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• How can I get a list of modified records from a SQL Server database?

  - by Pixelfish

  I am currently in the process of revamping my company's management system to run a little more lean in terms of network traffic. Right now I'm trying to figure out an effective way to query only the records that have been modified (by any user) since the last time I asked. When the application starts it loads the job information and caches it locally like the following: SELECT * FROM jobs. I am writing out the date/time a record was modified ala UPDATE jobs SET Widgets=@Widgets, LastModified=GetDate() WHERE JobID=@JobID. When any user requests the list of jobs I query all records that have been modified since the last time I requested the list like the following: SELECT * FROM jobs WHERE LastModified>=@LastRequested and store the date/time of the request to pass in as @LastRequest when the user asks again. In theory this will return only the records that have been modified since the last request. The issue I'm running into is when the user's date/time is not quite in sync with the server's date/time and also of server load when querying an un-indexed date/time column. Is there a more effective system then querying date/time information?

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• Google Drive API invalid_grant after removing access

  - by Sparafusile

  I have been writing a desktop application that uses the Google Drive API v2. I have the following code: var credential = GoogleWebAuthorizationBroker.AuthorizeAsync ( new ClientSecrets { ClientId = ClientID, ClientSecret = ClientSecret }, new[] { DriveService.Scope.Drive }, "user", CancellationToken.None ) .Result; this.Service = new DriveService( new BaseClientService.Initializer() { HttpClientInitializer = credential, ApplicationName = "My Test App", } ); var request = this.Service.Files.List(); request.Q = "title = 'foo' and trashed = false"; var result = request.Execute(); The first time I ran this code it opened a browser and asked me to grant permissions to the App, which I did. Everything worked successfully until I realized I was using the wrong Google account. At that point I logged into the wrong Google account and revoked access to my App. Now, whenever I run the same code it throws an exception: Error:"invalid_grant", Description:"", Uri:"" When I examine the service and request objects, it looks like the oauth_token isn't getting created any more. I know what I did to mess things up, but I can't figure out how to correct it so I can use a different Google account for testing. What do I need to do?

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• Can a second stored procedure doing the same thing finish before first one?

  - by evanmortland

  Hello, I have an audit record table that I am writing to. I am connecting to MyDb, which has a stored procedure called 'CreateAudit', which is a passthrough stored procedure to another database on the same machine called 'CreatedAudit' as well. I call the CreateAudit stored procedure from my application, using subsonic as the DAL. The first time I call it, I call it with the following (pseudocode): Result = CreateAudit(recordId, "Opened") Right after that, I call: Result2 = CreateAudit(recordId, "Closed") In my second stored procedure it is supposed to mark the record that was created by the CreateAudit(recordId, "Opened") with a status of closed. It works great if I run them independently of one another, but when they run in sequence in the application, the record is not marked as "Closed". When I run SQL profiler I see that both queries ran, and if I copy the queries out and run them from query analyzer the record gets marked as closed 100% of the time! When I run it from the application, about once every 20 times or so, the record is successfully marked closed - the other 19 times nothing happens, but I do not get an error! Is it possible for the .NET app to skip over the ouput from the first stored procedure and start executing the second stored procedure before the record in the first is created? When I add a "WAITFOR DELAY '00:00:00:003'" to the top of my stored procedure, the record is also closed 100% of the time. My head is spinning, any ideas why this is happening! Thanks for any responses, very interested in hearing how this can happen.

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• C++: Declare static variable in function argument list

  - by MDC

  Is there any way at all in C++ to declare a static variable while passing it to a function? I'm looking to use a macro to expand to the expression passed to the function. The expression needs to declare and initialize a static variable on that particular line (based on the filename and line number using FILE and LINE). int foo(int b) { int c = b + 2; return c; } int main() { int a = 3; a = foo(static int h = 2); //<---- see this! cout << a; return 0; } The problem I'm trying to solve is getting the filename and line number with the FILE and LINE macros provided by the preprocessor, but then creating a lookup table with integer keys leading to the FILE, LINE pairs. For example, the key 89 may map to file foo.cpp, line 20. To get this to work, I'm trying to use local static variables, so that they are initialized only once per line execution. The static variable will be initialized by calling a function that calculates the integer key and adds an entry to the lookup table if it is not there. Right now the program uses a message class to send exception information. I'm writing a macro to wrap this class into a new class: WRAPPER_MACRO(old_class_object) will expand to NewClass(old_class_object, key_value). If I add the static variable declaration as a second line right before this, it should work. The problem is that in most places in the code, the old class object is passed as an argument to a function. So the problem becomes declaring and initializing the static variable somehow with the macro, while keeping the existing function calls.

