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• Are "EXC_BREAKPOINT (SIGTRAP)" exceptions caused by debugging breakpoints?

  - by Dennis

  I have a multithreaded app that is very stable on all my test machines and seems to be stable for almost every one of my users (based on no complaints of crashes). The app crashes frequently for one user, though, who was kind enough to send crash reports. All the crash reports (~10 consecutive reports) look essentially identical: Date/Time: 2010-04-06 11:44:56.106 -0700 OS Version: Mac OS X 10.6.3 (10D573) Report Version: 6 Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000002, 0x0000000000000000 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.CoreFoundation 0x90ab98d4 __CFBasicHashRehash + 3348 1 com.apple.CoreFoundation 0x90adf610 CFBasicHashRemoveValue + 1264 2 com.apple.CoreText 0x94e0069c TCFMutableSet::Intersect(__CFSet const*) const + 126 3 com.apple.CoreText 0x94dfe465 TDescriptorSource::CopyMandatoryMatchableRequest(__CFDictionary const*, __CFSet const*) + 115 4 com.apple.CoreText 0x94dfdda6 TDescriptorSource::CopyDescriptorsForRequest(__CFDictionary const*, __CFSet const*, long (*)(void const*, void const*, void*), void*, unsigned long) const + 40 5 com.apple.CoreText 0x94e00377 TDescriptor::CreateMatchingDescriptors(__CFSet const*, unsigned long) const + 135 6 com.apple.AppKit 0x961f5952 __NSFontFactoryWithName + 904 7 com.apple.AppKit 0x961f54f0 +[NSFont fontWithName:size:] + 39 (....more text follows) First, I spent a long time investigating [NSFont fontWithName:size:]. I figured that maybe the user's fonts were screwed up somehow, so that [NSFont fontWithName:size:] was requesting something non-existent and failing for that reason. I added a bunch of code using [[NSFontManager sharedFontManager] availableFontNamesWithTraits:NSItalicFontMask] to check for font availability in advance. Sadly, these changes didn't fix the problem. I've now noticed that I forgot to remove some debugging breakpoints, including _NSLockError, [NSException raise], and objc_exception_throw. However, the app was definitely built using "Release" as the active build configuration. I assume that using the "Release" configuration prevents setting of any breakpoints--but then again I am not sure exactly how breakpoints work or whether the program needs to be run from within gdb for breakpoints to have any effect. My questions are: could my having left the breakpoints set be the cause of the crashes observed by the user? If so, why would the breakpoints cause a problem only for this one user? If not, has anybody else had similar problems with [NSFont fontWithName:size:]? I will probably just try removing the breakpoints and sending back to the user, but I'm not sure how much currency I have left with that user. And I'd like to understand more generally whether leaving the breakpoints set could possibly cause a problem (when the app is built using "Release" configuration).

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• LINQ to SQL Could not find key member. Only fails on server.

  - by Adam Carr

  I have a scenario where I am inheriting from an abstract class in my partial linq to sql auto generated class implementation. My base abstract class has an abstract property called ID which I have flagged inside my LINQ to SQL model with the instance modifier override. This works fine locally without any issues. I have also done some development on another machine and it works fine there too (both in VS2008 and using Subversion). I am running CI with TeamCity and the build succeeds and deploys as desired. The problem is when the server tries to hit the database for the first time via the LINQ to SQL data context, it generates the following error. "Could not find key member 'Id' of key 'Id' on type 'CustomType'. The key may be wrong or the field or property on 'CustomType' has changed names." I have tried changing my configuration by not implementing the Id field in my base class but this still fails. Why does it work on both of my DEV machines but not on the server? I am using LINQ to SQL in another project that runs on this server just fine. FYI: LINQ to SQL, SQL 2008, .NET 3.5, SERVER 2008, IIS 7.0 UPDATE I have gone back and added the same table a second time in the same data model but without a base class and have then displayed the results from that table and got no errors. This tells me it has something to do with my base abstract class and the need to flag a property on one of my linq to sql model classes (that belongs to a key relationship) with the instance modifier of override. No answer to this yet but am getting closer. UPDATE I have fixed my issue by simply changing my approach to my problem but I am still interested in why this doesn't work. I created a new WinSrv2008 VPC and patched it, deployed a pre-built version of my site to it and still got the same error. I now assume the issue is like what the person said here, a dependency issue with VS2008. My question is what or what? Will install VS2008 on the VPC to see if it works after that.

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• Possible to use Python with Intel's Atom Developer SDK (C/C++)?

  - by Jordan Magnuson

  So I've made a game in Python and PyGame. Now I'm interested in submitting the game to Intel's March Developer Challenge. However, the developer challenge requires use of Intel's Atom Developer SDK (http://appdeveloper.intel.com/en-us/sdk), which only has API's for C and C++. I'm new to Python and PyGame, and have no experience in C or C++. My question is, would it be possible to somehow implement Intel's Atom SDK through/with/from a Python application (as the first link above suggests)? I've read up a little bit on embedding/extending Python into/with C, but I'm not entirely sure what to embed or where. I mean, I know I can do things like this in C: #include <Python.h> int main(int argc, char *argv[]) { Py_Initialize(); PyRun_SimpleString("from time import time,ctime\n" "print 'Today is',ctime(time())\n"); Py_Finalize(); return 0; } But what do I do about all my dependencies on Python and Pygame, for people that don't have those installed on their machines? Normally Py2Exe takes care of compacting the required dependencies (I've managed to package my game into an exe/zip), but how do I take care of that stuff in the context of embedding within C? Can I somehow work with py2exe on this, or do I need to do something entirely different for embedding within C? It seems like it would be a lot easier to go the route of extending Python with the C validation code, rather than trying to embed my whole game within C, but I think that's not an option, "because the library provided is currently only available as a Visual Studio 2008 '.lib'", meaning the application has to be compiled with Visual Studio...? Any help, thoughts, or ideas are much appreciated! You can find the complete SDK Developer's Guide on the intel site above, but here is their "Hello World" using the C Language API: #include <stdio.h> #include “adpcore.h” int main( int argc, char* argv[] ) { ADP_RET_CODE ret_code; const ADP_APPLICATIONID myApplicationID = {{ 0x12345678,0x11112222,0x33331234,0x567890ab}}; if ((ret_code = ADP_Initialize()) != ADP_SUCCESS ){ printf( “ERROR: exiting” ); exit( -1 ); } if (( ret_code = ADP_IsAuthorized( myApplicationId )) == ADP_AUTHORIZED ) printf( “Hello World” ); else printf( “Not authorized to run” ); exit 0; } 35 Page SDK Developer Guide: http:// appdeveloper.intel.com/sites/files/pages/SDK%20Developer%20Guide.pdf

