development process but it seems it does not fit well with a embedded project with significant hardware change. I will describe below what we are currently doing (Ad-hoc way , no defined process yet). The change are divided to three categories and different process are used for them : complete hardware change example : use a different video codec IP a) Study the new IP b) RTL/FPGA simulation c) Implement the leagcy interface - go to b) d) Wait until hardware (tape out) is ready f) Test on the real Hardware hardware improvement example : enhance the image display quaulity by improving the underlie algorithm a)RTL/FPGA simulation b)Wait until hardware and test on the hardware Mino change exmaple : only change hardware register mapping a)Wait until hardware and test on the hardware The worry is it seems we don't have too much control and confidence about software maturity for the hardware change as the bring up schedule is always very tight and the customer desired a seemless change when updating to a new version hardware. How did you manage this kind of hardware hardware change? Did you solve that by a Hardware Abstraction Layer (HAL)? Did you have a automatical test for the HAL layer? How did you test when the hardware platform is not even ready? Do you have well documented process for this kind of change? Thanks for your insight.

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• Windows Service Conundrum

  - by Paul Johnson

  All, I have a Custom object which I have written using VB.NET (.net 2.0). The object instantiates its own threading.timer object and carries out a number of background process including periodic interrogation of an oracle database and delivery of emails via smtp according to data detected in the database. The following is the code implemented in the windows service class Public Class IncidentManagerService 'Fakes Private _fakeRepoFactory As IRepoFactory Private _incidentRepo As FakeIncidentRepo Private _incidentDefinitionRepo As FakeIncidentDefinitionRepo Private _incManager As IncidentManager.Session 'Real Private _started As Boolean = False Private _repoFactory As New NHibernateRepoFactory Private _psalertsEventRepo As IPsalertsEventRepo = _repoFactory.GetPsalertsEventRepo() Protected Overrides Sub OnStart(ByVal args() As String) ' Add code here to start your service. This method should set things ' in motion so your service can do its work. If Not _started Then Startup() _started = True End If End Sub Protected Overrides Sub OnStop() 'Tear down class variables in order to ensure the service stops cleanly _incManager.Dispose() _incidentDefinitionRepo = Nothing _incidentRepo = Nothing _fakeRepoFactory = Nothing _repoFactory = Nothing End Sub Private Sub Startup() Dim incidents As IList(Of Incident) = Nothing Dim incidentFactory As New IncidentFactory incidents = IncidentFactory.GetTwoFakeIncidents _repoFactory = New NHibernateRepoFactory _fakeRepoFactory = New FakeRepoFactory(incidents) _incidentRepo = _fakeRepoFactory.GetIncidentRepo _incidentDefinitionRepo = _fakeRepoFactory.GetIncidentDefinitionRepo 'Start an incident manager session _incManager = New IncidentManager.Session(_incidentRepo, _incidentDefinitionRepo, _psalertsEventRepo) _incManager.Start() End Sub End Class After a little bit of experimentation I arrived at the above code in the OnStart method. All functionality passed testing when deployed from VS2005 on my development PC, however when deployed on a true target machine, the service would not start and responds with the following message: "The service on local computer started and then stopped..." Am I going about this the correct way? If not how can I best implement my incident manager within the confines of the Windows Service class. It seems pointless to implement a timer for the incidentmanager because this already implements its own timer... Any assistance much appreciated. Kind Regards Paul J.

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• Using embedded standard HTML forms with ASP.NET

  - by RM

  I have a standard aspx page with which I need to add another standard HTML form into and have it submit to another location (external site), however whenever I press the submit button the page seems to do a post back rather than using the sub-forms action url. A mock up of what the form relationships is below. Note in the real deployment the form will be part of a content area of a master page layout, so the form needs to submit independantly from the master page form. <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> <form id="subscribe_form" method="post" action="https://someothersite.com" name="em_subscribe_form" > <input type="text" id="field1" name="field1" /> <input id="submitsubform" type="submit" value="Submit" /> </form> </div> </form> </body> </html>

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• Why can I run JUnit tests for my Spring project, but not a main method?

