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  • How is the PHP extensions/modules file structure logic based?

    - by dotpointer
    I'm trying to configure/build PHP 5.3.10 on Linux/Slackware 12 but the extensions appear in the wrong directory when I run make install. In the php.ini file is the extension dir defined: /usr/lib/php/extensions Problem is that when I run "make install" the newly built extensions are copied to a subfolder in extensions directory: /usr/lib/php/extensions/no-debug-non-zts-20090626 What am I supposed to do with this... copy the files down from the no-debug-non-zts-20090626 directory into the extensions directory, create symlinks from extensions to the modules in the no-debug-non-zts-20090626 directory (which will take a lot of time) or what? (I know I can do any of them, but I want to know the correct way...)

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  • MVC2 and MVC Futures causing RedirectToAction issues

    - by Darragh
    I've been trying to get the strongly typed version of RedirectToAction from the MVC Futures project to work, but I've been getting no where. Below are the steps I've followed, and the errors I've encountered. Any help is much appreciated. I created a new MVC2 app and changed the About action on the HomeController to redirect to the Index page. Return RedirectToAction("Index") However, I wanted to use the strongly typed extensions, so I downloaded the MVC Futures from CodePlex and added a reference to Microsoft.Web.Mvc to my project. I addded the following "import" statement to the top of HomeContoller.vb Imports Microsoft.Web.Mvc I commented out the above RedirectToAction and added the following line: Return RedirectToAction(Of HomeController)(Function(c) c.Index()) So far, so good. However, I noticed if I uncomment out the first (non Generic) RedirectToAction, it was now causing the following compile error: Error 1 Overload resolution failed because no accessible 'RedirectToAction' can be called with these arguments: Extension method 'Public Function RedirectToAction(Of TController)(action As System.Linq.Expressions.Expression(Of System.Action(Of TController))) As System.Web.Mvc.RedirectToRouteResult' defined in 'Microsoft.Web.Mvc.ControllerExtensions': Data type(s) of the type parameter(s) cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error. Extension method 'Public Function RedirectToAction(action As System.Linq.Expressions.Expression(Of System.Action(Of HomeController))) As System.Web.Mvc.RedirectToRouteResult' defined in 'Microsoft.Web.Mvc.ControllerExtensions': Value of type 'String' cannot be converted to 'System.Linq.Expressions.Expression(Of System.Action(Of mvc2test1.HomeController))'. Even though intelli-sense was showing 8 overloads (the original 6 non-generic overloads, plus the 2 new generic overloads from the Futures assembly), it seems when trying to complie the code, the compiler would only 'find' the 2 non-gneneric extension methods from the Futures assessmbly. I thought this might be an issue that I was using conflicting versions of the MVC2 assembly, and the futures assembly, so I added MvcDiaganotics.aspx from the Futures download to my project and everytyhing looked correct: ASP.NET MVC Assembly Information (System.Web.Mvc.dll) Assembly version: ASP.NET MVC 2 RTM (2.0.50217.0) Full name: System.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 Code base: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Web.Mvc/2.0.0.0__31bf3856ad364e35/System.Web.Mvc.dll Deployment: GAC-deployed ASP.NET MVC Futures Assembly Information (Microsoft.Web.Mvc.dll) Assembly version: ASP.NET MVC 2 RTM Futures (2.0.50217.0) Full name: Microsoft.Web.Mvc, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null Code base: file:///xxxx/bin/Microsoft.Web.Mvc.DLL Deployment: bin-deployed This is driving me crazy! Becuase I thought this might be some VB issue, I created a new MVC2 project using C# and tried the same as above. I added the following "using" statement to the top of HomeController.cs using Microsoft.Web.Mvc; This time, in the About action method, I could only manage to call the non-generic RedirectToAction by typing the full commmand as follows: return Microsoft.Web.Mvc.ControllerExtensions.RedirectToAction<HomeController>(this, c => c.Index()); Even though I had a "using" statement at the top of the class, if I tried to call the non-generic RedirectToAction as follows: return RedirectToAction<HomeController>(c => c.Index()); I would get the following compile error: Error 1 The non-generic method 'System.Web.Mvc.Controller.RedirectToAction(string)' cannot be used with type arguments What gives? It's not like I'm trying to do anything out of the ordinary. It's a simple vanilla MVC2 project with only a reference to the Futures assembly. I'm hoping that I've missed out something obvious, but I've been scratching my head for too long, so I figured I'd seek some assisstance. If anyone's managed to get this simple scenario working (in VB and/or C#) could they please let me know what, if anything, they did differently? Thanks!

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  • To divide the big text into columns.

    - by kalininew
    Problem: There is a big piece of the text: <div class="cont"> <p> Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo. Nemo enim ipsam voluptatem, quia voluptas sit, aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos, qui ratione voluptatem sequi nesciunt, neque porro quisquam est, qui dolorem ipsum, quia dolor sit, amet, </p> <p> consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt, ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit, qui in ea voluptate velit esse, quam nihil molestiae consequatur, vel illum, qui dolorem eum fugiat, quo voluptas nulla pariatur? At vero eos et </p> <p> accusamus et iusto odio dignissimos ducimus, qui blanditiis praesentium voluptatum deleniti atque corrupti, quos dolores et quas molestias excepturi sint, obcaecati cupiditate non provident, similique sunt in culpa, qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio, cumque nihil impedit, quo minus id, quod maxime placeat, </p> <p> facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet, ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat. </p> <p> Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo. Nemo enim ipsam voluptatem, quia voluptas sit, aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos, qui ratione voluptatem sequi nesciunt, neque porro quisquam est, qui dolorem ipsum, quia dolor sit, amet, </p> <p> consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt, ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit, qui in ea voluptate velit esse, quam nihil molestiae consequatur, vel illum, qui dolorem eum fugiat, quo voluptas nulla pariatur? At vero eos et </p> <p> accusamus et iusto odio dignissimos ducimus, qui blanditiis praesentium voluptatum deleniti atque corrupti, quos dolores et quas molestias excepturi sint, obcaecati cupiditate non provident, similique sunt in culpa, qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio, cumque nihil impedit, quo minus id, quod maxime placeat, </p> <p> facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet, ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat. </p> </div> It is necessary: To divide it on two columns. On page it should be divided on two about identical (on height) columns. If it is possible: at change of the sizes of the container of the text, a column should remain identical height. Whether probably to set number "n" - on how many columns to divide the big piece of the text. That is to divide the text into any number of columns. Is available: php, xslt, css, pure javascript (without jQuey). What tool is better for using? As it to make, that the decision was ?ross browser compatible.

