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• What function(s) call Control.ShouldSerializeVisible

  - by JDMX

  Does anyone know where Control.ShouldSerializeVisible is called from? The Reflector does not show it used by anything and google came up empty.

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• conditional beginReceive

  - by sbenderli

  I am writing a client program that uses Sockets. I would like the client to receive asyncronously UNLESS it is expecting a response, in which case I would like to receive syncronously. My current problem is that because I have to make a call to socket.BeginReceive which waits until there's data on the buffer, the async call always happens prior to the sync call.. How could I temporarily stop BeginReceive from executing? Is there a way to call EndReceive and then once I am done receiving syncronously, I can continue to receive asnycronously?

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• how do I instrospect appengine's datastore models?

  - by python for ever

  in order to dynamically create a form, i have to find the property types of a model's properties at runtime. appengine docs says that Model.properties() will return a dictionary of properties name and their class type. when i use this method in my code, only the name is returned and the classtype value is always empty.

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• How to identify end of InputStream in java

  - by Vardhaman

  I am trying to read bytes from server using Socket program, ie I am using InputStream to read the bytes. If I pass the length size I am able to read the bytes, but I am not sure what may be the length. So I am not able initialize the byte array. Also I tried while (in.read() !=-1), I observered it loop works fine when the data is sent , but the next line after the loop is not executable , I feel its still looking for the data in the stream but there is no ata. If I close the Server connection , then my client will execute the next line followed to the loop. I am not sure where I am going wrong? this.in = socket.getInputStream(); int dataInt = this.in.read(); while(dataInt != -1){ System.out.print(","+i+"--"+dataInt); i++; dataInt = this.in.read(); } System.out.print("End Of loop"); I get the output as:- ,1--0,2--62,3--96,4--131,5--142,6--1,7--133,8--2,9--16,10--48,11--56,12--1,13--0,14--14,15--128,16--0,17--0,18--0,19--48,20--0,21--0,22--0,23--0,24--0,25--1,26--0,27--0,28--38,29--114,30--23,31--20,32--70,33--3,34--20,35--1,36--133,37--48,38--51,39--49,40--52,41--49,42--55,43--49,44--52,45--52,46--54,47--55,48--50,49--51,50--52,51--48,52--53,53--56,54--51,55--48,56--48,57--57,58--57,59--57,60--57,61--57,62--57,63--57,64--56 But no output for :- End Of loop Please guide how shall I close the loop? Looking forward for you response. Thanking you all in advance.

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• how can i download a set of variable images in flex/as3 and display them?

  - by james

  hi guys.... suppose i have 10 image variables like this var image1:String = http://somewhere.com/image1.jpg var image2:string = .....image2.jpg var image3:string = .....image3.jpg and so forth......... i have a timer that displays each variable as an image one a time .... how do i "buffer" the image and display them instead of going out each time the timer runs? im asking because sometimes the server could slow or some other reason. so what i want to do is to download all those images and then display them from the clients computer. some sort like @Embed ??? complete newbie.. so please go slow on me ... :p

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• Replace beginning words

  - by Newbie

  I have the below tables. tblInput Id WordPosition Words -- ----------- ----- 1 1 Hi 1 2 How 1 3 are 1 4 you 2 1 Ok 2 2 This 2 3 is 2 4 me tblReplacement Id ReplacementWords --- ---------------- 1 Hi 2 are 3 Ok 4 This The tblInput holds the list of words while the tblReplacement hold the words that we need to search in the tblInput and if a match is found then we need to replace those. But the problem is that, we need to replace those words if any match is found at the beginning. i.e. in the tblInput, in case of ID 1, the words that will be replaced is only 'Hi' and not 'are' since before 'are', 'How' is there and it is not in the tblReplacement list. in case of Id 2, the words that will be replaced are 'Ok' & 'This'. Since these both words are present in the tblReplacement table and after the first word i.e. 'Ok' is replaced, the second word which is 'This' here comes first in the list of ID category 2 . Since it is available in the tblReplacement, and is the first word now, so this will also be replaced. So the desired output will be Id NewWordsAfterReplacement --- ------------------------ 1 How 1 are 1 you 2 is 2 me My approach so far: ;With Cte1 As( Select t1.Id ,t1.Words ,t2.ReplacementWords From tblInput t1 Cross Join tblReplacement t2) ,Cte2 As( Select Id, NewWordsAfterReplacement = REPLACE(Words,ReplacementWords,'') From Cte1) Select * from Cte2 where NewWordsAfterReplacement <> '' But I am not getting the desired output. It is replacing all the matching words. Urgent help needed*.( SET BASED )* I am using SQL Server 2005. Thanks

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• &nbsp; is inserted when user control is not visible in ASP.NET

  - by Sergej Andrejev

  Hi, I have a problem I have no idea how to solve. I have a user control wrapped inside update panel which works fine, but when I set userControl.Visible = false AJAX response containts   which generates empty lines in IE 7 and 6. As you can imagine this accupy a lot of space when I have 30 hidden user controls. What should I do to prevent   to be sent with response?

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• C++ vector that *doesn't* initialize its members?

  - by Mehrdad

  I'm making a C++ wrapper for a piece of C code that returns a large array, and so I've tried to return the data in a vector<unsigned char>. Now the problem is, the data is on the order of megabytes, and vector unnecessarily initializes its storage, which essentially turns out to cut down my speed by half. How do I prevent this? Or, if it's not possible -- is there some other STL container that would avoid such needless work? Or must I end up making my own container? (Pre-C++11) Note: I'm passing the vector as my output buffer. I'm not copying the data from elsewhere.

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• Get user IP via comment Form

  - by jasmine

  I have inserted a hidden input in my comment form: $ip = $_SERVER['REMOTE_ADDR']; <input type="hidden" name="c-ip" value="<?php echo $ip; ?>"> With this input, ip column is empty in mysql. What is wrong in input. Thanks in advance

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• what this json must work?

  - by user1772630

  hi i search alot for get a respone from php back and if that respone is ok do someting and if its false do something else(!!!!!!!! WHENE I HAVE OTHER OUTPUT FROM THAT PHP !!!!!!) this is my index file <head> <script src="jquery-1.7.2.js" type="text/javascript"></script> <script src="js.js" type="text/javascript"></script> </head> <body> <p> click </p> <input type="text" id="who"> <br> <input type="text" id="why"> <div id="bg" align="center"> </div> </body> this is my JS file $(document).ready(function(){ $('p').click(function(){ var who = $('input#who').val(); var why = $('input#why').val(); $.post('file.php',{who:who,why:why},function(data) { if(data.success){ alert(data.message); } else{ alert('ERROR:' + data.message); } }); }); }); and this is my file.php <?php $response = array('success' => 'true', 'code' => "jQuery('#bg').html('\"Javascript\", \"json\", \"PHP\"');"); echo json_encode($response); ?> my question : 1- why this is not work i get alert (error:undifined) 2- how i can get some result from that php file when its have other output like this: <?php echo "1"; echo "2"; echo "3"; and now echo that json ?> thanks :(