  - by FarmBoy

  I am using JDBC to connect to MySQL for a small application. In order to test without altering the real database, I'm using HSQL in memory for JUnit tests. I'm using Spring for DI and DAOs. Here is how I'm configuring my HSQL DataSource <bean id="mockDataSource" class="org.springframework.jdbc.datasource.SingleConnectionDataSource"> <property name="driverClassName" value="org.hsqldb.jdbcDriver"/> <property name="url" value="jdbc:hsqldb:mem:mockSeo"/> <property name="username" value="sa"/> </bean> This works fine for my JUnit tests which use the mock DB. But when I try to run a main method, I find the following error: Error creating bean with name 'mockDataSource' defined in class path resource [beans.xml]: Error setting property values; nested exception is org.springframework.beans.PropertyBatchUpdateException; nested PropertyAccessExceptions (1) are: PropertyAccessException 1: org.springframework.beans.MethodInvocationException: Property 'driverClassName' threw exception; nested exception is java.lang.IllegalStateException: Could not load JDBC driver class [org.hsqldb.jdbcDriver] I'm running from Eclipse, and I'm using the Maven plugin. Is there a reason why this would work as a Test, but not as a main()? I know that the main method itself is not the problem, because it works if I remove all references to the HSQL DataSource from my Spring Configuration file.

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• InvalidCastException in DataGridView

  - by Max Yaffe

  (Using VS 2010 Beta 2 - .Net 4.0 B2 Rel) I have a class, MyTable, derived from BindingList where S is a struct. S is made up of several other structs, for example: public class MyTable<S>:BindingList<S> where S: struct { ... } public struct MyStruct { public MyReal r1; public MyReal r2; public MyReal R1 {get{...} set{...}} public MyReal R2 {get{...} set{...}} ... } public struct MyReal { private Double d; private void InitFromString(string) {this.d = ...;} public MyReal(Double d) { this.d = d;} public MyReal(string val) { this.d = default(Double); InitFromString(val);} public override string ToString() { return this.real.ToString();} public static explicit operator MyReal(string s) { return new MyReal(s);} public static implicit operator String(MyReal r) { return r.ToString();} ... } OK, I use the MyTable as a binding source for a DataGridView. I can load the data grid easily using InitFromString on individual fields in MyStruct. The problem comes when I try to edit a value in a cell of the DataGridView. Going to the first row, first column, I change the value of the existing number. It gives an exception blizzard, the first line of which says: System.FormatException: Invalid cast from 'System.String' to 'MyReal' I've looked at the casting discussions and reference books but don't see any obvious problems. Any ideas?

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• sqrt(int_value + 0.0) -- Does it have a purpose?

  - by Earlz

  Hello, while doing some homework in my very strange C++ book, which I've been told before to throw away, had a very peculiar code segment. I know homework stuff always throws in extra "mystery" to try to confuse you like indenting 2 lines after a single-statement for-loop. But this one I'm confused on because it seems to serve some real-purpose. basically it is like this: int counter=10; ... if(pow(floor(sqrt(counter+0.0)),2) == counter) ... I'm interested in this part especially: sqrt(counter+0.0) Is there some purpose to the +0.0? Is this the poormans way of doing a static cast to a double? Does this avoid some compiler warning on some compiler I do not use? The entire program printed the exact same thing and compiled without warnings on g++ whenever I left out the +0.0 part. Maybe I'm not using a weird enough compiler? Edit: Also, does gcc just break standard and not make an error for Ambiguous reference since sqrt can take 3 different types of parameters? [earlz@EarlzBeta-~/projects/homework1] $ cat calc.cpp #include <cmath> int main(){ int counter=0; sqrt(counter); } [earlz@EarlzBeta-~/projects/homework1] $ g++ calc.cpp /usr/lib/libstdc++.so.47.0: warning: strcpy() is almost always misused, please use strlcpy() /usr/lib/libstdc++.so.47.0: warning: strcat() is almost always misused, please use strlcat() [earlz@EarlzBeta-~/projects/homework1] $