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  • Gone fishing, because i like it

    - by NewDi
    Integer orci risus, vestibulum et pharetra in, accumsan sit amet diam. Praesent rutrum faucibus tellus, at ullamcorper ligula vestibulum non. Nam felis tortor, tempor nec tincidunt vel, porta a nisi. Cras dictum, orci vitae varius feugiat, lorem nisi euismod nisi, vel sodales ante ipsum ut sapien. Praesent varius, ligula sit amet laoreet mattis, nulla nisi tincidunt urna, at placerat libero leo id mauris. Fusce pretium facilisis quam, nec vulputate nulla faucibus non. Donec sodales iaculis dui in gravida. Sed consequat scelerisque eros, quis pulvinar ipsum auctor ac. Sed odio felis, euismod at tincidunt in, sagittis vel lacus. Praesent vitae nisi non augue fringilla ornare. Phasellus interdum tellus quis elit blandit mattis eu id sapien. Duis at augue libero, quis mattis lorem. Morbi ut mauris ligula, nec dapibus quam. Suspendisse et ipsum enim. Suspendisse vel erat lorem. Sed id velit risus, porttitor pharetra urna. Fusce vestibulum elementum turpis in vehicula. Nullam eu nulla ipsum. Ut viverra diam quis urna congue in ullamcorper massa hendrerit. Curabitur convallis tempor ipsum et condimentum. Suspendisse eget enim tellus. Cras id sapien elit, sit amet rutrum tortor. Quisque ac odio tortor, et vestibulum turpis. Integer et magna in erat placerat placerat. Proin ac dapibus leo. Sed fringilla cursus quam quis ornare. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; In nec diam sapien. Mauris ac enim dolor, a fringilla lorem. Nulla facilisi. Fusce bibendum quam vitae lorem placerat imperdiet. Phasellus molestie quam vehicula dolor auctor a dapibus lorem rhoncus. Fusce non arcu augue. Aliquam mollis placerat molestie. Duis quis diam vel erat porta bibendum vel id lacus. Quisque nec purus id magna imperdiet adipiscing non dictum sem. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Donec enim metus, tincidunt quis eleifend at, tristique in sem. In elit elit, lobortis cursus lobortis eu, scelerisque vel mi. Fusce at leo ac mi porta feugiat. Etiam nec facilisis sem. Pellentesque bibendum, felis sit amet vehicula convallis, libero dolor venenatis sapien, in pretium nulla odio quis dolor. Praesent mollis porttitor quam, in elementum odio condimentum at. Sed elit odio, aliquam nec molestie in, tempor eget felis. Suspendisse lobortis magna lorem. Suspendisse nisl risus, sollicitudin non imperdiet eu, vestibulum sit amet elit. Praesent vulputate molestie ante, sit amet sagittis enim egestas a. Vestibulum ultrices iaculis dolor eget pharetra. Nam purus velit, sodales eu facilisis at, imperdiet at mauris. Nulla et enim vitae nulla luctus gravida a a dui. Pellentesque sollicitudin, libero nec scelerisque bibendum, ipsum tortor vehicula ipsum, at ultricies massa nisi in nibh. Suspendisse vel pharetra odio. Fusce neque sapien, commodo in interdum nec, scelerisque vitae nunc. Nunc eu sapien ac justo placerat cursus in eu felis. Maecenas ultrices vestibulum iaculis. Proin vel risus erat, nec consectetur turpis. Etiam odio erat, placerat quis porta vel, euismod vel nibh. Nulla tristique molestie lacinia. Pellentesque molestie enim vel enim condimentum eu imperdiet nulla pellentesque. Ut arcu lectus, sodales eget varius ac, pharetra quis mauris. Quisque odio est, posuere vel auctor ut, elementum nec.

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  • C++/msvc6 application crashes due to heap corruption, any hints?

    - by David Alfonso
    Hello all, let me say first that I'm writing this question after months of trying to find out the root of a crash happening in our application. I'll try to detail as much as possible what I've already found out about it. About the application It runs on Windows XP Professional SP2. It's built with Microsoft Visual C++ 6.0 with Service Pack 6. It's MFC based. It uses several external dlls (e.g. Xerces, ZLib or ACE). It has high performance requirements. It does a lot of network and hard disk I/O, but it's also cpu intensive. It has an exception handling mechanism which generates a minidump when an unhandled exception occurs. Facts about the crash It only happens on multiprocessor/multicore machines and under heavy loads of work. It happens at random (neither we nor our client have found a pattern yet). We cannot reproduce the crash on our testing lab. It only happens on some production systems (but always in multicore machines) It always ends up crashing at the same point, although the complete stack is not always the same. Let me add the stack of the crashing thread (obtained using WinDbg, sorry we don't have symbols) ChildEBP RetAddr Args to Child WARNING: Stack unwind information not available. Following frames may be wrong. 030af6c8 7c9206eb 77bfc3c9 01a80000 00224bc3 MyApplication+0x2a85b9 030af960 7c91e9c0 7c92901b 00000ab4 00000000 ntdll!RtlAllocateHeap+0xeac (FPO: [Non-Fpo]) 030af98c 7c9205c8 00000001 00000000 00000000 ntdll!ZwWaitForSingleObject+0xc (FPO: [3,0,0]) 030af9c0 7c920551 01a80898 7c92056d 313adfb0 ntdll!RtlpFreeToHeapLookaside+0x22 (FPO: [2,0,4]) 030afa8c 4ba3ae96 000307da 00130005 00040012 ntdll!RtlFreeHeap+0x1e9 (FPO: [Non-Fpo]) 030afacc 77bfc2e3 0214e384 3087c8d8 02151030 0x4ba3ae96 030afb00 7c91e306 7c80bfc1 00000948 00000001 msvcrt!free+0xc8 (FPO: [Non-Fpo]) 030afb20 0042965b 030afcc0 0214d780 02151218 ntdll!ZwReleaseSemaphore+0xc (FPO: [3,0,0]) 030afb7c 7c9206eb 02e6c471 02ea0000 00000008 MyApplication+0x2965b 030afe60 7c9205c8 02151248 030aff38 7c920551 ntdll!RtlAllocateHeap+0xeac (FPO: [Non-Fpo]) 030afe74 7c92056d 0210bfb8 02151250 02151250 ntdll!RtlpFreeToHeapLookaside+0x22 (FPO: [2,0,4]) 030aff38 77bfc2de 01a80000 00000000 77bfc2e3 ntdll!RtlFreeHeap+0x647 (FPO: [Non-Fpo]) 7c92056d c5ffffff ce7c94be ff7c94be 00ffffff msvcrt!free+0xc3 (FPO: [Non-Fpo]) 7c920575 ff7c94be 00ffffff 12000000 907c94be 0xc5ffffff 7c920579 00ffffff 12000000 907c94be 90909090 0xff7c94be *** WARNING: Unable to verify checksum for xerces-c_2_7.dll *** ERROR: Symbol file could not be found. Defaulted to export symbols for xerces-c_2_7.dll - 7c92057d 12000000 907c94be 90909090 8b55ff8b MyApplication+0xbfffff 7c920581 907c94be 90909090 8b55ff8b 08458bec xerces_c_2_7 7c920585 90909090 8b55ff8b 08458bec 04408b66 0x907c94be 7c920589 8b55ff8b 08458bec 04408b66 0004c25d 0x90909090 7c92058d 08458bec 04408b66 0004c25d 90909090 0x8b55ff8b The address MyApplication+0x2a85b9 corresponds to a call to erase() of a std::list. What I have tried so far Reviewing all the code related to the point where the crash ends happening. Trying to enable pageheap on our testing lab though nothing useful has been found by now. We have substituted the std::list for a C array and then it crashes in other part of the code (although it is related code, it's not in the code where the old list resided). Coincidentally, now it crashes in another erase, though this time of a std::multiset. Let me copy the stack contained in the dump: ntdll.dll!_RtlpCoalesceFreeBlocks@16() + 0x124e bytes ntdll.dll!_RtlFreeHeap@12() + 0x91f bytes msvcrt.dll!_free() + 0xc3 bytes MyApplication.exe!006a4fda() [Frames below may be incorrect and/or missing, no symbols loaded for MyApplication.exe] MyApplication.exe!0069f305() ntdll.dll!_NtFreeVirtualMemory@16() + 0xc bytes ntdll.dll!_RtlpSecMemFreeVirtualMemory@16() + 0x1b bytes ntdll.dll!_ZwWaitForSingleObject@12() + 0xc bytes ntdll.dll!_RtlpFreeToHeapLookaside@8() + 0x26 bytes ntdll.dll!_RtlFreeHeap@12() + 0x114 bytes msvcrt.dll!_free() + 0xc3 bytes c5ffffff() Possible solutions (that I'm aware of) which cannot be applied "Migrate the application to a newer compiler": We are working on this but It's not a solution at the moment. "Enable pageheap (normal or full)": We can't enable pageheap on production machines as this affects performance heavily. I think that's all I remember now, if I have forgotten something I'll add it asap. If you can give me some hint or propose some possible solution, don't hesitate to answer! Thank you in advance for your time and advice.