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• jquery plugin: creation

  - by user1542535

  The output am expecting is an unordered list which am creating with jquery...which takes in put from a json file (which works fine when i dont create it as a plugin). Am very new with the concept of building a plugin. i've tried to create one which doesnt output my unordered list json file structure { "Categories": [ { "cat_id":"1", "name":"Main Menu1", "sub_categories":[ { "cat_id":"10", "name":" Sub Menu11", "sub_level_one_link":"http:\/\/one.com" }, my js file //create plugin jQuery.fn.emrMenu= function (options) { myoptions = jQuery.extend ({ url: "error" }, options); if (myoptions.url=="error") { alert("Error:No data recieved"); return false; } $(this).html (myoptions.url); return this.each (function () { //alert(myoptions.url+this.id); $.getJSON(myoptions.url, function(data) { $.each(data.Categories, function(i, category) { alert("test1"); //get all sub menu items in list indexes var submenudata=''; $.each(category.sub_categories, function(i, sub_categories) { submenudata += "<li><a href='"+sub_categories.sub_level_one_link+"' <span>"+sub_categories.name+"</span></a></li>"; }); var menudata ="<li id='"+category.cat_id+"' class='has-sub '><a href='#'><span>"+category.name+"</span></a><ul>"+submenudata+"</ul></li>"; //stringify unordered list and bind to div var menu="<ul>"+menudata+"</ul>"; // $(menu).appendTo("#"this.id); }); }); //alert (this.id); }); } and am calling the plugin: <script> $(document).ready(function() { $('#menu_n').emrMenu ({ url: "menu_data.json"}); }); </script> I'am pretty confused at this point any help is greatly appreciated cheers!

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• Why does Java automatically decode %2F in URI encoded filenames?

  - by Lucas

  I have a java servlet that needs to write out files that have a user-configurable name. I am trying to use URI encoding to properly escape special characters, but the JRE appears to automatically convert encoded forward slashes (%2F) into path separators. Example: File dir = new File("C:\Documents and Setting\username\temp"); String fn = "Top 1/2.pdf"; URI uri = new URI( dir.toURI().toASCIIString() + URLEncoder.encoder( fn, "UTF-8" ).toString() ); File out = new File( uri ); System.out.println( dir.toURI().toASCIIString() ); System.out.println( URLEncoder.encoder( fn, "UTF-8" ).toString() ); System.out.println( uri.toASCIIString() ); System.out.println( output.toURI().toASCIIString() ); The output is: file:/C:/Documents%20and%20Settings/username/temp/ Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1/2.pdf After the new File object is instantiated, the %2F sequence is automatically converted to a forward slash and I end up with an incorrect path. Does anybody know the proper way to approach this issue? The core of the problem seems to be that uri.equals( new File(uri).toURI() ) == FALSE when there is a '%2F' in the URI. I'm planning to just use the URLEncoded string verbatim rather than trying to use the File(uri) constructor.

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• Links to my “Best of 2010” Posts

  - by ScottGu

  I hope everyone is having a Happy New Years! 2010 has been a busy blogging year for me (this is the 100th blog post I’ve done in 2010).  Several people this week suggested I put together a summary post listing/organizing my favorite posts from the year.  Below is a quick listing of some of my favorite posts organized by topic area: VS 2010 and .NET 4 Below is a series of posts I wrote (some in late 2009) about the VS 2010 and .NET 4 (including ASP.NET 4 and WPF 4) release we shipped in April: Visual Studio 2010 and .NET 4 Released Clean Web.Config Files Starter Project Templates Multi-targeting Multiple Monitor Support New Code Focused Web Profile Option HTML / ASP.NET / JavaScript Code Snippets Auto-Start ASP.NET Applications URL Routing with ASP.NET 4 Web Forms Searching and Navigating Code in VS 2010 VS 2010 Code Intellisense Improvements WPF 4 Add Reference Dialog Improvements SEO Improvements with ASP.NET 4 Output Cache Extensibility with ASP.NET 4 Built-in Charting Controls for ASP.NET and Windows Forms Cleaner HTML Markup with ASP.NET 4 - Client IDs Optional Parameters and Named Arguments in C# 4 - and a cool scenarios with ASP.NET MVC 2 Automatic Properties, Collection Initializers and Implicit Line Continuation Support with VB 2010 New <%: %> Syntax for HTML Encoding Output using ASP.NET 4 JavaScript Intellisense Improvements with VS 2010 VS 2010 Debugger Improvements (DataTips, BreakPoints, Import/Export) Box Selection and Multi-line Editing Support with VS 2010 VS 2010 Extension Manager (and the cool new PowerCommands Extension) Pinning Projects and Solutions VS 2010 Web Deployment Debugging Tips/Tricks with Visual Studio Search and Navigation Tips/Tricks with Visual Studio Visual Studio Below are some additional Visual Studio posts I’ve done (not in the first series above) that I thought were nice: Download and Share Visual Studio Color Schemes Visual Studio 2010 Keyboard Shortcuts VS 2010 Productivity Power Tools Fun Visual Studio 2010 Wallpapers Silverlight We shipped Silverlight 4 in April, and announced Silverlight 5 the beginning of December: Silverlight 4 Released Silverlight 4 Tools for VS 2010 and WCF RIA Services Released Silverlight 4 Training Kit Silverlight PivotViewer Now Available Silverlight Questions Announcing Silverlight 5 Silverlight for Windows Phone 7 We shipped Windows Phone 7 this fall and shipped free Visual Studio development tools with great Silverlight and XNA support in September: Windows Phone 7 Developer Tools Released Building a Windows Phone 7 Twitter Application using Silverlight ASP.NET MVC We shipped ASP.NET MVC 2 in March, and started previewing ASP.NET MVC 3 this summer.  ASP.NET MVC 3 will RTM in less than 2 weeks from today: ASP.NET MVC 2: Strongly Typed Html Helpers ASP.NET MVC 2: Model Validation Introducing ASP.NET MVC 3 (Preview 1) Announcing ASP.NET MVC 3 Beta and NuGet (nee NuPack) Announcing ASP.NET MVC 3 Release Candidate 1  Announcing ASP.NET MVC 3 Release Candidate 2 Introducing Razor – A New View Engine for ASP.NET ASP.NET MVC 3: Layouts with Razor ASP.NET MVC 3: New @model keyword in Razor ASP.NET MVC 3: Server-Side Comments with Razor ASP.NET MVC 3: Razor’s @: and <text> syntax ASP.NET MVC 3: Implicit and Explicit code nuggets with Razor ASP.NET MVC 3: Layouts and Sections with Razor IIS and Web Server Stack The IIS and Web Stack teams have made a bunch of great improvements to the core web server this year: Fix Common SEO Problems using the URL Rewrite Extension Introducing the Microsoft Web Farm Framework Automating Deployment with Microsoft Web Deploy Introducing IIS Express SQL CE 4 (New Embedded Database Support with ASP.NET) Introducing Web Matrix EF Code First EF Code First is a really nice new data option that enables a very clean code-oriented data workflow: Announcing Entity Framework Code-First CTP5 Release Class-Level Model Validation with EF Code First and ASP.NET MVC 3 Code-First Development with Entity Framework 4 EF 4 Code First: Custom Database Schema Mapping Using EF Code First with an Existing Database jQuery and AJAX Contributions My team began making some significant source code contributions to the jQuery project this year: jQuery Templates, Data Link and Globalization Accepted as Official jQuery Plugins jQuery Templates and Data Linking (and Microsoft contributing to jQuery) jQuery Globalization Plugin from Microsoft Patches and Hot Fixes Some useful fixes you can download prior to VS 2010 SP1: Patch for Cut/Copy “Insufficient Memory” issue with VS 2010 Patch for VS 2010 Find and Replace Dialog Growing Patch for VS 2010 Scrolling Context Menu Videos of My Talks Some recordings of technical talks I’ve done this year: ASP.NET 4, ASP.NET MVC, and Silverlight 4 Talks I did in Europe VS 2010 and ASP.NET 4 Web Forms Talk in Arizona Other About Technical Debates (and ASP.NET Web Forms and ASP.NET MVC debates in particular) ASP.NET Security Fix Now on Windows Update Upcoming Web Camps I’d like to say a big thank you to everyone who follows my blog – I really appreciate you reading it (the comments you post help encourage me to write it).  See you in the New Year! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• Adatbázis szerver konszolidáció Oracle technológiákkal - eroforrás allokálás