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• Modularity in Flex

  - by Fernando

  I'm working on a pretty big application for Flex/Air. We are using GraniteDS and Tide to interact with the model from our Java EE server. I've been reading about modularization and Modules in Flex. The application has already been built, and I'm figuring a way out to re-design some classes and parts. From what I've read so far, I understand a Module is a different swf which can be dynamically load. Most of the tutorials/documentation are oriented to Flash "programmers" who are using Flex or Air instead of real developers, so that makes online resources harder to get. What I can't understand - yet - is how to encapsulate ActionScript classes or MXML views under this module. I've separated some of the code into libraries. For example, the generated code from Granite is in a "server" library. But I would like to separate parts of the logic with its Moderators, Controllers and Views. Are modules the way to go? Is there a "modules for dummies" or "head first Flex Modules for programmers" like tutorial in order to get a better perspective in order to build my architecture? When to choose libraries and when to choose modules? I'm using Flex 3.5, and a migration to Flex 4 is way far into the future, so no Flex 4 answers please, thanks!

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• Jquery Livesearch with quicksilver plugin to include not just the <li>s

  - by 133794m3r

  Ok, what i'm trying to do here is to make the exact code found here here ordered list and make it so that it doesn't just not work when i try to add additional elements into the list. Also i'm planning on using the more effecient one linked to at the end but i cannot put it here so you'll have to find that link on your own sadly. Since i'm trying to use this for a knowledge base page i want to allow people to be able to search through the items on the page and go to the proper part(ie loading it into the viewing area) but it's not letting me even include a simple anchor in there. if there is anyway to do something similar or to edit it so that it'll include everything within the <li> that'd be great. I don't know if anyone out there has done something like this before, but if they have and wouldn't mind sharing the code with me i'd be extremely happy. If no one has but does know how to make it include everything within the <li> including text also a great thing to have. I imagine that i won't be the only person out there in this world with my exact query.

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• Load Images in WPF application

  - by LLS

  I am not familiar with WPF, and I just feel quite confusing. I am trying to create a little computer game, and there are elements I want to display dynamically. I use Image class and add the images to a canvas. But I'm not sure whether it's a good practice. I feel that adding controls to canvas seem to be a little wired. And I'm a little concerned about the performance, because I may need many images. The real problem is, I can't load the images from the image files. I see an example in a text book like this (XMAL): <Image Panel.ZIndex="0" Margin="0,0,0,0" Name ="image1"> <Image.Source> <BitmapImage UriSource="Bell.gif" /> </Image.Source> </Image> Where Bell.gif is added into the project. And I tried to copy this in code to create an image. new Image { Source = new BitmapImage(new Uri("Blockade.bmp"))} But I got invalid Uri exception. After some search in the Internet, I found that loading resources dynamically seems to be difficult. Can I load the files added to the project dynamically? If I use absolute path then it's OK. But I can't expect every computer will put the files in the same location. Can I use relative path? I tried new Image { Source = new BitmapImage(new Uri(@"Pictures\Blank Land.bmp", UriKind.Relative)) } But it doesn't work. (The image is blank) Thanks.

