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• Javascript/CSS rollover menus are patented and subject to licensing?

  - by Scott B

  Very interesting finding that a client brought to my attention today regarding javascript style rollover menus. They got a call from their legal dept that they need to change the manner in which their rollover menu is activated (at the risk of having to pay license to continue using the navigation technique). Its no April fools joke, apparently this is really happening. Apparently a company named Webvention LLC has obtained enforcement rights to a patent, U.S. Patent No. 5,251,294 - "Accessing, assembling, and using bodies of Information." A menu link, that when rolled over, expands to show a list of categorized, related links. Dropdown menus and slide-out menus are examples of this patented navigational methodology. A key component of this patent is that the dropdown/slide-out action must be initiated by a rollover or mouseover event. If the dropdown/slide-out action is initiated by any other event, such as a mouse-click event, then this behavior is not in violation of the patent. Anyone ever heard of this or know of the validity of its claims? Website is here: http://www.webventionllc.com/

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• How do I specify a crossdomain policy file to allow Flash to grab a bitmap from an RTMP (Wowza) vide

  - by Ken Smith

  I'm trying to get a bitmap/snapshot of a Wowza video stream playing on my client, like so: var bitmapData:BitmapData = new BitmapData(view.videoPlayerComponent.width, view.videoPlayerComponent.height); bitmapData.draw(view.videoPlayerComponent); When I do this, I get this error message: SecurityError: Error #2123: Security sandbox violation: BitmapData.draw: http://localhost:51150/Resources/WRemoteWebCam.swf cannot access rtmp://localhost/videochat/smithkl42._default/. No policy files granted access. I presume the error comes from not being able to locate the appropriate crossdomain.xml file. I'm not quite sure where it's looking for it, and a wireshark sniff was inconclusive, so I've tried placing one in each of the following places: http://localhost/crossdomain.xml http://localhost:1935/crossdomain.xml http://localhost:51150/crossdomain.xml I can retrieve the file successfully from each of those three locations. (I'm pretty sure that the last one wouldn't have any effect, since it's just the location of the web site which hosts the page that hosts the .swf file, but on the off chance...) These are the contents of the file that it's grabbing in each instance: <cross-domain-policy> <allow-access-from domain="*" to-ports="*" /> </cross-domain-policy> And it's still throwing that same error message. I've also followed the instructions on the Wowza forums, to turn on StreamVideoSampleAccess in the [install]\conf[appname]\Application.xml, with no joy: <Client> <IdleFrequency>-1</IdleFrequency> <Access> <StreamReadAccess>*</StreamReadAccess> <StreamWriteAccess>*</StreamWriteAccess> <StreamAudioSampleAccess>*</StreamAudioSampleAccess> <StreamVideoSampleAccess>*</StreamVideoSampleAccess> <SharedObjectReadAccess>*</SharedObjectReadAccess> <SharedObjectWriteAccess>*</SharedObjectWriteAccess> </Access> </Client> Any thoughts?

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• Implementation review for a MVC.NET app with custom membership