  - by Lajos Sárecz

  Szerver konszolidációnál alapmegoldás a virtualizáció, pedig az Oracle Database rendelkezik olyan képességekkel, melyekkel a virtualizáció elonyeit élvezhetjük, ám teljesítményben felülmúljuk azt. Több adatbázis konszolidációját meg lehet oldani egy nagy szerveren, vagy egy több szerverbol álló klaszteren. Bármelyik megoldást is választjuk (ezek elonyeivel és hátrányaival most nem foglalkozok), az egyik legfontosabb megoldandó probléma, hogy biztonsággal el tudjuk oket szeparálni akár adatbiztonsági, akár eroforrás kezelési szempontból. A szoftveres és hardveres virtualizációk lehetové teszik, hogy a szerver eroforrásait több virtuális szerver között felosszuk, ezáltal elszeparálhatók a párhuzamosan futó adatbázis példányok. Ezek a megoldások általában költségesek, plusz adminisztrációt jelentenek és teljesítmény csökkenést okoznak. Az alábbiakban röviden összeszedem, hogy az Oracle Database milyen eroforrás szeparációs technológiákkal rendelkezik, melyek jól használhatók adatbázis konszolidáció esetén: Adatbázis szolgáltatások: Azt talán minden Oracle adatbázis-kezelovel foglalkozó szakérto tudja, hogy akliensek az adatbázist az adatbázis szolgáltatás nevével érik el. Alapértelmezetten minden adatbázis egyetlen szolgáltatással rendelkezik, mely automatikusan a 'global database name' paraméterrel megegyezo nevet kapja az adatbázis létrehozásakor. Ugyanakkor egy adatbázishoz több szolgáltatás név is rendelheto. A szolgáltatásokkal csoportosíthatók a különbözo feladatokat végrehajtó kliensek, és a szolgáltatásokhoz rendelhetjük hogy melyik kliens csoportnak mennyi rendszer eroforrást allokálunk. Klaszteres adatbázisok (RAC) esetén egy szolgáltatás több adatbázis példányhoz (szerverhez) kapcsolódhat, amivel valós terheléstol függo terhelés elosztás valósítható meg (itt már szerepet kap egyébként a Resource Manager is, lásd késobb). Az alkalmazás számára irrelevánssá válik, hogy az adott szolgáltatást mely szerver szolgálja ki. A szolgáltatásokhoz kapcsolódó eroforrások menet közben dinamikusan bovíthetok, de kezelik a kieso eroforrások hiányát is (failover). Database Resource Manager: Az Oracle Database Resource Manager az adatbázis szintjén kezeli az eroforrásokat, a CPU használatot szabályozza az adatbázis terhelés kontrolljával. A Resource Manager egy CPU-n adott pillanatban csak egyetlen Oracle processz futtatását engedélyezi, miközben a többit várakoztatja (ahogy az egy operációs rendszer ütemezojében is muködik). A Resource Manager csak akkor lép muködésbe, amikor a CPU terhelése eléri a 100%-ot. Ekkor a Resource Plan-nek megfeleloen korlátozhatja az egyes eroforrás csoportok számára elérheto eroforrás (CPU) mennyiségét. Instance Caging: A Resource Manager részeként az Oracle Database 11gR2-tol elérheto Instance Caging technológiával virtualizáció és operációs rendszer szintu eroforrás felosztás nélkül az adatbázis példány szintjén lehet szabályozni az allokált CPU számot. Erre akkor lehet szükség, ha egy szerveren több példány futtatására van szükség. A Resource Manager bekapcsolásával és a cpu_count paraméter beállításával lehet adatbázis példányonként aktiválni az Instance Caging funkcionalitást. A cpu_count egy dinamikus paraméter, célszeru arra az értékre állítani, ahány CPU-t az adott adatbázis példány maximálisan igényelhet. Lehetoség van túlméretezni a példányok számára rendelkezésre álló processzorok számát. Például egy 4 CPUs- szerver esetében ha van 3 példányunk, mindháromnak adhatunk 3 CPU-t. Azonban ha mindegyik terhelés alatt van, akkor a példány számára maximum allokált CPU szám osztva összes allokált CPU számmal arányban részesül a processzorból, ami a példában 33,33%, azaz 1,33 CPU. Input Output Resource Manager (IORM):Nem csak a processzorok használatát szabályozhatjuk, lehetoség van a megosztott storage eroforrásainak felosztására is. Az Input Output Resorce Manager (IORM) alkalmazásával storage szinten tudjuk szabályozni az adatbázisok közötti és azokon belüli minimális I/O szinteket. Database Vault: Ugyanazon adatbázisba konszolidált alkalmazások esetén a rendszergazda szerepkörök szeparálása lehetséges az Oracle Database Vault technológiával. Ezzel elérheto az, hogy biztonságosan konszolidáljuk adatbázisainkat úgy, hogy minden adminisztrátor csak a hozzá tartozó adatokat, objektumokat lássa, módosíthassa.