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• .NET Application broken on one PC, unhandleable exception

  - by Bobby

  Hello people. I have a .NET 2.0 application with nothing fancy in it. It worked until yesterday on every PC I installed or copied it to, no matter if 2.0, 3.0, 3.5 or 3.5 SP1 was installed, no matter if it was Win2000, XP or even Win7 (in total 100+ machines). Yesterday I did my normal installation procedure and wanted to start it one time to check if everything is working...and it wasn't. The program crashed hard leaving me with the uninformative "Do you wanna report this error?" dialog. The problem is an exception in the Main(String[] args) routine of my application. The event viewer is showing the following entry: Event Type: ErrorEvent Source: .NET Runtime 2.0 Error Reporting Event Category: None Event ID: 5000 Date: 05/05/2010 Time: 16:09:09 User: N/A Computer: myClientPC Description: EventType clr20r3, P1 apomenu.exe, P2 1.4.90.53, P3 4bdedea4, P4 system.configuration, P5 2.0.0.0, P6 4889de74, P7 1a6, P8 136, P9 ioibmurhynrxkw0zxkyrvfn0boyyufow, P10 NIL. Well...great information. After a lot of searching I finally was able to get further information about this exception (by adding a handler for UnhandledExceptions directly in My.MyApplication.New(), Application.Designer.vb): System.Configuration.ConfigurationErrorsException Configuration system failed to initialize at System.Configuration.ClientConfigurationSystem.EnsureInit(String configKey) at System.Configuration.ClientConfigurationSystem.PrepareClientConfigSystem(String sectionName) at System.Configuration.ClientConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(String sectionName) at System.Configuration.ConfigurationManager.GetSection(String sectionName) at System.Configuration.PrivilegedConfigurationManager.GetSection(String sectionName) at System.Net.Configuration.SettingsSectionInternal.get_Section() at System.Net.Sockets.Socket.InitializeSockets() at System.Net.Sockets.Socket.get_SupportsIPv4() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.get_HostName() at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.RegisterChannel(Boolean SecureChannel) at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine) at MyAppNameHere.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:Line 81. And at this point I'm stuck...I'm out of ideas. I'm not using any kind of configuration system from the framework (no reference to System.Configuration, and there never was a MyAppnameHere.exe.config generated or distributed, nor have I seen this error before). I also found a bug report at Microsoft (Google Cache) about this bug (in another context, though). But as it seems, they won't even look at it. Every help is greatly appreciated! Edit: I'm using Visual Studio 2008 Prof.. Crash happens in Release- and Debug-Build on the client machine. Debugging the application directly on this machine is out of question I fear, 300+ Miles and they only have two computers to work with.

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• How do you stop a user-instance of Sql Server? (Sql Express user instance database files locked, eve

  - by Bittercoder

  When using SQL Server Express 2005's User Instance feature with a connection string like this: <add name="Default" connectionString="Data Source=.\SQLExpress; AttachDbFilename=C:\My App\Data\MyApp.mdf; Initial Catalog=MyApp; User Instance=True; MultipleActiveResultSets=true; Trusted_Connection=Yes;" /> We find that we can't copy the database files MyApp.mdf and MyApp_Log.ldf (because they're locked) even after stopping the SqlExpress service, and have to resort to setting the SqlExpress service from automatic to manual startup mode, and then restarting the machine, before we can then copy the files. It was my understanding that stopping the SqlExpress service should stop all the user instances as well, which should release the locks on those files. But this does not seem to be the case - could anyone shed some light on how to stop a user instance, such that it's database files are no longer locked? Update OK, I stopped being lazy and fired up Process Explorer. Lock was held by sqlserver.exe - but there are two instances of sql server: sqlserver.exe PID: 4680 User Name: DefaultAppPool sqlserver.exe PID: 4644 User Name: NETWORK SERVICE The file is open by the sqlserver.exe instance with the PID: 4680 Stopping the "SQL Server (SQLEXPRESS)" service, killed off the process with PID: 4644, but left PID: 4680 alone. Seeing as the owner of the remaining process was DefaultAppPool, next thing I tried was stopping IIS (this database is being used from an ASP.Net application). Unfortunately this didn't kill the process off either. Manually killing off the remaining sql server process does remove the open file handle on the database files, allowing them to be copied/moved. Unfortunately I wish to copy/restore those files in some pre/post install tasks of a WiX installer - as such I was hoping there might be a way to achieve this by stopping a windows service, rather then having to shell out to kill all instances of sqlserver.exe as that poses some problems: Killing all the sqlserver.exe instances may have undesirable consequencies for users with other Sql Server instances on their machines. I can't restart those instances easily. Introduces additional complexities into the installer. Does anyone have any further thoughts on how to shutdown instances of sql server associated with a specific user instance?

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• Boggling Direct3D9 dynamic vertex buffer Lock crash/post-lock failure on Intel GMA X3100.

  - by nj

  Hi, For starters I'm a fairly seasoned graphics programmer but as wel all know, everyone makes mistakes. Unfortunately the codebase is a bit too large to start throwing sensible snippets here and re-creating the whole situation in an isolated CPP/codebase is too tall an order -- for which I am sorry, do not have the time. I'll do my best to explain. B.t.w, I will of course supply specific pieces of code if someone wonders how I'm handling this-or-that! As with all resources in the D3DPOOL_DEFAULT pool, when the device context is taken away from you you'll sooner or later will have to reset your resources. I've built a mechanism to handle this for all relevant resources that's been working for years; but that fact nothingwithstanding I've of course checked, asserted and doubted any assumption since this bug came to light. What happens is as follows: I have a rather large dynamic vertex buffer, exact size 18874368 bytes. This buffer is locked (and discarded fully using the D3DLOCK_DISCARD flag) each frame prior to generating dynamic geometry (isosurface-related, f.y.i) to it. This works fine, until, of course, I start to reset. It might take 1 time, it might take 2 or it might take 5 resets to set off a bug that causes an access violation either on the pointer returned by the Lock() operation on the renewed resource or a plain crash -- regarding a somewhat similar address, but without the offset that it has tacked on to it in the first case because in that case we're somewhere halfway writing -- iside the D3D9 dll Lock() call. I've tested this on other hardware, upgraded my GMA X3100 drivers (using a MacBook with BootCamp) to the latest ones, but I can't reproduce it on any other machine and I'm at a loss about what's wrong here. I have tried to reproduce a similar situation with a similar buffer (I've got a large scratch pad of the same type I filled with quads) and beyond a certain amount of bytes it started to behave likewise. I'm not asking for a solution here but I'm very interested if there are other developers here who have battled with the same foe or maybe some who can point me in some insightful direction, maybe ask some questions that might shed a light on what I may or may not be overlooking. Another interesting artifact is that the vertex buffer starts to bug if I supply both D3DLOCK_DISCARD and D3DLOCK_NOOVERWRITE together which, even though not very logical (you're not going to overwrite if you've just discarded all), gives graphics glitches. Thanks and any corrections are more than welcome. Niels p.s - A friend of mine raised the valid point that it is a huge buffer for onboard video RAM and it's being at least double or triple buffered internally due to it's dynamic nature. On the other hand, the debug output (D3D9 debug DLL + max. warning output) remains silent. p.s 2 - Had it tested on more machines and still works -- it's probably a matter of circumstance: the huge dynamic, internally double/trippled buffered buffer, not a lot of memory and drivers that don't complain when they should.. Unless someone has a better suggestion; I'd still love to hear it :)