  - by mrjoltcola

  I'd like to hear if anyone sees any problems with how I implemented the security in this Oracle based MVC.NET app, either security issues, concurrency issues or scalability issues. First, I implemented a CustomOracleMembershipProvider to handle the database interface to the membership store. I implemented a custom Principal named User which implements IPrincipal, and it has a hashtable of Roles. I also created a separate class named AuthCache which has a simple cache for User objects. Its purpose is simple to avoid return trips to the database, while decoupling the caching from either the web layer or the data layer. (So I can share the cache between MVC.NET, WCF, etc.) The MVC.NET stock MembershipService uses the CustomOracleMembershipProvider (configured in web.config), and both MembershipService and FormsService share access to the singleton AuthCache. My AccountController.LogOn() method: 1) Validates the user via the MembershipService.Validate() method, also loads the roles into the User.Roles container and then caches the User in AuthCache. 2) Signs the user into the Web context via FormsService.SignIn() which accesses the AuthCache (not the database) to get the User, sets HttpContext.Current.User to the cached User Principal. In global.asax.cs, Application_AuthenticateRequest() is implemented. It decrypts the FormsAuthenticationTicket, accesses the AuthCache by the ticket.Name (Username) and sets the Principal by setting Context.User = user from the AuthCache. So in short, all these classes share the AuthCache, and I have, for thread synchronization, a lock() in the cache store method. No lock in the read method. The custom membership provider doesn't know about the cache, the MembershipService doesn't know about any HttpContext (so could be used outside of a web app), and the FormsService doesn't use any custom methods besides accessing the AuthCache to set the Context.User for the initial login, so it isn't dependent on a specific membership provider. The main thing I see now is that the AuthCache will be sharing a User object if a user logs in from multiple sessions. So I may have to change the key from just UserId to something else (maybe using something in the FormsAuthenticationTicket for the key?).

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• Ruby - Immutable Objects

  - by Chris Bunch

  I've got a highly multithreaded app written in Ruby that shares a few instance variables. Writes to these variables are rare (1%) while reads are very common (99%). What is the best way (either in your opinion or in the idiomatic Ruby fashion) to ensure that these threads always see the most up-to-date values involved? Here's some ideas so far that I had (although I'd like your input before I overhaul this): Have a lock that most be used before reading or writing any of these variables (from Java Concurrency in Practice). The downside of this is that it puts a lot of synchronize blocks in my code and I don't see an easy way to avoid it. Use Ruby's freeze method (see here), although it looks equally cumbersome and doesn't give me any of the synchronization benefits that the first option gives. These options both seem pretty similar but hopefully anyone out there will have a better idea (or can argue well for one of these ideas). I'd also be fine with making the objects immutable so they aren't corrupted or altered in the middle of an operation, but I don't know Ruby well enough to make the call on my own and this question seems to argue that objects are highly mutable.

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• multi thread apps crashes in release mode

  - by etzarfat

  Hello, I'm using Visual Studio 2008 (programming in c). I've a weird problem I worte a program that has 2 threads that runs simultaneously, a recording thread (using audio card to record into memory) and a translation thread (using a speech engine to recognize the words). when I run my program in debug mode (aka setting a breakpoint in the code) it runs great, however when I run in debug mode or release mode (outside the visual studio enviroment) it crashes and give me the following exception: "Unhandled exception at 0x7c911129 in LowLevel.exe: 0xC0000005: Access violation reading location 0x014c7245." My stack looks: LowLevel.exe!__set_flsgetvalue() Line 256 + 0xc bytes C LowLevel.exe!_isleadbyte_l(int c=4359676, localeinfo_struct * plocinfo=0x00000001) Line 57 C++ 014b00d8() LowLevel.exe!PlayDateOfExam(int option=1) Line 2240 + 0x7 bytes C++ LowLevel.exe!NSCThread(void * arg=0x00000000) Line 1585 + 0xb bytes C++ kernel32.dll!7c80b729() winmm.dll!76b5b294() I uses the following file in my project "nsc.lib" and WinMM.lib" I'm not really familiar with threads I used a sample (which works great) and built on it. I saw a similiar question year on the forum but I didn't really understand the answers since I'm not familiar with with threads. Can someone help me? Thanks

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• How to debug MySQL/Doctrine2 Queries?

