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• Programming Language, Turing Completeness and Turing Machine

  - by Amumu

  A programming language is said to be Turing Completeness if it can successfully simulate a universal TM. Let's take functional programming language for example. In functional programming, function has highest priority over anything. You can pass functions around like any primitives or objects. This is called first class function. In functional programming, your function does not produce side effect i.e. output strings onto screen, change the state of variables outside of its scope. Each function has a copy of its own objects if the objects are passed from the outside, and the copied objects are returned once the function finishes its job. Each function written purely in functional style is completely independent to anything outside of it. Thus, the complexity of the overall system is reduced. This is referred as referential transparency. In functional programming, each function can have its local variables kept its values even after the function exits. This is done by the garbage collector. The value can be reused the next time the function is called again. This is called memoization. A function usually should solve only one thing. It should model only one algorithm to answer a problem. Do you think that a function in a functional language with above properties simulate a Turing Machines? Functions (= algorithms = Turing Machines) are able to be passed around as input and returned as output. TM also accepts and simulate other TMs Memoization models the set of states of a Turing Machine. The memorized variables can be used to determine states of a TM (i.e. which lines to execute, what behavior should it take in a give state ...). Also, you can use memoization to simulate your internal tape storage. In language like C/C++, when a function exits, you lose all of its internal data (unless you store it elsewhere outside of its scope). The set of symbols are the set of all strings in a programming language, which is the higher level and human-readable version of machine code (opcode) Start state is the beginning of the function. However, with memoization, start state can be determined by memoization or if you want, switch/if-else statement in imperative programming language. But then, you can't Final accepting state when the function returns a value, or rejects if an exception happens. Thus, the function (= algorithm = TM) is decidable. Otherwise, it's undecidable. I'm not sure about this. What do you think? Is my thinking true on all of this? The reason I bring function in functional programming because I think it's closer to the idea of TM. What experience with other programming languages do you have which make you feel the idea of TM and the ideas of Computer Science in general? Can you specify how you think?

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• LWJGL - Mixing 2D and 3D

  - by nathan

  I'm trying to mix 2D and 3D using LWJGL. I have wrote 2D little method that allow me to easily switch between 2D and 3D. protected static void make2D() { glEnable(GL_BLEND); GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); glOrtho(0.0f, SCREEN_WIDTH, SCREEN_HEIGHT, 0.0f, 0.0f, 1.0f); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glLoadIdentity(); } protected static void make3D() { glDisable(GL_BLEND); GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); // Reset The Projection Matrix GLU.gluPerspective(45.0f, ((float) SCREEN_WIDTH / (float) SCREEN_HEIGHT), 0.1f, 100.0f); // Calculate The Aspect Ratio Of The Window GL11.glMatrixMode(GL11.GL_MODELVIEW); glLoadIdentity(); } The in my rendering code i would do something like: make2D(); //draw 2D stuffs here make3D(); //draw 3D stuffs here What i'm trying to do is to draw a 3D shape (in my case a quad) and i 2D image. I found this example and i took the code from TextureLoader, Texture and Sprite to load and render a 2D image. Here is how i load the image. TextureLoader loader = new TextureLoader(); Sprite s = new Sprite(loader, "player.png") And how i render it: make2D(); s.draw(0, 0); It works great. Here is how i render my quad: glTranslatef(0.0f, 0.0f, 30.0f); glScalef(12.0f, 9.0f, 1.0f); DrawUtils.drawQuad(); Once again, no problem, the quad is properly rendered. DrawUtils is a simple class i wrote containing utility method to draw primitives shapes. Now my problem is when i want to mix both of the above, loading/rendering the 2D image, rendering the quad. When i try to load my 2D image with the following: s = new Sprite(loader, "player.png); My quad is not rendered anymore (i'm not even trying to render the 2D image at this point). Only the fact of creating the texture create the issue. After looking a bit at the code of Sprite and TextureLoader i found that the problem appears after the call of the glTexImage2d. In the TextureLoader class: glTexImage2D(target, 0, dstPixelFormat, get2Fold(bufferedImage.getWidth()), get2Fold(bufferedImage.getHeight()), 0, srcPixelFormat, GL_UNSIGNED_BYTE, textureBuffer); Commenting this like make the problem disappear. My question is then why? Is there anything special to do after calling this function to do 3D? Does this function alter the render part, the projection matrix?

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• Creating a shared library that might be used with desktop applications and web projects

  - by dreza

  I have been involved in a number of MVC.NET and c# desktop projects in our company over the last year or so while also managing to kept my nose poked into other projects (in a read-only learning capacity of course). From this I've noticed that across the various projects and teams there is a-lot of functionality that has been well designed against good interfaces and abstractions. Because we tend to like our own work at times, I noticed a couple of projects had the exact same class, method copied into it as it had obviously worked on one and so was easily moved to a new project (probably by the same developer who originally wrote it) I mentioned this fact in one of our programmer meetings we have occasionally and suggested we pull some of this functionality into a core company library that we can build up over time and use across multiple projects. Everyone agreed and I started looking into this possibility. However, I've come across a stumbling block pretty early on. Our team primarily focuses on MVC at the moment and we have projects mainly in 2.0 but are starting to branch to 3.0. We also have a number of desktop applications that might benefit from some shared classes and basic helper methods. Initially when creating this DLL I included some shared classes that could be used across any project type (Web, Client etc) but then I started looking at adding some shared modules that would be useful in our MVC applications only. However this meant I had to include a reference to some Microsoft Web DLL's in order to leverage some of the classes I was creating (at this stage MVC 2.0). Now my issue is that we have a shared DLL that has references to web specific libraries that could also possibly be used in a client application. Not only that, our DLL referenced initially MVC 2.0 and we will eventually move onto MVC 3.0 for all projects. But alot of the classes in this library I expect to still be relevant to MVC 3 etc Our code within this DLL is separated into it's own namespaces such as: CompanyDLL.Primitives CompanyDLL.Web.Mvc CompanyDLL.Helpers etc etc So, my questions are: Is it OK to do a shared library like this, or if we have web specific features in it should we create a separate web DLL only targeted at a specific framework or MVC version? If it's OK, what kind of issues might we face when using the library that references MVC 2 in a MVC 3 project for example. I would be thinking that we might run into some sort of compatibility issue, or even issues where the developers using the library doesn't realize they need MVC 2.0 libraries. They might only want to use some of the generic classes etc The concept seemed like a good idea at the time, but I'm starting to think maybe it's not really a practical solution. But the number of times I've seen copied classes and methods across projects because they are proven tested code is a bit unnerving to be perfectly honest!