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• How do I prevent programmatically the "Program Compatibility Assistant" in Vista (and Windows 7) fro

  - by Asaf

  I develop a C++ program which might use adobe flash, although it is not essential. I use CoCreateInstance to create the flash object, and if it fails, I know flash is not installed so I don't use it. However, in Vista (and I think Windows 7 as well), when flash is not installed, after leaving the application, the "Program Compatibility Assistant" pops up a message saying that "This program requires a missing Windows component" specifying the flash.ocx. Is there a way to prevent this message from appearing? I don't want to force any user to install flash (especially since it's the IE ActiveX, and FireFox users might not have it installed), and my application can operate well without the flash. Plus this message is really annoying when it appears after every run. I don't mean of course disabling the PCA on the user's machine, but programmatically disable this specific appearance on all machines. Any thoughts? Thanks [EDIT:] I followed Shay's lead (thanks), and did some more digging of my own. I added the following XML to the application's manifest: <trustInfo xmlns="urn:schemas-microsoft-com:asm.v2"> <security> <requestedPrivileges> <requestedExecutionLevel level="asInvoker" uiAccess="false"> </requestedExecutionLevel> </requestedPrivileges> </security> </trustInfo> (see also: msdn.microsoft.com/en-us/library/bb756929.aspx) This solved the problem on Vista 64. To solve the same problem on Windows 7, I added the following: <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1"> <application> <!--The ID below indicates application support for Windows Vista --> <supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}"/> <!--The ID below indicates application support for Windows 7 --> <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}"/> </application> </compatibility> (See also: blogs.msdn.com/yvesdolc/archive/2009/09/22/the-new-compatibility-section-in-the-application-manifest.aspx) Solved Windows 7. But for some reason, it still happens in Vista 32... I also tried editing the manifest of the specific DLL which causes the problem, but it had no effect. Only the executable's manifest itself affected the problem. So... Vista 32?

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• How to I serialize a large graph of .NET object into a SQL Server BLOB without creating a large bu

  - by Ian Ringrose

  We have code like: ms = New IO.MemoryStream bin = New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bin.Serialize(ms, largeGraphOfObjects) dataToSaveToDatabase = ms.ToArray() // put dataToSaveToDatabase in a Sql server BLOB But the memory steam allocates a large buffer from the large memory heap that is giving us problems. So how can we stream the data without needing enough free memory to hold the serialized objects. I am looking for a way to get a Stream from SQL server that can then be passed to bin.Serialize() so avoiding keeping all the data in my processes memory. Likewise for reading the data back... Some more background. This is part of a complex numerical processing system that processes data in near real time looking for equipment problems etc, the serialization is done to allow a restart when there is a problem with data quality from a data feed etc. (We store the data feeds and can rerun them after the operator has edited out bad values.) Therefore we serialize the object a lot more often then we de-serialize them. The objects we are serializing include very large arrays mostly of doubles as well as a lot of small “more normal” objects. We are pushing the memory limit on a 32 bit system and make the garage collector work very hard. (Effects are being made elsewhere in the system to improve this, e.g. reusing large arrays rather then create new arrays.) Often the serialization of the state is the last straw that courses an out of memory exception; our peak memory usage is while this serialization is being done. I think we get large memory pool fragmentation when we de-serialize the object, I expect there are also other problem with large memory pool fragmentation given the size of the arrays. (This has not yet been investigated, as the person that first looked at this is a numerical processing expert, not a memory management expert.) Are customers use a mix of Sql Server 2000, 2005 and 2008 and we would rather not have different code paths for each version of Sql Server if possible. We can have many active models at a time (in different process, across many machines), each model can have many saved states. Hence the saved state is stored in a database blob rather then a file. As the spread of saving the state is important, I would rather not serialize the object to a file, and then put the file in a BLOB one block at a time. Other related questions I have asked How to Stream data from/to SQL Server BLOB fields? Is there a SqlFileStream like class that works with Sql Server 2005?

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• Why is it still so hard to write software?

  - by nornagon

  Writing software, I find, is composed of two parts: the Idea, and the Implementation. The Idea is about thinking: "I have this problem; how do I solve it?" and further, "how do I solve it elegantly?" The answers to these questions are obtainable by thinking about algorithms and architecture. The ideas come partially through analysis and partially through insight and intuition. The Idea is usually the easy part. You talk to your friends and co-workers and you nut it out in a meeting or over coffee. It takes an hour or two, plus revisions as you implement and find new problems. The Implementation phase of software development is so difficult that we joke about it. "Oh," we say, "the rest is a Simple Matter of Code." Because it should be simple, but it never is. We used to write our code on punch cards, and that was hard: mistakes were very difficult to spot, so we had to spend extra effort making sure every line was perfect. Then we had serial terminals: we could see all our code at once, search through it, organise it hierarchically and create things abstracted from raw machine code. First we had assemblers, one level up from machine code. Mnemonics freed us from remembering the machine code. Then we had compilers, which freed us from remembering the instructions. We had virtual machines, which let us step away from machine-specific details. And now we have advanced tools like Eclipse and Xcode that perform analysis on our code to help us write code faster and avoid common pitfalls. But writing code is still hard. Writing code is about understanding large, complex systems, and tools we have today simply don't go very far to help us with that. When I click "find all references" in Eclipse, I get a list of them at the bottom of the window. I click on one, and I'm torn away from what I was looking at, forced to context switch. Java architecture is usually several levels deep, so I have to switch and switch and switch until I find what I'm really looking for -- by which time I've forgotten where I came from. And I do that all day until I've understood a system. It's taxing mentally, and Eclipse doesn't do much that couldn't be done in 1985 with grep, except eat hundreds of megs of RAM. Writing code has barely changed since we were staring at amber on black. We have the theoretical groundwork for much more advanced tools, tools that actually work to help us comprehend and extend the complex systems we work with every day. So why is writing code still so hard?