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• Exploring packages in code

  In my previous post Searching for tasks with code you can see how to explore the control flow side of packages, drilling down through containers, task, and event handlers, but it didn’t cover the data flow. I recently saw a post on the MSDN forum asking how to edit an existing package programmatically, and the sticking point was how to find the the data flow and the components inside. This post builds on some of the previous code and shows how you can explore all objects inside a package. I took the sample Task Search application I’d written previously, and came up with a totally pointless little console application that just walks through the package and writes out the basic type and name of every object it finds, starting with the package itself e.g. Package – MyPackage . The sample package we used last time showed nested objects as well an event handler; a OnPreExecute event tucked away on the task SQL In FEL. The output of this sample tool would look like this: PackageObjects v1.0.0.0 (1.0.0.26627) Copyright (C) 2009 Konesans Ltd Processing File - Z:\Users\Darren Green\Documents\Visual Studio 2005\Projects\SSISTestProject\EventsAndContainersWithExe cSQLForSearch.dtsx Package - EventsAndContainersWithExecSQLForSearch For Loop - FOR Counter Loop Task - SQL In Counter Loop Sequence Container - SEQ For Each Loop Wrapper For Each Loop - FEL Simple Loop Task - SQL In FEL Task - SQL On Pre Execute for FEL SQL Task Sequence Container - SEQ Top Level Sequence Container - SEQ Nested Lvl 1 Sequence Container - SEQ Nested Lvl 2 Task - SQL In Nested Lvl 2 Task - SQL In Nested Lvl 1 #1 Task - SQL In Nested Lvl 1 #2 Connection Manager – LocalHost The code is very similar to what we had previously, but there are a couple of extra bits to deal with connections and to look more closely at a task and see if it is a Data Flow task. For connections your just examine the package's Connections collection as shown in the abridged snippets below. First you can see the call to the ProcessConnections method, followed by the method itself. // Load the package file Application application = new Application(); using (Package package = application.LoadPackage(filename, null)) { // Write out the package name Console.WriteLine("Package - {0}", package.Name); ... More ... // Look and the connections ProcessConnections(package.Connections); } private static void ProcessConnections(Connections connections) { foreach (ConnectionManager connectionManager in connections) { Console.WriteLine("Connection Manager - {0}", connectionManager.Name); } } What we didn’t see in the sample output above was anything to do with the Data Flow, but rest assured the code now handles it too. The following snippet shows how each task is examined to see if it is a Data Flow task, and if so we can then loop through all of the components inside the data flow. private static void ProcessTaskHost(TaskHost taskHost) { if (taskHost == null) { return; } Console.WriteLine("Task - {0}", taskHost.Name); // Check if the task is a Data Flow task MainPipe pipeline = taskHost.InnerObject as MainPipe; if (pipeline != null) { ProcessPipeline(pipeline); } } private static void ProcessPipeline(MainPipe pipeline) { foreach (IDTSComponentMetaData90 componentMetadata in pipeline.ComponentMetaDataCollection) { Console.WriteLine("Pipeline Component - {0}", componentMetadata.Name); // If you wish to make changes to the component then you should really use the managed wrapper. // CManagedComponentWrapper wrapper = componentMetadata.Instantiate(); // wrapper.SetComponentProperty("PropertyName", "Value"); } } Hopefully you can see how we get a reference to the Data Flow task, and then use the ComponentMetaDataCollection to find out what components we have inside the pipeline. If you wanted to know more about the component you could look at the ObjectType or ComponentClassID properties. After that it gets a bit harder and you should get a reference to the wrapper object as the comment suggest and start using the properties, just like you would in the create packages samples, see our Code Development category for some for these examples. Download Sample code project PackageObjects.zip (5KB)

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• ASP.NET Web API - Screencast series with downloadable sample code - Part 1

  - by Jon Galloway

  There's a lot of great ASP.NET Web API content on the ASP.NET website at http://asp.net/web-api. I mentioned my screencast series in original announcement post, but we've since added the sample code so I thought it was worth pointing the series out specifically. This is an introductory screencast series that walks through from File / New Project to some more advanced scenarios like Custom Validation and Authorization. The screencast videos are all short (3-5 minutes) and the sample code for the series is both available for download and browsable online. I did the screencasts, but the samples were written by the ASP.NET Web API team. So - let's watch them together! Grab some popcorn and pay attention, because these are short. After each video, I'll talk about what I thought was important. I'm embedding the videos using HTML5 (MP4) with Silverlight fallback, but if something goes wrong or your browser / device / whatever doesn't support them, I'll include the link to where the videos are more professionally hosted on the ASP.NET site. Note also if you're following along with the samples that, since Part 1 just looks at the File / New Project step, the screencast part numbers are one ahead of the sample part numbers - so screencast 4 matches with sample code demo 3. Note: I started this as one long post for all 6 parts, but as it grew over 2000 words I figured it'd be better to break it up. Part 1: Your First Web API [Video and code on the ASP.NET site] This screencast starts with an overview of why you'd want to use ASP.NET Web API: Reach more clients (thinking beyond the browser to mobile clients, other applications, etc.) Scale (who doesn't love the cloud?!) Embrace HTTP (a focus on HTTP both on client and server really simplifies and focuses service interactions) Next, I start a new ASP.NET Web API application and show some of the basics of the ApiController. We don't write any new code in this first step, just look at the example controller that's created by File / New Project. using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace NewProject_Mvc4BetaWebApi.Controllers { public class ValuesController : ApiController { // GET /api/values public IEnumerable<string> Get() { return new string[] { "value1", "value2" }; } // GET /api/values/5 public string Get(int id) { return "value"; } // POST /api/values public void Post(string value) { } // PUT /api/values/5 public void Put(int id, string value) { } // DELETE /api/values/5 public void Delete(int id) { } } } Finally, we walk through testing the output of this API controller using browser tools. There are several ways you can test API output, including Fiddler (as described by Scott Hanselman in this post) and built-in developer tools available in all modern browsers. For simplicity I used Internet Explorer 9 F12 developer tools, but you're of course welcome to use whatever you'd like. A few important things to note: This class derives from an ApiController base class, not the standard ASP.NET MVC Controller base class. They're similar in places where API's and HTML returning controller uses are similar, and different where API and HTML use differ. A good example of where those things are different is in the routing conventions. In an HTTP controller, there's no need for an "action" to be specified, since the HTTP verbs are the actions. We don't need to do anything to map verbs to actions; when a request comes in to /api/values/5 with the DELETE HTTP verb, it'll automatically be handled by the Delete method in an ApiController. The comments above the API methods show sample URL's and HTTP verbs, so we can test out the first two GET methods by browsing to the site in IE9, hitting F12 to bring up the tools, and entering /api/values in the URL: That sample action returns a list of values. To get just one value back, we'd browse to /values/5: That's it for Part 1. In Part 2 we'll look at getting data (beyond hardcoded strings) and start building out a sample application.