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• Why is my primitive xna square not drawn/shown?

  - by Mech0z

  I have made this class to draw a rectangle, but I cant get it to be drawn, I have no issues displaying a 3d model created in 3dmax, but shown these primitives seems much harder I use this to create it board = new Board(Vector3.Zero, 1000, 1000, Color.Yellow); And here is the implementation using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Shapes; using Quadro.Models; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace Quadro { public class Board : IGraphicObject { //Private Fields private Vector3 modelPosition; private BasicEffect effect; private VertexPositionColor[] vertices; private Matrix rotationMatrix; private GraphicsDevice graphicsDevice; private Matrix cameraProjection; //Constructor public Board(Vector3 position, float length, float width, Color color) { var _color = color; vertices = new VertexPositionColor[6]; vertices[0].Position = new Vector3(position.X, position.Y, position.Z); vertices[1].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[2].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[3].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[4].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[5].Position = new Vector3(position.X + length, position.Y + width, position.Z); for(int i = 0; i < vertices.Length; i++) { vertices[i].Color = color; } initFields(); } private void initFields() { graphicsDevice = SharedGraphicsDeviceManager.Current.GraphicsDevice; effect = new BasicEffect(graphicsDevice); modelPosition = Vector3.Zero; float screenWidth = (float)graphicsDevice.Viewport.Width; float screenHeight = (float)graphicsDevice.Viewport.Height; float aspectRatio = screenWidth / screenHeight; this.cameraProjection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); this.rotationMatrix = Matrix.Identity; } //Public Methods public void Update(GameTimerEventArgs e) { } public void Draw(Vector3 cameraPosition, GameTimerEventArgs e) { Matrix cameraView = Matrix.CreateLookAt(cameraPosition, Vector3.Zero, Vector3.Up); foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); effect.World = rotationMatrix * Matrix.CreateTranslation(modelPosition); effect.View = cameraView; effect.Projection = cameraProjection; graphicsDevice.DrawUserPrimitives(PrimitiveType.TriangleList, vertices, 0, 2, VertexPositionColor.VertexDeclaration); } } public void Rotate(Matrix rotationMatrix) { this.rotationMatrix = rotationMatrix; } public void Move(Vector3 moveVector) { this.modelPosition += moveVector; } } }

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• Database Mirroring on SQL Server Express Edition

  - by Most Valuable Yak (Rob Volk)

  Like most SQL Server users I'm rather frustrated by Microsoft's insistence on making the really cool features only available in Enterprise Edition.  And it really doesn't help that they changed the licensing for SQL 2012 to be core-based, so now it's like 4 times as expensive!  It almost makes you want to go with Oracle.  That, and a desire to have Larry Ellison do things to your orifices. And since they've introduced Availability Groups, and marked database mirroring as deprecated, you'd think they'd make make mirroring available in all editions.  Alas…they don't…officially anyway.  Thanks to my constant poking around in places I'm not "supposed" to, I've discovered the low-level code that implements database mirroring, and found that it's available in all editions! It turns out that the query processor in all SQL Server editions prepends a simple check before every edition-specific DDL statement: IF CAST(SERVERPROPERTY('Edition') as nvarchar(max)) NOT LIKE '%e%e%e% Edition%' print 'Lame' else print 'Cool' If that statement returns true, it fails. (the print statements are just placeholders)  Go ahead and test it on Standard, Workgroup, and Express editions compared to an Enterprise or Developer edition instance (which support everything). Once again thanks to Argenis Fernandez (b | t) and his awesome sessions on using Sysinternals, I was able to watch the exact process SQL Server performs when setting up a mirror.  Surprisingly, it's not actually implemented in SQL Server!  Some of it is, but that's something of a smokescreen, the real meat of it is simple filesystem primitives. The NTFS filesystem supports links, both hard links and symbolic, so that you can create two entries for the same file in different directories and/or different names.  You can create them using the MKLINK command in a command prompt: mklink /D D:\SkyDrive\Data D:\Data mklink /D D:\SkyDrive\Log D:\Log This creates a symbolic link from my data and log folders to my Skydrive folder.  Any file saved in either location will instantly appear in the other.  And since my Skydrive will be automatically synchronized with the cloud, any changes I make will be copied instantly (depending on my internet bandwidth of course). So what does this have to do with database mirroring?  Well, it seems that the mirroring endpoint that you have to create between mirror and principal servers is really nothing more than a Skydrive link.  Although it doesn't actually use Skydrive, it performs the same function.  So in effect, the following statement: ALTER DATABASE Mir SET PARTNER='TCP://MyOtherServer.domain.com:5022' Is turned into: mklink /D "D:\Data" "\\MyOtherServer.domain.com\5022$" The 5022$ "port" is actually a hidden system directory on the principal and mirror servers. I haven't quite figured out how the log files are included in this, or why you have to SET PARTNER on both principal and mirror servers, except maybe that mklink has to do something special when linking across servers.  I couldn't get the above statement to work correctly, but found that doing mklink to a local Skydrive folder gave me similar functionality. To wrap this up, all you have to do is the following: Install Skydrive on both SQL Servers (principal and mirror) and set the local Skydrive folder (D:\SkyDrive in these examples) On the principal server, run mklink /D on the data and log folders to point to SkyDrive: mklink /D D:\SkyDrive\Data D:\Data On the mirror server, run the complementary linking: mklink /D D:\Data D:\SkyDrive\Data Create your database and make sure the files map to the principal data and log folders (D:\Data and D:\Log) Viola! Your databases are kept in sync on multiple servers! One wrinkle you will encounter is that the mirror server will show the data and log files, but you won't be able to attach them to the mirror SQL instance while they are attached to the principal. I think this is a bug in the Skydrive, but as it turns out that's fine: you can't access a mirror while it's hosted on the principal either.  So you don't quite get automatic failover, but you can attach the files to the mirror if the principal goes offline.  It's also not exactly synchronous, but it's better than nothing, and easier than either replication or log shipping with a lot less latency. I will end this with the obvious "not supported by Microsoft" and "Don't do this in production without an updated resume" spiel that you should by now assume with every one of my blog posts, especially considering the date.