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• What facets have I missed for creating a 3 person guerilla dev team?

  - by Penguinix

  Sorry for the Windows developers out there, this solution is for Macs only. This set of applications accounts for: Usability Testing, Screen Capture (Video and Still), Version Control, Task Lists, Bug Tracking, a Developer IDE, a Web Server, A Blog, Shared Doc Editing on the Web, Team and individual Chat, Email, Databases and Continuous Integration. This does assume your team members provide their own machines, and one person has a spare old computer to be the Source Repository and Web Server. All for under $200 bucks. Usability Silverback Licenses = 3 x $49.95 "Spontaneous, unobtrusive usability testing software for designers and developers." Source Control Server and Clients (multiple options) Subversion = Free Subversion is an open source version control system. Versions (Currently in Beta) = Free Versions provides a pleasant work with Subversion on your Mac. Diffly = Free "Diffly is a tool for exploring Subversion working copies. It shows all files with changes and, clicking on a file, shows a highlighted view of the changes for that file. When you are ready to commit Diffly makes it easy to select the files you want to check-in and assemble a useful commit message." Bug/Feature/Defect Tracking (multiple options) Bugzilla = Free Bugzilla is a "Defect Tracking System" or "Bug-Tracking System". Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively. Most commercial defect-tracking software vendors charge enormous licensing fees. Trac = Free Trac is an enhanced wiki and issue tracking system for software development projects. Database Server & Clients MySQL = Free CocoaMySQL = Free Web Server Apache = Free Development and Build Tools XCode = Free CruiseControl = Free CruiseControl is a framework for a continuous build process. It includes, but is not limited to, plugins for email notification, Ant, and various source control tools. A web interface is provided to view the details of the current and previous builds. Collaboration Tools Writeboard = Free Ta-da List = Free Campfire Chat for 4 users = Free WordPress = Free "WordPress is a state-of-the-art publishing platform with a focus on aesthetics, web standards, and usability. WordPress is both free and priceless at the same time." Gmail = Free "Gmail is a new kind of webmail, built on the idea that email can be more intuitive, efficient, and useful." Screen Capture (Video / Still) Jing = Free "The concept of Jing is the always-ready program that instantly captures and shares images and video…from your computer to anywhere." Lots of great responses: TeamCity [Yo|||] Skype [Eric DeLabar] FogBugz [chakrit] IChatAV and Screen Sharing (built-in to OS) [amrox] Google Docs [amrox]

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• Sanity check on this idea for an Image Viewer in a web app

  - by Charlie Flowers

  I have an approach in mind for an image viewer in a web app, and want to get a sanity check and any thoughts you stackoverflowers might have. Here's the whirlwind nutshell summary: I'm working on an ASP.NET MVC application that will run in my company's retail stores. Even though it is a web application, we own the store machines and have control over them. We have a "windows agent" running on the store machine which we can talk to via http post (it is a WCF service, and our web app has permission to talk to it from the browser). One of the web pages needs to be an "image viewer" page with some common things like Rotate & Zoom. Now, there are some WebForms controls that offer Rotate and Zoom. However, they take up server resources and generate a good bit of traffic between the server and the browser. For example, the Rotate function would cause an ajax call to the server, which would then generate a new image written to a .NET Canvas object, which would then be written to a file on the server, which would then be returned from the ajax call and refreshed inside the browser. Normally, that's a pretty good way of doing things. But in our case, we have code running on the store machine that we can communicate with. This leads me to consider the following approach: When the user asks to view an image, we tell our "windows agent" to download it from our image server to the store machine. We then redirect our browser to our image viewer page, which will pull the image from the local file we just wrote to the store machine. When the user clicks "Rotate", we cause JavaScript code in the browser to call our "windows agent" software, asking it to perform the "Rotate" function. The "windows agent" does the rotation using the same kind of imaging control that would formerly have been used on the server, but it does so now on the store machine. Javascript in the browser then refreshes the image on the page to show the newly rotated image. Zoom and similar features would be implemented the same way. This seems to be much more efficient, scalable, and responsive for the end-users. However, I've never heard of anything like it being done, mostly because it's rare to have this combination of a web app plus a "windows agent" on the client machine. What do you think? Feasible? Reasonable? Any pitfalls I overlooked or improvements / suggestions you can see? Has anyone done anything like this who would like to offer the wisdom of experience? Thanks!

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• Can parser combination be made efficient?

  - by Jon Harrop

  Around 6 years ago, I benchmarked my own parser combinators in OCaml and found that they were ~5× slower than the parser generators on offer at the time. I recently revisited this subject and benchmarked Haskell's Parsec vs a simple hand-rolled precedence climbing parser written in F# and was surprised to find the F# to be 25× faster than the Haskell. Here's the Haskell code I used to read a large mathematical expression from file, parse and evaluate it: import Control.Applicative import Text.Parsec hiding ((<|>)) expr = chainl1 term ((+) <$ char '+' <|> (-) <$ char '-') term = chainl1 fact ((*) <$ char '*' <|> div <$ char '/') fact = read <$> many1 digit <|> char '(' *> expr <* char ')' eval :: String -> Int eval = either (error . show) id . parse expr "" . filter (/= ' ') main :: IO () main = do file <- readFile "expr" putStr $ show $ eval file putStr "\n" and here's my self-contained precedence climbing parser in F#: let rec (|Expr|) (P(f, xs)) = Expr(loop (' ', f, xs)) and shift oop f op (P(g, xs)) = let h, xs = loop (op, g, xs) loop (oop, f h, xs) and loop = function | ' ' as oop, f, ('+' | '-' as op)::P(g, xs) | (' ' | '+' | '-' as oop), f, ('*' | '/' as op)::P(g, xs) | oop, f, ('^' as op)::P(g, xs) -> let h, xs = loop (op, g, xs) let op = match op with | '+' -> (+) | '-' -> (-) | '*' -> (*) | '/' -> (/) | '^' -> pown loop (oop, op f h, xs) | _, f, xs -> f, xs and (|P|) = function | '-'::P(f, xs) -> let f, xs = loop ('~', f, xs) P(-f, xs) | '('::Expr(f, ')'::xs) -> P(f, xs) | c::xs when '0' <= c && c <= '9' -> P(int(string c), xs) My impression is that even state-of-the-art parser combinators waste a lot of time back tracking. Is that correct? If so, is it possible to write parser combinators that generate state machines to obtain competitive performance or is it necessary to use code generation?

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• The Math of a Jump in a 2D game.

