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  • RESTful issue with data access when using HTTP DELETE method ...

    - by Wilhelm Murdoch
    I'm having an issue accessing raw request information from PHP when accessing a script using the HTTP DELETE directive. I'm using a JS front end which is accessing a script using Ajax. This script is actually part of a RESTful API which I am developing. The endpoint in this example is: http://api.site.com/session This endpoint is used to generate an authentication token which can be used for subsequent API requests. Using the GET method on this URL along with a modified version of HTTP Basic Authentication will provide an access token for the client. This token must then be included in all other interactions with the service until it expires. Once a token is generated, it is passed back to the client in a format specified by an 'Accept' header which the client sends the service; in this case 'application/json'. Upon success it responds with an HTTP 200 Ok status code. Upon failure, it throws an exception using the HTTP 401 Authorization Required code. Now, when you want to delete a session, or 'log out', you hit the same URL, but with the HTTP DELETE directive. To verify access to this endpoint, the client must prove they were previously authenticated by providing the token they want to terminate. If they are 'logged in', the token and session are terminated and the service should respond with the HTTP 204 No Content status code, otherwise, they are greeted with the 401 exception again. Now, the problem I'm having is with removing sessions. With the DELETE directive, using Ajax, I can't seem to access any parameters I've set once the request hits the service. In this case, I'm looking for the parameter entitled 'token'. I look at the raw request headers using Firebug and I notice the 'Content-Length' header changes with the size of the token being sent. This is telling me that this data is indeed being sent to the server. The question is, using PHP, how the hell to I access parameter information? It's not a POST or GET request, so I can't access it as you normally would in PHP. The parameters are within the content portion of the request. I've tried looking in $_SERVER, but that shows me limited amount of headers. I tried 'apache_request_headers()', which gives me more detailed information, but still, only for headers. I even tried 'file_get_contents('php://stdin');' and I get nothing. How can I access the content portion of a raw HTTP request? Sorry for the lengthy post, but I figured too much information is better than too little. :)

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  • UNIX: Replace Newline w/ Colon, Preserving Newline Before EOF

    - by Maarx
    I have a text file ("INPUT.txt") of the format: A<LF> B<LF> C<LF> D<LF> X<LF> Y<LF> Z<LF> <EOF> which I need to reformat to: A:B:C:D:X:Y:Z<LF> <EOF> I know you can do this with 'sed'. There's a billion google hits for doing this with 'sed'. But I'm trying to emphasis readability, simplicity, and using the correct tool for the correct job. 'sed' is a line editor that consumes and hides newlines. Probably not the right tool for this job! I think the correct tool for this job would be 'tr'. I can replace all the newlines with colons with the command: cat INPUT.txt | tr '\n' ':' There's 99% of my work done. I have a problem, now, though. By replacing all the newlines with colons, I not only get an extraneous colon at the end of the sequence, but I also lose the carriage return at the end of the input. It looks like this: A:B:C:D:X:Y:Z:<EOF> Now, I need to remove the colon from the end of the input. However, if I attempt to pass this processed input through 'sed' to remove the final colon (which would now, I think, be a proper use of 'sed'), I find myself with a second problem. The input is no longer terminated by a newline at all! 'sed' fails outright, for all commands, because it never finds the end of the first line of input! It seems like appending a newline to the end of some input is a very, very common task, and considering I myself was just sorely tempted to write a program to do it in C (which would take about eight lines of code), I can't imagine there's not already a very simple way to do this with the tools already available to you in the Linux kernel.

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  • Servlet IOException when streaming a Byte Array

    - by MontyBongo
    I occasionally get an IOException from a Servlet I have that writes a byte array to the outputstream in order to provide a file download capability. This download servlet has a reasonable amount of traffic (100k hits a month) and this exception occurs rarely, around 1-2 times a month. I have tried recreating the exception by using the exact same Base64 String and no exception is raised and the Servlet behaves as designed. Is this IO Exception being caused by something outside my applications control? For example a network issue or the user resetting the connection? I have tried to google the cause of an IOException at this point in the stack but to no avail. The environment is running Tomcat 5.5 on CentOS 5.3 with an Apache HTTP Server acting as a proxy using proxy_ajp. ClientAbortException: java.io.IOException at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBufferjava:366) at org.apache.tomcat.util.buf.ByteChunk.append(ByteChunk.java:352) at org.apache.catalina.connector.OutputBuffer.writeBytes(OutputBuffer.java:392) at org.apache.catalina.connector.OutputBuffer.write(OutputBuffer.java:381) at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:89) at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:83) at com.myApp.Download.doPost(Download.java:34) at javax.servlet.http.HttpServlet.service(HttpServlet.java:710) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:691) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:469) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:403) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301) at com.myApp.EntryServlet.service(EntryServlet.java:278) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at com.myApp.filters.RequestFilter.doFilter(RequestFilter.java:16) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:210) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151) at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:444) at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:472) at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1286) at java.lang.Thread.run(Thread.java:636) Caused by: java.io.IOException at org.apache.coyote.ajp.AjpAprProcessor.flush(AjpAprProcessor.java:1200) at org.apache.coyote.ajp.AjpAprProcessor$SocketOutputBuffer.doWrite(AjpAprProcessor.java:1285) at org.apache.coyote.Response.doWrite(Response.java:560) at org.apache.catalina.connector.OutputBuffer.realWriteBytes(OutputBufferjava:361) And the code in the Download Servlet: @Override protected void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, java.io.IOException { try { response.setContentType("application/pdf"); response.setHeader("Pragma", ""); response.setHeader("Cache-Control", ""); response.setHeader("Content-Disposition", "Inline; Filename=myPDFFile..pdf"); ServletOutputStream out = response.getOutputStream(); byte[] downloadBytes = Base64.decode((String)request.getAttribute("fileToDownloadBase64")); out.write(downloadBytes); } catch (Base64DecodingException e) { e.printStackTrace(); response.getOutputStream().print("An error occurred"); } }

