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  • Status of VB6/ Best Desktop Application Language with Native Compliation

    - by Sandeep Jindal
    Hi, I was looking for a Desktop Application Programming Language with one of the biggest constraint: - “ I need to output as native executable”. I explored multiple options: a) Java is not a very good option for desktop programming, but still you can use it. But Java to Exe is a problem. [Only GCJ and Excelsior-Jet provides this][1]. b) .Net platform does not support native compilation. Only very few expensive tools are available which can do the job. c) Python is not an option for native compilation. Right? d) VB6 is the option I am left with. From the above list, if I am correct, VB6 is the only and probably the best option I have. But VB6 itself has issues like: a) It is no more under development since 2003. b) There are questions on support of VB6 IDE with Vista. Thus my questions are: a) From the list of programming language options, do you want to add any more? b) If VB6 is good/best option, looking at its development status, would you suggest using VB6 in this era? Regards Sandeep Jindal

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  • Status of VB6/ Best Desktop Application Language with Native Compilation

    - by Sandeep Jindal
    I was looking for a Desktop Application Programming Language with one of the biggest constraint: - “I need to output as native executable”. I explored multiple options: Java is not a very good option for desktop programming, but still you can use it. But Java to Exe is a problem. Only GCJ and Excelsior-Jet provides this. .Net platform does not support native compilation. Only very few expensive tools are available which can do the job. Python is not an option for native compilation. Right? VB6 is the option I am left with. From the above list, if I am correct, VB6 is the only and probably the best option I have. But VB6 itself has issues like: It is no more under development since There are questions on support of VB6 IDE with Vista Thus my questions are: From the list of programming language options, do you want to add any more? If VB6 is good/best option, looking at its development status, would you suggest using VB6 in this era?

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  • Pixel Perfect Collision Detection in HTML5 Canvas

    - by Armin Ronacher
    Hi, I want to check a collision between two Sprites in HTML5 canvas. So for the sake of the discussion, let's assume that both sprites are IMG objects and a collision means that the alpha channel is not 0. Now both of these sprites can have a rotation around the object's center but no other transformation in case this makes this any easier. Now the obvious solution I came up with would be this: calculate the transformation matrix for both figure out a rough estimation of the area where the code should test (like offset of both + calculated extra space for the rotation) for all the pixels in the intersecting rectangle, transform the coordinate and test the image at the calculated position (rounded to nearest neighbor) for the alpha channel. Then abort on first hit. The problem I see with that is that a) there are no matrix classes in JavaScript which means I have to do that in JavaScript which could be quite slow, I have to test for collisions every frame which makes this pretty expensive. Furthermore I have to replicate something I already have to do on drawing (or what canvas does for me, setting up the matrices). I wonder if I'm missing anything here and if there is an easier solution for collision detection.

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  • Design/Architecture Advice Needed

    - by Rachel
    Summary: I have different components on homepage and each components shows some promotion to the user. I have Cart as one Component and depending upon content of the cart promotion are show. I have to track user online activities and send that information to Omniture for Report Generation. Now my components are loaded asynchronously basically are loaded when AjaxRequest is fired up and so there is not fix pattern or rather information on when components will appear on the webpages. Now in order to pass information to Omniture I need to call track function on $(document).(ready) and append information for each components(7 parameters are required by Omniture for each component). So in the init:config function of each component am calling Omniture and passing paramters but now no. of Omniture calls is directly proportional to no. of Components on the webpage but this is not acceptable as each call to Omniture is very expensive. Now I am looking for a way where in I can club the information about 7 parameters and than make one Call to Omniture wherein I pass those information. Points to note is that I do not know when the components are loaded and so there is no pre-defined time or no. of components that would be loaded. The thing is am calling track function when document is ready but components are loaded after call to Omniture has been made and so my question is Q: How can I collect the information for all the components and than just make one call to Omniture to send those information ? As mentioned, I do not know when the components are loaded as they are done on the Ajax Request. Hope I am able to explain my challenge and would appreciate if some one can provide from Design/Architect Solutions for the Challenge.

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  • How to force two process to run on the same CPU?