  - by ONi

  I have been all around with this question and I can't find the correct answer! So, behold, the description of my question: I'm working in J2ME, I have my gameloop that do the following: public void run() { Graphics g = this.getGraphics(); while (running) { long diff = System.currentTimeMillis() - lastLoop; lastLoop = System.currentTimeMillis(); input(); this.level.doLogic(); render(g, diff); try { Thread.sleep(10); } catch (InterruptedException e) { stop(e); } } } so it's just a basic gameloop, the doLogic() function calls for all the logic functions of the characters in the scene and render(g, diff) calls the animateChar function of every character on scene, following this, the animChar function in the Character class sets up everything in the screen as this: protected void animChar(long diff) { this.checkGravity(); this.move((int) ((diff * this.dx) / 1000), (int) ((diff * this.dy) / 1000)); if (this.acumFrame > this.framerate) { this.nextFrame(); this.acumFrame = 0; } else { this.acumFrame += diff; } } This ensures me that everything must to move according to the time that the machine takes to go from cycle to cycle (remember it's a phone, not a gaming rig). I'm sure it's not the most efficient way to achieve this behavior so I'm totally open for criticism of my programming skills in the comments, but here my problem: When I make I character jump, what I do is that I put his dy to a negative value, say -200 and I set the boolean jumping to true, that makes the character go up, and then I have this function called checkGravity() that ensure that everything that goes up has to go down, checkGravity also checks for the character being over platforms so I will strip it down a little for the sake of your time: public void checkGravity() { if (this.jumping) { this.jumpSpeed += 10; if (this.jumpSpeed > 0) { this.jumping = false; this.falling = true; } this.dy = this.jumpSpeed; } if (this.falling) { this.jumpSpeed += 10; if (this.jumpSpeed > 200) this.jumpSpeed = 200; this.dy = this.jumpSpeed; if (this.collidesWithPlatform()) { this.falling = false; this.standing = true; this.jumping = false; this.jumpSpeed = 0; this.dy = this.jumpSpeed; } } } So, the problem is, that this function updates the dy regardless of the diff, making the characters fly like Superman in slow machines, and I have no idea how to implement the diff factor so that when a character is jumping, his speed decrement in a proportional way to the game speed. Can anyone help me fix this issue? or give me pointers on how to make a 2D Jump in J2ME the right way. Thank you very much for your time.

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• Tomcat JMX connection - Authentication failed.

  - by ziggy

  I am having some problems setting up Tomcat for JMX. I added the following properties to CATALINA_OPTS="-Dcom.sun.management.jmxremote.port=18070 -Dcom.sun.management.jmxremote.password.file=$CATALINA_BASE/conf/jmxremote.password -Dcom.sun .management.jmxremote.ssl=false" And have added the jmxremote.password file in to the conf directory. I wrote a client tool that connects to the JMX server running on port 18070. When i run the client program i get the following error. Exception in thread "main" java.lang.SecurityException: Authentication failed! Credentials required at com.sun.jmx.remote.security.JMXPluggableAuthenticator.authenticationFailure(JMXPluggableAuthenticator.java:193) at com.sun.jmx.remote.security.JMXPluggableAuthenticator.authenticate(JMXPluggableAuthenticator.java:145) at sun.management.jmxremote.ConnectorBootstrap$AccessFileCheckerAuthenticator.authenticate(ConnectorBootstrap.java:185) at javax.management.remote.rmi.RMIServerImpl.doNewClient(RMIServerImpl.java:213) at javax.management.remote.rmi.RMIServerImpl.newClient(RMIServerImpl.java:180) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:305) at sun.rmi.transport.Transport$1.run(Transport.java:159) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:155) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907) at java.lang.Thread.run(Thread.java:619) at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:255) at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:233) at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:142) at javax.management.remote.rmi.RMIServerImpl_Stub.newClient(Unknown Source) at javax.management.remote.rmi.RMIConnector.getConnection(RMIConnector.java:2312) at javax.management.remote.rmi.RMIConnector.connect(RMIConnector.java:277) at javax.management.remote.JMXConnectorFactory.connect(JMXConnectorFactory.java:248) at com.bt.c21sc.c21tkprobe.accessors.C21TkProbeJmxDAO.connect(Unknown Source) at com.bt.c21sc.c21tkprobe.service.C21TkProbeBD.execute(Unknown Source) at com.bt.c21sc.c21tkprobe.C21AppserverProbe.main(Unknown Source) If i change the CATALINA_OPTS properties to CATALINA_OPTS="-Dcom.sun.management.jmxremote.port=18070 -Dcom.sun.management.jmxremote.password.file=$CATALINA_BASE/conf/jmxremote.password -Dcom.sun .management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false" Then it works fine. I think what i am confused of is what is classed as remote access. I am running the client program away from the Tomcat instance but both Tomcat and the client tool are on the same machine (i.e. different virtual machines but same environemnt). I thought i had to configure the remote authentication if i access the JMX server remotely from a different machine. By remote access do they mean accessing the JMX server from any VM either locally or remotely?

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• Question about Architecture for Viewing Images in ASP.NET MVC App

  - by Charlie Flowers

  I have an approach in mind for an image viewer in a web app, and want to get a sanity check and any thoughts you stackoverflowers might have. Here's the whirlwind nutshell summary: I'm working on an ASP.NET MVC application that will run in my company's retail stores. Even though it is a web application, we own the store machines and have control over them. We have a "windows agent" running on the store machine which we can talk to from the browser via javascript (it is a WCF service, and our web app has permission to talk to it from the browser). One of the web pages needs to be an "image viewer" page with some common things like Rotate & Zoom. Now, there are some WebForms controls that offer Rotate and Zoom. However, they take up server resources and generate a good bit of traffic between the server and the browser. For example, the Rotate function would cause an ajax call to the server, which would then generate a new image written to a .NET Canvas object, which would then be written to a file on the server, which would then be returned from the ajax call and refreshed inside the browser. Normally, that's a pretty good way of doing things. But in our case, we have code running on the store machine that we can communicate with. This leads me to consider the following approach: When the user asks to view an image, we tell our "windows agent" to download it from our image server to the store machine. We then redirect our browser to our image viewer page, which will pull the image from the local file we just wrote to the store machine. When the user clicks "Rotate", we cause JavaScript code in the browser to call our "windows agent" software, asking it to perform the "Rotate" function. The "windows agent" does the rotation using the same kind of imaging control that would formerly have been used on the server, but it does so now on the store machine. Javascript in the browser then refreshes the image on the page to show the newly rotated image. Zoom and similar features would be implemented the same way. This seems to be much more efficient, scalable, and responsive for the end-users. However, I've never heard of anything like it being done, mostly because it's rare to have this combination of a web app plus a "windows agent" on the client machine. What do you think? Feasible? Reasonable? Any pitfalls I overlooked or improvements / suggestions you can see? Has anyone done anything like this who would like to offer the wisdom of experience? Thanks!