  - by jiewmeng

  I am using MySQL with Zend Framework & Doctrine 2. I think even if you don't use Doctrine 2, you will be familiar with errors like SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ASC' at line 1 The problem is that I don't see the full query. Without an ORM framework, I could probably echo the sql easily, but with a framework, how can I find out what SQL its trying to execute? I narrowed the error down to $progress = $task->getProgress(); $progress is declared // Application\Models\Task /** * @OneToMany(targetEntity="TaskProgress", mappedBy="task") * @OrderBy({"seq" = "ASC"}) */ protected $progress; In MySQL, the task class looks like CREATE TABLE `tasks` ( `id` int(11) NOT NULL AUTO_INCREMENT, `owner_id` int(11) DEFAULT NULL, `assigned_id` int(11) DEFAULT NULL, `list_id` int(11) DEFAULT NULL, `name` varchar(60) NOT NULL, `seq` int(11) DEFAULT NULL, PRIMARY KEY (`id`), KEY `tasks_owner_id_idx` (`owner_id`), KEY `tasks_assigned_id_idx` (`assigned_id`), KEY `tasks_list_id_idx` (`list_id`), CONSTRAINT `tasks_ibfk_1` FOREIGN KEY (`owner_id`) REFERENCES `users` (`id`), CONSTRAINT `tasks_ibfk_2` FOREIGN KEY (`assigned_id`) REFERENCES `users` (`id`), CONSTRAINT `tasks_ibfk_3` FOREIGN KEY (`list_id`) REFERENCES `lists` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=latin1$$

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• Updating multiple related tables in SQLite

  - by PerryJ

  Just some background, sorry so long winded. I'm using the System.Data.SQLite ADO.net adapter to create a local sqlite database and this will be the only process hitting the database, so I don't need to worry about concurrency. I'm building the database from various sources and don't want to build this all in memory using datasets or dataadapters or anything like that. I want to do this using SQL (DdCommands). I'm not very good with SQL and complete noob in sqlite. I'm basically using sqlite as a local database / save file structure. The database has a lot of related tables and the data has nothing to do with People or Regions or Districts, but to use a simple analogy, imagine: Region table with auto increment RegionID, RegionName column and various optional columns. District table with auto increment DistrictID, DistrictName, RegionId, and various optional columns Person table with auto increment PersonID, PersonName, DistrictID, and various optional columns So I get some data representing RegionName, DistrictName,PersonName, and other Person related data. The Region, District and/or Person may or may not be created at this point. Once again, not being the greatest with this, my thoughts would be something like: Check to see if Region exists and if so get the RegionID else create it and get RegionID Check to see if District exists and if so get the DistrictID else create it adding in RegionID from above and get DistrictID Check to see if Person exists and if so get the PersonID else create it adding in DistrictID from above and get PersonID Update Person with rest of data. In MS SQL Server I would create a stored procedure to handle all this. Only way I can see to do this with sqlite is a lot of commands. So I'm sure I'm not getting this. I've spent hours looking around on various sites but just don't feel like I'm going down the right road. Any suggestions would be greatly appreciated.

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• Fluent NHibernate - Cascade delete a child object when no explicit parent->child relationship exists

  - by John Price

  I've got an application that keeps track of (for the sake of an example) what drinks are available at a given restaurant. My domain model looks like: class Restaurant { public IEnumerable<RestaurantDrink> GetRestaurantDrinks() { ... } //other various properties } class RestaurantDrink { public Restaurant Restaurant { get; set; } public Drink { get; set; } public string DrinkVariety { get; set; } //"fountain drink", "bottled", etc. //other various properties } class Drink { public string Name { get; set; } public string Manufacturer { get; set; } //other various properties } My db schema is (I hope) about what you'd expect; "RestaurantDrinks" is essentially a mapping table between Restaurants and Drinks with some extra properties (like "DrinkVariety" tacked on). Using Fluent NHibernate to set up mappings, I've set up a "HasMany" relationship from Restaurants to RestaurantDrinks that causes the latter to be deleted when its parent Restaurant is deleted. My question is, given that "Drink" does not have any property on it that explicitly references RestaurantDrinks (the relationship only exists in the underlying database), can I set up a mapping that will cause RestaurantDrinks to be deleted if their associated Drink is deleted? Update: I've been trying to set up the mapping from the "RestaurantDrink" end of things using References(x => x.Drink) .Column("DrinkId") .Cascade.All(); But this doesn't seem to work (I still get an FK violation when deleting a Drink).