    - by kovan
    Context: I'm programming a software system that consists of multiple processes. It is programmed in C++ under Linux. and they communicate among them using Linux shared memory. Usually, in software development, is in the final stage when the performance optimization is made. Here I came to a big problem. The software has high performance requirements, but in machines with 4 or 8 CPU cores (usually with more than one CPU), it was only able to use 3 cores, thus wasting 25% of the CPU power in the first ones, and more than 60% in the second ones. After many research, and having discarded mutex and lock contention, I found out that the time was being wasted on shmdt/shmat calls (detach and attach to shared memory segments). After some more research, I found out that these CPUs, which usually are AMD Opteron and Intel Xeon, use a memory system called NUMA, which basically means that each processor has its fast, "local memory", and accessing memory from other CPUs is expensive. After doing some tests, the problem seems to be that the software is designed so that, basically, any process can pass shared memory segments to any other process, and to any thread in them. This seems to kill performance, as process are constantly accessing memory from other processes. Question: Now, the question is, is there any way to force pairs of processes to execute in the same CPU?. I don't mean to force them to execute always in the same processor, as I don't care in which one they are executed, altough that would do the job. Ideally, there would be a way to tell the kernel: If you schedule this process in one processor, you must also schedule this "brother" process (which is the process with which it communicates through shared memory) in that same processor, so that performance is not penalized.

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  • Using ThreadPool.QueueUserWorkItem in ASP.NET in a high traffic scenario

    - by Michael Hart
    I've always been under the impression that using the ThreadPool for (let's say non-critical) short-lived background tasks was considered best practice, even in ASP.NET, but then I came across this article that seems to suggest otherwise - the argument being that you should leave the ThreadPool to deal with ASP.NET related requests. So here's how I've been doing small asynchronous tasks so far: ThreadPool.QueueUserWorkItem(s => PostLog(logEvent)) And the article is suggesting instead to create a thread explicitly, similar to: new Thread(() => PostLog(logEvent)){ IsBackground = true }.Start() The first method has the advantage of being managed and bounded, but there's the potential (if the article is correct) that the background tasks are then vying for threads with ASP.NET request-handlers. The second method frees up the ThreadPool, but at the cost of being unbounded and thus potentially using up too many resources. So my question is, is the advice in the article correct? If your site was getting so much traffic that your ThreadPool was getting full, then is it better to go out-of-band, or would a full ThreadPool imply that you're getting to the limit of your resources anyway, in which case you shouldn't be trying to start your own threads? Clarification: I'm just asking in the scope of small non-critical asynchronous tasks (eg, remote logging), not expensive work items that would require a separate process (in these cases I agree you'll need a more robust solution).

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  • WinForms Control.BeginInvoke asynchronous callback

    - by Darran
    I have a number of Janus grid controls that need to be populated on an application startup. I'd like to load these grids on different threads to speed startup time and the time it takes to refresh these grids. Each grid is on a seperate tab. Ideally I'd like to use Control.BeginInvoke on each grid and on the grid load completing the tabs will become enabled. I know with Delegates you can do a Asynchronous callback when using BeginInvoke, so I could enable the tabs in the asynchronous callback, however when using Control.BeginInvoke this is not possible. Is there a way to do asynchronous callbacks using Control.BeginInvoke or possibly a better solution? So far I have: public delegate void BindDelegate(IMyGrid grid); private IAsyncResult InvokeBind(IMyGrid grid) { return ((Control)grid).BeginInvoke( new BindDelegate(DoBind), new object[] { grid } ); } private void DoBind(IMyGrid grid) { grid.Bind(); // Expensive operation } private void RefreshComplete() { IAsyncResult grid1Asynch = InvokeBind(grid1); IAsyncResult grid2Asynch = InvokeBind(grid2); IAsyncResult grid3Asynch = InvokeBind(grid2); IAsyncResult grid4Asynch = InvokeBind(grid3); IAsyncResult grid5Asynch = InvokeBind(grid4); IAsyncResult grid6Asynch = InvokeBind(grid5); } Now I could spin off a separate thread and keep checking to see if the IAsynchResults have completed and depending on which one completes I could re-enable the Tab control that the grid is contained in. Is there a better way of doing this?