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  • WCF Duplex Interaction with Web Server

    - by Mark Struzinski
    Here is my scenario, and it is causing us a considerable amount of grief at the moment: We have a vendor web service which provides base level telephony functionality. This service has a SOAP api, which we are leveraging to build up a custom UI that is integrated into our in house web apps. The api functions on 2 levels. You make standard client calls into the service to initiate actions, such as Login, Place Call, Hang Up, etc. On a different thread, the service sends events back to the client to alert the user of things that are occurring on the system (agent successfully logged in, call was disconnected, etc). I implemented a WCF service to sit between the web server and the vendor service. This WCF service operates in duplex mode, establishing a 2 way connection with the web server. The web server makes outbound calls to the WCF service, which routes them to the vendor's web service. Events are received back to the WCF service, which passes them onto the web server via a callback channel on the WCF client. As events are received on the web server, they are placed into a hash table with the user's name as the key, and a .NET queue as the value to hold the event. Each event is enqueued to the agent who owns it. On a 2 second interval, the web page polls the web server via an ajax request to get new events for the logged in user. It hits the hash table for the user key, dequeues any events that are present, and serializes them back up to the web page. From there, they are processed in order and appropriate messages are displayed to the user. This implementation performs well in a single user scenario. The second I put more than 1 user on the system, I start getting frequent timeouts with the following CommunicationException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond We are running Windows Server 2008 R2 both servers. Both the web app and WCF service are running on .NET 3.5. The WCF service is running under the net.tcp protocol in duplex mode. The web app is ASP.NET MVC 2. Has anyone dealt with anything like this scenario? Is there a more efficient way (or a widely accepted pattern) to implement this?

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  • Prolog: Sentence Parser Problem

    - by Devon
    Hey guys, Been sat here for hours now just staring at this code and have no idea what I'm doing wrong. I know what's happening from tracing the code through (it is going on an eternal loop when it hits verbPhrase). Any tips are more then welcome. Thank you. % Knowledge-base det(the). det(a). adjective(quick). adjective(brown). adjective(orange). adjective(sweet). noun(cat). noun(mat). noun(fox). noun(cucumber). noun(saw). noun(mother). noun(father). noun(family). noun(depression). prep(on). prep(with). verb(sat). verb(nibbled). verb(ran). verb(looked). verb(is). verb(has). % Sentece Structures sentence(Phrase) :- append(NounPhrase, VerbPhrase, Phrase), nounPhrase(NounPhrase), verbPhrase(VerbPhrase). sentence(Phrase) :- verbPhrase(Phrase). nounPhrase([]). nounPhrase([Head | Tail]) :- det(Head), nounPhrase2(Tail). nounPhrase(Phrase) :- nounPhrase2(Phrase). nounPhrase(Phrase) :- append(NP, PP, Phrase), nounPhrase(NP), prepPhrase(PP). nounPhrase2([]). nounPhrase2(Word) :- noun(Word). nounPhrase2([Head | Tail]) :- adjective(Head), nounPhrase2(Tail). prepPhrase([]). prepPhrase([Head | Tail]) :- prep(Head), nounPhrase(Tail). verbPhrase([]). verbPhrase(Word) :- verb(Word). verbPhrase([Head | Tail]) :- verb(Head), nounPhrase(Tail). verbPhrase(Phrase) :- append(VP, PP, Phrase), verbPhrase(VP), prepPhrase(PP).

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  • Passing const CName as this argument discards qualifiers

    - by Geno Diaz
    I'm having trouble with passing a constant class through a function. // test the constructors auto CName nameOne("Robert", "Bresson"); const CName nameTwo = nameOne; auto CName nameThree; // display the contents of each newly-constructed object... // should see "Robert Bresson" cout << "nameOne = "; nameOne.WriteFullName(); cout << endl; // should see "Robert Bresson" again cout << "nameTwo = "; nameTwo.WriteFullName(); cout << endl; As soon as the compiler hits nameTwo.WriteFullName() I get the error of abandoning qualifiers. I know that the class is a constant however I can't figure out how to work around it. The function is in a header file written as so: void const WriteFullName(ostream& outstream = cout) { outstream << m_first << ' ' << m_last; } I receive this error when const is put in back of the function header main.cpp:(.text+0x51): undefined reference to CName::CName()' main.cpp:(.text+0x7c): undefined reference toCName::WriteFullName(std::basic_ostream &) const' main.cpp:(.text+0xbb): undefined reference to CName::WriteFullName(std::basic_ostream<char, std::char_traits<char> >&) const' main.cpp:(.text+0xf7): undefined reference toCName::WriteFullName(std::basic_ostream &) const' main.cpp:(.text+0x133): undefined reference to operator>>(std::basic_istream<char, std::char_traits<char> >&, CName&)' main.cpp:(.text+0x157): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x1f4): undefined reference to operator<<(std::basic_ostream<char, std::char_traits<char> >&, CName const&)' main.cpp:(.text+0x22b): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x25f): undefined reference to operator<<(std::basic_ostream<char, std::char_traits<char> >&, CName const&)' main.cpp:(.text+0x320): undefined reference tooperator<<(std::basic_ostream &, CName const&)' main.cpp:(.text+0x347): undefined reference to `operator(std::basic_istream &, CName&)'

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  • Cocoa NSOutputStream send to a connection