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• Should the entity framework + self tracking entities be saving me time

  - by sipwiz

  I've been using the entity framework in combination with the self tracking entity code generation templates for my latest silverlight to WCF application. It's the first time I've used the entity framework in a real project and my hope was that I would save myself a lot of time and effort by being able to automatically update the whole data access layer of my project when my database schema changed. Happily I've found that to be the case, updating my database schema by adding a new table, changing column names, adding new columns etc. etc. can be propagated to my business object classes by using the update from database option on the entity framework model. Where I'm hurting is the CRUD operations within my WCF service in response to actions on my Silverlight client. I use the same self tracking entity framework business objects in my Silverlight app but I find I'm continually having to fight against problems such as foreign key associations not being handled correctly when updating an object or the change tracker getting confused about the state of an object at the Silverlight end and the data access operation within the WCF layer throwing a wobbly. It's got to a point where I have now spent more time dealing with this quirks than I have on my previous project where I used Linq-to-SQL as the starting point for rolling my own business objects. Is it just me being hopeless or is the self tracking entities approach something that should be avoided until it's more mature?

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• CodeDom : compile partial class

  - by James

  I'm attempting to compile code in a text file to change a value in a TextBox on the main form of a WinForms application. Ie. add another partial class with method to the calling form. The form has one button (button1) and one TextBox (textBox1). The code in the text file is: this.textBox1.Text = "Hello World!!"; And the code: namespace WinFormCodeCompile { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { // Load code from file StreamReader sReader = new StreamReader(@"Code.txt"); string input = sReader.ReadToEnd(); sReader.Close(); // Code literal string code = @"using System; using System.Windows.Forms; namespace WinFormCodeCompile { public partial class Form1 : Form { public void UpdateText() {" + input + @" } } }"; // Compile code CSharpCodeProvider cProv = new CSharpCodeProvider(); CompilerParameters cParams = new CompilerParameters(); cParams.ReferencedAssemblies.Add("mscorlib.dll"); cParams.ReferencedAssemblies.Add("System.dll"); cParams.ReferencedAssemblies.Add("System.Windows.Forms.dll"); cParams.GenerateExecutable = false; cParams.GenerateInMemory = true; CompilerResults cResults = cProv.CompileAssemblyFromSource(cParams, code); // Check for errors if (cResults.Errors.Count != 0) { foreach (var er in cResults.Errors) { MessageBox.Show(er.ToString()); } } else { // Attempt to execute method. object obj = cResults.CompiledAssembly.CreateInstance("WinFormCodeCompile.Form1"); Type t = obj.GetType(); t.InvokeMember("UpdateText", BindingFlags.InvokeMethod, null, obj, null); } } } } When I compile the code, the CompilerResults returns an error that says WinFormCodeCompile.Form1 does not contain a definition for textBox1. Is there a way to dynamically create another partial class file to the calling assembly and execute that code? I assume I'm missing something really simple here.

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• NSBorderlessWindow not responding to CMD-W/CMD-M

  - by Sean

  I have an NSBorderlessWindow subclass of NSWindow with a transparent and non-opaque background (so it's non-rectangular in appearance). I've added my own buttons to function as the close and minimize buttons when I click them, but for some reason the window will not respond to CMD-W or CMD-M like a normal one does. I have my NSWindow subclass set to return YES to canBecomeKeyWindow and canBecomeMainWindow. My NIB still has all the standard menu items in it that are there when you create a new project - including the "Minimize" item in the Window menu with the default shortcut CMD-M defined. It's hooked up to send performMiniaturize: to the first responder. However it is not enabled when the app is run, so it seems like it must be asking the window if it can minimize and the window says no or something. (I'm still very new to OSX/Cocoa.) What am I missing? Also, and maybe this is related, my borderless window has a shadow enabled - but unlike a normal titled window, when I make my window the active/front window by clicking on it, the shadow doesn't change. Normally an OSX focused window has a slightly larger/darker shadow to make it stand out more but mine never changes the shadow. It's like I'm missing something to make the OS treat this window as a real/normal/main window or something and as a result I lose the shadow change and functioning CMD-W/CMD-M.