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  • Beginner video capture and processing/Camera selection

    - by mattbauch
    I'll soon be undertaking a research project in real-time event recognition but have no experience with the programming aspect of video capture (I'm an upperclassman undergraduate in computer engineering). I want to start off on the right foot so advice from anyone with experience would be great. The ultimate goal is to track events such as a person standing up/sitting down, entering/leaving a room, possibly even shrugging/slumping in posture, etc. from a security camera-like vantage point. First of all, which cameras/companies would you recommend? I'm looking to spend ~$100, more if necessary but not much. Great resolution isn't a must, but is desirable if affordable. What about IP network cameras vs. a USB type webcam? Webcams are less expensive, but IP cameras seem like they'd be much less work to deal with in software. What features should I look for in the camera? Once I've selected a camera, what does converting its output to a series of RGB bitmaps entail? I've never dealt with video encoding/decoding so a starting point or a tutorial that will guide me up to this point would be great if anyone has suggestions. Finally, what is the best (least complicated/most efficient) way to display video from the camera plus my own superimposed images (boxes around events in progress, for instance) in a GUI application? I can work on any operating system in any language. I have some experience with win32 GUIs and Java GUIs. The focus of the project is on the algorithm and so I'm trying to get the video capture/display portion of the app done cleanly and quickly. Thanks for any responses!!

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  • Accounting System for Winforms / SQL Server applications

    - by Craig L
    If you were going to write a vertical market C# / WinForms / SQL Server application and needed an accounting "engine" for it, what software package would you chose ? By vertical market, I mean the application is intended to solve a particular set of business problems, not be a generic accounting application. Thus the value add of the program is the 70% of non-accounting related functionality present in the finished product. The 30% of accounting functionality is merely to enable the basic accounting needs of the business. I said all that to lead up to this: The accounting engine needs to be a royalty-free runtime license and not super expensive. I've found a couple C#/SQL Server accounting apps that can be had with source code and a royalty free run time for $150k+ and that would be fine for greenfield development funded by a large bankroll, but for smaller apps, that sort of capital outlay isn't feasible. Something along the lines of $5k to $15k for a royalty-free runtime would be more reasonable. Open-source would be even better. By accounting engine, I mean something that takes care of at a minimum: General Ledger Invoices Statements Accounts Receivable Payments / Credits Basically, an accounting engine should be something that lets the developer concentrate on the value added (industry specific business best practices / processes) part of the solution and not have to worry about how to implement the low level details of a double entry accounting system. Ideally, the accounting engine would be something that is licensed on a royalty free run-time basis. Suggestions, please ?

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  • Query Optimizing Request

    - by mithilatw
    I am very sorry if this question is structured in not a very helpful manner or the question itself is not a very good one! I need to update a MSSQL table call component every 10 minutes based on information from another table call materials_progress I have nearly 60000 records in component and more than 10000 records in materials_progress I wrote an update query to do the job, but it takes longer than 4 minutes to complete execution! Here is the query : UPDATE component SET stage_id = CASE WHEN t.required_quantity <= t.total_received THEN 27 WHEN t.total_ordered < t.total_received THEN 18 ELSE 18 END FROM ( SELECT mp.job_id, mp.line_no, mp.component, l.quantity AS line_quantity, CASE WHEN mp.component_name_id = 2 THEN l.quantity*2 ELSE l.quantity END AS required_quantity, SUM(ordered) AS total_ordered, SUM(received) AS total_received , c.component_id FROM line l LEFT JOIN component c ON c.line_id = l.line_id LEFT JOIN materials_progress mp ON l.job_id = mp.job_id AND l.line_no = mp.line_no AND c.component_name_id = mp.component_name_id WHERE mp.job_id IS NOT NULL AND (mp.cancelled IS NULL OR mp.cancelled = 0) AND (mp.manual_override IS NULL OR mp.manual_override = 0) AND c.stage_id = 18 GROUP BY mp.job_id, mp.line_no, mp.component, l.quantity, mp.component_name_id, component_id ) AS t WHERE component.component_id = t.component_id I am not going to explain the scenario as it too complex.. could somebody please please tell me what makes this query this much expensive and a way to get around it? Thank you very very much in advance!!!