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• How to stream semi-live audio over internet

  - by Thomas Tempelmann

  I want to write something like Skype, i.e. I have a constant audio stream on one computer and then recompress it in a format that's suitable for a latent internet connection, receive it on the other end and play it. Let's also assume that the internet connection is fairly modern and fast, i.e. DSL or alike, no slow connections over phone and such. The involved computers will also be rather modern (Dual Core Intel CPUs at 2GHz or more). I know how to handle the audio on the machines. What I don't know is how to transmit the audio in an efficient way. The challenges are: I'd like get good audio quality across the line. The stream should be received without drops. The stream may, however, be received with a little delay (a second delay is acceptable). I imagine that the transport software could first determine the average (and max) latency, then start the stream and tell the receiver to wait for that max latency before starting to play the audio. With that, if the latency doesn't get any higher, the entire stream will be playable on the other side without stutter or drops. If, due to unexpected IP latencies or blockages, the stream does get cut off, I want to be able to notice this so that I can take actions (e.g. abort the stream) and eventually start a new transmission. What are my options if I want do use ready-made software for the compression and tranmission? I have no intention to write my own audio compression engine, really. OTOH, I plan to sell the solution in a vertical market, meaning I can afford a few dollars of license fees per copy, but not $100s. I guess the simplest solution would be to just open a TCP stream, send a few packets back and forth to determine their running time (or even use UDP for that), then use the results as the guide for my max latency value, then simply fire the audio data in its raw form (uncompressed 16 bit stereo), along with a timing code over the TCP connection. The receiver reads the data and plays it with the pre-determined delay. That might just work with the type of fast connection I expect. I just wonder if there are better solutions to reach this goal, with better performance (lower latency) and less data (compressed). BTW, I first try to implement this on OS X, but might want to do it on Windows, too, if it proves successful.

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• Stored procedure performance randomly plummets; trivial ALTER fixes it. Why?

  - by gWiz

  I have a couple of stored procedures on SQL Server 2005 that I've noticed will suddenly take a significantly long time to complete when invoked from my ASP.NET MVC app running in an IIS6 web farm of four servers. Normal, expected completion time is less than a second; unexpected anomalous completion time is 25-45 seconds. The problem doesn't seem to ever correct itself. However, if I ALTER the stored procedure (even if I don't change anything in the procedure, except to perhaps add a space to the script created by SSMS Modify command), the completion time reverts to expected completion time. IIS and SQL Server are running on separate boxes, both running Windows Server 2003 R2 Enterprise Edition. SQL Server is Standard Edition. All machines have dual Xeon E5450 3GHz CPUs and 4GB RAM. SQL Server is accessed using its TCP/IP protocol over gigabit ethernet (not sure what physical medium). The problem is present from all web servers in the web farm. When I invoke the procedure from a query window in SSMS on my development machine, the procedure completes in normal time. This is strange because I was under the impression that SSMS used the same SqlClient driver as in .NET. When I point my development instance of the web app to the production database, I again get the anomalous long completion time. If my SqlCommand Timeout is too short, I get System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Question: Why would performing ALTER on the stored procedure, without actually changing anything in it, restore the completion time to less than a second, as expected? Edit: To clarify, when the procedure is running slow for the app, it simultaneously runs fine in SSMS with the same parameters. The only difference I can discern is login credentials (next time I notice the behavior, I'll be checking from SSMS with the same creds). The ultimate goal is to get the procs to sustainably run with expected speed without requiring occasional intervention. Resolution: I wanted to to update this question in case others are experiencing this issue. Following the leads of the answers below, I was able to consistently reproduce this behavior. In order to test, I utilize sp_recompile and pass it one of the susceptible sprocs. I then initiate a website request from my browser that will invoke the sproc with atypical parameters. Lastly, I initiate a website request to a page that invokes the sproc with typical parameters, and observe that the request does not complete because of a SQL timeout on the sproc invocation. To resolve this on SQL Server 2005, I've added OPTIMIZE FOR hints to my SELECT. The sprocs that were vulnerable all have the "all-in-one" pattern described in this article. This pattern is certainly not ideal but was a necessary trade-off given the timeframe for the project.

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• Strategies for "Always-Connected" Windows Client Data Architecture

  - by magz2010

  Hi. Let me start by saying: this is my 1st post here, this is a bit lenghty, and I havent done Windows Forms development in years....with that in mind please excuse me if this isn't directly a programming question and please bear with me as I really need the help!! I have been asked to develop a Windows Forms app for our company that talks to a central (local area network) Linux Server hosting a PostgreSQL database. The app is to allow users to authenticate themselves into the system and thereafter conduct the usual transactions with the PG database. Ordinarily, I would propose writing a webforms app against Mono, but the clients need to utilise local resources such as USB peripheral devices, so that is out of the question. While it might not seem clear, my questions are italised below: Dilemma #1: The application is meant to be always connected. How should I structure my DAL/BLL - Should this reside on the server or with the client? Dilemma #2: I have been reading up on Client Application Services (CAS), and it seems like a great fit for authentication, as everything is exposed via URIs. I know that a .NET Data Provider exists for PostgreSQL, but not too sure if CAS will all work on a Linux (Debian) server? Believe me, I would get my hands dirty and try myself, but I need to come up with a logical design first before resources are allocated to me for "trial purposes"! Dilemma #3: If the DAL/BLL is to reside on the server, is there any way I can create data services, and expose only these services to authenticated clients. There is a (security) requirement whereby a connection string with username and password to the database cannot be present on any client machines...even if security on the database side is quite rigid. I'm guessing that the only way for this to work would be to create the various CRUD data service methods that are exposed by an ASP.NET app, and have the WindowsForms make a request for data or persist data to the ASP.NET app (thru a URI) and have that return a resultset or value. Would I be correct in assuming this? Should I be looking into WCF Data Services? and will WCF work with a non-SQL Server database? Thank you for taking the time out to read this, but know that I am desperately seeking any advice on this! THANKS A MILLION!!!!

