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  • Providing custom database functionality to custom asp.net membership provider

    - by IrfanRaza
    Hello friends, I am creating custom membership provider for my asp.net application. I have also created a separate class "DBConnect" that provides database functionality such as Executing SQL statement, Executing SPs, Executing SPs or Query and returning SqlDataReader and so on... I have created instance of DBConnect class within Session_Start of Global.asax and stored to a session. Later using a static class I am providing the database functionality throughout the application using the same single session. In short I am providing a single point for all database operations from any asp.net page. I know that i can write my own code to connect/disconnect database and execute SPs within from the methods i need to override. Please look at the code below - public class SGI_MembershipProvider : MembershipProvider { ...... public override bool ChangePassword(string username, string oldPassword, string newPassword) { if (!ValidateUser(username, oldPassword)) return false; ValidatePasswordEventArgs args = new ValidatePasswordEventArgs(username, newPassword, true); OnValidatingPassword(args); if (args.Cancel) { if (args.FailureInformation != null) { throw args.FailureInformation; } else { throw new Exception("Change password canceled due to new password validation failure."); } } ..... //Database connectivity and code execution to change password. } .... } MY PROBLEM - Now what i need is to execute the database part within all these overriden methods from the same database point as described on the top. That is i have to pass the instance of DBConnect existing in the session to this class, so that i can access the methods. Could anyone provide solution on this. There might be some better techniques i am not aware of that. The approach i am using might be wrong. Your suggessions are always welcome. Thanks for sharing your valuable time.

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  • PHP curl timing mismatch

    - by JonoB
    I am running a php script that: queries a local database to retrieve an amount executes a curl statement to update an external database with the above amount + x queries the local database again to insert a new row reflecting that the curl statement has been executed. One of the problems that I am having is that the curl statement takes 2-4 seconds to execute, so I have two different users from the same company running the same script at the same time, the execution time of the curl command can cause a mismatch in what should be updated in the external database. This is the because the curl statement has not yet returned from the first user...so the second user is working off incorrect figures. I am not sure of the best options here, but basically I need to prevent two or more curl statements being run at the same time. I thought of storing a value in the database that indicates that the curl statement is being executed at that time, and prevent any other curl statements being run until its completed. Once the first curl statement has been executed, then the database flag is updated and the next one can run. If this field is 'locked', then I could loop through the code and sleep for (5) seconds, and then check again if the flag has been reset. If after (3) loops, then reset the flag automatically (i've never seen the curl take longer than 5 seconds) and continue processing. Are there any other (more elegant) ways of approaching this?

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  • Using Dispose on a Singleton to Cleanup Resources

    - by ImperialLion
    The question I have might be more to do with semantics than with the actual use of IDisposable. I am working on implementing a singleton class that is in charge of managing a database instance that is created during the execution of the application. When the application closes this database should be deleted. Right now I have this delete being handled by a Cleanup() method of the singleton that the application calls when it is closing. As I was writing the documentation for Cleanup() it struck me that I was describing what a Dispose() method should be used for i.e. cleaning up resources. I had originally not implemented IDisposable because it seemed out of place in my singleton, because I didn't want anything to dispose the singleton itself. There isn't currently, but in the future might be a reason that this Cleanup() might be called but the singleton should will need to still exist. I think I can include GC.SuppressFinalize(this); in the Dispose method to make this feasible. My question therefore is multi-parted: 1) Is implementing IDisposable on a singleton fundamentally a bad idea? 2) Am I just mixing semantics here by having a Cleanup() instead of a Dispose() and since I'm disposing resources I really should use a dispose? 3) Will implementing 'Dispose()' with GC.SuppressFinalize(this); make it so my singleton is not actually destroyed in the case I want it to live after a call to clean-up the database.

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  • Do database engines other than SQL Server behave this way?