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• Setting up App Engine to receive email addresses with ids in the address

  - by Mark M

  I am writing an App Engine app that is supposed to receive emails in this form: [email protected] (someID is an alphanumeric ID that I generate). I have this in my web.xml thinking it would catch emails that start with 'addcontact.': <servlet> <servlet-name>addNewContactServlet</servlet-name> <servlet-class>com.mycompany.server.AddNewContactServlet</servlet- class> </servlet> <servlet-mapping> <servlet-name>addNewContactServlet</servlet-name> <url-pattern>/_ah/mail/addcontact.*</url-pattern> </servlet-mapping> However, both on my dev machine and on google's servers email is not received. On the dev machine I get this message (I get a similar error in the deployed log) Message send failure HTTP ERROR 404 Problem accessing /_ah/mail/ [email protected]. Reason: NOT_FOUND I can receive email at fully specified addresses or when I use /_ah/mail/* The google documentation made me believe it was possible to include partial email addresses in web.xml. Am I not using the wildcard correctly? Does the period have something to do with it? Can this be done somehow?

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• My java program seems to be skipping over the try{}, executing the catch{} and then throwing a NullPointerException. What should I do?

  - by Matt Bolopue

  I am writing a program that calculates the number of words, syllables, and sentences in any given text file. I don't need help finding those numbers, however my program (which currently should only find the number of words in the text file) will not import the text file even when I type in the name of the file correctly. The text file is in the same folder as the source code. Instead it tells me every time that what I typed in has the wrong file extension (see my catch{}) and then proceeds to throw a null pointer. I am at a loss for what could be causing it. Any suggestions? import java.io.*; import java.util.*; public class Reading_Lvl_Calc { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub int words = 0; String fileName; Scanner scan; Scanner keyread = new Scanner(System.in); System.out.println("Please enter a file name (or QUIT to exit)"); fileName = keyread.nextLine(); File doc = new File(fileName); //while(scan.equals(null)){ try { scan = new Scanner(doc); } catch(Exception e) { if(fileName.substring(fileName.indexOf(".")) != ".txt") System.out.println("I'm sorry, the file \"" + fileName + "\" has an invalid file extension."); else System.out.println("I am sorry, the file \"" + fileName + " \" cannot be found.\n The file must be in the same directory as this program"); scan = null; } // } while(scan.hasNext()){ words++; scan.next(); } System.out.println(words); } }

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• Android designing an app to keep me logged into a wifi access point

  - by MrGibbage

  At the gym where I work out, they have an open wifi access point. The way it is set up, once you "connect", you have to navigate to a web page (it is a 1.1.X.X ip address) and click the "I agree" button, after presumably reading the user agreement. The problem is, they have it set up to log you out once an hour, which always happens in the middle of my workout. I have the SSID remembered, so it connects automatically when I come in range, but I get an android notification that further action is needed to fully connect. What I was wondering is if there a work around so that I don't have to click-through every hour? I was thinking of writing an app that could detect when I was in range, or when "half-connected", and then have it somehow complete the registration process. Perhaps this will have to be done by loading the web page in memory and then somehow clicking the "I agree" button. What I would like help with is: 1) what is the terminology involved here? What state is the connection in when I am connected, but I haven't clicked through? What other connection states may apply? If I knew that, I might just be able to research this and come up with a solution. Are these different states "detectable"? It seems like it is since I get a notification that I need to complete the registration process when I am "half-connected". 2) I know there are plugins for desktop browsers that can click buttons (like the keepass plugins, which will log you into a site). How could I replicate this in Android? Ideally I would like to do it internally, in memory, rather than firing up a browser. Possible? Comments? Is my understanding and thought process sound here, or am I overlooking something?

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• Sorting text and attached images in MFMailCompositeViewController?