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  • How to switch users in a smooth way in a Point-Of-Sale system?

    - by Sanoj
    I am designing a Point-Of-Sale system for a small shop. The shop just have one Point-Of-Sale but often they are one to three users (sellers) in the shop. Each user have their own user account in the system so they login and logout very often. How should I design the login/logout system in a good way? For the moment the users don't use passwords, because it takes so long time to type the password each time they login. The Platform is Windows Vista but I would like to support Windows 7 too. We use Active Directory on the Network. The system is developed in Java/Swing for the moment, but I'm thinking about to change to C#.NET/WPF. I am thinking about an SmartCard solution, but I don't know if that fits my situation. It would be more secure (which I like) but I don't know if it will be easy to implement and smooth to use, i.e. can I have the POS-system running in the background or started very quickly when the users switch? Are SmartCard solutions very expensive? (My customers are small shops) Is it preferred to use .NET or Java in a SmartCard solution? What other solutions do I have other than passwords/no passwords/smartcards? How should I design the login/logout system in a good way? Is there any good solution using SmartCards for this purpose? I would like suggested solutions both for C#.NET/WPF and Java/Swing platforms. I would like suggested solutions both for Active Directory solutions and solutions that only use one user profile in Windows. How is this problem solved in similar products? I have only seen password-solutions, but they are clumsy.

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  • Which CEP product to start with?

    - by Andreas
    Hi, I want to learn more on how to build CEP based applications. So I looked around and found several products (overview found here: http://rulecore.com/CEPblog/?page_id=47). But as there are quite a few at the moment, I don't know which is the best to start with. And overall I just would consider the one available for free. The rest is a bit to expensive for just private use ;) Esper is for free, but without Esper studio it seems quite tedious to develop a cep app. Streambase offers a free trial, but I couldn't find out how long you can use this (if only for a month, no that helpful for longer research). Oracle CEP suite seems quite complete, but in the cep scene - as far as I can see - it is the least recognized compared to Esper or Streambase. So do you have any hints on what is the best way to start with cep development? Is it worth to spent time on working through the oracle documenation or is it better to start with Esper or Streambase? Cheers, Andreas

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  • Android: How to get a custom view to redraw partially?

    - by Peterdk
    I have a custom view that fills my entire screen. (A piano keyboard) When a user touches the key, it would cause a invalidate() to be called and the whole keyboard gets redrawn to show the new state with a touched key. Currently the view is very simple, but I plan to add a bit more nice graphics. Since the whole keyboard is dynamically rendered this would make redrawing the entire keyboard more expensive. So I thought, let's look into partial redrawing. Now I call invalidate(Rect dirty) with the correct dirty region. I set my onDraw(Canvas canvas) method to only draw the keys in the dirty region if I do indeed want a partial redraw. This results in those keys being drawn, but the rest of the keyboard is totally black/not drawn at all. Am I wrong in expecting that calling invalidate(Rect dirty) would "cache" the current canvas, and only "allows" drawing in the dirty region? Is there any way I can achieve what I want? (A way to "cache" the canvas and only redraw the dirty area?"

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  • Optimal Serialization of Primitive Types

    - by Greg Dean
    We are beginning to roll out more and more WAN deployments of our product (.Net fat client w/ IIS hosted Remoting backend). Because of this we are trying to reduce the size of the data on the wire. We have overridden the default serialization by implementing ISerializable (similar to this), we are seeing anywhere from 12% to 50% gains. Most of our efforts focus on optimizing arrays of primitive types. I would like to know if anyone knows of any fancy way of serializing primitive types, beyond the obvious? For example today we serialize an array of ints as follows: [4-bytes (array length)][4-bytes][4-bytes] Can anyone do significantly better? The most obvious example of a significant improvement, for boolean arrays, is putting 8 bools in each byte, which we already do. Note: Saving 7 bits per bool may seem like a waste of time, but when you are dealing with large magnitudes of data (which we are), it adds up very fast. Note: We want to avoid general compression algorithms because of the latency associated with it. Remoting only supports buffered requests/responses(no chunked encoding). I realize there is a fine line between compression and optimal serialization, but our tests indicate we can afford very specific serialization optimizations at very little cost in latency. Whereas reprocessing the entire buffered response into new compressed buffer is too expensive.