    - by Yishai
    I have a stored procedure that goes something like this (pseudo code) storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin select * from SOME_VIEW order by somecolumn end else if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent end All ran well for a long time. Suddenly, the query started running forever if param4 was 'Y'. Changing the code to this: storedprocedure param1, param2, param3, param4 begin if (param4 = 'Y') begin set param2 = null set param3 = null end if (param1 is null) begin select * from SOME_VIEW where (param2 is null or param2 = SOME_VIEW.Somecolumn2) and (param3 is null or param3 = SOME_VIEW.SomeColumn3) order by somecolumn end else select somethingcompletelydifferent And it runs again within expected parameters (15 seconds or so for 40,000+ records). This is with SQL Server 2005. The gist of my question is this particular "feature" specific to SQL Server, or is this a common feature among RDBMS' in general that: Queries that ran fine for two years just stop working as the data grows. The "new" execution plan destroys the ability of the database server to execute the query even though a logically equivalent alternative runs just fine? This may seem like a rant against SQL Server, and I suppose to some degree it is, but I really do want to know if others experience this kind of reality with Oracle, DB2 or any other RDBMS. Although I have some experience with others, I have only seen this kind of volume and complexity on SQL Server, so I'm curious if others with large complex databases have similar experience in other products.

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  • Looking for best practise for writing a serial device communication app in C#

    - by cdotlister
    I am pretty new to serial comms, but would like advise on how to best achieve a robust application which speak to and listens to a serial device. I have managed to make use of System.IO.serialport, and successfully connected to, sent data to and recieved from my device. The way things work is this. My application connects to the Com Port and opens the port.... I then connect my device to the com port, and it detects a connectio to the PC, so sends a bit of text. it's really just copyright info, as well as the version of the firmware. I don't do anything with that, except display it in my 'activity' window. The device then waits. I can then query information, but sending a command such as 'QUERY PARAMETER1'. It then replies with something like: 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n' I then process that. I can then update it by sending 'SET PARAMETER1 12345', and it will reply with 'QUERY PARAMETER1\r\n\r\n12345\r\n\r\n'. All pretty basic. So, what I have done is created a Communication Class. this call is called in it's own thread, and sends data back to the main form... and also allows me to send messages to it. Sending data is easy. Recieving is a bit more tricky. I have employed the use of the datarecieved event, and when ever data comes in, I echo that to my screen. My problem is this: When I send a command, I feel I am being very dodgy in my handling. What I am doing is, lets say I am sending 'QUERY PARAMETER1'. I send the command to the device, I then put 'PARAMETER1' into a global variable, and I do a Thread.Sleep(100). On the data recieved, I then have a bit of logic that checks the incoming data, and sees if the string CONTAINS the value in the gloabl variable. As the reply may be 'QUERY PARAMETER1\r\n\r\n76767\r\n\r\n', it sees that it contains my parameter, parses the string, and returns the value I am looking for, but placing it into another global variable. My sending method was sleeping for 100ms. It then wakes, and checks the returned global variable. If it has data... then I'm happy, and I process the data. Problem is... if the sleep is too short.. it will fail. And I feel it's flakey.. putting stuff into variables.. then waiting... The other option is to use ReadLine instead, but that's very blocking. So I remove the datarecieved method, and instead... just send the data... then call ReadLine(). That may give me better results. There's no time, except when we connect initially, that data comes from the device, without me requesting it. So, maybe readline will be simpler and safer? Is this known as 'Blocking' reads? Also, can I set a timeout? Hopefully someone can guide me.

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  • NullPointerException in generated JSP code calling setJspId()