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  • Thread Synchronization and Synchronization Primitives

    When considering synchronization in an application, the decision truly depends on what the application and its worker threads are going to do. I would use synchronization if two or more threads could possibly manipulate the same instance of an object at the same time. An example of this in C# can be demonstrated through the use of storing data in a static object. A static object is initialized once per application and the data within the object can be accessed by all threads. I would use the synchronization primitives to prevent any data from being manipulated by multiple threads simultaneously. This would reduce any data corruption from occurring within the object. On the other hand if all the threads used non static objects and were independent of the other tasks there would be no need to use synchronization. Synchronization Primitives in C#: Basic Blocking Locking Signaling Non-Blocking Synchronization Constructs The Basic Blocking methods include Sleep, Join, and Task.Wait.  These methods force threads to wait until other threads have completed. In addition, these methods can also force a thread to wait a set amount of time before continuing to work.   The Locking primitive prevents a thread from entering a critical section of code while another thread is in the same critical section.  If another thread attempts to enter a locked code, it will wait, until the code block is released. The Signaling primitive allows a thread to temporarily pause work until receiving a notification from another thread that it is ok to continue working. The Signaling primitive removes the need for polling.The Non-Blocking Synchronization Constructs protect access to a common field by calling upon processor primitives.

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  • Node.js Adventure - Node.js on Windows