  - by eOgas

  In the app I'm currently writing I'd like to populate the message body of an e-mail with a combination of text and images. It took me forever to find out that in order to get an embedded image, you had to have bold tags in the message body (...uhhh, yeah), otherwise the image just shows up as an attachment. But now I have the problem that all of the images just go to the end of the body, and I can't programmatically put text after or in between any of the attachments. So far I've tried: Adding images as part of the body string using tags and a base64 string. This would have worked, but most e-mail clients reject images embedded in this manner. Using normal tags with a references to the attached files, using the assigned filenames. Didn't work at all. Attaching images normally, but also attaching blocks of text to the e-mail. The text is not embedded in the same manner as the images. Turns out to be an attached txt file on the receiving end. Apple has restricted their MFMailComposieViewController class to the point of ridiculousness, but I know there has to be a way to do this, because they add in their stupid "Sent from my *apple device name here*" message at the end of every e-mail. So does anyone have any ideas?

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• Calculating distance between two X,Y coordinates

  - by Umopepisdn

  I am writing a tool for a game that involves calculating the distance between two coordinates on a spherical plane 500 units across. That is, [0,0] through [499,499] are valid coordinates, and [0,0] and [499,499] are also right next to each other. Currently, in my application, I am comparing the distance between a city with an [X,Y] location respective to the user's own [X,Y] location, which they have configured in advance. To do this, I found this algorithm, which kind of works: Math.sqrt ( dx * dx + dy * dy ); Because sorting a paged list by distance is a useful thing to be able to do, I implemented this algorithm in a MySQL query and have made it available to my application using the following part of my SELECT statement: SQRT( POW( ( ".strval($sourceX)." - cityX ) , 2 ) + POW( ( ".strval($sourceY)." - cityY ) , 2 ) ) AS distance This works fine for many calculations, but does not take into account the fact that [0,0] and [499,499] are kitty-corner to one another. Is there any way I can tweak this algorithm to generate an accurate distance, given that 0 and 499 are adjacent? Thanks, -Umo

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• Can I set NHibernate's default "OrderBy" to be "CreatedDate" not "Id"?

  - by Chris F

  This is an oddball question I figure. Can I get NHibernate to ask SQL to sort data by CreatedDate by default unless I set an OrderBy in my HQL or Criteria? I'm interested in knowing whether this sort can be accomplished at the DB level to avoid bringing in LINQ. The reason is that I use GUIDs for Ids and when I do something like this: Sheet sheet = sheetRepository.Get(_someGUID); IList<SheetLineItems> lineItems = sheet.LineItems; to fetch all of the lineItems, they come back in whatever arbitrary way that SQL sorts that fetch, which I figure is GUID. At some point I'll add ordinals to my line items, but for now, I just want to use CreatedDate as the sort criteria. I don't want to be forced to do: IList<SheetLineItem> lineItems = sheetLineItemRepository.GetAll(_sheetGUID); and then writing that method to sort by CreatedDate. I figure if everything is just sorted on CreatedDate by default, that would be fine, unless specifically requested otherwise.

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• Java for loop with multiple incrementers

  - by user2517280

  Im writing a program which combines the RGB pixel values for 3 images, e.g. red pixel of image 1, green pixel of image 2 and blue pixel of image 3 and I want to then create a final image of it. Im using the code below, but this seems to be incrementing x2 and x3 whilst x1 is the same, i.e. not giving the right pixel value for same co-ordinate for each image. for (int x = 0; x < image.getWidth(); x++) { for (int x2 = 0; x2 < image2.getWidth(); x2++) { for (int x3 = 0; x3 < image3.getWidth(); x3++) { for (int y = 0; y < image.getHeight(); y++) { for (int y2 = 0; y2 < image2.getHeight(); y2++) { for (int y3 = 0; y3 < image3.getHeight(); y3++) { So I was wondering if anyone can tell me how to iterate through each of the 3 images on the same co-ordinate, so for example read 1, 1 of each image and record the red, green and blue value accordingly. Apologies if it doesnt make complete sense, its a bit hard to explain. I can iterate the values for one image fine but when I add in another, things start to go a bit wrong as obviously its quite a bit more complicated! I was thinking it might be easier to create an array and replace the according values in that just not sure how to do that effectively either. Thanks

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• Multithreading: Read from / write to a pipe