    - by Chuck
    Hi, I am new to Cocoa, but managed to get a connection (to a FTP) up and running, and I've set up an eventhandler for the NSInputStream iStream to alert every response (which also works). What I manage to get is simply the hello message and a connection timeout 60 sec, closing control connection. After searching stackoverflow and finding a lot of NSOutputStream write problems (e.g. http://stackoverflow.com/questions/703729/how-to-use-nsoutputstreams-write-message) and a lot of confusion in my google hits, I figured I'd try to ask my own question: I've tried reading the developer.apple.com doc on OutputStream, but it seems almost impossible for me to send some data (in this case just a string) to the "connection" via the NSOutputStream oStream. - (IBAction) send_something: sender { const char *send_command_char = [@"USER foo" UTF8String]; send_command_buffer = [NSMutableData dataWithBytes:send_command_char length:strlen(send_command_char) + 1]; uint8_t *readBytes = (uint8_t *)[send_command_buffer mutableBytes]; NSInteger byteIndex = 0; readBytes += byteIndex; int data_len = [send_command_buffer length]; unsigned int len = ((data_len - byteIndex >= 1024) ? 1024 : (data_len-byteIndex)); uint8_t buf[len]; (void)memcpy(buf, readBytes, len); len = [oStream write:(const uint8_t *)buf maxLength:len]; byteIndex += len; } the above seems not to result in any useable events. typing it under NSStreamEventHasSpaceAvailable sometimes give a response if I spam the ftp by keep creating new connection instances and keep sending some command whenever oStream has free space. In other words, nothing "right" and so I'm still unclear how to properly send a command to the connection. Should I open - write - close every time i want to write to oStream (and thus to the ftp) and can I then expect a reply (hasBytesAvailable event on iStream)? For some reason I find it very difficult to find any clear tutorials on this matter. Seems like there are more than a few in the same position as me: unclear how to use oStream write? Any little bit that can help clear this up is greatly appreciated! If needed I can write the rest of the code. Chuck

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  • paypal IPN sends two different twice

    - by Patrick
    I've come across something a bit strange I was hoping someone with more experience with Paypal can explain, Specifically the IPN feature. It seems I'm getting two very different hits to my IPN listener. The first one always fails, The second one passes. Now I know Paypal tends to send duplicates, But what I've noticed is two very different $_POST arrays being recieved. Here's the respones : [2014-06-08 23:51:19] RAW POST DATA : Array ( [transaction] => Array ( [0] => ILS 20.00 ) [payment_request_date] => Sun Jun 08 13:52:12 PDT 2014 [return_url] => MY_URL [fees_payer] => EACHRECEIVER [ipn_notification_url] => MY_URL [sender_email] => [email protected] //fake email [verify_sign] => ANp5TpLat3.2ylx.cECtVZ..5HejAsVcs05tdVC7RldmeYNJ91SKaqFJ [test_ipn] => 1 [cancel_url] => MY_URL [pay_key] => AP-04B74091M7083584A [action_type] => PAY [transaction_type] => Adaptive Payment PAY [tracking_id] => 13 // This is a number I passed, But it doesn't exist in the 2nd POST [status] => COMPLETED [log_default_shipping_address_in_transaction] => false [charset] => windows-1252 [notify_version] => UNVERSIONED [reverse_all_parallel_payments_on_error] => false ) [2014-06-08 23:51:19] RAW POST DATA : Array ( [transaction_subject] => [payment_date] => 13:52:28 Jun 08, 2014 PDT [txn_type] => web_accept [last_name] => test [residence_country] => US [item_name] => .... (this continues for quite a bit more) .... [payment_fee] => [mc_fee] => 1.78 [mc_gross] => 20.00 [custom] => [charset] => windows-1252 [notify_version] => 3.8 [ipn_track_id] => f93ce8bdd4382 ) My problem The first IPN with the juicy tracking_id fails, the 2nd IPN is verified, But once the IPN is verified I no longer have access to the tracking_id. My questions Why does paypal send two different IPN's Why are they different? Why isn't any of this documented on Paypal? :(

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  • How can I test caching and cache busting?

    - by Nathan Long
    In PHP, I'm trying to steal a page from the Rails playbook (see 'Using Asset Timestamps' here): By default, Rails appends assets' timestamps to all asset paths. This allows you to set a cache-expiration date for the asset far into the future, but still be able to instantly invalidate it by simply updating the file (and hence updating the timestamp, which then updates the URL as the timestamp is part of that, which in turn busts the cache). It‘s the responsibility of the web server you use to set the far-future expiration date on cache assets that you need to take advantage of this feature. Here‘s an example for Apache: # Asset Expiration ExpiresActive On <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$"> ExpiresDefault "access plus 1 year" </FilesMatch> If you look at a the source for a Rails page, you'll see what they mean: the path to a stylesheet might be "/stylesheets/scaffold.css?1268228124", where the numbers at the end are the timestamp when the file was last updated. So it should work like this: The browser says 'give me this page' The server says 'here, and by the way, this stylesheet called scaffold.css?1268228124 can be cached for a year - it's not gonna change.' On reloads, the browser says 'I'm not asking for that css file, because my local copy is still good.' A month later, you edit and save the file, which changes the timestamp, which means that the file is no longer called scaffold.css?1268228124 because the numbers change. When the browser sees that, it says 'I've never seen that file! Give me a copy, please.' The cache is 'busted.' I think that's brilliant. So I wrote a function that spits out stylesheet and javascript tags with timestamps appended to the file names, and I configured Apache with the statement above. Now: how do I tell if the caching and cache busting are working? I'm checking my pages with two plugins for Firebug: Yslow and Google Page Speed. Both seem to say that my files are caching: "Add expires headers" in Yslow and "leverage browser caching" in Page Speed are both checked. But when I look at the Page Speed Activity, I see a lot of requests and waiting and no 'cache hits'. If I change my stylesheet and reload, I do see the change immediately. But I don't know if that's because the browser never cached in the first place or because the cache is busted. How can I tell?