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• 2nd Year College - Learning - Microsoft Server Products

  - by Ryan

  As the title says, I just finished my first year of college (majoring in Software Engineering). Fortunately my school likes Microsoft enough, and I can get pretty much anything I want that Microsoft sells. I also can get IBM Websphere and the like for free as well. Earlier this year, I set up an oldish computer (2.6 Pentium D, x64) to run ubuntu server headless. I'm predominately a Java developer, so Apache, Maven, Nexus, Sonar, SVN, etc made it onto the machine. It worked really well for personal and school projects, especially team projects (quick ramp up). Anyways, I started to pick up C# to complement my Java knowledge (don't judge me :P), and am interested in working with some of the associated Microsoft equivalents. The machine currently has the Ubuntu install, as well as Windows 7 Ultimate. I do all of my actual development work off my laptop, also running Windows 7 Ultimate. I was wondering what software you would recommend putting on the machine. I’m not actually serving anything off the machine itself, but in Ubuntu I had it doing integration tests with Hudson on every commit, and profiling my applications, etc, etc. The machine would be running headless, and I would remote into it. Here is what I am currently leaning towards / wondering about: Windows 7 Ultimate vs Windows Server 2008 (R2) (no one is really clear why I should go with one over the other) Windows Team Foundation Sharepoint (Never used it before, kind of meh about it) IBM Websphere or Glassfish (Some Java EE web server) SQL Server 2008 A DVCS In order to better control product conflicts / limit resource use, I’m wondering if I should install things into virtual machines (I can get VmWare or Microsoft Virtualization Products) I also plan on installing everything I had running under Linux (it’s almost entirely Java based development software, so it’ll run on both, only reason I went with ubuntu during the year was because the apache build seemed better). I’m primarily looking to become familiar with enterprise software development tools, as well as get something functional that will help my development process. (IE, I’ll still use project and assign tasks even though I might be the only one to assign tasks to, just to practice doing so). Is there any other software / configuration details I should explore? Opinions on my current list? I primarily use C#, Java, and PHP. I'm familiar with ruby, and python as well. Thanks!

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• Running OpenMPI on Windows XP

  - by iamweird

  Hi there. I'm trying to build a simple cluster based on Windows XP. I compiled OpenMPI-1.4.2 successfully, and tools like mpicc and ompi_info work too, but I can't get my mpirun working properly. The only output I can see is Z:\orterun --hostfile z:\hosts.txt -np 2 hostname [host0:04728] Failed to initialize COM library. Error code = -2147417850 [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\mca\ess\hnp\ess_hnp_module.c at line 218 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_plm_init failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\runtime\orte_init.c at line 132 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_ess_set_name failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\..\..\openmpi -1.4.2\orte\tools\orterun\orterun.c at line 543 Where z:\hosts.txt appears as follows: host0 host1 Z: is a shared network drive available to both host0 and host1. What my problem is and how do I fix it? Upd: Ok, this problem seems to be fixed. It seems to me that WideCap driver and/or software components causes this error to appear. A "clean" machine runs local task successfully. Anyway, I still cannot run a task within at least 2 machines, I'm getting following message: Z:\mpirun --hostfile z:\hosts.txt -np 2 hostname connecting to host1 username:cluster password:******** Save Credential?(Y/N) y [host0:04728] This feature hasn't been implemented yet. [host0:04728] Could not connect to namespace cimv2 on node host1. Error code =-2147024891 -------------------------------------------------------------------------- mpirun was unable to start the specified application as it encountered an error. More information may be available above. -------------------------------------------------------------------------- I googled a little and did all the things as described here: http://www.open-mpi.org/community/lists/users/2010/03/12355.php but I'm still getting the same error. Can anyone help me? Upd2: Error code -2147024891 might be WMI error WBEM_E_INVALID_PARAMETER (0x80041008) which occures when one of the parameters passed to the WMI call is not correct. Does this mean that the problem is in OpenMPI source code itself? Or maybe it's because of wrong/outdated wincred.h and credui.lib I used while building OpenMPI from the source code?

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• Excel 2008 Cant Parse HTML

  - by VictorV

  I need to export a gridview to excel, I put the return html code from the gridview to a HtmlTextWriter and put this into the response. The result file work fine in excel, excel can parse the html and the result is readable, work perfect on excel 2003 and 2007, but in some machines with Excel 2008 (MACOS) excel shows only the raw html code and can't process this html code. Any idea to configure excel? This is the code to convert: public static void ToExcel(GridView gridView, string fileName) { HttpResponse response = HttpContext.Current.Response; response.Clear(); response.Buffer = true; fileName = fileName.Replace(".xls", string.Empty) + ".xls"; response.AddHeader("content-disposition", "attachment;filename=" + fileName); response.Charset = ""; response.ContentEncoding = Encoding.Unicode; response.BinaryWrite(Encoding.Unicode.GetPreamble()); response.ContentType = MimeTypes.GetContentType(fileName); StringWriter sw = new StringWriter(); HtmlTextWriter hw = new HtmlTextWriter(sw); gridView.AllowPaging = false; //gridView.DataBind(); //Change the Header Row back to white color gridView.HeaderRow.Style.Add("background-color", "#FFFFFF"); //Apply style to Individual Cells for (int i = 0; i < gridView.HeaderRow.Cells.Count; i++) { gridView.HeaderRow.Cells[i].Style.Add("background-color", "yellow"); } for (int i = 0; i < gridView.Rows.Count; i++) { GridViewRow row = gridView.Rows[i]; //Change Color back to white row.BackColor = System.Drawing.Color.White; //Apply text style to each Row row.Attributes.Add("class", "textmode"); //Apply style to Individual Cells of Alternating Row if (i % 2 != 0) { for (int j = 0; j < row.Cells.Count; j++) { row.Cells[j].Style.Add("background-color", "#C2D69B"); } } } gridView.RenderControl(hw); //style to format numbers to string string style = @"<style> .textmode { mso-number-format:\@; } </style>"; response.Write(style); response.Output.Write(sw.ToString()); response.Flush(); response.End(); }

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• Trying to run multiple HTTP requests in parallel, but being limited by Windows (registry)