  - by Tero Jokinen

  I write some data to a pipe - possibly lots of data and at random intervals. How to read the data from the pipe? Is this ok: in the main thread (current process) create two more threads (2, 3) the second thread writes sometimes to the pipe (and flush-es the pipe?) the 3rd thread has infinite loop which reads the pipe (and then sleeps for some time) Is this so far correct? Now, there are a few thing I don't understand: do I have to lock (mutex?) the pipe on write? IIRC, when writing to pipe and its buffer gets full, the write end will block until I read the already written data, right? How to check for read data in the pipe, not too often, not too rarely? So that the second thread wont block? Is there something like select for pipes? It is possible to set the pipe to unbuffered more or I have to flush it regularly - which one is better? Should I create one more thread, just for flushing the pipe after write? Because flush blocks as well, when the buffer is full, right? I just don't want the 1st and 2nd thread to block.... [Edit] Sorry, I thought the question is platform agnostic but just in case: I'm looking at this from Win32 perspective, possibly MinGW C...

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• Indy client receive string

  - by Eszee

  Im writing an Indy chat app, and am wondering if there is a way for the server component to tell the client that there is a string waiting, or even a way for the client to have an "OnExecute" like event. This is what i have now: server: procedure TServer.ServerExecute(AContext: TIdContext); var sResponse: string; I: Integer; list: Tlist; begin List := Server.Contexts.LockList; sResponse:= AContext.Connection.Socket.ReadLn; try for I := 0 to List.Count-1 do begin try TIdContext(List[I]).Connection.IOHandler.WriteLn(sResponse); except end; end; finally Server.Contexts.UnlockList; end; end; Client: procedure TForm1.Button1Click(Sender: TObject); var sMsg : string; begin Client.Socket.WriteLn(edit1.Text); sMsg := Client.Socket.ReadLn; Memo1.Lines.Add(sMsg); end; The problem is when i have 2 or more clients running the messages keep stacking because the button only processes 1 message a time. I'd like a way for the client to wait for messages and when it is triggered it processes those messages, like it does now under the button procedure. I've tried to put the "readln" part under a timer, but that causes some major problems. Im Using Delphi 2010 and Indy 10

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• finding the maximum in the range

  - by comfreak

  I need to know a code that will automatically:- search a specific word in excel notes it row or column number (depends on data arrangement) searches numerical type values in the respective row or column with that numeric value(suppose a[7][0]or a[0][7]) it compares all other values of respective row or column(ie. a[i][0] or a[0][i]) sets that value to the highest value only if IT HAS GOT NO FORMULA FOR DERIVATION i know most of coding but at a few places i got myself stuck... i'm writing a part of my program upto which i know: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Threading; using Microsoft.Office.Interop; using Excel = Microsoft.Office.Interop.Excel; Excel.Application oExcelApp; namespace a{ class b{ static void main(){ try { oExcelApp = (Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application"); ; if(oExcelApp.ActiveWorkbook != null) {Excel.Workbook xlwkbook = (Excel.Workbook)oExcelApp.ActiveWorkbook; Excel.Worksheet ws = (Excel.Worksheet)xlwkbook.ActiveSheet; Excel.Range rn; rn = ws.Cells.Find("maximum", Type.Missing, Excel.XlFindLookIn.xlValues, Excel.XlLookAt.xlPart,Excel.XlSearchOrder.xlByRows, Excel.XlSearchDirection.xlNext, false, Type.Missing, Type.Missing); }}} now ahead of this i only know tat i have to use cell.value2 ,cell.hasformula methods..... & no more idea can any one help me with this..

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• Peoplesoft queries - performance

  - by DBa

  Hi, I'm facing a problem with PeopleSoft queries (using Oracle backend database): when a rather complex query involving multiple records is set off by a user, PS does an enforced join of security records, thus producing SQL like this: select .... from ps_job a, PS_EMPL_SRCQRY a1, ps_table2 b, ps_sec_rcd2 b1, ps_table3 c, ps_sec_rcd3 c1 where (...security joins a-a1, b-b1, c-c1...) and (...joins of a, b and c...) and a.setid_dept = 'XYZ'; (let's assume the last condition has a high selectivity and there is an index on the column) Obviously, due to the arrangement of the conditions, first a huge join is created, written to the temp segment, and when the last condition is finally applied, only a small subset is selected. A query formulated in this way is very likely to hit the preset timeout of the APPSRV, and even of the QRYSRV. When writing the query manually, I would rather move the most selective condition to the start, thus limiting the amount of the data being handled, to a considerable level. Any ideas on how to make PS behave like this? Actually, already rewriting "Oracle-styled" SQL to ANSI SQL seems to accelerate the queries - however, PS writes Oracle-style queries... Thanks in advance DBa