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  • HttpSession problem in Google App Engine/J

    - by Tahir Akram
    I am writting a Twitter web app by using Twitter4J on GAE/J. I am saving Twitter and Request Token objects in session so that to be used after call back. I have two servlets. IndexServlet sets session and HomeServlet get from session (hits on call back by twitter oAuth). If I comment out session handling lines in both servlets then call backs works fine. Please suggest any workaround. I am sharing my code here. IndexServlet.java Twitter twitter = new Twitter(); twitter.setOAuthConsumer("<masked>", "<masked>"); RequestToken requestToken = null; try { requestToken = twitter.getOAuthRequestToken(); log.info("OAuth token has been taken"); } catch (TwitterException e) { log.warning(e.toString()); } HttpSession session = request.getSession(); if (session.getAttribute("twitter")==null){ session.setAttribute("twitter", twitter); out.println("-----------------------------> session is set"); } if (session.getAttribute("token")==null){ session.setAttribute("token", requestToken); out.println("-----------------------------> session is set"); } String authUrl = requestToken.getAuthorizationURL(); HomeServlet.java HttpSession session = request.getSession(); twitter = (Twitter)session.getAttribute("twitter"); r = (RequestToken)session.getAttribute("token"); twitter.setOAuthAccessToken(r.getAccessToken()); twitter.updateStatus("Hello World!"); Exception javax.servlet.ServletException: java.lang.ArrayStoreException: [Ljava.lang.String; at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:239) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139) at org.mortbay.jetty.Server.handle(Server.java:313) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506) at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:830) at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381) at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:139) at com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:235) at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4950) at com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4948) at com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:24) at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:359) at com.google.net.rpc.impl.Server$2.run(Server.java:823) at com.google.tracing.LocalTraceSpanRunnable.run(LocalTraceSpanRunnable.java:56)

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  • How to dispose of a NET COM interop object on Release()

    - by mhenry1384
    I have a COM object written in managed code (C++/CLI). I am using that object in standard C++. How do I force my COM object's destructor to be called immediately when the COM object is released? If that's not possible, call I have Release() call a MyDispose() method on my COM object? My code to declare the object (C++/CLI): [Guid("57ED5388-blahblah")] [InterfaceType(ComInterfaceType::InterfaceIsIDispatch)] [ComVisible(true)] public interface class IFoo { void Doit(); }; [Guid("417E5293-blahblah")] [ClassInterface(ClassInterfaceType::None)] [ComVisible(true)] public ref class Foo : IFoo { public: void MyDispose(); ~Foo() {MyDispose();} // This is never called !Foo() {MyDispose();} // This is called by the garbage collector. virtual ULONG Release() {MyDispose();} // This is never called virtual void Doit(); }; My code to use the object (native C++): #import "..\\Debug\\Foo.tlb" ... Bar::IFoo setup(__uuidof(Bar::Foo)); // This object comes from the .tlb. setup.Doit(); setup-Release(); // explicit release, not really necessary since Bar::IFoo's destructor will call Release(). If I put a destructor method on my COM object, it is never called. If I put a finalizer method, it is called when the garbage collector gets around to it. If I explicitly call my Release() override it is never called. I would really like it so that when my native Bar::IFoo object goes out of scope it automatically calls my .NET object's dispose code. I would think I could do it by overriding the Release(), and if the object count = 0 then call MyDispose(). But apparently I'm not overriding Release() correctly because my Release() method is never called. Obviously, I can make this happen by putting my MyDispose() method in the interface and requiring the people using my object to call MyDispose() before Release(), but it would be slicker if Release() just cleaned up the object. Is it possible to force the .NET COM object's destructor, or some other method, to be called immediately when a COM object is released? Googling on this issue gets me a lot of hits telling me to call System.Runtime.InteropServices.Marshal.ReleaseComObject(), but of course, that's how you tell .NET to release a COM object. I want COM Release() to Dispose of a .NET object.

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  • Joomla - Force File Download / CSV Export

    - by lautaro.dragan
    I'm in need of help... this is my first time asking a question in SO, so please be kind :) I'm trying to force-download a file from php, so when the user hits a certain button, he gets a file download. The file is a csv (email, username) of all registered users. I decided to add this button to the admin users screen, as you can see in this screenshot. So I added the following code to the addToolbar function in administrator/components/com_users/views/users/view.html.php: JToolBarHelper::custom('users.export', 'export.png', 'export_f2.png', 'Exportar', false); This button is mapped to the following function in the com_users\controller\users.php controller: public function exportAllUsers() { ob_end_clean(); $app = JFactory::getApplication(); header("Content-type: text/csv"); header("Content-Disposition: attachment; filename=ideary_users.csv"); header("Pragma: no-cache"); header("Expires: 0"); echo "email,name\n"; $model = $this->getModel("Users"); $users = $model->getAllUsers(); foreach ($users as $user) { echo $user->email . ", " . ucwords(trim($user->name)) . "\r\n"; } $app->close(); } Now, this is actually working perfectly fine. The issue here is that after I download a file, if I hit any button in the admin that causes a POST, instead of it performing the action it should, it just downloads the file over again! For example: I hit the "Export" button "users.csv" downloads Then, I hit the "search" button "users.csv" downloads... what the hell? I'm guessing that when I hit the export button, a JS gets called and sets a form's action attribute to an URL... and expects a response or something, and then other button's are prevented from re-setting the form's action attribute. I can't think of any real solution for this, but I'd rather avoid hacks if possible. So, what would be the standard, elegant solution that joomla offers in this case?