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  • Large Reports for MSRS

    - by Greg Lorenz
    I have a report that needs to be able to render a very large amount of pages (about 4500 in this instance) in a web browser. The total time needed to finish on the report server from start time to end time is about 30 mins for the instance that I am looking at. Does anyone know what options exist for handling the rendering of such a large report in a web browser? In terms of looking into how this can be resolved I have already performed the following tasks. The report gets its data off of a database table that already has the data flattened to the point that the TimeDataRetrieval on the report server is 17812 or about 18 secs. The report itself has been reformatted to include the least expensive report objects that it can in order to render the data in the correct format. I basically consists of a table with about 4 nested tables and thats it. We were trying to accomplish this on a 2005 report server but continued to run into memory issues that were not feasible for our clients. In response to that we moved this onto a 2008 report server to take advantage of the fact that it uses the file system instead of memory and finally were able to get this to work without running out of the available memory but of course it takes much longer.

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  • Frame Accurate Browser Launchable Video Player ... ?

    - by cliftonc
    I have a requirement where I need to enable playback (full screen) of a h.264 MPEG4 (thanks for the correction!) video from a local network, launchable from a browser link on a Windows workstation, and be frame accurate. By frame accurate I mean that I need to be able to scrub through the video in the same way you would with a vtr, stop at a frame, and then move backwards and forwards frame by frame (it is for a very specific compliance requirement where have to be able to check every frame if there is something that is potentially against broadcasting guidelines). The application itself is used to capture notes while viewing the material, so the end model is for a dual monitor workstation, with a web form in one, the video playing full screen in the second (no issue launching the video and manually having to move it to the second screen), and then the user controls the video via keyboard shortcuts or a jog shuttle. I have looked at QT, but the java bindings seem to be dead or nearly so, flash isn't frame accurate, VLC given its streaming heritage seems to be only able to move forward by a frame and not backwards, and all I have left are commercial offerings that in my experience are difficult and expensive to change. Any ideas of where I should look or alternative options? Any advice appreciated!

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  • Autodetect Presence of CSV Headers in a File

    - by banzaimonkey
    Short question: How do I automatically detect whether a CSV file has headers in the first row? Details: I've written a small CSV parsing engine that places the data into an object that I can access as (approximately) an in-memory database. The original code was written to parse third-party CSV with a predictable format, but I'd like to be able to use this code more generally. I'm trying to figure out a reliable way to automatically detect the presence of CSV headers, so the script can decide whether to use the first row of the CSV file as keys / column names or start parsing data immediately. Since all I need is a boolean test, I could easily specify an argument after inspecting the CSV file myself, but I'd rather not have to (go go automation). I imagine I'd have to parse the first 3 to ? rows of the CSV file and look for a pattern of some sort to compare against the headers. I'm having nightmares of three particularly bad cases in which: The headers include numeric data for some reason The first few rows (or large portions of the CSV) are null There headers and data look too similar to tell them apart If I can get a "best guess" and have the parser fail with an error or spit out a warning if it can't decide, that's OK. If this is something that's going to be tremendously expensive in terms of time or computation (and take more time than it's supposed to save me) I'll happily scrap the idea and go back to working on "important things". I'm working with PHP, but this strikes me as more of an algorithmic / computational question than something that's implementation-specific. If there's a simple algorithm I can use, great. If you can point me to some relevant theory / discussion, that'd be great, too. If there's a giant library that does natural language processing or 300 different kinds of parsing, I'm not interested.