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• Swing data binding frameworks

  - by Ahe

  Hi Almost the same question has been asked a year ago, but the there has been some new development in this area. Selecting a (data binding) framework for swing application seems to be quite difficult. JSR-295 is abandoned, many swing frameworks which provide binding are work-in-progress, abandoned or too heavy for my quite simple app. JGoodies Swing suite is expensive, but luckily its libraries are free. Has anyone any real-world experience of new UFaceKit. It looks promising, but quite immature. I am particularly interested in Swing implementation and documentation. Any insight on UFaceKits development schedule would be appreciated, because I can hold by framework choice for a while. Requirements are not anything fancy, just working binding with a nice API. I also found Mogwai dataBinding, but it seems quite incomplete and requires manual synchronization activation, which makes it useless compared to coarse grained synchronization easily written by hand. Incomplete frameworks include at least Spring RCP and many JSR-296 forks. So, is the JGoodies data binding really the only realistic choice? Or are there any other viable solutions available?

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• How to use Java varargs with the GWT Javascript Native Interface? (aka, "GWT has no printf()")

  - by markerikson

  I'm trying to quickly learn GWT as part of a new project. I found out that GWT doesn't implement Java's String.format() function, so there's no printf()-like functionality. I knew that some printf() implementations exist for Javascript, so I figured I could paste one of those in as a GWT Javascript Native Interface function. I ran into problems, and decided I'd better make sure that the varargs values were being passed in correctly. That's where things got ugly. First, some example code: // From Java, call the JSNI function: test("sourceString", "params1", "params2", "params3"); .... public static native void test(Object... params) /*-{ // PROBLEM: this kills GWT! // alert(params.length); // returns "function" alert(typeof(params)); // returns "[Ljava.lang.Object;@b97ff1" alert(params); }-*/; The GWT docs state that "calling a varargs JavaScript method from Java will result in the callee receiving the arguments in an array". I figured that meant I could at least check params.length, but accessing that throws a JavascriptException wrapped in an UmbrellaException, with no real information. When I do "typeof(params)", it returns "function". As if that weren't odd enough, if I check the string value of params, it returns what appears to be a string version of a Java reference. So, I guess I'm asking a few different questions here: 1) How do GWT/JSNI varargs actually work, and do I need to do something special to pass in values? 2) What is actually going on here? 3) Is there any easier way to get printf()-style formatting in a GWT application?

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• Is there a way to effect user defined data types in MySQL?

  - by Dancrumb

  I have a database which stores (among other things), the following pieces of information: Hardware IDs BIGINTs Storage Capacities BIGINTs Hardware Names VARCHARs World Wide Port Names VARCHARs I'd like to be able to capture a more refined definition of these datatypes. For instance, the hardware IDs have no numerical significance, so I don't care how they are formatted when displayed. The Storage Capacities, however, are cardinal numbers and, at a user's request, I'd like to present them with thousands and decimal separators, e.g. 123,456.789. Thus, I'd like to refine BIGINT into, say ID_NUMBER and CARDINAL. The same with Hardware Names, which are simple text and WWPNs, which are hexstrings, e.g. 24:68:AC:E0. Thus, I'd like to refine VARCHAR into ENGLISH_WORD and HEXSTRING. The specific datatypes I made up are just for illustrative purposes. I'd like to keep all this information in one place and I'm wondering if anybody knows of a good way to hold this all in my MySQL table definitions. I could use the Comment field of the table definition, but that smells fishy to me. One approach would be to define the data structure elsewhere and use that definition to generate my CREATE TABLEs, but that would be a major rework of the code that I currently have, so I'm looking for alternatives. Any suggestions? The application language in use is Perl, if that helps.