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• Surviving MATLAB and R as a Hardcore Programmer

  - by dsimcha

  I love programming in languages that seem geared towards hardcore programmers. (My favorites are Python and D.) MATLAB is geared towards engineers and R is geared towards statisticians, and it seems like these languages were designed by people who aren't hardcore programmers and don't think like hardcore programmers. I always find them somewhat awkward to use, and to some extent I can't put my finger on why. Here are some issues I have managed to identify: (Both): The extreme emphasis on vectors and matrices to the extent that there are no true primitives. (Both): The difficulty of basic string manipulation. (Both): Lack of or awkwardness in support for basic data structures like hash tables and "real", i.e. type-parametric and nestable, arrays. (Both): They're really, really slow even by interpreted language standards, unless you bend over backwards to vectorize your code. (Both): They seem to not be designed to interact with the outside world. For example, both are fairly bulky programs that take a while to launch and seem to not be designed to make simple text filter programs easy to write. Furthermore, the lack of good string processing makes file I/O in anything but very standard forms near impossible. (Both): Object orientation seems to have a very bolted-on feel. Yes, you can do it, but it doesn't feel much more idiomatic than OO in C. (Both): No obvious, simple way to get a reference type. No pointers or class references. For example, I have no idea how you roll your own linked list in either of these languages. (MATLAB): You can't put multiple top level functions in a single file, encouraging very long functions and cut-and-paste coding. (MATLAB): Integers apparently don't exist as a first class type. (R): The basic builtin data structures seem way too high level and poorly documented, and never seem to do quite what I expect given my experience with similar but lower level data structures. (R): The documentation is spread all over the place and virtually impossible to browse or search. Even D, which is often knocked for bad documentation and is still fairly alpha-ish, is substantially better as far as I can tell. (R): At least as far as I'm aware, there's no good IDE for it. Again, even D, a fairly alpha-ish language with a small community, does better. In general, I also feel like MATLAB and R could be easily replaced by plain old libraries in more general-purpose langauges, if sufficiently comprehensive libraries existed. This is especially true in newer general purpose languages that include lots of features for library writers. Why do R and MATLAB seem so weird to me? Are there any other major issues that you've noticed that may make these languages come off as strange to hardcore programmers? When their use is necessary, what are some good survival tips? Edit: I'm seeing one issue from some of the answers I've gotten. I have a strong personal preference, when I analyze data, to have one script that incorporates the whole pipeline. This implies that a general purpose language needs to be used. I hate having to write a script to "clean up" the data and spit it out, then another to read it back in a completely different environment, etc. I find the friction of using MATLAB/R for some of my work and a completely different language with a completely different address space and way of thinking for the rest to be a huge source of friction. Furthermore, I know there are glue layers that exist, but they always seem to be horribly complicated and a source of friction.

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• ArchBeat Link-o-Rama Top 10 for September 9-15, 2012