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• Creating typed WSDL’s for generic WCF services of the ESB Toolkit

  - by charlie.mott

  source: http://geekswithblogs.net/charliemott Question How do you make it easy for client systems to consume the generic WCF services exposed by the ESB Toolkit using messages that conform to agreed schemas\contracts?  Usually the developer of a system consuming a web service adds a service reference using a WSDL. However, the WSDL’s for the generic services exposed by the ESB Toolkit do not make it easy to develop clients that conform to agreed schemas\contracts. Recommendation Take a copy of the generic WSDL’s and modify it to use the proper contracts. This is very easy.  It will work with the generic on ramps so long as the <part>?</part> wrapping is removed from the WCF adapter configuration in the BizTalk receive locations.  Attempting to create a WSDL where the input and output messages are sent/returned with a <part> wrapper is a nightmare.  I have not managed it.  Consequences I can only see the following consequences of removing the <part> wrapper: ESB Test Client – I needed to modify the out-of-the-box ESB Test Client source code to make it send non-wrapped messages.  Flat file formatted messages – the endpoint will no longer support flat file message formats.  However, even if you needed to support this integration pattern through WCF, you would most-likely want to create a separate receive location anyway with its’ own independently configured XML disassembler pipeline component. Instructions These steps show how to implement a request-response implementation of this. WCF Receive Locations In BizTalk, for the WCF receive location for the ESB on-ramp, set the adapter Message settings\bindings to “UseBodyPath”: Inbound BizTalk message body  = Body Outbound WCF message body = Body Create a WSDL’s for each supported integration use-case Save a copy of the WSDL for the WCF generic receive location above that you intend the client system to use. Give it a name that mirrors the interface agreement (e.g. Esb_SuppliersSearchCommand_wsHttpBinding.wsdl).   Add any xsd schemas files imported below to this same folder.   Edit the WSDL to import schemas For example, this: <xsd:schema targetNamespace=http://microsoft.practices.esb/Imports /> … would become something like: <xsd:schema targetNamespace="http://microsoft.practices.esb/Imports">     <xsd:import schemaLocation="SupplierSearchCommand_V1.xsd"                            namespace="http://schemas.acme.co.uk/suppliersearchcommand/1.0"/>     <xsd:import  schemaLocation="SuppliersDocument_V1.xsd"                              namespace="http://schemas.acme.co.uk/suppliersdocument/1.0"/>     <xsd:import schemaLocation="Types\Supplier_V1.xsd"                              namespace="http://schemas.acme.co.uk/types/supplier/1.0"/>     <xsd:import  schemaLocation="GovTalk\bs7666-v2-0.xsd"                               namespace="http://www.govtalk.gov.uk/people/bs7666"/>     <xsd:import  schemaLocation="GovTalk\CommonSimpleTypes-v1-3.xsd"                             namespace="http://www.govtalk.gov.uk/core"/>     <xsd:import  schemaLocation="GovTalk\AddressTypes-v2-0.xsd"                              namespace="http://www.govtalk.gov.uk/people/AddressAndPersonalDetails"/> </xsd:schema> Modify the Input and Output message For example, this: <wsdl:message name="ProcessRequestResponse_SubmitRequestResponse_InputMessage">   <wsdl:part name="part" type="xsd:anyType"/> </wsdl:message> <wsdl:message name="ProcessRequestResponse_SubmitRequestResponse_OutputMessage">   <wsdl:part name="part" type="xsd:anyType"/> </wsdl:message> … would become something like: <wsdl:message name="ProcessRequestResponse_SubmitRequestResponse_InputMessage">   <wsdl:part name="part"                       element="ssc:SupplierSearchEvent"                         xmlns:ssc="http://schemas.acme.co.uk/suppliersearchcommand/1.0" /> </wsdl:message> <wsdl:message name="ProcessRequestResponse_SubmitRequestResponse_OutputMessage">   <wsdl:part name="part"                       element="sd:SuppliersDocument"                       xmlns:sd="http://schemas.acme.co.uk/suppliersdocument/1.0"/> </wsdl:message> This WSDL can now be added as a service reference in client solutions.

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• Subterranean IL: Pseudo custom attributes

  - by Simon Cooper

  Custom attributes were designed to make the .NET framework extensible; if a .NET language needs to store additional metadata on an item that isn't expressible in IL, then an attribute could be applied to the IL item to represent this metadata. For instance, the C# compiler uses DecimalConstantAttribute and DateTimeConstantAttribute to represent compile-time decimal or datetime constants, which aren't allowed in pure IL, and FixedBufferAttribute to represent fixed struct fields. How attributes are compiled Within a .NET assembly are a series of tables containing all the metadata for items within the assembly; for instance, the TypeDef table stores metadata on all the types in the assembly, and MethodDef does the same for all the methods and constructors. Custom attribute information is stored in the CustomAttribute table, which has references to the IL item the attribute is applied to, the constructor used (which implies the type of attribute applied), and a binary blob representing the arguments and name/value pairs used in the attribute application. For example, the following C# class: [Obsolete("Please use MyClass2", true)] public class MyClass { // ... } corresponds to the following IL class definition: .class public MyClass { .custom instance void [mscorlib]System.ObsoleteAttribute::.ctor(string, bool) = { string('Please use MyClass2' bool(true) } // ... } and results in the following entry in the CustomAttribute table: TypeDef(MyClass) MemberRef(ObsoleteAttribute::.ctor(string, bool)) blob -> {string('Please use MyClass2' bool(true)} However, there are some attributes that don't compile in this way. Pseudo custom attributes Just like there are some concepts in a language that can't be represented in IL, there are some concepts in IL that can't be represented in a language. This is where pseudo custom attributes come into play. The most obvious of these is SerializableAttribute. Although it looks like an attribute, it doesn't compile to a CustomAttribute table entry; it instead sets the serializable bit directly within the TypeDef entry for the type. This flag is fully expressible within IL; this C#: [Serializable] public class MySerializableClass {} compiles to this IL: .class public serializable MySerializableClass {} For those interested, a full list of pseudo custom attributes is available here. For the rest of this post, I'll be concentrating on the ones that deal with P/Invoke. P/Invoke attributes P/Invoke is built right into the CLR at quite a deep level; there are 2 metadata tables within an assembly dedicated solely to p/invoke interop, and many more that affect it. Furthermore, all the attributes used to specify p/invoke methods in C# or VB have their own keywords and syntax within IL. For example, the following C# method declaration: [DllImport("mscorsn.dll", SetLastError = true)] [return: MarshalAs(UnmanagedType.U1)] private static extern bool StrongNameSignatureVerificationEx( [MarshalAs(UnmanagedType.LPWStr)] string wszFilePath, [MarshalAs(UnmanagedType.U1)] bool fForceVerification, [MarshalAs(UnmanagedType.U1)] ref bool pfWasVerified); compiles to the following IL definition: .method private static pinvokeimpl("mscorsn.dll" lasterr winapi) bool marshal(unsigned int8) StrongNameSignatureVerificationEx( string marshal(lpwstr) wszFilePath, bool marshal(unsigned int8) fForceVerification, bool& marshal(unsigned int8) pfWasVerified) cil managed preservesig {} As you can see, all the p/invoke and marshal properties are specified directly in IL, rather than using attributes. And, rather than creating entries in CustomAttribute, a whole bunch of metadata is emitted to represent this information. This single method declaration results in the following metadata being output to the assembly: A MethodDef entry containing basic information on the method Four ParamDef entries for the 3 method parameters and return type An entry in ModuleRef to mscorsn.dll An entry in ImplMap linking ModuleRef and MethodDef, along with the name of the function to import and the pinvoke options (lasterr winapi) Four FieldMarshal entries containing the marshal information for each parameter. Phew! Applying attributes Most of the time, when you apply an attribute to an element, an entry in the CustomAttribute table will be created to represent that application. However, some attributes represent concepts in IL that aren't expressible in the language you're coding in, and can instead result in a single bit change (SerializableAttribute and NonSerializedAttribute), or many extra metadata table entries (the p/invoke attributes) being emitted to the output assembly.