    - by Dobbo
    I am trying to deploy the Duke's Bank example form the J2EE 5 tutorial on JBoss 7.1.1. I have only used (unaltered) the source, and the standard XML configuration files for deployment, part of the exercise here is to see how I might structure a JSP based project of my own. The exception I get is as follows: ERROR [[jsp]] Servlet.service() for servlet jsp threw exception: java.lang.NullPointerException at javax.faces.webapp.UIComponentClassicTagBase.setJspId(UIComponentClassicTagBase.java:1858) [jboss-jsf-api_2.1_spec-2.0.1.Final.jar:2.0.1.Final] at org.apache.jsp.main_jsp._jspx_meth_f_005fview_005f0(main_jsp.java:99) at org.apache.jsp.main_jsp._jspService(main_jsp.java:76) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) [jbossweb-7.0.13.Final.jar:] at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final] at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369) [jbossweb-7.0.13.Final.jar:] at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:326) [jbossweb-7.0.13.Final.jar:] at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:253) [jbossweb-7.0.13.Final.jar:] at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [jboss-servlet-api_3.0_spec-1.0.0.Final.jar:1.0.0.Final] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:329) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:248) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:397) [jbossweb-7.0.13.Final.jar:] at org.jboss.as.jpa.interceptor.WebNonTxEmCloserValve.invoke(WebNonTxEmCloserValve.java:50) [jboss-as-jpa-7.1.1.Final.jar:7.1.1.Final] at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.1.Final.jar:7.1.1.Final] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.13.Final.jar:] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.13.Final.jar:] at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.13.Final.jar:] at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:671) [jbossweb-7.0.13.Final.jar:] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:930) [jbossweb-7.0.13.Final.jar:] at java.lang.Thread.run(Thread.java:636) [rt.jar:1.6.0_18] I have not given any JBoss configuration files, the WAR's WEB-INF part looks like this: $ jar tvf build/lib/dukebank-web.war 0 Sat Dec 15 22:00:12 GMT 2012 META-INF/ 123 Sat Dec 15 22:00:10 GMT 2012 META-INF/MANIFEST.MF 0 Sat Dec 15 22:00:12 GMT 2012 WEB-INF/ 2514 Fri Dec 14 14:29:20 GMT 2012 WEB-INF/web.xml 1348 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/dukesBank.tld 7245 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/faces-config.xml 2153 Sat Dec 15 08:19:46 GMT 2012 WEB-INF/tutorial-template.tld 0 Sat Dec 15 22:00:12 GMT 2012 WEB-INF/classes/... The JSP file (main.jsp) that causes this problem is: <f:view> <h:form> <jsp:include page="/template/template.jsp"/> <center> <h3><h:outputText value="#{bundle.Welcome}"/></h3> </center> </h:form> </f:view> The template file it includes: <%@ taglib uri="/WEB-INF/tutorial-template.tld" prefix="tt" %> <%@ page errorPage="/template/errorpage.jsp" %> <%@ include file="/template/screendefinitions.jspf" %> <html> <head> <title> <tt:insert definition="bank" parameter="title"/> </title> <link rel="stylesheet" type="text/css" href="stylesheet.css"> </head> <body bgcolor="#ffffff"> <tt:insert definition="bank" parameter="banner"/> <tt:insert definition="bank" parameter="links"/> </body> </html> I will refrain from coping any more files because, as I said at the start I haven't altered any of the files I have used. Many thanks for your help, Steve

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  • Memory leaks while using array of double

    - by Gacek
    I have a part of code that operates on large arrays of double (containing about 6000 elements at least) and executes several hundred times (usually 800) . When I use standard loop, like that: double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... } The memory usage rises for about 40MB (from 40MB at the beggining of the loop, to the 80MB at the end). When I force to use the garbage collector to execute at every iteration, the memory usage stays at the level of 40MB (the rise is unsignificant). double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... GC.Collect() } But the execution time is 3 times longer! (it is crucial) How can I force the C# to use the same area of memory instead of allocating new ones? Note: I have the access to the code of someObject class, so if it would be needed, I can change it.

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  • multiple clients - one server connection with sockets tcp/ip c# .net

    - by jagse
    Hello guys, I need to develop a client server system where I can have multiple clients communicating with one server at the same time. I want to communicate xml serialized objects and also need to send and receive other commands to invoke methods. Now, I am just starting with socket programming in C# and .Net and found that the asynchronous I/O is the way to go so that the methods dont block the execution of code. Also there are many examples of how to make a simple client server system. So I have a basic understanding of how that works. Anyway, what still is not clear to me is how I can set up a server which can manage connections to multiple clients? Can I just create a new socket per connection and then store those in some kind of list? Do I need some kind of multiplexing to achieve this? Do I have to listen at multiple ports? What`s the best way here? And the other thing is if I need to develop my own protocol to differentiate between what I am actually sending over the network -- xml serialized object or a command which might be just a string encoded in ascII or something. Or would I develop my own protocol just to send these commands? Any kind of help is apreciated! If someone knows a good book which covers this sort of stuff, let me know. Cheers I forgot to mention that some of my clients which are supposed to communicate with my server will be pda and I therefore use the compact framework... So this might bring in some restrictions...