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• MSMQ on Win2008 R2 won’t receive messages from older clients

  - by Graffen

  Hi all I'm battling a really weird problem here. I have a Windows 2008 R2 server with Message Queueing installed. On another machine, running Windows 2003 is a service that is set up to send messages to a public queue on the 2008 server. However, messages never show up on the server. I've written a small console app that just sends a "Hello World" message to a test queue on the 2008 machine. Running this app on XP or 2003 results in absolutely nothing. However, when I try running the app on my Windows 7 machine, a message is delivered just fine. I've been through all sorts of security settings, disabled firewalls on all machines etc. The event log shows nothing of interest, and no exceptions are being thrown on the clients. Running a packet sniffer (WireShark) on the server reveals only a little. When trying to send a message from XP or 2003 I only see an ICMP error "Port Unreachable" on port 3527 (which I gather is an MQPing packet?). After that, silence. Wireshark shows a nice little stream of packets when I try from my Win7 client (as expected - messages get delivered just fine from Win7). I've enabled MSMQ End2End logging on the server, but only entries from the messages sent from my Win7 machine are appearing in the log. So somehow it seems that messages are being dropped silently somewhere along the route from XP or 2003 to my 2008 server. Does anyone have any clues as to what might be causing this mysterious behaviour? -- Jesper

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• JDK-7 SwingWorker deadlocks?

  - by kd304

  I have a small image processing application which does multiple things at once using SwingWorker. However, if I run the following code (oversimplified excerpt), it just hangs on JDK 7 b70 (windows) but works in 6u16. It starts a new worker within another worker and waits for its result (the real app runs multiple sub-workers and waits for all this way). Did I use some wrong patterns here (as mostly there is 3-5 workers in the swingworker-pool, which has limit of 10 I think)? import javax.swing.SwingUtilities; import javax.swing.SwingWorker; public class Swing { static SwingWorker<String, Void> getWorker2() { return new SwingWorker<String, Void>() { @Override protected String doInBackground() throws Exception { return "Hello World"; } }; } static void runWorker() { SwingWorker<String, Void> worker = new SwingWorker<String, Void>() { @Override protected String doInBackground() throws Exception { SwingWorker<String, Void> sw2 = getWorker2(); sw2.execute(); return sw2.get(); } }; worker.execute(); try { System.out.println(worker.get()); } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { runWorker(); } }); } }

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• Why do I get "Illegal characters in path" while using XmlDiff to compare 2 xml files?

  - by Patryk

  I have a problem trying to compare 2 xml files with the XmlDiff library from Microsoft. I am using an overloaded function which passes 2 xmls as strings : xmldiff = new XmlDiff(XmlDiffOptions.IgnoreChildOrder | XmlDiffOptions.IgnorePrefixes | XmlDiffOptions.IgnoreNamespaces); bool identical = xmldiff.Compare(first, last, false); where first and last look more or less like this : <?xml version="1.0" encoding="ISO-8859-1"?> <breakfast_menu> <food> <name>Belgian Waffles</name> <price>$5.95</price> <description>two of our famous Belgian Waffles with plenty of real maple syrup</description> <calories>650</calories> </food> <food> <name>Strawberry Belgian Waffles</name> <price>$7.95</price> <description>light Belgian waffles covered with strawberries and whipped cream</description> <calories>900</calories> </food> </breakfast_menu> And I get this error

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• Any good tutorials or resources for learning how to design a scalable and "component" based game 'fr

  - by CodeJustin.com

  In short I'm creating a 2D mmorpg and unlike my last "mmo" I started developing I want to make sure that this one will scale well and work well when I want to add new in-game features or modify existing ones. With my last attempt with an avatar chat within the first few thousand lines of code and just getting basic features added into the game I seen my code quality lowering and my ability to add new features or modify old ones was getting lower too as I added more features in. It turned into one big mess that some how ran, lol. This time I really need to buckle down and find a design that will allow me to create a game framework that will be easy to add and remove features (aka things like playing mini-games within my world or a mail system or buddy list or a new public area with interactive items). I'm thinking that maybe a component based approach MIGHT be what I'm looking for but I'm really not sure. I have read documents on mmorpg design and 2d game engine architecture but nothing really explained a way of designing a game framework that will basically let me "plug-in" new features into the main game and use the resources of the main game without changing much within my 'main game code'. Hope someone understands what I mean, any help will is appreciated.