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• String trouble in Rave Reports 8

  - by Jørn E. Angeltveit

  We are currently working with Delphi 2006, but we are now very ready to move on to Delphi 2010. The problem lies in our Rave reports, though... We just get to many string errors when running our reports with Rave 8. And they just don't make any sense. (The reports compile with no error, and we can even run them without any error in Rave 6.) For instance: //This event causes access violation (in rtl14.bpl) at run time { Event for Page1.OnBeforeReport } function Page1_OnBeforeReport(Self: TRavePage); var s: String; begin s := 'My text in param'; s := s + ' and som more text'; s := copy(s,1,length(s)) + ' and then some more'; RaveProject.SetParam('MyTestParam', s); end OnBeforeReport; //This event works OK { Event for Page1.OnBeforeReport } function Page1_OnBeforeReport(Self: TRavePage); var s: String; begin s := 'My text in param'; s := s + ' and som more text'; s := copy(s,1,length(s)); // + ' and then some more'; RaveProject.SetParam('MyTestParam', s); end OnBeforeReport; //This event works OK too { Event for Page1.OnBeforeReport } function Page1_OnBeforeReport(Self: TRavePage); var s: String; begin s := 'My text in param'; s := s + ' and som more text'; s := copy(s,1,length(s)) + s; RaveProject.SetParam('MyTestParam', s); end OnBeforeReport; We really want to stick to Rave, because we have a lot of reports (150+) with a lot of functionality (sql statements, events etc). Besides, we have customers who have designed their own custom reports as well. Does anybody know the reason for these errors? Is there any solution or workaround to these problems?

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• Retrieve input entered in a JDialog

  - by Jules Olléon

  I extended JDialog to create a custom dialog where the user must fill some fields : How should I retrieve the data entered ? I came up with a solution that works. It mimics JOptionPane but the way I do it looks ugly to me because of the static fields involved... Here is roughly my code : public class FObjectDialog extends JDialog implements ActionListener { private static String name; private static String text; private JTextField fName; private JTextArea fText; private JButton bAdd; private JButton bCancel; private FObjectDialog(Frame parentFrame) { super(parentFrame,"Add an object",true); // build the whole dialog buildNewObjectDialog(); setVisible(true); } @Override public void actionPerformed(ActionEvent ae) { if(ae.getSource()==bAdd){ name=fName.getText(); text=fText.getText(); } else { name=null; text=null; } setVisible(false); dispose(); } public static String[] showCreateDialog(Frame parentFrame){ new FObjectDialog(parentFrame); String[] res={name,text}; if((name==null)||(text==null)) res=null; return res; } } As I said, that works properly, but I guess that might raise serious concurrency issues... Is there a cleaner way to do that ? How is it done in JOptionPane ?

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• How to capture page with google map?

  - by Max

  I have a UIComponent with Google map in the continer. I need to capture this container for making a preview. My integration looks like the following: <mx:UIComponent id="mapContainer" width="410" height="300" /> googleMap = new Map(); mapContainer.addChild(googleMap); But if I do("this" - is my UIComponent) var bmd:BitmapData = new BitmapData(this.width, this.height, true, 0x00ffffff); bmd.draw(this); I see the following: An ActionScript error has occurred: SecurityError: Error #2123: Security sandbox violation: BitmapData.draw: http://localhost/ cannot access http://mt1.google.com/vt/lyrs=m@121&hl=en&src=api&x=1&y=1&z=1&s=Gali. No policy files granted access. at flash.display::BitmapData/draw() I now, that I can to add it host to allowed on the custom client. But I need to have working system on any computer ) I've tried to hide it: templateGoogleMapRenderer.mapContainer.setVisible(false); templateGoogleMapRenderer.mapContainer.includeInLayout = false; But it was unsuccessfully. May be I can override some method in my UIComponent, that flex use during BitmapData/draw() ? Capture with hidden map is success result for me )