  - by Bob Rhubart

  The Top 10 most-viewed items shared on the OTN ArchBeat Facebook page for the week of September 9-15, 2017. 15 Lessons from 15 Years as a Software Architect | Ingo Rammer In this presentation from the GOTO Conference in Copenhagen, Ingo Rammer shares 15 tips regarding people, complexity and technology that he learned doing software architecture for 15 years. Attend OTN Architect Day – by Architects, for Architects – October 25 You won't need 3D glasses to take in these live presentations (8 sessions, two tracks) on Cloud computing, SOA, and engineered systems. And the ticket price is: Zero. Nothing. Absolutely free. Register now for Oracle Technology Network Architect Day in Los Angeles. Thursday October 25, 2012, 8:00 a.m. – 5:00 p.m. Sofitel Los Angeles , 8555 Beverly Boulevard , Los Angeles, CA 90048. Cloud API and service designers, stop thinking small | Cloud Computing - InfoWorld "The focus must shift away from fine-grained APIs that provide some type of primitive service, such as pushing data to a block of storage or perhaps making a request to a cloud-rooted database," says InfoWorld's David Linthicum. "To go beyond primitives, you must understand how these services should be used in a much larger architectural context. In other words, you need to understand how businesses will employ these services to form real workplace solutions—inside and outside the enterprise." Adding a runtime picker to a taskflow parameter in WebCenter | Yannick Ongena Oracle ACE Yannick Ongena shows how to create an Oracle WebCenter popup to allow users to "select items or do more complex things." Oracle IAM 11g R2 docs are now available "One of the great things about the new doc set is the inclusion of ePub files," says Fusion Middleware A-Team blogger Chris Johnson. "This means that if you have an iPad you can load up the doc library onto that and read the docs on the couch." Setting up a local Yum Server using the Exalogic ZFS Storage Appliance | Donald A concise technical post from the man named Donald. What's New in Oracle VM VirtualBox 4.2? | The Fat Bloke Sings "One of the trends we've seen is that as the average host platform becomes more powerful, our users are consistently running more and more vm's," says The Fat Bloke. "Some of our users have large libraries of vm's of various vintages, whilst others have groups of vm's that are run together as an assembly of the various tiers in a multi-tiered software solution, for example, a database tier, middleware tier, and front-ends." The new VirtualBox release, a year in the making, addresses the needs of these users, he explains. Configuring Oracle Business Intelligence 11g MDS XML Source Control Management with Git Version Control | Christian Screen Oracle ACE Christian Screen developed this tutorial for those interested in learning how to configure the Oracle Business Intelligence 11g (11.1.1.6) metadata repository for development using the new MDS XML source control management functionality. Identity and Access Management at Oracle Open World 2012 | Brian Eidelman Fusion Middleware A-Team blogger Brian Eideleman highlights three Oracle Openworld sessions that will put Identity and Access Management in the spotlight, and shares a link to the "Focus On: Identity Management" document, a comprehensive listing of Openworld activities also dealing with IM. Starting and stopping WebLogic automatically using Upstart | Chris Johnson "In Ubuntu, RedHat and Oracle Linux there's a new flavor of init called Upstart that all the kids are using," says Oracle Fusion Middleware A-Team member Chris Johnson. "It's the new hotness when it comes to making programs into daemons and wiring them to start and stop at appropriate times." Thought for the Day "The purpose of software engineering is to control complexity, not to create it." — Pamela Zave Source: SoftwareQuotes.com

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• ORE graphics using Remote Desktop Protocol

  - by Sherry LaMonica

  Oracle R Enterprise graphics are returned as raster, or bitmap graphics. Raster images consist of tiny squares of color information referred to as pixels that form points of color to create a complete image. Plots that contain raster images render quickly in R and create small, high-quality exported image files in a wide variety of formats. However, it is a known issue that the rendering of raster images can be problematic when creating graphics using a Remote Desktop connection. Raster images do not display in the windows device using Remote Desktop under the default settings. This happens because Remote Desktop restricts the number of colors when connecting to a Windows machine to 16 bits per pixel, and interpolating raster graphics requires many colors, at least 32 bits per pixel.. For example, this simple embedded R image plot will be returned in a raster-based format using a standalone Windows machine:  R> library(ORE) R> ore.connect(user="rquser", sid="orcl", host="localhost", password="rquser", all=TRUE)  R> ore.doEval(function() image(volcano, col=terrain.colors(30))) Here, we first load the ORE packages and connect to the database instance using database login credentials. The ore.doEval function executes the R code within the database embedded R engine and returns the image back to the client R session. Over a Remote Desktop connection under the default settings, this graph will appear blank due to the restricted number of colors. Users who encounter this issue have two options to display ORE graphics over Remote Desktop: either raise Remote Desktop's Color Depth or direct the plot output to an alternate device. Option #1: Raise Remote Desktop Color Depth setting In a Remote Desktop session, all environment variables, including display variables determining Color Depth, are determined by the RCP-Tcp connection settings. For example, users can reduce the Color Depth when connecting over a slow connection. The different settings are 15 bits, 16 bits, 24 bits, or 32 bits per pixel. To raise the Remote Desktop color depth: On the Windows server, launch Remote Desktop Session Host Configuration from the Accessories menu.Under Connections, right click on RDP-Tcp and select Properties.On the Client Settings tab either uncheck LimitMaximum Color Depth or set it to 32 bits per pixel. Click Apply, then OK, log out of the remote session and reconnect.After reconnecting, the Color Depth on the Display tab will be set to 32 bits per pixel.  Raster graphics will now display as expected. For ORE users, the increased color depth results in slightly reduced performance during plot creation, but the graph will be created instead of displaying an empty plot. Option #2: Direct plot output to alternate device Plotting to a non-windows device is a good option if it's not possible to increase Remote Desktop Color Depth, or if performance is degraded when creating the graph. Several device drivers are available for off-screen graphics in R, such as postscript, pdf, and png. On-screen devices include windows, X11 and Cairo. Here we output to the Cairo device to render an on-screen raster graphic.  The grid.raster function in the grid package is analogous to other grid graphical primitives - it draws a raster image within the current plot's grid.  R> options(device = "CairoWin") # use Cairo device for plotting during the session R> library(Cairo) # load Cairo, grid and png libraries  R> library(grid) R> library(png)  R> res <- ore.doEval(function()image(volcano,col=terrain.colors(30))) # create embedded R plot  R> img <- ore.pull(res, graphics = TRUE)$img[[1]] # extract image  R> grid.raster(as.raster(readPNG(img)), interpolate = FALSE) # generate raster graph R> dev.off() # turn off first device   By default, the interpolate argument to grid.raster is TRUE, which means that what is actually drawn by R is a linear interpolation of the pixels in the original image. Setting interpolate to FALSE uses a sample from the pixels in the original image.A list of graphics devices available in R can be found in the Devices help file from the grDevices package: R> help(Devices)

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• WF4 &ndash; Guess the number game!