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• Figuring out the Nyquist performance limitation of an ADC on an example PIC microcontroller

  - by AKE

  I'm spec-ing the suitability of a dsPIC microcontroller for an analog-to-digital application. This would be preferable to using dedicated A/D chips and a separate dedicated DSP chip. To do that, I've had to run through some computations, pulling the relevant parameters from the datasheets. I'm not sure I've got it right -- would appreciate a check! (EDITED NOTE: The PIC10F220 in the example below was selected ONLY to walk through a simple example to check that I'm interpreting Tacq, Fosc, TAD, and divisor correctly in working through this sort of Nyquist analysis. The actual chips I'm considering for the design are the dsPIC33FJ128MC804 (with 16b A/D) or dsPIC30F3014 (with 12b A/D).) A simple example: PIC10F220 is the simplest possible PIC with an ADC Runs at clock speed of 8MHz. Has an instruction cycle of 0.5us (4 clock steps per instruction) So: Taking Tacq = 6.06 us (acquisition time for ADC, assume chip temp. = 50*C) [datasheet p34] Taking Fosc = 8MHz (? clock speed) Taking divisor = 4 (4 clock steps per CPU instruction) This gives TAD = 0.5us (TAD = 1/(Fosc/divisor) ) Conversion time is 13*TAD [datasheet p31] This gives conversion time 6.5us ADC duration is then 12.56 us [? Tacq + 13*TAD] Assuming at least 2 instructions for load/store: This is another 1 us [0.5 us per instruction] Which would give max sampling rate of 73.7 ksps (1/13.56) Supposing 8 more instructions for real-time processing: This is another 4 us Thus, total ADC/handling time = 17.56us (12.56us + 1us + 4us) So expected upper sampling rate is 56.9 ksps. Nyquist frequency for this sampling rate is therefore 28 kHz. If this is right, it suggests the (theoretical) performance suitability of this chip's A/D is for signals that are bandlimited to 28 kHz. Is this a correct interpretation of the information given in the data sheet in obtaining the Nyquist performance limit? Any opinions on the noise susceptibility of ADCs in PIC / dsPIC chips would be much appreciated! AKE

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• Java & android: Help linking an item in a listView to its correct view, but not the way i know of.

  - by Capsud

  Hi, i'm developing an android app, and what i have is a String array of restaurants in one class... static final String[] AtoZ = new String[] { "Ananda", "Brambles Cafe", "Brannigans", "Buona Sera", "Cafe Mao", "Cafe Mimo", "Dante", "Eddie Rockets", "Frango's World Cuisine", "Nando's", "Overends Restaurant @ Airfield House", "Pizza Hut", "Roly Saul", "Siam Thai","Smokey Joes","Sohag Tandoori", "TGI Friday","The Rockfield Lounge", "Winters Bar", "Al Boschetto","Baan Thai", "Bella Cuba", "Bellamys","Bianconis","Canal Bank Cafe", "Canalettos Restaurant","Chandni Restaurant", "Chill Out Cafe", "Crowes", "Da Vincenzo", "Druids", "Dylan", "Epic Restaurant", "Jewel in the Crown", "Juniors", "Kanum Thai","Kites", "Koishi","Maia Restaurant", "Mangetu Restaurant", "Millers Pizza Kitchens", "O'Connells Restaurant", "Ocras Restaurant", "Orchid Szechuan Restaurant", "Roly's Bistro", "Ryans Beggars Bush", }; i have created a view for each of these restaurants aswell in my layouts folder. so this array is going to be displayed in a listView in my android app. What i want to know is what is the quickest way of linking the item clicked to its correct view, without having to type out each position in the array and have a serious of if statements which would take a year with this! i dont want to be doing something like this if(position == 1){ setContentView(R.layout.bentleys); as it would take a year doing that for each one... Please help. thanks alot.