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• argv Memory Allocation

  - by Joshua Green

  I was wondering if someone could tell me what I am doing wrong that I get this Unhandled Exception error message: 0xC0000005: Access violation reading location 0x0000000c. with a green pointer pointing at my first Prolog code (fid_t): Here is my header file: class UserTaskProlog { public: UserTaskProlog( ArRobot* r ); ~UserTaskProlog( ); protected: int cycles; char* argv[ 1 ]; term_t tf; term_t tx; term_t goal_term; functor_t goal_functor; ArRobot* robot; void logTask( ); }; And here is my main code: UserTaskProlog::UserTaskProlog( ArRobot* r ) : robot( r ), robotTaskFunc( this, &UserTaskProlog::logTask ) { cycles = 0; argv[ 0 ] = "libpl.dll"; argv[ 1 ] = NULL; PL_initialise( 1, argv ); PlCall( "consult( 'myPrologFile.pl' )" ); robot->addSensorInterpTask( "UserTaskProlog", 50, &robotTaskFunc ); } UserTaskProlog::~UserTaskProlog( ) { robot->remSensorInterpTask( &robotTaskFunc ); } void UserTaskProlog::logTask( ) { cycles++; fid_t fid = PL_open_foreign_frame( ); tf = PL_new_term_ref( ); PL_put_integer( tf, 5 ); tx = PL_new_term_ref( ); goal_term = PL_new_term_ref( ); goal_functor = PL_new_functor( PL_new_atom( "factorial" ), 2 ); PL_cons_functor( goal_term, goal_functor, tf, tx ); int fact; if ( PL_call( goal_term, NULL ) ) { PL_get_integer( tx, &fact ); cout << fact << endl; } PL_discard_foreign_frame( fid ); } int main( int argc, char** argv ) { ArRobot robot; ArArgumentParser argParser( &argc, argv ); UserTaskProlog talk( &robot ); } Thank you,

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• Magento install errors

  - by nXqd

  I try to install new magento version 1.4.xx . But after the config menu I meet after I copy and change local.example.xml to local.xml . Error in file: "E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Catalog\sql\catalog_setup\mysql4-install-1.4.0.0.0.php" - SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '4-page_layout' for key 'entity_type_id' Trace: #0 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(374): Mage::exception('Mage_Core', 'Error in file: ...') #1 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(260): Mage_Core_Model_Resource_Setup->_modifyResourceDb('install', '', '1.4.0.0.21') #2 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(224): Mage_Core_Model_Resource_Setup->_installResourceDb('1.4.0.0.21') #3 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(153): Mage_Core_Model_Resource_Setup->applyUpdates() #4 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(363): Mage_Core_Model_Resource_Setup::applyAllUpdates() #5 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(295): Mage_Core_Model_App->_initModules() #6 E:\Soft\Programming\xampp\htdocs\magento\app\Mage.php(596): Mage_Core_Model_App->run(Array) #7 E:\Soft\Programming\xampp\htdocs\magento\index.php(78): Mage::run('', 'store') #8 {main} I really need your help , thanks so much :)

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• Execute remote Lua Script

  - by Bruno Lee

  Hi, I want to make an application that executes a remote script. The user can create a script (probabily a LUA script) then stores it in the server. Then he can uses an API for execute the script. I was thinking that API could be a webservice. So my questions are: I need high performance to execute the script. So my first choice was LUA script. Someone has another sugestion? Cause I need high perfomance, I was thinking if the webservice is the best solution. Maybe I could create a TCP/IP Windows Service that hold the users request. It is important to say that I will have many user executing scripts at the same time. So I will have a concurrency problem. My scripts will query in a database. I will use Tokyo Cabinet or Tokio Tyrant. I think Tokio Tyrant is the only solution cause I will have many requests. For perfomance, Do I need to make a connection pooling? Is there anyway to share variables between webservices requests? To make the webservice or the Windows service i was thinking to use C++. Can someone help with these questions? thanks

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• Blackberry Apps - Importing a code-signed jar into an application project