  - by MarkPearl

  I posted yesterday how really good WF4 was looking. Today I thought I would show some real basics that I was able to figure out. This will be a simple example, I am going to make a flowchart workflow – which will prompt the user to guess the number until they guess the right number. Lets begin… Make a new project and make it a Workflow console Application. Then select the Workflow file and drag a FlowChart (2) to point 3. This will now show a green start circle in the designer form. We are going to work with primitives to start with. We are now going to drag a few objects onto the Workflow, We drag the WriteLine, Assign & Decision items onto the designer. Once they are dragged onto the designer we will want to link them up. The order that they are linked is critical since this will determine the order of the solution. In this case, we want the system to first ask “Guess a number”, then to wait for the user to input some code, and then to display “You got it” if they got it right, and “Try again” if they got it wrong. So we now link the arrows to the objects. This is done by moving the mouse pointer over the start objects and clicking on one of the toggles and then dragging it to the next object and releasing the button over one of the toggles. This will place an arrow from the source object to the target object. Okay… pretty simple stuff – now we just need these primitive objects to do stuff. Lets start with the WriteLine primitive. We place the text in inverted commas in the Text field. Because this field accepts any valid VB expression we could have put variables etc. in there if we wanted to. The next thing we want to do is allow the user to input a number. This brings up an interesting problem, if a user were to type in a number, there would need to be someway to declare a variable to hold that value for the life of the workflow. We can achieve this by declaring a variable. To declare a variable, move your cursor over the variables tab at the bottom of the workflow, and then type the name of the new variable in the “Create Variable” field and set it as shown in the image above. Now that we have a variable, we want to call the Console.Readline method and assign the inputted value from the Console to that variable. The code that cannot be seen is actually this – Convert.ToInt32(Console.ReadLine()) We now have a workflow that first prompts the user for a number, then allows the user to type in a number. We are almost done, we just need to make the system react to the value inputted. There are a few ways we could do this, I am going to use the Decision item. So select the Decision object on the designer and then view its properties (F4 for me), and in the condition field place a condition. For simplicity sake I have decided that if the user guesses 10, they will have guessed the number. This is now the completed workflow. Its really easy to understand and shows some really powerful principles for Business applications. You can run the application and see what it does. Imagine writing business solutions that do not worry about the exact flow of objects, but simply allows a business analyst or someone to configure the solution to work exactly as the business rules would dictate. And if the rules changed six months later all they would need to do is re-drag some of the flows. Now I do not know if WF4 will allow for this, but it feels like it is a step in the right direct.

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• Asynchrony in C# 5 (Part II)

  - by javarg

  This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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• how do I add a texture to a triangle in three.js?

  - by Kae Verens

  I've created a scene which has many cubes, spheres, etc, in it, and have been able to apply textures to those primitives, but when I want to add a texture to a simple triangle, I'm totally lost. Here's the closest I've come to getting it right: var texture=THREE.ImageUtils.loadTexture('/f/3d-images/texture-steel.jpg'); var materialDecalRoof=new THREE.MeshBasicMaterial( { 'map': texture, 'wireframe': false, 'overdraw': true } ); var geometry = new THREE.Geometry(); geometry.vertices.push(new THREE.Vector3(tentX/2+1, tentY, tentZ/2+1)); geometry.vertices.push(new THREE.Vector3(0, tentT, 0)); geometry.vertices.push(new THREE.Vector3(0, tentT, 0)); geometry.vertices.push(new THREE.Vector3(-tentX/2-1, tentY, tentZ/2+1)); geometry.faces.push(new THREE.Face4(0, 1, 2, 3)); geometry.faceVertexUvs[0].push([ new THREE.UV(0, 0), new THREE.UV(0, 0), new THREE.UV(0, 0), new THREE.UV(0, 0) ]); geometry.computeFaceNormals(); geometry.computeCentroids(); geometry.computeVertexNormals(); var mesh= new THREE.Mesh( geometry, materialDecalRoof); scene.add(mesh); This does not work. All i get is a flickering triangle (when the scene is moved) where an image should be. To test this, go to https://www.poptents.eu/3dFrame.php, upload an image in the Roof section, and drag the view to see the roof flicker. Does anyone know what I'm doing wrong here?

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• Silverlight ComboBox Attached Behavior

  - by Mark Cooper

  I am trying to create an attached behavior that can be applied to a Silverlight ComboBox. My behavior is this: using System.Windows.Controls; using System.Windows; using System.Windows.Controls.Primitives; namespace AttachedBehaviours { public class ConfirmChangeBehaviour { public static bool GetConfirmChange(Selector cmb) { return (bool)cmb.GetValue(ConfirmChangeProperty); } public static void SetConfirmChange(Selector cmb, bool value) { cmb.SetValue(ConfirmChangeProperty, value); } public static readonly DependencyProperty ConfirmChangeProperty = DependencyProperty.RegisterAttached("ConfirmChange", typeof(bool), typeof(Selector), new PropertyMetadata(true, ConfirmChangeChanged)); public static void ConfirmChangeChanged(DependencyObject d, DependencyPropertyChangedEventArgs args) { Selector instance = d as Selector; if (args.NewValue is bool == false) return; if ((bool)args.NewValue) instance.SelectionChanged += OnSelectorSelectionChanged; else instance.SelectionChanged -= OnSelectorSelectionChanged; } static void OnSelectorSelectionChanged(object sender, RoutedEventArgs e) { Selector item = e.OriginalSource as Selector; MessageBox.Show("Unsaved changes. Are you sure you want to change teams?"); } } } This is used in XAML as this: <UserControl x:Class="AttachedBehaviours.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:this="clr-namespace:AttachedBehaviours" mc:Ignorable="d"> <Grid x:Name="LayoutRoot"> <StackPanel> <ComboBox ItemsSource="{Binding Teams}" this:ConfirmChangeBehaviour.ConfirmChange="true" > </ComboBox> </StackPanel> </Grid> </UserControl> I am getting an error: Unknown attribute ConfirmChangeBehaviour.ConfirmChange on element ComboBox. [Line: 13 Position: 65] Intellisense is picking up the behavior, why is this failing at runtime? Thanks, Mark EDIT: Register() changed to RegisterAttached(). Same error appears.