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  • Finding cause of memory leaks in large PHP stacks

    - by Mike B
    I have CLI script that runs over several thousand iterations between runs and it appears to have a memory leak. I'm using a tweaked version of Zend Framework with Smarty for view templating and each iteration uses several MB worth of code. The first run immediately uses nearly 8MB of memory (which is fine) but every following run adds about 80kb. My main loop looks like this (very simplified) $users = UsersModel::getUsers(); foreach($users as $user) { $obj = new doSomethingAwesome(); $obj->run($user); $obj = null; unset($obj); } The point is that everything in scope should be unset and the memory freed. My understanding is that PHP runs through its garbage collection process at it's own desire but it does so at the end of functions/methods/scripts. So something must be leaking memory inside doSomethingAwesome() but as I said it is a huge stack of code. Ideally, I would love to find some sort of tool that displayed all my variables no matter the scope at some point during execution. Some sort of symbol-table viewer for php. Does anything like that or any other tools that could help nail down memory leaks in php exist?

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  • ASP.NET Web Application: use 1 or multiple virtual directories

    - by tster
    I am working on a (largish) internal web application which has multiple modules (security, execution, features, reports, etc.). All the pages in the app share navigation, CSS, JS, controls, etc. I want to make a single "Web Application" project, which includes all the pages for the app, then references various projects which will have the database and business logic in them. However, some of the people on the project want to have separate projects for the pages of each module. To make this more clear, this is what I'm advocating to be the projects. /WebInterface* /SecurityLib /ExecutionLib etc... And here is what they are advocating: /SecurityInterface* /SecutiryLib /ExecutionInterface* /ExecutionLib etc... *project will be published to a virtual directory of IIS Basically What I'm looking for is the advantages of both approaches. Here is what I can think of so far: Single Virtual Directory Pros Modules can share a single MasterPage Modules can share UserControls (this will be common) Links to other modules are within the same Virtual directory, and thus don't need to be fully qualified. Less chance of having incompatible module versions together. Multiple Virtual Directories Pros Can publish a new version of a single module without disrupting other modules Module is more compartmentalized. Less likely that changes will break other modules. I don't buy those arguments though. First, using load balanced servers (which we will have) we should be able to publish new versions of the project with zero downtime assuming there are no breaking database changes. Second, If something "breaks" another module, then there is either an improper dependency or the break will show up eventually in the other module, when the developers copy over the latest version of the UserControl, MasterPage or dll. As a point of reference, there are about 10 developers on the project for about 50% of their time. The initial development will be about 9 months.

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  • Preprocessor "macro function" vs. function pointer - best practice?

    - by Dustin
    I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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  • SQL server 2005 agent not working

    - by flaggers
    Sql server 2005 service pack 2 version: 9.00.3042.00 All maintenance plans fail with the same error. The details of the error are:- Execute Maintenance Plan Execute maintenance plan. test7 (Error) Messages Execution failed. See the maintenance plan and SQL Server Agent job history logs for details. The advanced information section shows the following; Job 'test7.Subplan_1' failed. (SqlManagerUI) Program Location: at Microsoft.SqlServer.Management.SqlManagerUI.MaintenancePlanMenu_Run.PerformActions() At this point the following appear in the windows event log: Event Type: Error Event Source: SQLISPackage Event Category: None Event ID: 12291 Date: 28/05/2009 Time: 16:09:08 User: 'DOMAINNAME\username' Computer: SQLSERVER4 Description: Package "test7" failed. and also this: Event Type: Warning Event Source: SQLSERVERAGENT Event Category: Job Engine Event ID: 208 Date: 28/05/2009 Time: 16:09:10 User: N/A Computer: SQLSERVER4 Description: SQL Server Scheduled Job 'test7.Subplan_1' (0x96AE7493BFF39F4FBBAE034AB6DA1C1F) - Status: Failed - Invoked on: 2009-05-28 16:09:02 - Message: The job failed. The Job was invoked by User 'DOMAINNAME\username'. The last step to run was step 1 (Subplan_1). There are no entries in the SQl Agent log at all.