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• finding the maximum in series

  - by peril brain

  I need to know a code that will automatically:- search a specific word in excel notes it row or column number (depends on data arrangement) searches numerical type values in the respective row or column with that numeric value(suppose a[7][0]or a[0][7]) it compares all other values of respective row or column(ie. a[i][0] or a[0][i]) sets that value to the highest value only if IT HAS GOT NO FORMULA FOR DERIVATION i know most of coding but at a few places i got myself stuck... i'm writing a part of my program upto which i know: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Threading; using Microsoft.Office.Interop; using Excel = Microsoft.Office.Interop.Excel; Excel.Application oExcelApp; namespace a{ class b{ static void main(){ try { oExcelApp = (Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application"); ; if(oExcelApp.ActiveWorkbook != null) {Excel.Workbook xlwkbook = (Excel.Workbook)oExcelApp.ActiveWorkbook; Excel.Worksheet ws = (Excel.Worksheet)xlwkbook.ActiveSheet; Excel.Range rn; rn = ws.Cells.Find("maximum", Type.Missing, Excel.XlFindLookIn.xlValues, Excel.XlLookAt.xlPart,Excel.XlSearchOrder.xlByRows, Excel.XlSearchDirection.xlNext, false, Type.Missing, Type.Missing); }}} now ahead of this i only know tat i have to use cell.value2 ,cell.hasformula methods..... & no more idea can any one help me with this..

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• Should core application configuration be stored in the database, and if so what should be done to se

  - by Rl

  I'm writing an application around a lot of hierarchical data. Currently the hierarchy is fixed, but it's likely that new items will be added to the hierarchy in the future. (please let them be leaves) My current application and database design is fairly generic and nothing dealing with specific nodes in the hierarchy is hardcoded, with the exception of validation and lookup functions written to retrieve external data from each node's particular database. This pleases me from a design point of view, but I'm nervous at the realization that the entire application rests on a handful of records in the database. I'm also frustrated that I have to enforce certain aspects of data integrity with database triggers rather than by foreign key constraints (an example is where several different nodes in the hierarchy have their own proprietary IDs and I store them in a single column which, when coupled with the node ID can be used to locate the foreign data). I'm starting to wonder whether it may have been appropriate to simply hardcoded these known nodes into the system so that it would be more "type safe" and less generic. How does one know when something should be hardcoded, and when it should be a configuration item? Is it just a cost-benefit analysis of clarity/safety now vs less work later, or am I missing some metric I should be using to determine whether or not this is appropriate. The steps I'm taking to protect these valuable configurations are to add triggers that prevent updates/deletes. The database user that this application uses will only have the ability to manipulate data through stored procedures. What else can I do?

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• How to easily apply a function to a collection in C++

  - by Jesse Beder

  I'm storing images as arrays, templated based on the type of their elements, like Image<unsigned> or Image<float>, etc. Frequently, I need to perform operations on these images; for example, I might need to add two images, or square an image (elementwise), and so on. All of the operations are elementwise. I'd like get as close as possible to writing things like: float Add(float a, float b) { return a+b; } Image<float> result = Add(img1, img2); and even better, things like complex ComplexCombine(float a, float b) { return complex(a, b); } Image<complex> result = ComplexCombine(img1, img2); or struct FindMax { unsigned currentMax; FindMax(): currentMax(0) {} void operator(unsigned a) { if(a > currentMax) currentMax = a; } }; FindMax findMax; findMax(img); findMax.currentMax; // now contains the maximum value of 'img' Now, I obviously can't exactly do that; I've written something so that I can call: Image<float> result = Apply(img1, img2, Add); but I can't seem to figure out a generic way for it to detect the return type of the function/function object passed, so my ComplexCombine example above is out; also, I have to write a new one for each number of arguments I'd like to pass (which seems inevitable). Any thoughts on how to achieve this (with as little boilerplate code as possible)?