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• How do you install a USB CD Rom drive?

  - by Matt Allen

  Hello, I recently purchased a USB CD ROM drive, but I don't know how to get it to work with my computer which runs Ubuntu 10.04. http://www.amazon.com/gp/product/B00303H908/ref=oss_product When I issue the lsusb command, it shows up as: Bus 002 Device 016: ID 05e3:0701 Genesys Logic, Inc. USB 2.0 IDE Adapter The computer doesn't recognize it automatically. How can I get this drive to show up as an actual drive on my computer? If this particular drive can't handle Linux, can you recommended one which can and provide a link to it so I can purchase it? Thanks! Update: I was asked by Scaine to run a command and report back with the output: joe@joe-laptop:~$ tail -f /var/log/kern.log Dec 29 12:51:35 joe-laptop kernel: [103190.551437] sr 7:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 12:51:35 joe-laptop kernel: [103190.551446] sr 7:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 12:51:35 joe-laptop kernel: [103190.551463] end_request: I/O error, dev sr1, sector 0 Dec 29 12:51:35 joe-laptop kernel: [103190.877542] sr 7:0:0:0: [sr1] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Dec 29 12:51:35 joe-laptop kernel: [103190.877551] sr 7:0:0:0: [sr1] Sense Key : Illegal Request [current] Dec 29 12:51:35 joe-laptop kernel: [103190.877559] Info fld=0x0, ILI Dec 29 12:51:35 joe-laptop kernel: [103190.877562] sr 7:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 12:51:35 joe-laptop kernel: [103190.877572] sr 7:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 12:51:35 joe-laptop kernel: [103190.877588] end_request: I/O error, dev sr1, sector 0 Dec 29 13:08:46 joe-laptop kernel: [104221.558911] usb 2-2.2: USB disconnect, address 16 Then when I plugged the drive back into the computer, I got: Dec 29 13:10:29 joe-laptop kernel: [104324.668320] usb 2-2.2: new high speed USB device using ehci_hcd and address 17 Dec 29 13:10:29 joe-laptop kernel: [104324.761702] usb 2-2.2: configuration #1 chosen from 1 choice Dec 29 13:10:29 joe-laptop kernel: [104324.762700] scsi8 : SCSI emulation for USB Mass Storage devices Dec 29 13:10:29 joe-laptop kernel: [104324.762935] usb-storage: device found at 17 Dec 29 13:10:29 joe-laptop kernel: [104324.762938] usb-storage: waiting for device to settle before scanning Dec 29 13:10:34 joe-laptop kernel: [104329.760521] usb-storage: device scan complete Dec 29 13:10:34 joe-laptop kernel: [104329.761344] scsi 8:0:0:0: CD-ROM TEAC CD-224E 1.7A PQ: 0 ANSI: 0 CCS Dec 29 13:10:34 joe-laptop kernel: [104329.767425] sr1: scsi3-mmc drive: 24x/24x cd/rw xa/form2 cdda tray Dec 29 13:10:34 joe-laptop kernel: [104329.767612] sr 8:0:0:0: Attached scsi CD-ROM sr1 Dec 29 13:10:34 joe-laptop kernel: [104329.767720] sr 8:0:0:0: Attached scsi generic sg2 type 5 Dec 29 13:10:34 joe-laptop kernel: [104330.141060] sr 8:0:0:0: [sr1] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Dec 29 13:10:34 joe-laptop kernel: [104330.141069] sr 8:0:0:0: [sr1] Sense Key : Illegal Request [current] Dec 29 13:10:34 joe-laptop kernel: [104330.141077] Info fld=0x0, ILI Dec 29 13:10:34 joe-laptop kernel: [104330.141081] sr 8:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 13:10:34 joe-laptop kernel: [104330.141090] sr 8:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 13:10:34 joe-laptop kernel: [104330.141106] end_request: I/O error, dev sr1, sector 0 Dec 29 13:10:34 joe-laptop kernel: [104330.141113] __ratelimit: 18 callbacks suppressed There was more output than this (the number of lines started growing after the drive was plugged back in, and kept growing), but this is the first few lines.

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• Getting Started with Chart control in ASP.Net 4.0

  - by sreejukg

  In this article I am going to demonstrate the Chart control available in ASP.Net 4 and Visual Studio 2010. Most of the web applications need to generate reports for business users. The business users are happy to view the results in a graphical format more that seeing it in numbers. For the purpose of this demonstration, I have created a sales table. I am going to create charts from this sale data. The sale table looks as follows I have created an ASP.Net web application project in Visual Studio 2010. I have a default.aspx page that I am going to use for the demonstration. First I am going to add a chart control to the page. Visual Studio 2010 has a chart control. The Chart Control comes under the Data Tab in the toolbox. Drag and drop the Chart control to the default.aspx page. Visual Studio adds the below markup to the page. <asp:Chart ID="Chart1" runat="server"></asp:Chart> In the designer view, the Chart controls gives the following output. As you can see this is exactly similar to other server controls in ASP.Net, and similar to other controls under the data tab, Chart control is also a data bound control. So I am going to bind this with my sales data. From the design view, right click the chart control and select “show smart tag” Here you need so choose the Data source property and the chart type. From the choose data source drop down, select new data source. In the data source configuration wizard, select the SQL data base and write the query to retrieve the data. At first I am going to show the chart for amount of sales done by each sales person. I am going to use the following query inside sqldatasource select command. “SELECT SUM(SaleAmount) AS Expr1, salesperson FROM SalesData GROUP BY SalesPerson” This query will give me the amount of sales achieved by each sales person. The mark up of SQLDataSource is as follows. <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:SampleConnectionString %>" SelectCommand="SELECT SUM(SaleAmount) as amount, SalesPerson FROM SalesData GROUP BY SalesPerson"></asp:SqlDataSource> Once you selected the data source for the chart control, you need to select the X and Y values for the columns. I have entered salesperson in the X Value member and amount in the Y value member. After modifications, the Chart control looks as follows Click F5 to run the application. The output of the page is as follows. Using ASP.Net it is much easier to represent your data in graphical format. To show this chart, I didn’t even write any single line of code. The chart control is a great tool that helps the developer to show the business intelligence in their applications without using third party products. I will write another blog that explore further possibilities that shows more reports by using the same sales data. If you want to get the Project in zipped format, post your email below.

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• Do NOT Change "Copy Local” project references to false, unless understand subsequences.