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  • SharedObject (Flex 3.2) behaving unexpectedly when query string present in URL

    - by rhtx
    Summary: The behavior detailed below seems to indicate that if your app at www.someplace.com sets/retrieves data via a SharedObject, there is some sort of .sol collision if the user hits your app at someplace.com, and then later at someplace.com?name=value. Can anyone confirm or refute this? I'm working on a Flex web app that presents the user with a login page. When the user has logged in, he/she is presented with a 'room' which is associated with a 'group'. We store the last-visited room/group combination in a SharedObject - so when a given user logs in, they are taken into the most recent room in which they were active. That works fine, but we also have an auto-login system which involves the user clicking on a link to the app url with a query string attached. There are two types of these links. 1) the query string includes username, groupId, and roomId 2) the query string includes only the username Because we are working fast and have only a few developers, the auto-login system is built on the last-vist system. During the auto-login process, the url is inspected and if groupId and roomId values are found in the query string, the SharedObject is opened and the last-visit group/room id values are overwritten by the param values. That works fine, also, when the app is hit with a query string of the second type (no groupId and roomId params), the app goes to the SharedObject to get the stored room and group id values, as it normally would. And here's the problem: The values it comes back with are whatever the last room/group param values were, not whatever the last last-visit room/group values are. And if the given user has never hit the app with query string that included group and room id values, the app gets null values from the SharedObject. It took some digging around, but what it looks like is happening is that a second set of data is being stored/expected in the SharedObject if a query string is present in the URL. Looking at the .sol file in a text editor I see more untranslated code, and additional group and room values, once I've hit the app with URLs that contain query strings. I'm not finding anything on the web about this, but that may just be due to a lack of necessary search skills. Has anyone else run into anything similar? Or do you know how to address this? I've tried setting Security.exactSettings to false, already - was really hoping that was going to work.

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  • Read variable-length records from a buffer - weird memory issues

    - by bsg
    Hi, I'm trying to implement an i/o intensive quicksort (C++ qsort) on a very large dataset. In the interests of speed, I'd like to read in a chunk of data at a time into a buffer and then use qsort to sort it inside the buffer. (I am currently working with text files but would like to move to binary soon.) However, my data is composed of variable-length records, and qsort needs to be told the length of the record in order to sort. Is there any way to standardize this? The only thing I could think of was rather convoluted: my program currently reads from the buffer until it hits a linefeed character ('10' in ascii), transferring each character over to another array. When it finds a linefeed (the delimiter in the input file), it fills the number of spaces remaining in the buffer for that record (record size is set to 30) with null characters. This way, I should end up with a buffer full of fixed-size records to give qsort. I know there are several problems with my approach, one being that it's just clumsy, another that the record size might conceivably be larger than 30, but is generally much less. Is there a better way of doing this? As well, my current code doesn't even work. When I debug it, it seems to be transferring characters from one buffer to the other, but when I try to print out the buffer, it contains only the first record. Here is my code: FILE *fp; unsigned char *buff; unsigned char *realbuff; FILE *inputFiles[NUM_INPUT_FILES]; buff = (unsigned char *) malloc(2048); realbuff = (unsigned char *) malloc(NUM_RECORDS * RECORD_SIZE); fp = fopen("postings0.txt", "r"); if(fp) { fread(buff, 1, 2048, fp); /*for(int i=0; i <30; i++) cout << buff[i] <<endl;*/ int y=0; int recordcounter = 0; //cout << buff; for(int i=0;i <100; i++) { if(buff[i] != char(10)) { realbuff[y] = buff[i]; y++; recordcounter++; } else { if(recordcounter < RECORD_SIZE) for(int j=recordcounter; j < RECORD_SIZE;j++) { realbuff[y] = char(0); y++; } recordcounter = 0; } } cout << realbuff <<endl; cout << buff; } else cout << "sorry"; Thank you very much, bsg

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  • Ajax to read updated values from XML

    - by punit
    I am creating file upload progress bar. I have a CGI script which copies the data, and here I increment the progress bar value by ONE after certain iterations. I am storing the incremented value in XML file (I also tried using plain text file). On the other side I have ajax reading incremented value from xml and depending on that it increments the DIV element. However, what happens here is, it seems to me that although the ajax reads all the incremented values but it processes it after the CGI has finished execution. That is progress bar starts execution once the file copying and other stuff in CGI is completed. My code is: AJAX:::: function polling_start() { //GETS CALLED WHEN USER HITS FILE UPLOAD BUTTON intervalID = window.setInterval(send_request,100); } window.onload = function (){ request = initXMLHttpClient(); request.overrideMimeType('text/xml'); progress = document.getElementById('progress'); } function initXMLHttpClient() { if (window.XMLHttpRequest){ // code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp = new XMLHttpRequest(); } else{ // code for IE6, IE5 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } return xmlhttp } function send_request() { request.open("GET","progress_bar.xml",true); request.onreadystatechange = request_handler; request.send(); } function request_handler() { if (request.readyState == 4 && request.status == 200) { var level=request.responseXML.getElementsByTagName('PROGRESS')[0].firstChild; progress.style.width = progress.innerHTML = level.nodeValue + '%'; progress.style.backgroundColor = "green"; } } /****ON SERVER SIDE*********/ char xmlDat1[] = "<DOCUMENT><PROGRESS>"; char xmlDat2[] = "</PROGRESS></DOCUMENT>"; fptr = fopen("progress_bar.xml", "w"); .........OTHER STUFF.............................. ................................. if(i == inc && j<=100) { fprintf(fptr, "%s\n", "\n\n\n]"); //fprintf(fptr, "%s\n", ""); fprintf(fptr, "%s", xmlDat1); // fprintf(fptr, "%d" ,j); fprintf(fptr, "%s" ,xmlDat2); fseek(fptr, 0, SEEK_SET); /*fprintf(fptr, "%d" ,j); fseek(fptr, 0, SEEK_SET);*/ i = 0; //sleep(1); j++; } (I also tried to write in .text, but same response) Any quick response would be appreciable.