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• Why does a MFC application behaves mysteriously in encrypted hard drive environment.

  - by MauriceL

  I'm working on a bug where I have an MFC application that does weird things when installed in when Sophos Safeguard hard drive encryption is installed. I'm sorry to be so vague here, but I'm writing this away from the office so this is all from my (poor) memory. Three things I've noticed: AfxGetResourceHandle() doesn't return a consistent resource handle. There is a single case where we try to load a string resource, and for some reason, the resource handle that we get from this method is different to all the other stings. Can't construct a CDocumentTemplate. There is a trace error which I cant seem to recall. Will edit and post when I'm in tomorrow. This behaviour appears to manifest in a Visual Studio 2005 version of the project, but not a Visual Studio 2008 version. Unfortunately moving to the 2008 version is not an option. The bug is not always reproducable if I step through with a debugger. Also, bringing up debug message boxes changes the behaviuor, which leads me to think that either there is some kind of race condition going on with the way MFC events are being handled, but I'm not sure how I'll ever know for sure, or even what I can do about it if I did. I think there's some underlying reason that the app is behaving weirdly, but what I've posted are more symptoms. Can anyone think of what I should check for? I've run Windows update on the test environment to ensure everything was up to date, and I've examined the process in procmon to see if the disk encryption stuff was getting in the way and conflicting with files - it didn't appear to be, but it does appear to be involved in some way as our app accesses Sophos related paths in the temp directory.

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• .NET: bool vs enum as a method parameter

  - by Julien Lebosquain

  Each time I'm writing a method that takes a boolean parameter representing an option, I find myself thinking: "should I replace this by an enum which would make reading the method calls much easier?". Consider the following with an object that takes a parameter telling whether the implementation should use its thread-safe version or not (I'm not asking here if this way of doing this is good design or not, only the use of the boolean): public void CreateSomeObject(bool makeThreadSafe); CreateSomeObject(true); When the call is next to the declaration the purpose of the parameter seems of course obvious. When it's in some third party library you barely know, it's harder to immediately see what the code does, compared to: public enum CreationOptions { None, MakeThreadSafe } public void CreateSomeObject(CreationOptions options); CreateSomeObject(CreationOptions.MakeThreadSafe); which describes the intent far better. Things get worse when there's two boolean parameters representing options. See what happened to ObjectContext.SaveChanges(bool) between Framework 3.5 and 4.0. It has been obsoleted because a second option has been introduced and the whole thing has been converted to an enum. While it seems obvious to use an enumeration when there's three elements or more, what's your opinion and experiences about using an enum instead a boolean in these specific cases?

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• NServiceBus & MSMQ: How To Change the Default Permissions on the Queue?

  - by Amy T

  My team is on our first attempt at using NServiceBus (v2.0), using MSMQ as the backing storage. We're getting stuck on queue permissions. We're using it in a Web Forms application, where the user account the website runs under is not an administrator on the machine. When NServiceBus creates the MSMQ queue, it gives the local administrators group full control, and the local everyone and anonymous groups permissions to send messages. But then later, as part of initializing the queue, NServiceBus tries to read all of its messages. That's where we run into the permissions error. Since the website isn't running as an administrator, it's not allowed to read messages. How are other people dealing with this? Do your applications run as administrators? Or do you create the MSMQ queue in your code first, giving it the permissions you need, so that NServiceBus doesn't have to create it? Or is there a bit of configuration we're missing? Or are we likely writing our code that uses NServiceBus incorrectly to be running into this?

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• Is a web-server (e.g servlets) a good solution for an IM server?