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  • How to store an interger value of 4 bytes in a memory of chunk which is malloced as type char

    - by Adi
    Dear all, Hello Guys!! This is my first post in the forum . I am really looking forward to having good fun in this site. My question is : int mem_size = 10; char *start_ptr; if((start_ptr= malloc(mem_size*1024*1024*sizeof(char)))==NULL) {return -1;} I have allocated a chunk of memory of type char and size is say 10 MB (i.e mem_size = 10 ); Now I want to store the size information in the header of the memory chunk, To make myself more clear Lets Say : start_ptr = 0xaf868004 (This is the value I got from my execution, it changes every time) Now I want to put the size information in the start of this pointer.. i.e *start_ptr = mem_size*1024*1024; But I am not able to put this information in the start_ptr. I think the reason is because my ptr is of type char which only takes one byte but I am trying to store int which takes 4 bytes, is the problem . I am not sure how to fix this problem.. I would greatly appreciate your suggestions. Cheers!! Aditya

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  • Mimic Coldfusion's debug output in PHP?

    - by TekiusFanatikus
    I'm trying to mimic Coldfusion's debug output in PHP. Here's an example of what it looks like (ie. Execution Time section): I've turned to XDebug. Ideally, the exception stack error output would be what I'd be looking for. However, it only shows up when an exception occurs. I also tried something like (in our CMS-ish app) this (original question here): $content.= "<?php xdebug_start_trace('e:/xdebug/trace');?>"; $content.= "<?php require('".$page['file_'.LG]."'); ?>"; $content.= "<?php xdebug_stop_trace();?>"; ... $content.= "<?php echo readfile('e:/xdebug/trace.xt');?>"; However, I get an insane, browser crashing HTML table dropped at the bottom of page. Not very efficient. My php.ini config: xdebug.trace_format = 2 xdebug.collect_vars = 1 xdebug.collect_params = 4 xdebug.dump_globals = 1 xdebug.dump.SERVER = 'REQUEST_URI' xdebug.show_local_vars = 1 xdebug.show_mem_delta = 1 I'm just wondering if someone has already done something similar?

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  • use Ghostscript to convert pcl to postscript

    - by Bryon
    So I want to use Ghostscript to convert files that are created in pcl format to postscript. That's the gist of my problem. I am simply trying to run it on the command line, but in the final stage it will have to be run on a lp command like lp -d < gs something something GPL Ghostscript 9.00 (2010-09-14) I will be running this on a solaris 10 server but I believe any unix system should work similar. bash-3.00# /usr/local/bin/gs -sDEVICE=pswrite -dLanguageLevel=1 -dNOPAUSE -dBATCH -dSAFER -sOutputFile=output.ps cms-form.pcl GPL Ghostscript 9.00 (2010-09-14) Copyright (C) 2010 Artifex Software, Inc. All rights reserved. This software comes with NO WARRANTY: see the file PUBLIC for details. Error: /undefined in &k2G-210z100u0l6d0e63fa0V Operand stack: Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1910 1 3 %oparray_pop 1909 1 3 %oparray_pop 1893 1 3 %oparray_pop 1787 1 3 %oparray_pop --nostringval-- %errorexec_pop .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- Dictionary stack: --dict:1154/1684(ro)(G)-- --dict:0/20(G)-- --dict:77/200(L)-- Current allocation mode is local Current file position is 30 GPL Ghostscript 9.00: Unrecoverable error, exit code 1

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  • Servlet Security question about j_security_check, j_username and j_password

    - by Nitesh Panchal
    Hello, I used jdbcRealm in my web application and it's working fine. I defined all constraints also in my web.xml. Like all pages of url pattern /Admin/* should be accessed by only admin. I have a login form with uses standard j_security_check, j_username and j_password. Now, when i type Admin/home.jsf it rightly redirects me login.jsf and there when i type the password i am redirected to home.jsf. This works alright but problem comes i directly go to login.jsf and then type password and username. This time it again redirects me to login.jsf. Is there any way through which i can specify which page to go when successful login is there? I need to specify different different pages for different roles. For Admin, it is /Admin/home.jsf for general users it is /General/home.jsf because login form is shared between different type of users. Where do i specify all these things? Secondly, i want to have a remember me checkbox at the end of login form. How do i do this? By default, it is submitted to j_security_check servlet and i have no control over its execution. Please help. This doesn't seem so hard but looks like i am missing something.

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  • ADO.NET DataTable/DataRow Thread Safety

    - by Allen E. Scharfenberg
    Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

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  • Should I pass a SqlDataReader by reference or not when passing it out to multiple threads.