    - by Shaun
    Two weeks ago I had had a talk with Wang Tao, a C# MVP in China who is currently running his startup company and product named worktile. He asked me to figure out a synchronization solution which helps his product in the future. And he preferred me implementing the service in Node.js, since his worktile is written in Node.js. Even though I have some experience in ASP.NET MVC, HTML, CSS and JavaScript, I don’t think I’m an expert of JavaScript. In fact I’m very new to it. So it scared me a bit when he asked me to use Node.js. But after about one week investigate I have to say Node.js is very easy to learn, use and deploy, even if you have very limited JavaScript skill. And I think I became love Node.js. Hence I decided to have a series named “Node.js Adventure”, where I will demonstrate my story of learning and using Node.js in Windows and Windows Azure. And this is the first one.   (Brief) Introduction of Node.js I don’t want to have a fully detailed introduction of Node.js. There are many resource on the internet we can find. But the best one is its homepage. Node.js was created by Ryan Dahl, sponsored by Joyent. It’s consist of about 80% C/C++ for core and 20% JavaScript for API. It utilizes CommonJS as the module system which we will explain later. The official definition of Node.js is Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices. First of all, Node.js utilizes JavaScript as its development language and runs on top of V8 engine, which is being used by Chrome. It brings JavaScript, a client-side language into the backend service world. So many people said, even though not that actually, “Node.js is a server side JavaScript”. Additionally, Node.js uses an event-driven, non-blocking IO model. This means in Node.js there’s no way to block currently working thread. Every operation in Node.js executed asynchronously. This is a huge benefit especially if our code needs IO operations such as reading disks, connect to database, consuming web service, etc.. Unlike IIS or Apache, Node.js doesn’t utilize the multi-thread model. In Node.js there’s only one working thread serves all users requests and resources response, as the ST star in the figure below. And there is a POSIX async threads pool in Node.js which contains many async threads (AT stars) for IO operations. When a user have an IO request, the ST serves it but it will not do the IO operation. Instead the ST will go to the POSIX async threads pool to pick up an AT, pass this operation to it, and then back to serve any other requests. The AT will actually do the IO operation asynchronously. Assuming before the AT complete the IO operation there is another user comes. The ST will serve this new user request, pick up another AT from the POSIX and then back. If the previous AT finished the IO operation it will take the result back and wait for the ST to serve. ST will take the response and return the AT to POSIX, and then response to the user. And if the second AT finished its job, the ST will response back to the second user in the same way. As you can see, in Node.js there’s only one thread serve clients’ requests and POSIX results. This thread looping between the users and POSIX and pass the data back and forth. The async jobs will be handled by POSIX. This is the event-driven non-blocking IO model. The performance of is model is much better than the multi-threaded blocking model. For example, Apache is built in multi-threaded blocking model while Nginx is in event-driven non-blocking mode. Below is the performance comparison between them. And below is the memory usage comparison between them. These charts are captured from the video NodeJS Basics: An Introductory Training, which presented at Cloud Foundry Developer Advocate.   Node.js on Windows To execute Node.js application on windows is very simple. First of you we need to download the latest Node.js platform from its website. After installed, it will register its folder into system path variant so that we can execute Node.js at anywhere. To confirm the Node.js installation, just open up a command windows and type “node”, then it will show the Node.js console. As you can see this is a JavaScript interactive console. We can type some simple JavaScript code and command here. To run a Node.js JavaScript application, just specify the source code file name as the argument of the “node” command. For example, let’s create a Node.js source code file named “helloworld.js”. Then copy a sample code from Node.js website. 1: var http = require("http"); 2:  3: http.createServer(function (req, res) { 4: res.writeHead(200, {"Content-Type": "text/plain"}); 5: res.end("Hello World\n"); 6: }).listen(1337, "127.0.0.1"); 7:  8: console.log("Server running at http://127.0.0.1:1337/"); This code will create a web server, listening on 1337 port and return “Hello World” when any requests come. Run it in the command windows. Then open a browser and navigate to http://localhost:1337/. As you can see, when using Node.js we are not creating a web application. In fact we are likely creating a web server. We need to deal with request, response and the related headers, status code, etc.. And this is one of the benefit of using Node.js, lightweight and straightforward. But creating a website from scratch again and again is not acceptable. The good news is that, Node.js utilizes CommonJS as its module system, so that we can leverage some modules to simplify our job. And furthermore, there are about ten thousand of modules available n the internet, which covers almost all areas in server side application development.   NPM and Node.js Modules Node.js utilizes CommonJS as its module system. A module is a set of JavaScript files. In Node.js if we have an entry file named “index.js”, then all modules it needs will be located at the “node_modules” folder. And in the “index.js” we can import modules by specifying the module name. For example, in the code we’ve just created, we imported a module named “http”, which is a build-in module installed alone with Node.js. So that we can use the code in this “http” module. Besides the build-in modules there are many modules available at the NPM website. Thousands of developers are contributing and downloading modules at this website. Hence this is another benefit of using Node.js. There are many modules we can use, and the numbers of modules increased very fast, and also we can publish our modules to the community. When I wrote this post, there are totally 14,608 modules at NPN and about 10 thousand downloads per day. Install a module is very simple. Let’s back to our command windows and input the command “npm install express”. This command will install a module named “express”, which is a MVC framework on top of Node.js. And let’s create another JavaScript file named “helloweb.js” and copy the code below in it. I imported the “express” module. And then when the user browse the home page it will response a text. If the incoming URL matches “/Echo/:value” which the “value” is what the user specified, it will pass it back with the current date time in JSON format. And finally my website was listening at 12345 port. 1: var express = require("express"); 2: var app = express(); 3:  4: app.get("/", function(req, res) { 5: res.send("Hello Node.js and Express."); 6: }); 7:  8: app.get("/Echo/:value", function(req, res) { 9: var value = req.params.value; 10: res.json({ 11: "Value" : value, 12: "Time" : new Date() 13: }); 14: }); 15:  16: console.log("Web application opened."); 17: app.listen(12345); For more information and API about the “express”, please have a look here. Start our application from the command window by command “node helloweb.js”, and then navigate to the home page we can see the response in the browser. And if we go to, for example http://localhost:12345/Echo/Hello Shaun, we can see the JSON result. The “express” module is very populate in NPM. It makes the job simple when we need to build a MVC website. There are many modules very useful in NPM. - underscore: A utility module covers many common functionalities such as for each, map, reduce, select, etc.. - request: A very simple HTT request client. - async: Library for coordinate async operations. - wind: Library which enable us to control flow with plain JavaScript for asynchronous programming (and more) without additional pre-compiling steps.   Node.js and IIS I demonstrated how to run the Node.js application from console. Since we are in Windows another common requirement would be, “can I host Node.js in IIS?” The answer is “Yes”. Tomasz Janczuk created a project IISNode at his GitHub space we can find here. And Scott Hanselman had published a blog post introduced about it.   Summary In this post I provided a very brief introduction of Node.js, includes it official definition, architecture and how it implement the event-driven non-blocking model. And then I described how to install and run a Node.js application on windows console. I also described the Node.js module system and NPM command. At the end I referred some links about IISNode, an IIS extension that allows Node.js application runs on IIS. Node.js became a very popular server side application platform especially in this year. By leveraging its non-blocking IO model and async feature it’s very useful for us to build a highly scalable, asynchronously service. I think Node.js will be used widely in the cloud application development in the near future.   In the next post I will explain how to use SQL Server from Node.js.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Davicom Semiconductor, Inc. 21x4x DEC-Tulip not detected by Wireshark but IP operational

    - by deepsix86
    Recently flipped to Ubuntu 11.10 on a Dell 4300 (Intel). Getting IP address and no issues (ping/surf) but Wireshark unable to detect eth0 interface. I see references in forums to blacklist tulip but looks like I am running dmfe. Not sure if the blacklist is required and where to go from here. Maybe Driver update? Got a little lost looking in that area. Some h/w details below (IP/MAC/HOSTNAME removed) Linux xxxxxx 3.0.0-17-generic #30-Ubuntu SMP Thu Mar 8 17:34:21 UTC 2012 i686 i686 i386 GNU/Linux network-admin (HOSTS TAB) does not list eth0, only loopback and bunch of IPv6 interfaces ifconfig eth0 Link encap:Ethernet HWaddr xxxxxxxx inet addr:192.168.x.xx Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: xxxxxxxxxxx 64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:36662 errors:0 dropped:1 overruns:0 frame:0 TX packets:24975 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:42115779 (42.1 MB) TX bytes:3056435 (3.0 MB) Interrupt:18 Base address:0xe800 lspci 02:09.0 Ethernet controller: Davicom Semiconductor, Inc. 21x4x DEC-Tulip compatible 10/100 Ethernet (rev 31) Subsystem: Device 4554:434e Flags: bus master, medium devsel, latency 64, IRQ 18 I/O ports at e800 [size=256] Memory at fe1ffc00 (32-bit, non-prefetchable) [size=256] Expansion ROM at fe200000 [disabled] [size=256K] Capabilities: [50] Power Management version 2 Kernel driver in use: dmfe Kernel modules: dmfe hwinfo --netcard 20: PCI 209.0: 0200 Ethernet controller [Created at pci.318] Unique ID: rBUF.0NgK5ZS9c0D Parent ID: 6NW+.siohrLUzzI4 SysFS ID: /devices/pci0000:00/0000:00:1e.0/0000:02:09.0 SysFS BusID: 0000:02:09.0 Hardware Class: network Model: "Davicom 21x4x DEC-Tulip compatible 10/100 Ethernet" Vendor: pci 0x1282 "Davicom Semiconductor, Inc." Device: pci 0x9102 "21x4x DEC-Tulip compatible 10/100 Ethernet" SubVendor: pci 0x4554 SubDevice: pci 0x434e Revision: 0x31 Driver: "dmfe" Driver Modules: "dmfe" Device File: eth0 I/O Ports: 0xe800-0xe8ff (rw) Memory Range: 0xfe1ffc00-0xfe1ffcff (rw,non-prefetchable) Memory Range: 0xfe200000-0xfe23ffff (ro,non-prefetchable,disabled) IRQ: 18 (61379 events) HW Address: 00:08:a1:01:35:70 Link detected: yes Module Alias: "pci:v00001282d00009102sv00004554sd0000434Ebc02sc00i00" Driver Info #0: Driver Status: dmfe is active Driver Activation Cmd: "modprobe dmfe" Config Status: cfg=new, avail=yes, need=no, active=unknown Attached to: #11 (PCI bridge)