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  • dynamically horizontal scalable key value store

    - by Zubair
    Hi, Is there a key value store that will give me the following: Allow me to simply add and remove nodes and will redstribute the data automatically Allow me to remove nodes and still have 2 extra data nodes to provide redundancy Allow me to store text or images up to 1GB in size Can store small size data up to 100TB of data Fast (so will allow queries to be performed on top of it) Make all this transparent to the client Works on Ubuntu/FreeBSD or Mac Free or open source I basically want something I can use a "single", and not have to worry about having memcached, a db, and several storage components so yes, I do want a database "silver bullet" you could say. Thanks Zubair Answers so far: MogileFS on top of BackBlaze - As far as I can see this is just a filesystem, and after some research it only seems to be appropriate for large image files Tokyo Tyrant - Needs lightcloud. This doesn't auto scale as you add new nodes. I did look into this and it seems it is very fast for queries which fit onto a single node though Riak - This is one I am looking into myself, but I don't have any results yet Amazon S3 - Is anyone using this as their sole persistance layer in production? From what I have seen it seems to be used for storage of images as complex queries are too expensive @shaman suggested Cassandra - definitely one I am looking into So far it seems that there is no database or key value store that fulfills the criteria I mentioned, not even after offering a bounty of 100 points did the question get answered!

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  • Big Nerd Ranch's Android Bootcamp - worth it?

    - by Matt Luongo
    At work, I've been told that I must, before the end of the year, get a certification. The shop is Microsoft heavy, and I'm not. That's why I was excited when I suggested something in support of Android development, and they agreed. Before I go any further, I should say that I don't know what I think about the whole certification question. Frankly, though, I need to do this, regardless of whether I think certification in general is particularly appealing to clients. I realize that the technology is fairly accessible without all this expensive process- but I'd rather focus on Android than, say, getting some MC* scrap of paper. I don't know of any actual Android certification. Instead, I was thinking that the best regarded Android training in the industry should suffice. I've looked into Big Nerd Ranch's Android Bootcamp, and it looks promising. I live in Atlanta, which is a boon. Given that my Java skills are good, does this seem like a decent course? Or is there a better known training program that I should look into?

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  • Swing data binding frameworks

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

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  • A business Case for Enterprise Python

    - by Srirangan
    Hi all, This will not be a "programming" question but more technology / platform related question. I'm trying to figure out whether Python can be a suitable Java alternative for enterprise / web applications. Which are the ideal cases where you would prefer to use Python instead of Java? How would a typical Python web application (databases/sessions/concurrency) perform as compared to a typical Java application? How do specific Python frameworks square up against Java based frameworks (Spring, SEAM, Grails etc.)? For businesses, switching from the Java infrastructure to a Python infrastructure .. is it too hard/expensive/resource intensive/not viable? Also shed some light on the business case for providing a Python + Google AppEngine based solution to the end customer. Will it be cost effective in an typical scenario? Sorry if I am asking too wide a question, I would have liked to keep it specific, but I need your help to evaluate Python as a whole from the perspectives of the programmers, service providing company and end business customer. For an SME, a Python/GoogleAppEngine based technology stack is a clear scalable and affordable platform. But what about a large MNC that already has a lot invested in Java. Thank you so much. I am researching this myself and will gladly share my conclusions here! Thank you, Srirangan

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  • Synchronizing ASP.NET MVC action methods with ReaderWriterLockSlim

    - by James D
    Any obvious issues/problems/gotchas with synchronizing access (in an ASP.NET MVC blogging engine) to a shared object model (NHibernate, but it could be anything) at the Controller/Action level via ReaderWriterLockSlim? (Assume the object model is very large and expensive to build per-request, so we need to share it among requests.) Here's how a typical "Read Post" action would look. Enter the read lock, do some work, exit the read lock. public ActionResult ReadPost(int id) { // ReaderWriterLockSlim allows multiple concurrent writes; this method // only blocks in the unlikely event that some other client is currently // writing to the model, which would only happen if a comment were being // submitted or a new post were being saved. _lock.EnterReadLock(); try { // Access the model, fetch the post with specificied id // Pseudocode, etc. Post p = TheObjectModel.GetPostByID(id); ActionResult ar = View(p); return ar; } finally { // Under all code paths, we must release the read lock _lock.ExitReadLock(); } } Meanwhile, if a user submits a comment or an author authors a new post, they're going to need write access to the model, which is done roughly like so: [AcceptVerbs(HttpVerbs.Post)] public ActionResult SaveComment(/* some posted data */) { // try/finally omitted for brevity _lock.EnterWriteLock(); // Save the comment to the DB, update the model to include the comment, etc. _lock.ExitWriteLock(); } Of course, this could also be done by tagging those action methods with some sort of "synchronized" attribute... but however you do it, my question is is this a bad idea? ps. ReaderWriterLockSlim is optimized for multiple concurrent reads, and only blocks if the write lock is held. Since writes are so infrequent (1000s or 10,000s or 100,000s of reads for every 1 write), and since they're of such a short duration, the effect is that the model is synchronized , and almost nobody ever locks, and if they do, it's not for very long.