    - by deroby
    Hi all, being new to c# I've run into this 'conundrum' when passing around a SqlDataReader between different threads. Without going into too much detail, the idea is to have a main thread fetching data from the database (a large recordset) and then have a helper-task run through this record by record and doing some stuff based upon the contents of this. There is no feedback to the recordset, it simply wades through until no records are left. This works fine, but given the nature of the job at hand it should be possible to have this job spread over different threads (CPUs) to maximize throughput (the order of execution is of no significance). The question then becomes, when I pass this recordset in a SqlDataReader, do I have to use ref or not ? It kind of boils down to the question : if I pass the object around without specifying ref, won't it create new copies in memory and have records processed n times ? Or, don't I risk having the record-position being moved forward while not all fields have been fully read yet ? The latter seems more like a 'data racing' issue and probably is covered by the lock()ing mechanism (or not?). My initial take on the problem was that it doesn't really hurt passing the variable using ref, yet as a colleague put it : "you only need ref when you're doing something wrong" =) Additionally using ref restricts me from applying a Using() construction too which isn't very nice either. I thus create a "basic" project that tackles the same approach but without the ref notation. Tests so far show that it works flawlessly on a Core2Duo (2cpu) using any number of threads, yet I'm still a bit wary... What do you experts think about this ? Use ref or not ? You can find the test-project here as it seems I can't upload it to this question directly ?!? ps: it's just a test-project and I'm new to c#, so please be gentle on me when breaking down the code =P

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  • python socket related question.

    - by paul
    Hello,All im totally new to socket programming in python. i was read some tutorial and manual, but i didn't found what i want to make python related socket script in manual or tutorial. i want to make socket script which can send some info to server and also receive some info from server. For example, i want to send my login information to server, and want to receive result reply from server. but i have no idea..how to send my login information(id and password) to server. i was captured with wireshark, some process to send login info to server. and i was found port number is 5300 and server ip is 58.225.56.152 and i was send id is 'aaaaaaa' and password 'bbbbbbb' and i was received 'USER NOT FOUND' result from server. how can i make this kind of process with python socket ? if anyone help me some reference or some example or anything help much appreciate! 0000 00 50 56 f2 c8 cc 00 0c 29 a8 f8 c0 08 00 45 00 .PV.....).....E. 0010 00 e2 2a 19 40 00 80 06 d0 55 c0 a8 cb 85 3a e1 ..*[email protected]....:. 0020 38 98 05 f3 15 9a b9 86 62 7b 0d ab 0f ba 50 18 8.......b{....P. 0030 fa f0 26 14 00 00 50 54 3f 09 a2 91 7f 13 00 00 ..&...PT?....... 0040 00 1f 14 00 02 00 00 00 00 00 00 00 07 00 00 00 ................ 0050 61 61 61 61 61 61 61 50 54 3f 09 a2 91 7f 8b 00 aaaaaaaPT?...... 0060 00 00 1f 15 00 08 00 00 00 07 00 00 00 61 61 61 .............aaa 0070 61 61 61 61 07 00 00 00 62 62 62 62 62 62 62 01 aaaa....bbbbbbb. 0080 00 00 00 31 02 00 00 00 4b 52 0f 00 00 00 31 39 ...1....KR....19 0090 32 2e 31 36 38 2e 32 30 33 2e 31 33 33 30 00 00 2.168.203.1330.. 00a0 00 4d 69 63 72 6f 73 6f 66 74 20 57 69 6e 64 6f .Microsoft Windo 00b0 77 73 20 58 50 20 50 72 6f 66 65 73 73 69 6f 6e ws XP Profession 00c0 61 6c 20 53 65 72 76 69 63 65 20 50 61 63 6b 20 al Service Pack 00d0 32 14 00 00 00 31 30 30 31 33 30 30 35 33 31 35 2....10013005315 00e0 37 38 33 37 32 30 31 32 33 03 00 00 00 34 37 30 783720123....470 0000 00 0c 29 a8 f8 c0 00 50 56 f2 c8 cc 08 00 45 00 ..)....PV.....E. 0010 00 28 ae 37 00 00 80 06 8c f1 3a e1 38 98 c0 a8 .(.7......:.8... 0020 cb 85 15 9a 05 f3 0d ab 0f ba b9 86 63 35 50 10 ............c5P. 0030 fa f0 5f 8e 00 00 00 00 00 00 00 00 .._......... 0000 00 0c 29 a8 f8 c0 00 50 56 f2 c8 cc 08 00 45 00 ..)....PV.....E. 0010 00 4c ae 38 00 00 80 06 8c cc 3a e1 38 98 c0 a8 .L.8......:.8... 0020 cb 85 15 9a 05 f3 0d ab 0f ba b9 86 63 35 50 18 ............c5P. 0030 fa f0 3e 75 00 00 50 54 3f 09 a2 91 7f 16 00 00 ..>u..PT?....... 0040 00 1f 18 00 01 00 00 00 0e 00 00 00 55 73 65 72 ............User 0050 20 4e 6f 74 20 46 6f 75 6e 64 Not Found