  - by Eric Sniff

  Hi everyone, I'm working on a library project that Blackberry Java developers can import into their projects. It uses protected RIM APIs which require that it be code-signed, which I have done. But, I can't get my Jar imported and working with a simple helloWorld app. I'm using the eclipse plug-in Blackberry-JDE. Here is what I have tried: First: Building myLibProject with BlackBerry_JDE_PluginFull_1.0.0.67 into a JAR, signing it and importing it into a BlackBerry_JDE_PluginFull_1.0.0.67 application project -- I get a class not found error, while compiling the application project. Next: I imported myLibProject into an BlackBerry_JDE_PluginFull_1.1.1.* library project, built it into a jar, signed it and imported it into a BlackBerry_JDE_PluginFull_1.1.1.* application project. It built this time, but while loading up the simulator to test it I get the following error ( Access violation reading from 0xFFFFFFC ) before the simulator can loadup and it crashs the simulator. Other stuff I've tried: I also tried importing the jar into it's own project and having the HelloWorld app project reference that project. If I include the src in my application project it works fine... But Im looking for a way to deploy this as compiled code. Any Ideas? Or help?

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• Using StringBuilder to process csv files to save heap space

  - by portoalet

  I am reading a csv file that has about has about 50,000 lines and 1.1MiB in size (and can grow larger). In Code1, I use String to process the csv, while in Code2 I use StringBuilder (only one thread executes the code, so no concurrency issues) Using StringBuilder makes the code a little bit harder to read that using normal String class. Am I prematurely optimizing things with StringBuilder in Code2 to save a bit of heap space and memory? Code1 fr = new FileReader(file); BufferedReader reader = new BufferedReader(fr); String line = reader.readLine(); while ( line != null ) { int separator = line.indexOf(','); String symbol = line.substring(0, seperator); int begin = separator; separator = line.indexOf(',', begin+1); String price = line.substring(begin+1, seperator); // Publish this update publisher.publishQuote(symbol, price); // Read the next line of fake update data line = reader.readLine(); } Code2 fr = new FileReader(file); StringBuilder stringBuilder = new StringBuilder(reader.readLine()); while( stringBuilder.toString() != null ) { int separator = stringBuilder.toString().indexOf(','); String symbol = stringBuilder.toString().substring(0, separator); int begin = separator; separator = stringBuilder.toString().indexOf(',', begin+1); String price = stringBuilder.toString().substring(begin+1, separator); publisher.publishQuote(symbol, price); stringBuilder.replace(0, stringBuilder.length(), reader.readLine()); }

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• Repackaging Jasper-Reports into an application specific OSGi bundle, legal or not?

  - by Chris

  Hi, I wanted to ask (probably a silly) question regarding the packaging of existing open-source components as OSGi bundles (more specifically Jasper Reports). I have an application that I am converting from a monolithic jar-hell type architecture to something more moduler and OSGi is my weapon of choice. There are various modules I have in mind but one of the modules is a reporting module. My own reporting module will be a jar file containing my code that should reference a Jasper Reports bundle. Trouble is, Jasper reports depends on far far too many libraries and is quite monolithic in its own right. I therefore wish to build my own Jasper Reports bundle but this is where I start getting confused about the legality of repackaging. I don't plan to re-compile but I do plan to re-bundle removing known items that I do not require. Can anyone offer advice on whether I am permitted to repackage (not recompile or extend) open-source libraries into OSGi bundles without falling foul of 'derivative works' clause of LGPL? I noticed that Groovy seems to offer some monolithic jars that include all dependancies and actually goes so far as to re-arrange the packages of its dependancies so that there are no namespace conflicts. This seems to me to be a violation of the license but if anyone can reassure me that this is legal then I would feel safer about my less intrusive custom-bundling of Jasper reports. Thanks for your time, Chris

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• How do people know so much about programming?