  - by John

  I'm looking at a new app, broadly speaking an IM application with a strong client-server model - all communications go through a server so they can be logged centrally. The server will be Java in some form, clients could at this point be anything from a .NET Desktop app to Flex/Silverlight, to a simple web-interface using JS/AJAX. I had anticipated doing the server using standard J2EE so I get a thread-safe, multi-user server for 'free'... to make things simple let's say using Servlets (but in practice SpringMVC would be likely). This all seemed very neat but I'm concerned if the stateless nature of Servlets is the best approach. If my memory of servlets (been a year or two) is right, each time a client sent a HTTP request, typically a new message entered by the user, the servlet could not assume it had the user/chat in memory and might have to get it from the DB... regardless it has to look it up. Then it either has to use some PUSH system to inform other members of the chat, or cache that there are new messages, for other clients who poll the server using AJAX or similar - and when they poll it again has to lookup the chat, including new messages, and send the new data. I'm wondering if a better system would be the server is running core Java, and implements a socket-based communication with clients. This allows much more immediate data transfer and is more flexible if say the IM client included some game you could play. But then you're writing a custom server and sockets don't sound very friendly to a browser-based client on current browsers. Am I missing some big piece of the puzzle here, it kind of feels like I am? Perhaps a better way to ask the question would simply be "if the client was browser-based using HTML/JS and had to run on IE7+,FF2+ (i.e no HTML5), how would you implement the server?" edit: if you are going to suggest using XMPP, I have been trying to get my head around this in another question, so please consider if that's a more appropriate place to discuss this specifically.

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• how can I store the current status of the game in cocos2d ?

  - by srikanth rongali

  I am writing a shooting game in cocos2d. And each enemy enters the screen after the current one is dead. I have stores the enemies and their properties in plist. I need to save the current state of the game. If any phone call comes the game should be started from the current state. So, I usedNsUserDefaults in this way, - (void) applicationDidFinishLaunching:(UIApplication*)application { ... NSUserDefaults *myDefaultOptions = [[myDefaultOptions stringForKey:@"enemyNumber"]intValue] ; //tempCount4 is the current Enemy number. It was declared in another class. I am using extern and using the value here. tempCount4 = [[myDefaultOptions stringForKey:@"enemyNumber"]intValue] ; } - (void)applicationWillTerminate:(UIApplication *)application { [[CCDirector sharedDirector] end]; [myDefaultOptions setObject:tempCount4 forKey:@"enemyNumber"]; } The control is not entering in to the (void)applicationWillTerminate:(UIApplication *)application when I pressed the Home button. And when I touched the game icon on the screen the game is running from first screen and in log (terminal )it is not showing any values. And what should I store to resume my game from stored state. Can you explain where I was wrong ? Thank You.

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• Freeing ImageData when deleting a Canvas

  - by user578770

  I'm writing a XUL application using HTML Canvas to display Bitmap images. I'm generating ImageDatas and imporingt them in a canvas using the putImageData function : for(var pageIndex=0;pageIndex<100;pageIndex++){ this.img = imageDatas[pageIndex]; /* Create the Canvas element */ var imgCanvasTmp = document.createElementNS("http://www.w3.org/1999/xhtml",'html:canvas'); imgCanvasTmp.setAttribute('width', this.img.width); imgCanvasTmp.setAttribute('height', this.img.height); /* Import the image into the Canvas */ imgCanvasTmp.getContext('2d').putImageData(this.img, 0, 0); /* Use the Canvas into another part of the program (Commented out for testing) */ // this.displayCanvas(imgCanvasTmp,pageIndex); } The images are well imported but there seems to be a memory leak due to the putImageData function. When exiting the "for" loop, I would expect the memory allocated for the Canvas to be freed but, by executing the code without executing putImageData, I noticed that my program at the end use 100Mb less (my images are quite big). I came to the conclusion that the putImageData function prevent the garbage collector to free the allocated memory. Do you have any idea how I could force the garbage collector to free the memory? Is there any way to empty the Canvas? I already tried to delete the canvas using the delete operator or to use the clearRect function but it did nothing. I also tried to reuse the same canvas to display the image at each iteration but the amount of memory used did not changed, as if the image where imported without deleting the existing ones...

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• Saving and restoring OpenGL model-view

  - by Tom

  I am a new-comer to OpenGL, and much of it remains mysterious to my feeble brain. I have been studying the NeHe demos as well as the Red Book. I am writing an Android application that displays the Earth in the center of the screen. The user can rotate the Earth about any axis (much like a very simple "Google Earth"). This code is working (I based it on the NeHe examples). Now I want to add a feature; the user should be able to save the current model orientation, then later return to that same orientation. For example, the user may save the Earth orientation such that the viewer is looking down at her hometown, and north-east is "up". How do I do this with OpenGL-ES? To capture and save the current orientation, my code could get the current model-view transformation matrix - I think I understand how to do that. But later on how do I apply that saved matrix to restore the view?

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