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• Google App Engine: Unit testing concurrent access to memcache

  - by Phuong Nguyen de ManCity fan

  Would you guys show me a way to simulating concurrent access to memcache on Google App Engine? I'm trying with LocalServiceTestHelpers and threads but don't have any luck. Every time I try to access Memcache within a thread, then I get this error: ApiProxy$CallNotFoundException: The API package 'memcache' or call 'Increment()' was not found I guess that the testing library of GAE SDK tried to mimic the real environment and thus setup the environment for only one thread (the thread that running the test) which cannot be seen by other thread. Here is a piece of code that can reproduce the problem package org.seamoo.cache.memcacheImpl; import org.testng.Assert; import org.testng.annotations.AfterMethod; import org.testng.annotations.BeforeMethod; import org.testng.annotations.Test; import com.google.appengine.api.memcache.MemcacheService; import com.google.appengine.api.memcache.MemcacheServiceFactory; import com.google.appengine.tools.development.testing.LocalMemcacheServiceTestConfig; import com.google.appengine.tools.development.testing.LocalServiceTestHelper; public class MemcacheTest { LocalServiceTestHelper helper; public MemcacheTest() { LocalMemcacheServiceTestConfig memcacheConfig = new LocalMemcacheServiceTestConfig(); helper = new LocalServiceTestHelper(memcacheConfig); } /** * */ @BeforeMethod public void setUp() { helper.setUp(); } /** * @see LocalServiceTest#tearDown() */ @AfterMethod public void tearDown() { helper.tearDown(); } @Test public void memcacheConcurrentAccess() throws InterruptedException { final MemcacheService service = MemcacheServiceFactory.getMemcacheService(); Runnable runner = new Runnable() { @Override public void run() { // TODO Auto-generated method stub service.increment("test-key", 1L, 1L); try { Thread.sleep(200L); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } service.increment("test-key", 1L, 1L); } }; Thread t1 = new Thread(runner); Thread t2 = new Thread(runner); t1.start(); t2.start(); while (t1.isAlive()) { Thread.sleep(100L); } Assert.assertEquals((Long) (service.get("test-key")), new Long(4L)); } }

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• Problem Linking Boost Filesystem Library in Microsoft Visual C++

  - by Scott

  Hello. I am having trouble getting my project to link to the Boost (version 1.37.0) Filesystem lib file in Microsoft Visual C++ 2008 Express Edition. The Filesystem library is not a header-only library. I have been following the Getting Started on Windows guide posted on the official boost web page. Here are the steps I have taken: I used bjam to build the complete set of lib files using: bjam --build-dir="C:\Program Files\boost\build-boost" --toolset=msvc --build-type=complete I copied the /libs directory (located in C:\Program Files\boost\build-boost\boost\bin.v2) to C:\Program Files\boost\boost_1_37_0\libs. In Visual C++, under Project Properties Additional Library Directories I added these paths: C:\Program Files\boost\boost_1_37_0\libs C:\Program Files\boost\boost_1_37_0\libs\filesystem\build\msvc-9.0express\debug\link-static\threading-multi I added the second one out of desperation. It is the exact directory where libboost_system-vc90-mt-gd-1_37.lib resides. In Configuration Properties C/C++ General Additional Include Directories I added the following path: C:\Program Files\boost\boost_1_37_0 Then, to put the icing on the cake, under Tools Options VC++ Directories Library files, I added the same directories mentioned in step 3. Despite all this, when I build my project I get the following error: fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-gd-1_37.lib' Additionally, here is the code that I am attempting to compile as well as a screen shot of the aformentioned directory where the (assumedly correct) lib file resides: #include "boost/filesystem.hpp" // includes all needed Boost.Filesystem declarations #include <iostream> // for std::cout using boost::filesystem; // for ease of tutorial presentation; // a namespace alias is preferred practice in real code using namespace std; int main() { cout << "Hello, world!" << endl; return 0; } Can anyone help me out? Let me know if you need to know anything else. As always, thanks in advance.

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