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  • Installazione ATI Mobility Radeon HD 5650 su Ubuntu 11.10

    - by Antonio
    Salve a tutti, possiedo un portatile HP Pavillion dv6 3110 con scheda video dedicata ATI Mobility Radeon HD 5650 da 1 Giga ed ho installato da poco Ubuntu 11.10 Versione 64 bit. Ho seguito molte guide su internet per installare i driver per la mia scheda video ma nessuna ha dato esito positivo. Nella finestra "driver aggiuntivi" sono riuscito ad installare i "Driver grafici fglrx proprietari ATI/AMD" ma dopo il riavvio non riesco ad utilizzare correttamente la scheda video. Mentre i "Driver grafici fglrx proprietari ATI/AMD (aggiornamenti post-release)" non me li fa proprio installare segnalando un errore che riporto di seguito "L'installazione di questo driver non è riuscita.Consultare i file di registro per maggiori informazioni: /var/log/jockey.log". Ho pensato allora di scaricare direttamente dal sito di AMD gli ultimi driver rilasciati attraverso il pacchetto "amd-driver-installer-12-3-x86.x86_64.run", l'ho lanciato, ho seguito il wizard di installazione, l'installazione viene completata, digito "sudo aticonfig --initial" per la configurazione iniziale, ma al riavvio del pc appaiono soltanto scritte su schermo nero con una serie di "OK" e qualche "FAIL". Ho provato questa procedura anche per le versioni precedenti dei driver, ma il risultato è sempre lo stesso. Sono disperato. Riuscirò mai ad utilizzare la mia scheda video? Vi incollo per completezza ciò che mi appare all'esecuzione del comando "lspci -nn | grep VGA" per visualizzare i processori grafici presenti sul mio pc: 00:02.0 VGA compatible controller [0300]: Intel Corporation Core Processor Integrated Graphics Controller [8086:0046] (rev 02) 01:00.0 VGA compatible controller [0300]: ATI Technologies Inc Madison [AMD Radeon HD 5000M Series] [1002:68c1] Grazie anticipatamente a coloro che potranno aiutarmi. Cordiali Saluti Antonio Giordano

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  • Modular programming is the method of programming small task or programs

    Modular programming is the method of programming small task or sub-programs that can be arranged in multiple variations to perform desired results. This methodology is great for preventing errors due to the fact that each task executes a specific process and can be debugged individually or within a larger program when combined with other tasks or sub programs. C# is a great example of how to implement modular programming because it allows for functions, methods, classes and objects to be use to create smaller sub programs. A program can be built from smaller pieces of code which saves development time and reduces the chance of errors because it is easier to test a small class or function for a simple solutions compared to testing a full program which has layers and layers of small programs working together.Yes, it is possible to write the same program using modular and non modular programming, but it is not recommend it. When you deal with non modular programs, they tend to contain a lot of spaghetti code which can be a pain to develop and not to mention debug especially if you did not write the code. In addition, in my experience they seem to have a lot more hidden bugs which waste debugging and development time. Modular programming methodology in comparision to non-mondular should be used when ever possible due to the use of small components. These small components allow business logic to be reused and is easier to maintain. From the user’s view point, they cannot really tell if the code is modular or not with today’s computers.

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  • ASP.NET ViewState Tips and Tricks #1

    - by João Angelo
    In User Controls or Custom Controls DO NOT use ViewState to store non public properties. Persisting non public properties in ViewState results in loss of functionality if the Page hosting the controls has ViewState disabled since it can no longer reset values of non public properties on page load. Example: public class ExampleControl : WebControl { private const string PublicViewStateKey = "Example_Public"; private const string NonPublicViewStateKey = "Example_NonPublic"; // DO public int Public { get { object o = this.ViewState[PublicViewStateKey]; if (o == null) return default(int); return (int)o; } set { this.ViewState[PublicViewStateKey] = value; } } // DO NOT private int NonPublic { get { object o = this.ViewState[NonPublicViewStateKey]; if (o == null) return default(int); return (int)o; } set { this.ViewState[NonPublicViewStateKey] = value; } } } // Page with ViewState disabled public partial class ExamplePage : Page { protected override void OnLoad(EventArgs e) { base.OnLoad(e); this.Example.Public = 10; // Restore Public value this.Example.NonPublic = 20; // Compile Error! } }

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  • The Stub Proto: Not Just For Stub Objects Anymore