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  • Choosing a distributed shared memory solution

    - by mindas
    I have a task to build a prototype for a massively scalable distributed shared memory (DSM) app. The prototype would only serve as a proof-of-concept, but I want to spend my time most effectively by picking the components which would be used in the real solution later on. The aim of this solution is to take data input from an external source, churn it and make the result available for a number of frontends. Those "frontends" would just take the data from the cache and serve it without extra processing. The amount of frontend hits on this data can literally be millions per second. The data itself is very volatile; it can (and does) change quite rapidly. However the frontends should see "old" data until the newest has been processed and cached. The processing and writing is done by a single (redundant) node while other nodes only read the data. In other words: no read-through behaviour. I was looking into solutions like memcached however this particular one doesn't fulfil all our requirements which are listed below: The solution must at least have Java client API which is reasonably well maintained as the rest of app is written in Java and we are seasoned Java developers; The solution must be totally elastic: it should be possible to add new nodes without restarting other nodes in the cluster; The solution must be able to handle failover. Yes, I realize this means some overhead, but the overall served data size isn't big (1G max) so this shouldn't be a problem. By "failover" I mean seamless execution without hardcoding/changing server IP address(es) like in memcached clients when a node goes down; Ideally it should be possible to specify the degree of data overlapping (e.g. how many copies of the same data should be stored in the DSM cluster); There is no need to permanently store all the data but there might be a need of post-processing of some of the data (e.g. serialization to the DB). Price. Obviously we prefer free/open source but we're happy to pay a reasonable amount if a solution is worth it. In any way, paid 24hr/day support contract is a must. The whole thing has to be hosted in our data centers so SaaS offerings like Amazon SimpleDB are out of scope. We would only consider this if no other options would be available. Ideally the solution would be strictly consistent (as in CAP); however, eventual consistence can be considered as an option. Thanks in advance for any ideas.

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  • A SelfHosted WCF Service over Basic HTTP Binding doesn't support more than 1000 concurrent requests

    - by Krishnan
    I have self hosted a WCF Service over BasicHttpBinding consumed by an ASMX Client. I'm simulating a concurrent user load of 1200 users. The service method takes a string parameter and returns a string. The data exchanged is less than 10KB. The processing time for a request is fixed at 2 seconds by having a Thread.Sleep(2000) statement. Nothing additional. I have removed all the DB Hits / business logic. The same piece of code runs fine for 1000 concurrent users. I get the following error when I bump up the number to 1200 users. System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a receive. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags) at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size) --- End of inner exception stack trace --- at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size) at System.Net.PooledStream.Read(Byte[] buffer, Int32 offset, Int32 size) at System.Net.Connection.SyncRead(HttpWebRequest request, Boolean userRetrievedStream, Boolean probeRead) --- End of inner exception stack trace --- at System.Web.Services.Protocols.WebClientProtocol.GetWebResponse(WebRequest request) at System.Web.Services.Protocols.HttpWebClientProtocol.GetWebResponse(WebRequest request) at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) at WCF.Throttling.Client.Service.Function2(String param) This exception is often reported on DataContract mismatch and large data exchange. But never when doing a load test. I have browsed enough and have tried most of the options which include, Enabled Trace & Message log on server side. But no errors logged. To overcome Port Exhaustion MaxUserPort is set to 65535, and TcpTimedWaitDelay 30 secs. MaxConcurrent Calls is set to 600, and MaxConcurrentInstances is set to 1200. The Open, Close, Send and Receive Timeouts are set to 10 Minutes. The HTTPWebRequest KeepAlive set to false. I have not been able to nail down the issue for the past two days. Any help would be appreciated. Thank you.

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  • Want to set 'src' of script to my IP-Won't load in Safari or Chrome. Relative link asp.netmvc

    - by Ozaki
    I have a script that links to the server I am hosting (IP can change) usually I would just use for links: var url ='http://' + window.location.hostname + 'end of url'; But in this case it isnt appearing to be so easy. I have tried: (1) $('#scriptid').attr('src', url); as well as: (2) var script = document.createElement( 'script' ); script.type = 'text/javascript'; script.src = url; $("#insert").append( script ); Now case (2) works loads the script runs the script. But when at the end of my script it hits the 'write data' it decides to replace the entire page with just the data. Any idea on how I can do this? Note: I am using plain html not ASP. With ASP backend that is just the way it has to be. Ok it now is <script src="myscript.js"></script> C# router.AddAsyncRoute("myscript.js"...... It workes in IE & FF. But I get blank pages in Chrome & Safari. I am using document.write to write a script onto my page. Any ideas why Chrome & Safari don't like this? I am so far assuming that in Crhome & Safari it takes longer to run the script therefore launching the document.write after the DOM has loaded therefore replacing the page with a blank one. edit the script im trying to run is a modification of: d = new dTree('d'); d.add(0,-1,'My example tree'); d.add(1,0,'Node 1','default.html'); d.add(2,0,'Node 2','default.html'); d.add(3,1,'Node 1.1','default.html'); d.add(4,0,'Node 3','default.html'); d.add(5,3,'Node 1.1.1','default.html') document.write(d); Any ideas how I can get around this? I am not to sure how to implement an appenChild in this case as the script is changing constantly with live data. So every refresh it will generally have changed some...

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  • If statement within If statement's else

    - by maebe
    Still new to Java/android so trying to figure out the best way to code a multilevel if statement. What I'm trying to do is for a combat system that needs to check if player/npc is alive. If they are alive it then will check to see if they scored a critical hit. If they didn't critical hit then will see if they hit or missed. combat = mydbhelper.getCombat(); startManagingCursor(combat); if(playerCurHp == 0){ combat.moveToPosition(11); npcCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} else{ if(playerCritFlag.equals("Critical")){ combat.moveToPosition(2); playerCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} else{ if(playerHitFlag.equals("Hit")){ combat.moveToPosition(1); playerCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} if(playerHitFlag.equals("Miss")){ combat.moveToPosition(3); playerCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} }} if (npcCurHp == 0){ combat.moveToPosition(10); npcCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} else{ if(npcCritFlag.equals("Critical")){ combat.moveToPosition(5); npcCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} else{ if(npcHitFlag.equals("Hit")){ combat.moveToPosition(4); npcCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} if(npcHitFlag.equals("Miss")){ combat.moveToPosition(6); npcCombatStory = combat.getString(combat.getColumnIndex(dbhelper.KEY_COMBATDESC));} }} } Is what I'm using. Was working when I had the if statements all separate. But it would check each one and do actions I don't need (If they hit, pull String, if crit pull another, then if dead pull again). Trying to make it stop when it finds the "Flag" that matches. When doing my rolls if the player hits it sets the flag to "Hit" like below code. Random attackRandom = new Random(); int attackRoll = attackRandom.nextInt(100); totalAtt = attackRoll + bonusAttack + weaponAtt + stanceAtt; Random defensiveRandom = new Random(); int defenseRoll = defensiveRandom.nextInt(100); npcDef = defenseRoll + npcDodge + npcBonusDodge; if (totalAtt > npcDef){ playerHitFlag = "Hit"; playerDamage();} else{playerHitFlag = "Miss"; npcAttack();} At the end it takes these playerCombatStory and npcCombatStory strings and uses them to setText to show the player what happened on that turn of combat.