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  • Using .NET XmlSerializer with get properties and setter functions

    - by brone
    I'm trying to use XmlSerializer from C# to save out a class that has some values that are read by properties (the code being just a simple retrieval of field value) but set by setter functions (since there is a delegate called if the value changes). What I'm currently doing is this sort of thing. The intended use is to use the InT property to read the value, and use SetInT to set it. Setting it has side-effects, so a method is more appropriate than a property here. XmlSerializationOnly_InT exists solely for the benefit of the XmlSerializer (hence the name), and shouldn't be used by normal code. class X { public double InT { get { return _inT; } } public void SetInT(double newInT) { if (newInT != _inT) { _inT = newInT; Changed();//includes delegate call; potentially expensive } } private double _inT; // not called by normal code, as the property set is not just a simple // field set or two. [XmlElement(ElementName = "InT")] public double XmlSerializationOnly_InT { get { return InT; } set { SetInT(value); } } } This works, it's easy enough to do, and the XML file looks like you'd expect. It's manual labour though, and a bit ugly, so I'm only somewhat satisfied. What I'd really like is to be able to tell the XML serialization to read the value using the property, and set it using the setter function. Then I wouldn't need XmlSerializationOnly_InT at all. I seem to be following standard practise by distinguishing between property sets and setter functions in this way, so I'm sure I'm not the only person to have encountered this (though google suggests I might be). What have others done in this situation? Is there some easy way to persuade the XmlSerializer to handle this sort of thing better? If not, is there perhaps some other easy way to do it?

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  • Updating a Minimum spanning tree when a new edge is inserted

    - by Lynette
    Hello, I've been presented the following problem in University: Let G = (V, E) be an (undirected) graph with costs ce = 0 on the edges e € E. Assume you are given a minimum-cost spanning tree T in G. Now assume that a new edge is added to G, connecting two nodes v, tv € V with cost c. a) Give an efficient algorithm to test if T remains the minimum-cost spanning tree with the new edge added to G (but not to the tree T). Make your algorithm run in time O(|E|). Can you do it in O(|V|) time? Please note any assumptions you make about what data structure is used to represent the tree T and the graph G. b)Suppose T is no longer the minimum-cost spanning tree. Give a linear-time algorithm (time O(|E|)) to update the tree T to the new minimum-cost spanning tree. This is the solution I found: Let e1=(a,b) the new edge added Find in T the shortest path from a to b (BFS) if e1 is the most expensive edge in the cycle then T remains the MST else T is not the MST It seems to work but i can easily make this run in O(|V|) time, while the problem asks O(|E|) time. Am i missing something? By the way we are authorized to ask for help from anyone so I'm not cheating :D Thanks in advance

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  • Methods for Lazy Initialization with properties

    - by Stuart Pegg
    I'm currently altering a widely used class to move as much of the expensive initialization from the class constructor into Lazy Initialized properties. Below is an example (in c#): Before: public class ClassA { public readonly ClassB B; public void ClassA() { B = new ClassB(); } } After: public class ClassA { private ClassB _b; public ClassB B { get { if (_b == null) { _b = new ClassB(); } return _b; } } } There are a fair few more of these properties in the class I'm altering, and some are not used in certain contexts (hence the Laziness), but if they are used they're likely to be called repeatedly. Unfortunately, the properties are often also used inside the class. This means there is a potential for the private variable (_b) to be used directly by a method without it being initialized. Is there a way to make only the public property (B) available inside the class, or even an alternative method with the same initialized-when-needed? This is reposted from Programmers (not subjective enough apparently): http://programmers.stackexchange.com/questions/34270/best-methods-for-lazy-initialization-with-properties

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