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• java converting int to short

  - by changed

  Hi I am calculating 16 bit checksum on my data which i need to send to server where it has to recalculate and match with the provided checksum. Checksum value that i am getting is in int but i have only 2 bytes for sending the value.So i am casting int to short while calling shortToBytes method. This works fine till checksum value is less than 32767 thereafter i am getting negative values. Thing is java does not have unsigned primitives, so i am not able to send values greater than max value of signed short allowed. How can i do this, converting int to short and send over the network without worrying about truncation and signed & unsigned int. Also on both the side i have java program running. private byte[] shortToBytes(short sh) { byte[] baValue = new byte[2]; ByteBuffer buf = ByteBuffer.wrap(baValue); return buf.putShort(sh).array(); } private short bytesToShort(byte[] buf, int offset) { byte[] baValue = new byte[2]; System.arraycopy(buf, offset, baValue, 0, 2); return ByteBuffer.wrap(baValue).getShort(); }

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• Saturated addition of two signed Java 'long' values

  - by finnw

  How can one add two long values (call them x and y) in Java so that if the result overflows then it is clamped to the range Long.MIN_VALUE..Long.MAX_VALUE? For adding ints one can perform the arithmetic in long precision and cast the result back to an int, e.g.: int saturatedAdd(int x, int y) { long sum = (long) x + (long) y; long clampedSum = Math.max((long) Integer.MIN_VALUE, Math.min(sum, (long) Integer.MAX_VALUE)); return (int) clampedSum; } or import com.google.common.primitives.Ints; int saturatedAdd(int x, int y) { long sum = (long) x + (long) y; return Ints.saturatedCast(sum); } but in the case of long there is no larger primitive type that can hold the intermediate (unclamped) sum. Since this is Java, I cannot use inline assembly (in particular SSE's saturated add instructions.) It can be implemented using BigInteger, e.g. static final BigInteger bigMin = BigInteger.valueOf(Long.MIN_VALUE); static final BigInteger bigMax = BigInteger.valueOf(Long.MAX_VALUE); long saturatedAdd(long x, long y) { BigInteger sum = BigInteger.valueOf(x).add(BigInteger.valueOf(y)); return bigMin.max(sum).min(bigMax).longValue(); } however performance is important so this method is not ideal (though useful for testing.) I don't know whether avoiding branching can significantly affect performance in Java. I assume it can, but I would like to benchmark methods both with and without branching. Related: http://stackoverflow.com/questions/121240/saturating-addition-in-c

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• Why not systematically attach event in WPF instead of using delegate ?

  - by user310291

  For a button to handle event, we can add a delegate to the click property of the button: this.button1.Click += new System.EventHandler(this.button1_Click); But in WPF contrary to Winform, you can also attach a handler http://msdn.microsoft.com/en-us/magazine/cc785480.aspx So why not do so for the button ? Is performance better in first case maybe ? Update: I mean this Attached Events In order to enable elements to handle events that are declared in a different element, WPF supports something called attached events. Attached events are routed events that support a hookup in XAML on elements other than the type on which the event is declared. For example, if you want the Grid element to listen for a Button.Click event to bubble past, you would simply hook it up like the following: <Grid Button.Click="myButton_Click"> <Button Name="myButton" >Click Me</Button> </Grid> The resulting code in the compile-time-generated partial class now looks like this: #line 5 "..\..\Window1.xaml" ((System.Windows.Controls.Grid)(target)).AddHandler( System.Windows.Controls.Primitives.ButtonBase.ClickEvent, new System.Windows.RoutedEventHandler(this.myButton_Click));

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• What specific features of LabView are frustrating to you?

  - by Underflow

  Please bear with me: this isn't a language debate or a flame. It's a real request for opinions. Occasionally, I have to help educate a traditional text coder in how to think in LabVIEW (LV). Often during this process, I get to hear about how LV sucks. Rarely is this insight accompanied by rational observations other than "Language X is just so much better!". While this statement is satisfying to them, it doesn't help me understand what is frustrating them. So, for those of you with LabVIEW and text language experience, what specific things about LV drive you nuts? ------ Summaries ------- Thanks for all the answers! Some of the issues are answered in the comments below, some exist on other sites, and some are just genuine problems with LV. In the spirit of the original question, I'm not going to try to answer all of these here: check LAVA or NI's website, and you'll be pleasantly surprised at how many of these things can be overcome. Unintentional concurrency No access to tradition text manipulation tools Binary-only source code control Difficult to branch and merge Too many open windows Text has cleaner/clearer/more expressive syntax Clean coding requires a lot of time and manipulation Large, difficult to access API/palette system Mouse required File namespacing: no duplicate files with the same name in memory LV objects are natively by-value only Requires dev environment to view code Lack of zoom Slow startup Memory pig "Giant" code is difficult to work with UI lockup is easy to do Trackpads and LV don't mix well String manipulation is graphically bloated Limited UI customization "Hidden" primitives (yes, these exist) Lack of official metaprogramming capability (not for much longer, though) Lack of unicode support [1]: http://www.lavag.org LAVA