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  • What is the difference between NULL in C++ and null in Java?

    - by Stephano
    I've been trying to figure out why C++ is making me crazy typing NULL. Suddenly it hits me the other day; I've been typing null (lower case) in Java for years. Now suddenly I'm programming in C++ and that little chunk of muscle memory is making me crazy. Wikiperipatetic defines C++ NULL as part of the stddef: A macro that expands to a null pointer constant. It may be defined as ((void*)0), 0 or 0L depending on the compiler and the language. Sun's docs tells me this about Java's "null literal": The null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters. A null literal is always of the null type. So this is all very nice. I know what a null pointer reference is, and thank you for the compiler notes. Now I'm a little fuzzy on the idea of a literal in Java so I read on... A literal is the source code representation of a fixed value; literals are represented directly in your code without requiring computation. There's also a special null literal that can be used as a value for any reference type. null may be assigned to any variable, except variables of primitive types. There's little you can do with a null value beyond testing for its presence. Therefore, null is often used in programs as a marker to indicate that some object is unavailable. Ok, so I think I get it now. In C++ NULL is a macro that, when compiled, defines the null pointer constant. In Java, null is a fixed value that any non-primitive can be assigned too; great for testing in a handy if statement. Java does not have pointers, so I can see why they kept null a simple value rather than anything fancy. But why did java decide to change the all caps NULL to null? Furthermore, am I missing anything here?

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  • ASP.net: Radio Button Not Maintaining Selection After Postback, Inside DIV/Thickbox

    - by jlrolin
    I have a set of radio buttons inside a hidden DIV. <div id="reports" style="display:none;"> <center> <br /> <table cellpadding="4" cellspacing="0"> <tr> <td class="label"> Report Type::&nbsp; </td> <td class="value"> <asp:RadioButton ID="rbReportTypeCust" runat="server" Text="By Customer" Enabled="True" Checked="True" GroupName="rbType" />&nbsp;<asp:RadioButton ID="rbReportTypeProg" runat="server" Text="By Program" Enabled="True" GroupName="rbType" /> </td> </tr> <tr> <td class="label"> Customer:&nbsp; </td> <td class="value"> <asp:DropDownList ID="ddlCustomer" runat="server" /> </td> </tr> <tr> <td class="label"> Program Group::&nbsp; </td> <td class="value"> <asp:DropDownList ID="ddlProgramGroups" runat="server" /> </td> </tr> </table> <br /> <asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClientClick="doPostBack(this);" /> </center> </div> The DIV is displayed using Thickbox as a modal popup. The doPostback javascript function posts the button click back, and hits btnSubmit_Click where a report is then generated. If I see if a radio button is checked, it's always rbReportTypeCust.checked = True, never the rbReportTypeProg.checked = True even if I click it. Any suggestions?

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  • Android pluginable application

    - by Alxandr
    I've been trying to create an android-application the last couple of weeks, and mostly everything has worked out great, but there is one thing that I was wondering about, and that is pluginability trough the use of intents. What I'm trying to create is basically a comic-reader. As of the version I use now, I open the application and get a list of commics that are my favourites, then I enter one to get a detailed view, and finally I enter a page. This is managed trough 3 activities. List, Details and Page. However, as of now the application can only read comics of one source (a specialiced xml-feed comming from my server), and I was hoping to be able to expand this a litle (also, the page-activity and some other stuff needs to be cleaned up in, so I'm thinking about remaking from scratch, and just take the first go as a learning-round). And I came up with an idea which I think sounds great, but I don't know if it's possible, but this is what I'm thinking about: The user enters the application and get an (first time empty) list of comics. The user hits a button to find comics, this launces an intent that says something like "find comic" or something like that. This should cause the system to display all matching activities. This would make it possible to provide different comic-providers trough different applications. Another activity kicks in and might displays some options to the user (for instance a file-browser), or might not (in the example of an xml-feed, which should just load). The list is returned to the first activity and displayed to the user. The second (find) activity is closed. The user picks a comic from the list. This should open some details-activity. The details-activity should receive a key which corresponds to the comic selected. This should be unique amongst the comic-providers. The details-view should get it's data trough some cind of content-provider, or an activity (whichever is most suited, if one of them is). The user can select a page. This should be the same routine as step 5. My question is, is this possible in the android system, and if it is, is it a bad idea? And also, is there any better way to achieve more or less the same thing?