  - by Michael Freidgeim

  To optimize performance of visual studio build I've found multiple recommendations to change CopyLocal property for dependent dlls to false,e.g. From http://stackoverflow.com/questions/690033/best-practices-for-large-solutions-in-visual-studio-2008 CopyLocal? For sure turn this offhttp://stackoverflow.com/questions/280751/what-is-the-best-practice-for-copy-local-and-with-project-referencesAlways set the Copy Local property to false and enforce this via a custom msbuild stephttp://codebetter.com/patricksmacchia/2007/06/20/benefit-from-the-c-and-vb-net-compilers-perf/BenefitBenefitMy advice is to always set ‘Copy Local’ to falseSome time ago we've tried to change the setting to false, and found that it causes problem for deployment of top-level projects.Recently I've followed the suggestion and changed the settings for middle-level projects. It didn't cause immediate issues, but I was warned by Readify Consultant Colin Savage about possible errors during deploymentsI haven't undone the changes immediately and we found a few issues during testing.There are many scenarios, when you need to have Copy Local’ left to True.The concerns are highlighted in some stack overflow answers, but they have small number of votes.Top-level projects:  set copy local = true.First of all, it doesn't work correctly for top-level projects, i.e. executables or web sites.As pointed in the answer http://stackoverflow.com/a/6529461/52277for all the references in the one at the top set copy local = true.Alternatively you have to change output directory as it's described in http://www.simple-talk.com/dotnet/.net-framework/partitioning-your-code-base-through-.net-assemblies-and-visual-studio-projects/If you set ‘ Copy Local = false’, VS will, unless you tell it otherwise, place each assembly alone in its own .\bin\Debugdirectory. Because of this, you will need to configure VS to place assemblies together in the same directory. To do so, for each VS project, go to VS > Project Properties > Build tab > Output path, and set the Ouput path to ..\bin\Debugfor debug configuration, and ..\bin\Release for release configuration.Second-level  dependencies:  set copy local = true.Another example when copylocal =false fails on run-time, is when top level assembly doesn't directly referenced one of indirect dependencies.E..g. Top-level assembly A has reference to assembly B with copylocal =true, but assembly B has reference to assembly C with copylocal =false. Most likely assembly C will be missing on runtime and will cause errors E.g. http://stackoverflow.com/questions/602765/when-should-copy-local-be-set-to-true-and-when-should-it-not?lq=1Copy local is important for deployment scenarios and tools. As a general rule you should use CopyLocal=True and http://stackoverflow.com/questions/602765/when-should-copy-local-be-set-to-true-and-when-should-it-not?lq=1 Unfortunately there are some quirks and CopyLocal won't necessary work as expected for assembly references in secondary assemblies structured as shown below.MainApp.exe MyLibrary.dll ThirdPartyLibrary.dll (if in the GAC CopyLocal won't copy to MainApp bin folder)This makes xcopy deployments difficult . .Reflection called DLLs  dependencies:  set copy local = true.E.g user can see error "ISystem.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information."The fix for the issue is recommended in http://stackoverflow.com/a/6200173/52277"I solved this issue by setting the Copy Local attribute of my project's references to true."In general, the problems with investigation of deployment issues may overweight the benefits of reduced build time. Setting the Copy Local to false without considering deployment issues is not a good idea.

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• No more internet connection after update in 14.04 with Intel Dual Band Wireless AC 7260

  - by luis

  My Dell XPS 15 (haswell) was working fine until I stupidly accepted recently to apply Ubuntu updates. Since then, my wifi does not work (it shows "device not managed" when clicking wifi icon in toolbar). Even USB to Ethernet adapter does not seem to work. Bluetooth at least "sees" other bluetooth devices around... See below output from dmesg (dmesg |grep iwl) : [ 886.462459] iwlwifi 0000:06:00.0: irq 51 for MSI/MSI-X [ 886.462561] iwlwifi 0000:06:00.0: Direct firmware load failed with error -2 [ 886.462562] iwlwifi 0000:06:00.0: Falling back to user helper [ 886.463284] iwlwifi 0000:06:00.0: loaded firmware version 22.1.7.0 op_mode iwlmvm [ 886.475345] iwlwifi 0000:06:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144 [ 886.475433] iwlwifi 0000:06:00.0: L1 Enabled; Disabling L0S [ 886.475684] iwlwifi 0000:06:00.0: L1 Enabled; Disabling L0S [ 886.689214] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs' Below the output from modinfo iwlwifi: filename: /lib/modules/3.13.0-29- generic/kernel/drivers/net/wireless/iwlwifi/iwlwifi.ko license: GPL author: Copyright(c) 2003-2013 Intel Corporation <[email protected]> version: in-tree: description: Intel(R) Wireless WiFi driver for Linux firmware: iwlwifi-100-5.ucode firmware: iwlwifi-1000-5.ucode firmware: iwlwifi-135-6.ucode firmware: iwlwifi-105-6.ucode firmware: iwlwifi-2030-6.ucode firmware: iwlwifi-2000-6.ucode firmware: iwlwifi-5150-2.ucode firmware: iwlwifi-5000-5.ucode firmware: iwlwifi-6000g2b-6.ucode firmware: iwlwifi-6000g2a-5.ucode firmware: iwlwifi-6050-5.ucode firmware: iwlwifi-6000-4.ucode firmware: iwlwifi-3160-7.ucode firmware: iwlwifi-7260-7.ucode srcversion: 1E6912E109D5A43B310FB34 alias: pci:v00008086d0000095Asv*sd00005490bc*sc*i* (a pack of lines of kind "alias: pci:xxxxx...." that I guess are not helpful) alias: pci:v00008086d0000095Bsv*sd00005290bc*sc*i* depends: cfg80211 intree: Y vermagic: 3.13.0-29-generic SMP mod_unload modversions signer: Magrathea: Glacier signing key sig_key: 66:02:CB:36:F1:31:3B:EA:01:C4:BD:A9:65:67:CF:A7:23:C9:70:D8 sig_hashalgo: sha512 parm: swcrypto:using crypto in software (default 0 [hardware]) (int) parm: 11n_disable:disable 11n functionality, bitmap: 1: full, 2: disable agg TX, 4: disable agg RX, 8 enable agg TX (uint) parm: amsdu_size_8K:enable 8K amsdu size (default 0) (int) parm: fw_restart:restart firmware in case of error (default true) (bool) parm: antenna_coupling:specify antenna coupling in dB (defualt: 0 dB) (int) parm: wd_disable:Disable stuck queue watchdog timer 0=system default, 1=disable, 2=enable (default: 0) (int) parm: nvm_file:NVM file name (charp) parm: bt_coex_active:enable wifi/bt co-exist (default: enable) (bool) parm: led_mode:0=system default, 1=On(RF On)/Off(RF Off), 2=blinking, 3=Off (default: 0) (int) parm: power_save:enable WiFi power management (default: disable) (bool) parm: power_level:default power save level (range from 1 - 5, default: 1) (int) I downloaded the latest versions of iwlwifi firmware from git (git clone git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git; copy iwlwifi-3160-9.ucode iwlwifi-7260-9.ucode iwlwifi-7265-9.ucode to /lib/firmware and reboot) but as you can imagine it did not help. Update #1: Downloaded from http://wireless.kernel.org/en/users/Drivers/iwlwifi?action=AttachFile&do=get&target=iwlwifi-7260-ucode-22.15.8.0.tgz and copied the file into /lib/firmware. After reloading it with modprobe, it seems to be OK: [ 14.761283] iwlwifi 0000:06:00.0: enabling device (0000 -> 0002) [ 14.761472] iwlwifi 0000:06:00.0: irq 51 for MSI/MSI-X [ 14.772478] iwlwifi 0000:06:00.0: loaded firmware version 22.15.8.0 op_mode iwlmvm [ 14.800274] iwlwifi 0000:06:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144 [ 14.800349] iwlwifi 0000:06:00.0: L1 Enabled; Disabling L0S [ 14.800657] iwlwifi 0000:06:00.0: L1 Enabled; Disabling L0S [ 15.007048] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs' However, clicking in wifi in the toolbar still shows "device not managed". Any clues? Many thanks! Luis