    - by user9154181
    One of the great pleasures of programming is to invent something for a narrow purpose, and then to realize that it is a general solution to a broader problem. In hindsight, these things seem perfectly natural and obvious. The stub proto area used to build the core Solaris consolidation has turned out to be one of those things. As discussed in an earlier article, the stub proto area was invented as part of the effort to use stub objects to build the core ON consolidation. Its purpose was merely as a place to hold stub objects. However, we keep finding other uses for it. It turns out that the stub proto should be more properly thought of as an auxiliary place to put things that we would like to put into the proto to help us build the product, but which we do not wish to package or deliver to the end user. Stub objects are one example, but private lint libraries, header files, archives, and relocatable objects, are all examples of things that might profitably go into the stub proto. Without a stub proto, these items were handled in a variety of ad hoc ways: If one part of the workspace needed private header files, libraries, or other such items, it might modify its Makefile to reach up and over to the place in the workspace where those things live and use them from there. There are several problems with this: Each component invents its own approach, meaning that programmers maintaining the system have to invest extra effort to understand what things mean. In the past, this has created makefile ghettos in which only the person who wrote the makefiles feels confident to modify them, while everyone else ignores them. This causes many difficulties and benefits no one. These interdependencies are not obvious to the make, utility, and can lead to races. They are not obvious to the human reader, who may therefore not realize that they exist, and break them. Our policy in ON is not to deliver files into the proto unless those files are intended to be packaged and delivered to the end user. However, sometimes non-shipping files were copied into the proto anyway, causing a different set of problems: It requires a long list of exceptions to silence our normal unused proto item error checking. In the past, we have accidentally shipped files that we did not intend to deliver to the end user. Mixing cruft with valuable items makes it hard to discern which is which. The stub proto area offers a convenient and robust solution. Files needed to build the workspace that are not delivered to the end user can instead be installed into the stub proto. No special exceptions or custom make rules are needed, and the intent is always clear. We are already accessing some private lint libraries and compilation symlinks in this manner. Ultimately, I'd like to see all of the files in the proto that have a packaging exception delivered to the stub proto instead, and for the elimination of all existing special case makefile rules. This would include shared objects, header files, and lint libraries. I don't expect this to happen overnight — it will be a long term case by case project, but the overall trend is clear. The Stub Proto, -z assert_deflib, And The End Of Accidental System Object Linking We recently used the stub proto to solve an annoying build issue that goes back to the earliest days of Solaris: How to ensure that we're linking to the OS bits we're building instead of to those from the running system. The Solaris product is made up of objects and files from a number of different consolidations, each of which is built separately from the others from an independent code base called a gate. The core Solaris OS consolidation is ON, which stands for "Operating System and Networking". You will frequently also see ON called the OSnet. There are consolidations for X11 graphics, the desktop environment, open source utilities, compilers and development tools, and many others. The collection of consolidations that make up Solaris is known as the "Wad Of Stuff", usually referred to simply as the WOS. None of these consolidations is self contained. Even the core ON consolidation has some dependencies on libraries that come from other consolidations. The build server used to build the OSnet must be running a relatively recent version of Solaris, which means that its objects will be very similar to the new ones being built. However, it is necessarily true that the build system objects will always be a little behind, and that incompatible differences may exist. The objects built by the OSnet link to other objects. Some of these dependencies come from the OSnet, while others come from other consolidations. The objects from other consolidations are provided by the standard library directories on the build system (/lib, /usr/lib). The objects from the OSnet itself are supposed to come from the proto areas in the workspace, and not from the build server. In order to achieve this, we make use of the -L command line option to the link-editor. The link-editor finds dependencies by looking in the directories specified by the caller using the -L command line option. If the desired dependency is not found in one of these locations, ld will then fall back to looking at the default locations (/lib, /usr/lib). In order to use OSnet objects from the workspace instead of the system, while still accessing non-OSnet objects from the system, our Makefiles set -L link-editor options that point at the workspace proto areas. In general, this works well and dependencies are found in the right places. However, there have always been failures: Building objects in the wrong order might mean that an OSnet dependency hasn't been built before an object that needs it. If so, the dependency will not be seen in the proto, and the link-editor will silently fall back to the one on the build server. Errors in the makefiles can wipe out the -L options that our top level makefiles establish to cause ld to look at the workspace proto first. In this case, all objects will be found on the build server. These failures were rarely if ever caught. As I mentioned earlier, the objects on the build server are generally quite close to the objects built in the workspace. If they offer compatible linking interfaces, then the objects that link to them will behave properly, and no issue will ever be seen. However, if they do not offer compatible linking interfaces, the failure modes can be puzzling and hard to pin down. Either way, there won't be a compile-time warning or error. The advent of the stub proto eliminated the first type of failure. With stub objects, there is no dependency ordering, and the necessary stub object dependency will always be in place for any OSnet object that needs it. However, makefile errors do still occur, and so, the second form of error was still possible. While working on the stub object project, we realized that the stub proto was also the key to solving the second form of failure caused by makefile errors: Due to the way we set the -L options to point at our workspace proto areas, any valid object from the OSnet should be found via a path specified by -L, and not from the default locations (/lib, /usr/lib). Any OSnet object found via the default locations means that we've linked to the build server, which is an error we'd like to catch. Non-OSnet objects don't exist in the proto areas, and so are found via the default paths. However, if we were to create a symlink in the stub proto pointing at each non-OSnet dependency that we require, then the non-OSnet objects would also be found via the paths specified by -L, and not from the link-editor defaults. Given the above, we should not find any dependency objects from the link-editor defaults. Any dependency found via the link-editor defaults means that we have a Makefile error, and that we are linking to the build server inappropriately. All we need to make use of this fact is a linker option to produce a warning when it happens. Although warnings are nice, we in the OSnet have a zero tolerance policy for build noise. The -z fatal-warnings option that was recently introduced with -z guidance can be used to turn the warnings into fatal build errors, forcing the programmer to fix them. This was too easy to resist. I integrated 7021198 ld option to warn when link accesses a library via default path PSARC/2011/068 ld -z assert-deflib option into snv_161 (February 2011), shortly after the stub proto was introduced into ON. This putback introduced the -z assert-deflib option to the link-editor: -z assert-deflib=[libname] Enables warning messages for libraries specified with the -l command line option that are found by examining the default search paths provided by the link-editor. If a libname value is provided, the default library warning feature is enabled, and the specified library is added to a list of libraries for which no warnings will be issued. Multiple -z assert-deflib options can be specified in order to specify multiple libraries for which warnings should not be issued. The libname value should be the name of the library file, as found by the link-editor, without any path components. For example, the following enables default library warnings, and excludes the standard C library. ld ... -z assert-deflib=libc.so ... -z assert-deflib is a specialized option, primarily of interest in build environments where multiple objects with the same name exist and tight control over the library used is required. If is not intended for general use. Note that the definition of -z assert-deflib allows for exceptions to be specified as arguments to the option. In general, the idea of using a symlink from the stub proto is superior because it does not clutter up the link command with a long list of objects. When building the OSnet, we usually use the plain from of -z deflib, and make symlinks for the non-OSnet dependencies. The exception to this are dependencies supplied by the compiler itself, which are usually found at whatever arbitrary location the compiler happens to be installed at. To handle these special cases, the command line version works better. Following the integration of the link-editor change, I made use of -z assert-deflib in OSnet builds with 7021896 Prevent OSnet from accidentally linking to build system which integrated into snv_162 (March 2011). Turning on -z assert-deflib exposed between 10 and 20 existing errors in our Makefiles, which were all fixed in the same putback. The errors we found in our Makefiles underscore how difficult they can be prevent without an automatic system in place to catch them. Conclusions The stub proto is proving to be a generally useful construct for ON builds that goes beyond serving as a place to hold stub objects. Although invented to hold stub objects, it has already allowed us to simplify a number of previously difficult situations in our makefiles and builds. I expect that we'll find uses for it beyond those described here as we go forward.

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  • Spotlight: How Scandinavia's Largest Nuclear Power Plant Increased Productivity and Reduced Costs wi

    - by [email protected]
    Ringhals nuclear power plant, which is part of the Vattenfall Group, is located about 60 km south-west of the beautiful coastal city of Gothenburg in Sweden. A deep concern to reduce environmental impact coupled with an effort to increase plant safety and operational efficiency have led to a recent surge in investments and initiatives around plant modification and plant optimization at Ringhals. A multitude of challenges were faced by the users in various groups that were involved in these projects. First, it was very difficult for users to easily access complex and layered asset and engineering information, which was critical to increased productivity and completing projects on time. Moreover, the 20 or so different solutions that were being used to view various document formats, not only resulted in collaboration complexity but also escalated IT administration costs and woes. Finally, there was a considerable non-engineering community comprising non-CAD specialists that needed easy access to plant data in an effort to minimize engineering disruption. Oracle's AutoVue significantly simplified the ability to efficiently view and use digital asset information by providing a standardized visualization solution for the enterprise. The key benefits achieved by Ringhals include: Increased productivity of plant optimization and plant modification by 3% Saved around $ 500 K annually Cut IT maintenance costs by 50% by using a single solution Reduced engineering disruption by allowing non-CAD users easy access to digital plant data The complete case-study can be found here

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  • Language redirect affecting pagerank and search listing?