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  • asp.net Multiple Page_Load events for a user control when using URL Routing

    - by Paul Hutson
    Hello, I've recently set up an ASP.net site (not using MVC.net) to use URL Routing (more on the code below) - when using user controls on the site (i.e I've created a "menu" user control to hold menu information) the page_load event for that control will fire twice when URLs have more than one variable passed over. i.e. pageName/VAR1 : will only fire the page_load event once. while pageName/VAR1/VAR2 : will fire the page_load event twice. *Multiple extra VARs added on the end will still only fire the page_load event twice*. Below are the code snippits from the files, the first is the MapPageRoute, located in the Global.asax : // Register a route for the Example page, with the NodeID and also the Test123 variables allowed. // This demonstrates how to have several items linked with the page routes. routes.MapPageRoute( "Multiple Data Example", // Route name "Example/{NodeID}/{test123}/{variable}", // Route URL - note the NodeID bit "~/Example.aspx", // Web page to handle route true, // Check for physical access new System.Web.Routing.RouteValueDictionary { { "NodeID", "1" }, // Default Node ID { "test123", "1" }, // Default addtional variable value { "variable", "hello"} // Default test variable value } ); Next is the way I've directed to the page in the menu item, this is a list item within a UL tag : <li class="TopMenu_ListItem"><a href="<%= Page.GetRouteUrl("Multiple Data Example", new System.Web.Routing.RouteValueDictionary { { "NodeID", "4855" }, { "test123", "2" } }) %>">Example 2</a></li> And finally the control that gets hit multiple times on a page load : // For use when the page loads. protected void Page_Load(object sender, EventArgs e) { // Handle the routing variables. // this handles the route data value for NodeID - if the page was reached using URL Routing. if (Page.RouteData.Values["NodeID"] != null) { nodeID = Page.RouteData.Values["NodeID"] as string; }; // this handles the route data value for Test123 - if the page was reached using URL Routing. if (Page.RouteData.Values["Test123"] != null) { ExampleOutput2.Text = "I am the output of the third variable : " + Page.RouteData.Values["Test123"] as string; }; // this handles the route data value for variable - if the page was reached using URL Routing. if (Page.RouteData.Values["variable"] != null) { ExampleOutput3.Text = "I say " + Page.RouteData.Values["variable"] as string; }; } Note, that when I'm just hitting the page and it uses the default values for items, the reloads do not happen. Any help or guidance that anyone can offer would be very much appreciated! EDIT : The User Control is only added to the page once. I've tested the load sequence by putting a breakpoint in the page_load event - it only hits twice when the extra routes are added. Thanks in Advance, Paul Hutson

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  • Foreign key pointing to different tables

    - by Álvaro G. Vicario
    I'm implementing a table per subclass design I discussed in a previous question. It's a product database where products can have very different attributes depending on their type, but attributes are fixed for each type and types are not manageable at all. I have a master table that holds common attributes: product_type ============ product_type_id INT product_type_name VARCHAR E.g.: 1 'Magazine' 2 'Web site' product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id valid_since DATETIME valid_to DATETIME E.g. 1 'Foo Magazine' 1 '1998-12-01' NULL 2 'Bar Weekly Review' 1 '2005-01-01' NULL 3 'E-commerce App' 2 '2009-10-15' NULL 4 'CMS' 2 '2010-02-01' NULL ... and one subtable for each product type: item_magazine ============= item_magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id issue_number INT pages INT copies INT close_date DATETIME release_date DATETIME E.g. 1 'Foo Magazine Regular Issue' 1 89 52 150000 '2010-06-25' '2010-06-31' 2 'Foo Magazine Summer Special' 1 90 60 175000 '2010-07-25' '2010-07-31' 3 'Bar Weekly Review Regular Issue' 2 12 16 20000 '2010-06-01' '2010-06-02' item_web_site ============= item_web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id bandwidth INT hits INT date_from DATETIME date_to DATETIME E.g. 1 'The Carpet Store' 3 10 90000 '2010-06-01' NULL 2 'Penauts R Us' 3 20 180000 '2010-08-01' NULL 3 'Springfield Cattle Fair' 4 15 150000 '2010-05-01' '2010-10-31' Now I want to add some fees that relate to one specific item. Since there are very little subtypes, it's feasible to do this: fee === fee_id INT fee_description VARCHAR item_magazine_id INT -> Foreign key to item_magazine.item_magazine_id item_web_site_id INT -> Foreign key to item_web_site.item_web_site_id net_price DECIMAL E.g.: 1 'Front cover' 2 NULL 1999.99 2 'Half page' 2 NULL 500.00 3 'Square banner' NULL 3 790.50 4 'Animation' NULL 3 2000.00 I have tight foreign keys to handle cascaded editions and I presume I can add a constraint so only one of the IDs is NOT NULL. However, my intuition suggests that it would be cleaner to get rid of the item_WHATEVER_id columns and keep a separate table: fee_to_item =========== fee_id INT -> Foreign key to fee.fee_id product_id INT -> Foreign key to product.product_id item_id INT -> ??? But I can't figure out how to create foreign keys on item_id since the source table varies depending on product_id. Should I stick to my original idea?

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  • Instance caching in Objective C

    - by zoul
    Hello! I want to cache the instances of a certain class. The class keeps a dictionary of all its instances and when somebody requests a new instance, the class tries to satisfy the request from the cache first. There is a small problem with memory management though: The dictionary cache retains the inserted objects, so that they never get deallocated. I do want them to get deallocated, so that I had to overload the release method and when the retain count drops to one, I can remove the instance from cache and let it get deallocated. This works, but I am not comfortable mucking around the release method and find the solution overly complicated. I thought I could use some hashing class that does not retain the objects it stores. Is there such? The idea is that when the last user of a certain instance releases it, the instance would automatically disappear from the cache. NSHashTable seems to be what I am looking for, but the documentation talks about “supporting weak relationships in a garbage-collected environment.” Does it also work without garbage collection? Clarification: I cannot afford to keep the instances in memory unless somebody really needs them, that is why I want to purge the instance from the cache when the last “real” user releases it. Better solution: This was on the iPhone, I wanted to cache some textures and on the other hand I wanted to free them from memory as soon as the last real holder released them. The easier way to code this is through another class (let’s call it TextureManager). This class manages the texture instances and caches them, so that subsequent calls for texture with the same name are served from the cache. There is no need to purge the cache immediately as the last user releases the texture. We can simply keep the texture cached in memory and when the device gets short on memory, we receive the low memory warning and can purge the cache. This is a better solution, because the caching stuff does not pollute the Texture class, we do not have to mess with release and there is even a higher chance for cache hits. The TextureManager can be abstracted into a ResourceManager, so that it can cache other data, not only textures.

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