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• value types in the vm

  - by john.rose

  value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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• Clone a Hard Drive Using an Ubuntu Live CD

  - by Trevor Bekolay

  Whether you’re setting up multiple computers or doing a full backup, cloning hard drives is a common maintenance task. Don’t bother burning a new boot CD or paying for new software – you can do it easily with your Ubuntu Live CD. Not only can you do this with your Ubuntu Live CD, you can do it right out of the box – no additional software needed! The program we’ll use is called dd, and it’s included with pretty much all Linux distributions. dd is a utility used to do low-level copying – rather than working with files, it works directly on the raw data on a storage device. Note: dd gets a bad rap, because like many other Linux utilities, if misused it can be very destructive. If you’re not sure what you’re doing, you can easily wipe out an entire hard drive, in an unrecoverable way. Of course, the flip side of that is that dd is extremely powerful, and can do very complex tasks with little user effort. If you’re careful, and follow these instructions closely, you can clone your hard drive with one command. We’re going to take a small hard drive that we’ve been using and copy it to a new hard drive, which hasn’t been formatted yet. To make sure that we’re working with the right drives, we’ll open up a terminal (Applications > Accessories > Terminal) and enter in the following command sudo fdisk –l We have two small drives, /dev/sda, which has two partitions, and /dev/sdc, which is completely unformatted. We want to copy the data from /dev/sda to /dev/sdc. Note: while you can copy a smaller drive to a larger one, you can’t copy a larger drive to a smaller one with the method described below. Now the fun part: using dd. The invocation we’ll use is: sudo dd if=/dev/sda of=/dev/sdc In this case, we’re telling dd that the input file (“if”) is /dev/sda, and the output file (“of”) is /dev/sdc. If your drives are quite large, this can take some time, but in our case it took just less than a minute. If we do sudo fdisk –l again, we can see that, despite not formatting /dev/sdc at all, it now has the same partitions as /dev/sda.  Additionally, if we mount all of the partitions, we can see that all of the data on /dev/sdc is now the same as on /dev/sda. Note: you may have to restart your computer to be able to mount the newly cloned drive. And that’s it…If you exercise caution and make sure that you’re using the right drives as the input file and output file, dd isn’t anything to be scared of. Unlike other utilities, dd copies absolutely everything from one drive to another – that means that you can even recover files deleted from the original drive in the clone! Similar Articles Productive Geek Tips Reset Your Ubuntu Password Easily from the Live CDHow to Browse Without a Trace with an Ubuntu Live CDRecover Deleted Files on an NTFS Hard Drive from a Ubuntu Live CDCreate a Bootable Ubuntu 9.10 USB Flash DriveWipe, Delete, and Securely Destroy Your Hard Drive’s Data the Easy Way TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 Windows Media Player Glass Icons (icons we like) How to Forecast Weather, without Gadgets Outlook Tools, one stop tweaking for any Outlook version Zoofs, find the most popular tweeted YouTube videos Video preview of new Windows Live Essentials 21 Cursor Packs for XP, Vista & 7

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• Assign highest priority to my local repository

  - by Anwar Shah

  Original question was : "How to assign highest priority to local repository without using sources.list file" I have setup a local repository with packages I downloaded. I use it to avoid downloading the same packages over the Internet, when I need to reinstall my Ubuntu. It is a basic repository, created with apt-ftparchive packages . > Packages. I made this a trusted repository to avoid "unauthenticated repository" warning. (When you have a untrusted repository, apt or synaptic try to download the same packages over the Internet, 'cause it is trusted). I have been using this local repository for at least 1 years. But I have to always put my local repository line at the top of the sources.list file to use this. But this is annoying, since I must open a terminal and do some typing on it every time I reinstall Ubuntu, though there is a better tool software-properties-gtk. I cannot use this tool since it place the source line at the end of `sources.list. And the real problem is that, the apt or synaptic always download a package from the source which is mentioned earlier, without inspecting whether the packages are already available in the local repository. So, I have no choice but to place the local source at the top of sources.list doing terminal (I actually don't hate terminal, but I need a solution) . I have tried this method. But this does not help me. My preference file is this in /etc/apt/preferences.d/local-pin-900 Package: * Pin: release o=Local,n=ubuntu-local Pin-Priority: 900 My release file is this Origin: Local Label: Local-Ubuntu Description: Local Ubuntu Repository Codename: ubuntu-local MD5Sum: ed43222856d18f389c637ac3d7dd6f85 1043412 Packages d41d8cd98f00b204e9800998ecf8427e 0 Sources When I enable the apt-preference, the apt-cache policy correctly shows the preference, e.g. It shows the local repository has the highest priority. But when I do this sudo apt-get install <package-name>, apt tries to download it from Internet. But when I place my local-repo at the top, it installs from local repository. So, My question is - 'Is it possible to force apt to use local repository when the package is available in local repository, without explicitly placing "the local source" at the top of my repository list (e.g sources.list file) ?' Edit: output of apt-cache policy $package_name is as follows nautilus-wipe: Installed: (none) Candidate: 0.1.1-2 Version table: 0.1.1-2 0 500 http://archive.ubuntu.com/ubuntu/ precise/universe i386 Packages 900 file:/media/Main/Linux-Software/Ubuntu/Precise/ Packages It is showing that my local repository has higher preference, though it is not the one which comes first in sources.list file. Here is the output of apt-get install nautilus-wipe Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: nautilus-wipe 0 upgraded, 1 newly installed, 0 to remove and 131 not upgraded. Need to get 30.7 kB of archives. After this operation, 150 kB of additional disk space will be used. 'http://archive.ubuntu.com/ubuntu/pool/universe/n/nautilus-wipe/nautilus-wipe_0.1.1-2_i386.deb' nautilus-wipe_0.1.1-2_i386.deb 30730 MD5Sum:7d497b8dfcefe1c0b51a45f3b0466994 It is still trying to get the file from Internet, though I think it should be happy with the local one.

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