  - by Nailuj

  I'm developing an application (winforms C# .NET 4.0) where I access a lookup functionality from a 3rd party through a simple HTTP request. I call an url with a parameter, and in return I get a small string with the result of the lookup. Simple enough. The challenge is however, that I have to do lots of these lookups (a couple of thousands), and I would like to limit the time needed. Therefore I would like to run requests in parallel (say 10-20). I use a ThreadPool to do this, and the short version of my code looks like this: public void startAsyncLookup(Action<LookupResult> returnLookupResult) { this.returnLookupResult = returnLookupResult; foreach (string number in numbersToLookup) { ThreadPool.QueueUserWorkItem(lookupNumber, number); } } public void lookupNumber(Object threadContext) { string numberToLookup = (string)threadContext; string url = @"http://some.url.com/?number=" + numberToLookup; WebClient webClient = new WebClient(); Stream responseData = webClient.OpenRead(url); LookupResult lookupResult = parseLookupResult(responseData); returnLookupResult(lookupResult); } I fill up numbersToLookup (a List<String>) from another place, call startAsyncLookup and provide it with a call-back function returnLookupResult to return each result. This works, but I found that I'm not getting the throughput I want. Initially I thought it might be the 3rd party having a poor system on their end, but I excluded this by trying to run the same code from two different machines at the same time. Each of the two took as long as one did alone, so I could rule out that one. A colleague then tipped me that this might be a limitation in Windows. I googled a bit, and found amongst others this post saying that by default Windows limits the number of simultaneous request to the same web server to 4 for HTTP 1.0 and to 2 for HTTP 1.1 (for HTTP 1.1 this is actually according to the specification (RFC2068)). The same post referred to above also provided a way to increase these limits. By adding two registry values to [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings] (MaxConnectionsPerServer and MaxConnectionsPer1_0Server), I could control this myself. So, I tried this (sat both to 20), restarted my computer, and tried to run my program again. Sadly though, it didn't seem to help any. I also kept an eye on the Resource Monitor (see screen shot) while running my batch lookup, and I noticed that my application (the one with the title blacked out) still only was using two TCP connections. So, the question is, why isn't this working? Is the post I linked to using the wrong registry values? Is this perhaps not possible to "hack" in Windows any longer (I'm on Windows 7)? Any ideas would be highly appreciated :) And just in case anyone should wonder, I have also tried with different settings for MaxThreads on ThreadPool (everyting from 10 to 100), and this didn't seem to affect my throughput at all, so the problem shouldn't be there either.

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• Separation of domain and ui layer in a composite

  - by hansmaad

  Hi all, i'm wondering if there is a pattern how to separate the domain logic of a class from the ui responsibilities of the objects in the domain layer. Example: // Domain classes interface MachinePart { CalculateX(in, out) // Where do we put these: // Draw(Screen) ?? // ShowProperties(View) ?? // ... } class Assembly : MachinePart { CalculateX(in, out) subParts } class Pipe : MachinePart { CalculateX(in, out) length, diamater... } There is an application that calculates the value X for machines assembled from many machine parts. The assembly is loaded from a file representation and is designed as a composite. Each concrete part class stores some data to implement the CalculateX(in,out) method to simulate behaviour of the whole assembly. The application runs well but without GUI. To increase the usability a GUi should be developed on top of the existing implementation (changes to the existing code are allowed). The GUI should show a schematic graphical representation of the assembly and provide part specific dialogs to edit several parameters. To achieve these goals the application needs new functionality for each machine part to draw a schematic representation on the screen, show a property dialog and other things not related to the domain of machine simulation. I can think of some different solutions to implement a Draw(Screen) functionality for each part but i am not happy with each of them. First i could add a Draw(Screen) method to the MachinePart interface but this would mix-up domain code with ui code and i had to add a lot of functionality to each machine part class what makes my domain model hard to read and hard to understand. Another "simple" solution is to make all parts visitable and implement ui code in visitors but Visitor does not belong to my favorite patterns. I could derive UI variants from each machine part class to add the UI implementation there but i had to check if each part class is suited for inheritance and had to be careful on changes to the base classes. My currently favorite design is to create a parallel composite hierarchy where each component stores data to define a machine part, has implementation for UI methods and a factory method which creates instances of the corresponding domain classes, so that i can "convert" a UI assembly to a domain assembly. But there are problems to go back from the created domain hierarchy to the UI hierarchy for showing calculation results in the drawing for example (imagine some parts store some values during the calculation i want to show in the schematic representation after the simluation). Maybe there are some proven patterns for such problems?

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• Planning to create PDF files in Ruby on Rails

  - by deau

  Hi there, A Ruby on Rails app will have access to a number of images and fonts. The images are components of a visual layout which will be stored separately as a set of rules. The rules specify document dimensions along with which images are used and where. The app needs to take these rules, fetch the images, and generate a PDF that is ready for local printing or emailing. The fonts will also be important. The user needs to customize the layout by inputting text which will be included in the PDF. The PDF must therefore also contain the desired font so that the document renders identically across different machines. Each PDF may have many pages. Each page may have different dimensions but this is not essential. Either way, the ability to manipulate the dimensions and margins given by the PDF is essential. The only thing that needs to be regularly changed is the text. If this is takes too much development then the app can store the layouts in 3rd party PDFs and edit the textual content directly. Eventually though, this will prove too restrictive on the apps intended functionality so I would prefer the app to generate the PDF's itself. I have never worked with PDFs before and, for the most part, I've never had to output anything to the user outside their monitor. A printed medium could require a very different approach to get the best results. If anyone has any advice on how to model the PDF format this it would be really appreciated. The technical aspects of printing such as bleed, resolution and colour have already been factored in to the layouts and images. I am aware that PDF is a proprietary file format and I want to use free or open source software. I have seen a number of Ruby libraries for generating PDF files but because I am new on this scene I have no way to reliably compare them and too little time to implement and test them all. I also have the option of using C to handle this feature and if this is process intensive then that might be preferred. What should I be thinking about and how should I be planning to implement this?

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• Windows MAchine Debugging

  - by PrettyFlower

  I've been learning how to program for Windows for some time now and am getting pretty comfy with COM. I had thought to go over to Linux and do some C++ programming there and I wished to run Rosetta Commons so I installed Fedora. I had tried installing Ubuntu a few months ago and things got messy. I had a glitch, maybe caused by one of the live cd creators, my video card or something I don't know. Who Crashed suggested it was my video card and I had regular messages about ntfs.sys and page file issues. At any rate I just installed Fedora and the same thing is happening again. I would like to think with the twenty five years of doing this that I might finally make some headway into debugging my system. I think I may have overlooked a lot of what could be done in favor of simply uninstalling, reinstalling and formatting and starting from scratch. I have opened up the folder windows debugging tools, quite accidentally and just before I was going to clean sweep again, and I found KD and WinDbg. I had never seen these before and I felt that maybe I should look into this. I am quite familiar with the modern machine that is known as the computer, I know what a Kernel is and am now pretty familiar with at the very least Windows Operating System Services. I wish to begin tracking my own machines errors. I understand that most kernel debugging is done on a second machine but I don't have one. And also I understand the goal of the debugger seems to be less about run of the mill errors and more about development time strategies but I'm sure there is more to this. This is my first go at this and I thought maybe I could get some suggestions on where to go from here. I would really like to learn ways to fix my machine and also maybe pick up some tricks on the dev side as well. I hope this isn't too broad a question or too generalized. I'm really just looking for the keywords and an overview of the more routine strategies used. thx

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