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• does actionscript addChild require a display object first

  - by touB

  I'm trying to move away from mxml to actionsctipt. I have a <s:Rect> that I've created and set its properties, but having trouble adding it. var aRect:Rect = new Rect(); //set properties like aRect.x, aRect.y, aRect.width, aRect.height //tried adding it various ways addChild(aRect); Application.addChild(aRect); Application.application.addChild(aRect); stage.addChild(aRect); But I keep getting the error 1067: Implicit coercion of a value of type spark.primitives:Rect to an unrelated type flash.display:DisplayObject Originally in the mxml, it was right inside <s:Application> not nested inside anything <s:Application> <s:Rect id="aRect" x="10" y="10" width="15%" height="15%"> //then fill code here, removed for readability </s:Rect> </s:Application> What's the deal, I thought actionscript would be nicer than mxml.

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• Draw LINE_STRIP with Unity

  - by Boozzz

  For a new project I am thinking about whether to use OpenGL or Unity3d. I have a bit of experience with OpenGL, but I am completely new to Unity. I already read through the Unity documentation and tutorials on the Unity Website. However, I could not find a way to draw a simple Line-Strip with Unity. In the following example (C#, OpenGL/SharpGL) I draw a round trajectory from a predifined point to an obstacle, which can be imagined as a divided circle with midpoint [cx,cy] and radius r. The position (x-y coordinates) of the obstacle is given by obst_x and obst_y. Question 1: How could I do the same with Unity? Question 2: In my new project, I will have to draw quite a lot of such geometric primitives. Does it make any sense to use Unity for those things? void drawCircle(float cx, float cy, float r, const float obst_x, const float obst_y) { float theta = 0.0f, pos_x, pos_y, dist; const float delta = 0.1; glBegin(GL_LINE_STRIP); while (theta < 180) { theta += delta; //get the current angle float x = r * cosf(theta); //calculate the x component float y = r * sinf(theta); //calculate the y component pos_x = x + cx; //calculate current x position pos_y = y + cy; //calculate current y position //calculate distance from current vertex to obstacle dist = sqrt(pow(pos_x - obst_x) + pow(pos_y - obst_y)); //check if current vertex intersects with obstacle if dist <= 0 { break; //stop drawing circle } else { glVertex2f(pos_x, pos_y); //draw vertex } } glEnd(); }

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• Java: Is clone() really ever used? What about defensive copying in getters/setters?

  - by GreenieMeanie

  Do people practically ever use defensive getters/setters? To me, 99% of the time you intend for the object you set in another object to be a copy of the same object reference, and you intend for changes you make to it to also be made in the object it was set in. If you setDate(Date dt) and modify dt later, who cares? Unless I want some basic immutable data bean that just has primitives and maybe something simple like a Date, I never use it. As far as clone, there are issues as to how deep or shallow the copy is, so it seems kind of "dangerous" to know what is going to come out when you clone an Object. I think I have only used clone() once or twice, and that was to copy the current state of the object because another thread (ie another HTTP request accessing the same object in Session) could be modifying it. Edit - A comment I made below is more the question: But then again, you DID change the Date, so it's kind of your own fault, hence whole discussion of term "defensive". If it is all application code under your own control among a small to medium group of developers, will just documenting your classes suffice as an alternative to making object copies? Or is this not necessary, since you should always assume something ISN'T copied when calling a setter/getter?

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• OpenGL Tearing Problem

  - by kaykun

  Hi, I'm using win32 and opengl and I have a window set up with the projection at glOrtho of the window's coordinates. I have double buffering enabled, tested it with glGet as well. My program always seems to tear any primitives that I try to draw on it if it's being constantly translated. Here is my OpenGL initialization function: glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glViewport(0, 0, 640, 480); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0, 640, 0, 480, 0, 100); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glDrawBuffer(GL_BACK); glLoadIdentity(); And this is my rendering function, gMouseX and gMouseY are the coordinates of the mouse: glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glTranslatef(gMouseX, gMouseY, 0.0f); glColor3f(0.5f, 0.5f, 0.5f); glBegin(GL_TRIANGLES); glVertex2f(0.0f, 128.0f); glVertex2f(128.0f, 0.0f); glVertex2f(0.0f, 0.0f); glEnd(); SwapBuffers(hDC); The same tearing problem occurs regardless of how often the rendering function runs. Is there something I'm doing wrong or missing here? Thanks for any help.

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• SDL with OpenGL (freeglut) crashes on call to glutBitmapCharacter

  - by stett

  I have a program using OpenGL through freeglut under SDL. The SDL/OpenGL initialization is as follows: // Initialize SDL SDL_Init(SDL_INIT_VIDEO); // Create the SDL window SDL_SetVideoMode(SCREEN_W, SCREEN_H, SCREEN_DEPTH, SDL_OPENGL); // Initialize OpenGL glClearColor(BG_COLOR_R, BG_COLOR_G, BG_COLOR_B, 1.f); glViewport(0, 0, SCREEN_W, SCREEN_H); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0f, SCREEN_W, SCREEN_H, 0.0f, -1.0f, 1.0f); glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); I've been using glBegin() ... glEnd() blocks without any trouble to draw primitives. However, in this program when I call any glutBitmapX function, the program simply exits without an error status. The code I'm using to draw text is: glColor3f(1.f, 1.f, 1.f); glRasterPos2f(x, y); glutStrokeString(GLUT_BITMAP_8_BY_13, (const unsigned char*)"test string"); In previous similar programs I've used glutBitmapCharacter and glutStrokeString to draw text and it's seemed to work. The only difference being that I'm using freeglut with SDL now instead of just GLUT as I did in previous programs. Is there some fundamental problem with my setup that I'm not seeing, or is there a better way of drawing text?