    - by Janoszen
    Preface We have a number of sites that use the same redirect mechanism across the board. We recently transitioned one site from non-localised to localised and detected that the Google+ integration doesn't show up on the search results any more AND the PageRank is gone from 2 to 0. How the redirect works If the UA sends a cookie (e.g. lang=en), redirect the user to /language (e.g. /en) If the UA is a bot (.*bot.*), redirect to /en If the Accept-Language header contains a usable, non-English language, redirect to /language (English is the default on many browsers in non-English regions) If there is a valid GeoIP lookup and the detected region is linked to a supported language, redirect to /language Redirect to /en We do of course on all pages have the proper markup to indicate the alternate language: <link hreflang="de" href="/de" rel="alternate" /> As far as we can tell, we follow all publicly available guidelines from Google, so we are a bit at odds if this is a bug in Google or we have done something wrong. Question Does not having content on the root URL of a domain adversely affect search engine rankings and if yes, how does one implement a proper language redirection?

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  • Get to Know a Candidate (6 of 25): Jill Stein&ndash;Green Party

    - by Brian Lanham
    DISCLAIMER: This is not a post about “Romney” or “Obama”. This is not a post for whom I am voting. Information sourced for Wikipedia. Stein is a physician with degrees from Harvard College and Harvard Medical School.  She serves on the boards of Greater Boston Physicians for Social Responsibility and MassVoters for Fair Elections, and has been active with the Massachusetts Coalition for Healthy Communities Jill Stein advocates a "Green New Deal" in which renewable energy jobs would be created to address climate change and environmental issues with the objective of employing "every American willing and able to work". Citing the research of Dr. Phillip Harvey, Professor of Law & Economics at Rutgers University, as evidence of the successful economic effects of the 1930s' New Deal projects, Stein would fund the plan with a 30% reduction in the U.S. military budget, returning US troops home, and increasing taxes on areas such as capital gains, offshore tax havens and multimillion dollar real estate. Stein plans on impacting what she sees as a growing convergence of environmental crises in water, soil, fisheries and forests, through the creation of sustainable infrastructure based in clean renewable energy generation and sustainable communities principles such as increasing intra-city mass transit and inter-city railroads, creating 'complete streets' that safely encourage bike and pedestrian traffic and regional food systems based on sustainable organic agriculture The Green Party of the United States was founded in 1991 as a voluntary association of state green parties. With its founding, the Green Party of the United States became the primary national Green organization in the United States, eclipsing the Greens/Green Party USA, which emphasized non-electoral movement building. The Green Party of the United States of America emphasizes environmentalism, non-hierarchical participatory democracy, social justice, respect for diversity, peace and nonviolence. Their "Ten Key Values," which are described as non-authoritative guiding principles, are as follows: Grassroots democracy Social justice and equal opportunity Ecological wisdom Nonviolence Decentralization Community-based economics Feminism and gender equality Respect for diversity Personal and global responsibility Future focus and sustainability The Green Party does not accept donations from corporations. Thus, the party's platforms and rhetoric critique any corporate influence and control over government, media, and American society at large. Stein has access to 403 electoral votes and is a write-in candidate in GA, IN, and MS Learn more about Jill Stein and Green Party on Wikipedia.

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  • Thinking skills to be a good programmer

    - by Paul
    I have been programming for last 15 years with non-CS degree. Main reason I got into programming was that I liked to learn new things and apply them to my work. And I was able to find and fix programming errors and their causes faster than others. But I never find myself a a guru or an expert, maybe due to my non-CS major. And when I saw great programmers, I observed they are very good, much better than me of course, at solving problems. One skill I found good in my mid-career is thinking of requirements and tasks in a reverse order and in abstract. In that way, I can see what is really required for me to do without detail and can quickly find parts of solution that already exist. So I wonder if there are other thinking skills to be a good programmer. I've followed Q&As below and actually read some of books recommended there. But I couldn't really pickup good methods directly applicable for my programming work. What non-programming books should a programmer read to help develop programming/thinking skills? Skills and habits to develop to be good at programming (I'm a newbie)

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  • NoSQL

    - by NoReasoning
    Last night, (Tuesday, June 28), at the KC .NET User group meeting, George Westwater gave a terrific presentation on NoSQL. The best way to define it (the best way is to see George explain it, and he says he will record his presentation and make it available through his blog – link above)  is databases  that does not use relational technology. And his point, and this is true – I have been around awhile – is that non-relational databases have been used for over 50 years in the business. He points out that Wall Street firms have been using non-relational technology ever since they started using computers. IBM still fully supports IMS, now in version 11 (12 is in beta), because these firms are still using this product and will continue to do so for a long time. Of course, like a lot of computer business technology, there are a lot of new NoSQL products available these days, simply as a reaction to the problems of scaling relational databases for internet use. As a result, it almost looks as though NoSQL is something new. And there are a lot, I mean a LOT, I mean a L-O-T , of new products out there for this technology. The best resource to cover all of these products is http://nosql-database.org/, which has a huge listing of what is available. My interest in the subject is primarily due to my interest in Windows Azure and the fact that Windows Azure storage is all non-relational, even the table storage. It is very fascinating and most of all, far cheaper than using SQL Azure for storage in the “cloud."

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  • Blank screen during boot after clean Ubuntu 11.10 install (Intel N10 graphics)

    - by Coen
    After a clean install of Ubuntu 11.10 on my Asus eee PC 1005p, Ubuntu seems to boot correctly, except for initialization of the LCD screen. What I observe: I choose Ubuntu 11.10 in the GRUB 2 menu A blank screen with a blinking cursor in the top left of the screen, for 15-20 seconds. The ubuntu logo with 5 red dots in the center of the screen, for 1 second. The LCD screen is entirely blank The startup sound plays (Ubuntu is configured to auto-login) Still, the LCD screen is entirely blank. When I press Fn-F8 (the switch between LCD screen and external VGA), the LCD screen shows my desktop correctly and everything seems to work fine. Except for the adjust contrast buttons (Fn-F5 and Fn-F6), these seem to cycle through random brightness modes. Something like: 0% - 50% - 20% - 0% - 20% - 0% Any ideas what's causing this or how to solve this? coen@elpicu:~$ lspci -v 00:02.0 VGA compatible controller: Intel Corporation N10 Family Integrated Graphics Controller (prog-if 00 [VGA controller]) Subsystem: ASUSTeK Computer Inc. Device 83ac Flags: bus master, fast devsel, latency 0, IRQ 44 Memory at f7e00000 (32-bit, non-prefetchable) [size=512K] I/O ports at dc00 [size=8] Memory at d0000000 (32-bit, prefetchable) [size=256M] Memory at f7d00000 (32-bit, non-prefetchable) [size=1M] Expansion ROM at <unassigned> [disabled] Capabilities: <access denied> Kernel driver in use: i915 Kernel modules: i915 00:02.1 Display controller: Intel Corporation N10 Family Integrated Graphics Controller Subsystem: ASUSTeK Computer Inc. Device 83ac Flags: bus master, fast devsel, latency 0 Memory at f7e80000 (32-bit, non-prefetchable) [size=512K] Capabilities: <access denied>

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  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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  • Concrete examples of Python's "only one way to do it" maxim

    - by Charles Roper
    I am learning Python and am intrigued by the following point in PEP 20 The Zen of Python: There should be one-- and preferably only one --obvious way to do it. Although that way may not be obvious at first unless you're Dutch. Could anyone offer any concrete examples of this maxim? I am particularly interested in the contrast to other languages such as Ruby. Part of the Ruby design philosophy (originating with Perl, I think?) is that multiple ways of doing it is A Good Thing. Can anyone offer some examples showing the pros and cons of each approach. Note, I'm not after an answer to which is better (which is probably too subjective to ever be answered), but rather an unbiased comparison of the two styles.