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  • form:select items problem in spring mvc portlet

    - by dhaval
    I have a set of drop-down control which I want to render with my custom tag library. The following is the code of the tag lib: <spring:bind path="${path}"> <c:choose> <c:when test="${readOnly}"> <span class="readOnly">${status.value}</span> </c:when> <c:otherwise> <form:select path="${path }" itemLabel="${label }" itemValue="${value }" items="${itemList}"> </form:select> </c:otherwise> </c:choose> And this is the code I have written in the JSP file: <tag:conditionalListControl path="model.selectedCountry" readOnly="false" label="name" value="id" listItems="model.countryList" className="simple" /> Upon execution the paring returns the following error: [jsp:165] javax.servlet.jsp.JspException: Type [java.lang.String] is not valid for option items But if i change the items="${itemList}" to items="${model.countryList}" which is the list I want to display, it works fine without any problem and also bind to required variables on form submit. But i don't want to hard code any variables in the tag lib. Any suggestions???

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  • How do I create an exception-wrapping fubumvc behaviour?

    - by Jon M
    How can I create a fubumvc behaviour that wraps actions with a particular return type, and if an exception occurs while executing the action, then the behaviour logs the exception and populates some fields on the return object? I have tried the following: public class JsonExceptionHandlingBehaviour : IActionBehavior { private static readonly Logger logger = LogManager.GetCurrentClassLogger(); private readonly IActionBehavior _innerBehavior; private readonly IFubuRequest _request; public JsonExceptionHandlingBehaviour(IActionBehavior innerBehavior, IFubuRequest request) { _innerBehavior = innerBehavior; _request = request; } public void Invoke() { try { _innerBehavior.Invoke(); var response = _request.Get<AjaxResponse>(); response.Success = true; } catch(Exception ex) { logger.ErrorException("Error processing JSON request", ex); var response = _request.Get<AjaxResponse>(); response.Success = false; response.Exception = ex.ToString(); } } public void InvokePartial() { _innerBehavior.InvokePartial(); } } But, although I get the AjaxResponse object from the request, any changes I make don't get sent back to the client. Also, any exceptions thrown by the action don't make it as far as this, the request is terminated before execution gets to the catch block. What am I doing wrong? For completeness, the behaviour is wired up with the following in my WebRegistry: Policies .EnrichCallsWith<JsonExceptionHandlingBehaviour>(action => typeof(AjaxResponse).IsAssignableFrom(action.Method.ReturnType)); And AjaxResponse looks like: public class AjaxResponse { public bool Success { get; set; } public object Data { get; set; } public string Exception { get; set; } }

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  • Efficient way to maintain a sorted list of access counts in Python

    - by David
    Let's say I have a list of objects. (All together now: "I have a list of objects.") In the web application I'm writing, each time a request comes in, I pick out up to one of these objects according to unspecified criteria and use it to handle the request. Basically like this: def handle_request(req): for h in handlers: if h.handles(req): return h return None Assuming the order of the objects in the list is unimportant, I can cut down on unnecessary iterations by keeping the list sorted such that the most frequently used (or perhaps most recently used) objects are at the front. I know this isn't something to be concerned about - it'll make only a miniscule, undetectable difference in the app's execution time - but debugging the rest of the code is driving me crazy and I need a distraction :) so I'm asking out of curiosity: what is the most efficient way to maintain the list in sorted order, descending, by the number of times each handler is chosen? The obvious solution is to make handlers a list of (count, handler) pairs, and each time a handler is chosen, increment the count and resort the list. def handle_request(req): for h in handlers[:]: if h[1].handles(req): h[0] += 1 handlers.sort(reverse=True) return h[1] return None But since there's only ever going to be at most one element out of order, and I know which one it is, it seems like some sort of optimization should be possible. Is there something in the standard library, perhaps, that is especially well-suited to this task? Or some other data structure? (Even if it's not implemented in Python) Or should/could I be doing something completely different?