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• Determining the color of a pixel in a bitmap using C# in a WPF app

  - by DanM

  The only way I found so far is System.Drawing.Bitmap.GetPixel(), but Microsoft has warnings for System.Drawing that are making me wonder if this is the "old way" to do it. Are there any alternatives? Here's what Microsoft says about the System.Drawing namespace. I also noticed that the System.Drawing assembly was not automatically added to the references when I created a new WPF project. System.Drawing Namespace The System.Drawing namespace provides access to GDI+ basic graphics functionality. More advanced functionality is provided in the System.Drawing.Drawing2D, System.Drawing.Imaging, and System.Drawing.Text namespaces. The Graphics class provides methods for drawing to the display device. Classes such as Rectangle and Point encapsulate GDI+ primitives. The Pen class is used to draw lines and curves, while classes derived from the abstract class Brush are used to fill the interiors of shapes. Caution Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions. - http://msdn.microsoft.com/en-us/library/system.drawing.aspx

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• Get a button in itemscontrol and add eventhandler to its click event

  - by rockdale

  I have a custom control shows a customer info with an itemscontrol shows this customer's invoices. within the itemscontrol, I have button, in my code behind I want to wire the button's click event to my host window, but do now know how. //public event RoutedEventHandler ViewDetailClick; public static readonly RoutedEvent ButtonViewClickEvent = EventManager.RegisterRoutedEvent( "ButtonViewClick", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(custitem)); public event RoutedEventHandler ButtonViewClick { add { AddHandler(ButtonViewClickEvent, value); } remove {RemoveHandler(ButtonViewClickEvent, value);} } public override void OnApplyTemplate() { base.OnApplyTemplate(); this.lstInv = GetTemplateChild("lstInv") as ItemsControl; lstInv.ItemContainerGenerator.StatusChanged += new EventHandler(ItemContainerGenerator_StatusChanged); } private void ItemContainerGenerator_StatusChanged(object sender, EventArgs e) { if (lstInv.ItemContainerGenerator.Status == System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated) { lstInv.ItemContainerGenerator.StatusChanged -= ItemContainerGenerator_StatusChanged; for (int i = 0; i < this.lstInv.Items.Count; i++) { ContentPresenter c = lstInv.ItemContainerGenerator.ContainerFromItem(lstInv.Items[i]) as ContentPresenter; DataTemplate dt = c.ContentTemplate; Grid grd = dt.LoadContent() as Grid; Button btnView = grd.FindName("btnView") as Button; if (btnView != null) { btnView.Click += new RoutedEventHandler(ButtonView_Click); //btnView.Click+= delegate(object senderObj, RoutedEventArgs eArg) //{ // if (this.ViewDetailClick != null) // { // this.ViewDetailClick(this, eArg); // } //}; } } private void ButtonView_Click(object sender, RoutedEventArgs e) { MessageBox.Show("clicked"); //e.RoutedEvent = ButtonViewClickEvent; //e.Source = sender; //RaiseEvent(e); } I succeed getting the btnView, then attach the click event, but the click event never get fired. Thanks in advance -rockdale

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• Atomic swap in GNU C++

  - by Steve

  I want to verify that my understanding is correct. This kind of thing is tricky so I'm almost sure I am missing something. I have a program consisting of a real-time thread and a non-real-time thread. I want the non-RT thread to be able to swap a pointer to memory that is used by the RT thread. From the docs, my understanding is that this can be accomplished in g++ with: // global Data *rt_data; Data *swap_data(Data *new_data) { #ifdef __GNUC__ // Atomic pointer swap. Data *old_d = __sync_lock_test_and_set(&rt_data, new_data); #else // Non-atomic, cross your fingers. Data *old_d = rt_data; rt_data = new_data; #endif return old_d; } This is the only place in the program (other than initial setup) where rt_data is modified. When rt_data is used in the real-time context, it is copied to a local pointer. For old_d, later on when it is sure that the old memory is not used, it will be freed in the non-RT thread. Is this correct? Do I need volatile anywhere? Are there other synchronization primitives I should be calling? By the way I am doing this in C++, although I'm interested in whether the answer differs for C. Thanks ahead of time.

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• Pump Messages During Long Operations + C# (it is urgent)

  - by Newbie

  Hi I have a web service that is doing huge computation and is taking more than a minute. I have generated the proxy file of the web service and then from my client end I am using the dll(of course I generated the proxy dll). My client side code is TimeSeries3D t = new TimeSeries3D(); int portfolioId = 4387919; string[] str = new string[2]; str[0] = "MKT_CAP"; DateRange dr = new DateRange(); dr.mStartDate = DateTime.Today; dr.mEndDate = DateTime.Today; Service1 sc = new Service1(); t = sc.GetAttributesForPortfolio(portfolioId, true, str, dr); But since it is taking to much time for the server to compute, after 1 minute I am receiving an error message The CLR has been unable to transition from COM context 0x33caf30 to COM context 0x33cb0a0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. Kindly guide me what to do? It is very urgent. Thanks

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