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  • In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

    - by Heinzi
    In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a practical point of view, every learner of SQL has, one time or another, made the classic WHERE myField = NULL mistake or learned the hard way that NOT IN does not do what one would expect when NULL values are present. It is my impression (please correct me if I am wrong) that the cases where this three-valued logic helps (e.g. WHERE myField IS NOT NULL AND myField <> 2 can be shortened to WHERE myField <> 2) are rare and, in those cases, people tend to use the longer version anyway for clarity, just like you would add a comment when using a clever, non-obvious hack. Is there some obvious advantage that I am missing? Or is there a general consensus among the development community that this has been a mistake?

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  • Running Multiple Queries in Oracle SQL Developer

    - by thatjeffsmith
    There are two methods for running queries in SQL Developer: Run Statement Run Statement, Shift+Enter, F9, or this button Run Script No grids, just script (SQL*Plus like) ouput is fine, thank you very much! What’s the Difference? There are some obvious differences between the two features, the most obvious being the format of the output delivered. But there are some other, more subtle differences here, primarily around fetching. What is Fetch? After you run send your query to Oracle, it has to do 3 things: Parse Execute Fetch Technically it has to do at least 2 things, and sometimes only 1. But, to get the data back to the user, the fetch must occur. If you have a 10 row query or a 1,000,000 row query, this can mean 1 or many fetches in groups of records. Ok, before I went on the Fetch tangent, I said there were two ways to run statements in SQL Developer: Run Statement Run statement brings your query results to a grid with a single fetch. The user sees 50, 100, 500, etc rows come back, but SQL Developer and the database know that there are more rows waiting to be retrieved. The process on the server that was used to execute the query is still hanging around too. To alleviate this, increase your fetch size to 500. Every query ran will come back with the first 500 rows, and rows will be continued to be fetched in 500 row increments. You’ll then see most of your ad hoc queries complete with a single fetch. Scroll down, or hit Ctrl+End to force a full fetch and get all your rows back. Run Script Run Script runs the contents of the worksheet (or what’s highlighted) as a ‘script.’ What does that mean exactly? Think of this as being equivalent to running this in SQL*Plus: @my_script.sql; Each statement is executed. Also, ALL rows are fetched. So once it’s finished executing, there are no open cursors left around. The more obvious difference here is that the output comes back formatted as plain old text. Run one or more commands plus SQL*Plus commands like SET and SPOOL The Trick: Run Statement Works With Multiple Statements! It says ‘run statement,’ but if you select more than one with your mouse and hit the button – it will run each and throw the results to 1 grid for each statement. If you mouse hover over the Query Result panel tab, SQL Developer will tell you the query used to populate that grid. This will work regardless of what you have this preference set to: DATABASE – WORKSHEET – SHOW QUERY RESULTS IN NEW TABS Mind the fetch though! Close those cursors by bring back all the records or closing the grids when you’re done with them.

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  • Armchair Linguists: 'code' vs. 'codes'--or why I write 'code' and my manager asks for 'codes'

    - by Ukko
    I wanted to tap into the collective wisdom here to see if I can get some insight into one of my pet peeves, people who thread "code" as a countable noun. Let me also preface this by saying that I am not talking about anyone who speaks english as a second language, this is a native phenomenon. For those of us who slept through grammar class there are two classes of nouns which basically refer to things that are countable and non-countable (sometimes referred to as count and noncount). For instance 'sand' is a non-count noun and 'apple' is count. You can talk about "two apples" but "two sands" does not parse. The bright students then would point out a word like "beer" where is looks like this is violated. Beer as a substance is certainly a non-count noun, but I can ask for "two beers" without offending the grammar police. The reason is that there are actually two words tied up in that one utterance, Definition #1 is a yummy golden substance and Definition #2 is a colloquial term for a container of said substance. #1 is non-count and #2 is countable. This gets to my problem with "codes" as a countable noun. In my mind the code that we programmers write is non-count, "I wrote some code today." When used in the plural like "Have you got the codes" I can only assume that you are asking if I have the cryptographically significant numbers for launching a missile or the like. Every time my peer in marketing asks about when we will have the new codes ready I have a vision of rooms of code breakers going over the latest Enigma coded message. I corrected the usage in all the documents I am asked to review, but then I noticed that our customer was also using the work "codes" when they meant "code". At this point I have realized that there is a significant sub-population that uses "codes" and they seem to be impervious to what I see as the dominant "correct" usage. This is the part I want some help on, has anyone else noticed this phenomenon? Do you know what group it is associated with, old Fortran programmer perhaps? Is it a regionalism? I have become quick to change my terms when I notice a customer's usage, but it would be nice to know if I am sending a proposal somewhere what style they expect. I would hate to get canned with a review of "Ha, these guy's must be morons they don't even know 'code' is plural!"

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  • Not-So-Well-Known features of Ubuntu

    - by Khaja Minhajuddin
    Ubuntu always surprises me by making things easier in unexpected ways. But, it isn't always obvious, For instance When I was looking for a tool to RDP into windows, I found that Ubuntu already has an pre-installed app called Terminal Server Client which has this functionality. I am sure there are many such hidden things which are not known to the average user. This thread could be used to expose these little gems. EDIT: Maybe the choice of my words was wrong, Are there any things which you found were not very obvious?

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  • Goals are not registering in Google Analytics

    - by Adjam
    I've had a site online for a few weeks, and Google Analytics is working fine. Except Goals, which are not registering for some strange reason. To be clear: visits to the site are being registered, but no goals are being registered. This is not correct, as people are visiting the goal pages. I've set up two pages specifically to test this, Funnel Page and Goal Page. (You can visit these, but please do not visit any other pages on the site, as I am performing an experiment and SO referrals would taint results). Below is a screenshot of Profiles > Goals on Analytics. Can you see any obvious mistakes I have made? I think I must have missed something really obvious, as this is my first time using Analytics, but I must get this fixed ASAP. It's driving me crazy.

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