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  • Function Returning Negative Value

    - by Geowil
    I still have not run it through enough tests however for some reason, using certain non-negative values, this function will sometimes pass back a negative value. I have done a lot of manual testing in calculator with different values but I have yet to have it display this same behavior. I was wondering if someone would take a look at see if I am missing something. float calcPop(int popRand1, int popRand2, int popRand3, float pERand, float pSRand) { return ((((((23000 * popRand1) * popRand2) * pERand) * pSRand) * popRand3) / 8); } The variables are all contain randomly generated values: popRand1: between 1 and 30 popRand2: between 10 and 30 popRand3: between 50 and 100 pSRand: between 1 and 1000 pERand: between 1.0f and 5500.0f which is then multiplied by 0.001f before being passed to the function above Edit: Alright so after following the execution a bit more closely it is not the fault of this function directly. It produces an infinitely positive float which then flips negative when I use this code later on: pPMax = (int)pPStore; pPStore is a float that holds popCalc's return. So the question now is, how do I stop the formula from doing this? Testing even with very high values in Calculator has never displayed this behavior. Is there something in how the compiler processes the order of operations that is causing this or are my values simply just going too high? If the later I could just increase the division to 16 I think.

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  • ASP.NET Web Optimization - confusion about loading order

    - by Ciel
    Using the ASP.NET Web Optimization Framework, I am attempting to load some javascript files up. It works fine, except I am running into a peculiar situation with either the loading order, the loading speed, or its execution. I cannot figure out which. Basically, I am using ace code editor for javascript, and I also want to include its autocompletion package. This requires two files. /ace.js /ext-language_tools.js This isn't an issue, if I load both of these files the normal way (with <script> tags) it works fine. But when I try to use the web optimization bundles, it seems as if something goes wrong. Trying this out... bundles.Add(new ScriptBundle("~/bundles/js") { .Include("~/js/ace.js") .Include("~/js/ext-language_tools.js") }); and then in the view .. @Scripts.Render("~/bundles/js") I get the error ace is not defined This means that the ace.js file hasn't run, or hasn't loaded. Because if I break it apart into two bundles, it starts working. bundles.Add(new ScriptBundle("~/bundles/js") { .Include("~/js/ace.js") }); bundles.Add(new ScriptBundle("~/bundles/js/language_tools") { .Include("~/js/ext-language_tools.js") }); Can anyone explain why this would behave in this fashion?

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  • CreateThread() fails on 64 bit Windows, works on 32 bit Windows. Why?

    - by Stephen Kellett
    Operating System: Windows XP 64 bit, SP2. I have an unusual problem. I am porting some code from 32 bit to 64 bit. The 32 bit code works just fine. But when I call CreateThread() for the 64 bit version the call fails. I have three places where this fails. 2 call CreateThread(). 1 calls beginthreadex() which calls CreateThread(). All three calls fail with error code 0x3E6, "Invalid access to memory location". The problem is all the input parameters are correct. HANDLE h; DWORD threadID; h = CreateThread(0, // default security 0, // default stack size myThreadFunc, // valid function to call myParam, // my param 0, // no flags, start thread immediately &threadID); All three calls to CreateThread() are made from a DLL I've injected into the target program at the start of the program execution (this is before the program has got to the start of main()/WinMain()). If I call CreateThread() from the target program (same params) via say a menu, it works. Same parameters etc. Bizarre. If I pass NULL instead of &threadID, it still fails. If I pass NULL as myParam, it still fails. I'm not calling CreateThread from inside DllMain(), so that isn't the problem. I'm confused and searching on Google etc hasn't shown any relevant answers. If anyone has seen this before or has any ideas, please let me know. Thanks for reading.

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