  - by Luciano

  I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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• Far jump in ntdll.dll's internal ZwCreateUserProcess

  - by user49164

  I'm trying to understand how the Windows API creates processes so I can create a program to determine where invalid exes fail. I have a program that calls kernel32.CreateProcessA. Following along in OllyDbg, this calls kernel32.CreateProcessInternalA, which calls kernel32.CreateProcessInternalW, which calls ntdll.ZwCreateUserProcess. This function goes: mov eax, 0xAA xor ecx, ecx lea edx, dword ptr [esp+4] call dword ptr fs:[0xC0] add esp, 4 retn 0x2C So I follow the call to fs:[0xC0], which contains a single instruction: jmp far 0x33:0x74BE271E But when I step this instruction, Olly just comes back to ntdll.ZwCreateUserProcess at the add esp, 4 right after the call (which is not at 0x74BE271E). I put a breakpoint at retn 0x2C, and I find that the new process was somehow created during the execution of add esp, 4. So I'm assuming there's some magic involved in the far jump. I tried to change the CS register to 0x33 and EIP to 0x74BE271E instead of actually executing the far jump, but that just gave me an access violation after a few instructions. What's going on here? I need to be able to delve deeper beyond the abstraction of this ZwCreateUserProcess to figure out how exactly Windows creates processes.

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• How to mmap the stack for the clone() system call on linux?

  - by Joseph Garvin

  The clone() system call on Linux takes a parameter pointing to the stack for the new created thread to use. The obvious way to do this is to simply malloc some space and pass that, but then you have to be sure you've malloc'd as much stack space as that thread will ever use (hard to predict). I remembered that when using pthreads I didn't have to do this, so I was curious what it did instead. I came across this site which explains, "The best solution, used by the Linux pthreads implementation, is to use mmap to allocate memory, with flags specifying a region of memory which is allocated as it is used. This way, memory is allocated for the stack as it is needed, and a segmentation violation will occur if the system is unable to allocate additional memory." The only context I've ever heard mmap used in is for mapping files into memory, and indeed reading the mmap man page it takes a file descriptor. How can this be used for allocating a stack of dynamic length to give to clone()? Is that site just crazy? ;) In either case, doesn't the kernel need to know how to find a free bunch of memory for a new stack anyway, since that's something it has to do all the time as the user launches new processes? Why does a stack pointer even need to be specified in the first place if the kernel can already figure this out?

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• Updating multiple related tables in SQLite with C#

  - by PerryJ

  Just some background, sorry so long winded. I'm using the System.Data.SQLite ADO.net adapter to create a local sqlite database and this will be the only process hitting the database, so I don't need to worry about concurrency. I'm building the database from various sources and don't want to build this all in memory using datasets or dataadapters or anything like that. I want to do this using SQL (DdCommands). I'm not very good with SQL and complete noob in sqlite. I'm basically using sqlite as a local database / save file structure. The database has a lot of related tables and the data has nothing to do with People or Regions or Districts, but to use a simple analogy, imagine: Region table with auto increment RegionID, RegionName column and various optional columns. District table with auto increment DistrictID, DistrictName, RegionId, and various optional columns Person table with auto increment PersonID, PersonName, DistrictID, and various optional columns So I get some data representing RegionName, DistrictName,PersonName, and other Person related data. The Region, District and/or Person may or may not be created at this point. Once again, not being the greatest with this, my thoughts would be something like: Check to see if Region exists and if so get the RegionID else create it and get RegionID Check to see if District exists and if so get the DistrictID else create it adding in RegionID from above and get DistrictID Check to see if Person exists and if so get the PersonID else create it adding in DistrictID from above and get PersonID Update Person with rest of data. In MS SQL Server I would create a stored procedure to handle all this. Only way I can see to do this with sqlite is a lot of commands. So I'm sure I'm not getting this. I've spent hours looking around on various sites but just don't feel like I'm going down the right road. Any suggestions would be greatly appreciated.

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• LinqToSQL Double Insert issue

  - by Vaccano

  I have a WCF service with an object structure similar to this: public class MyClass { public List<MySubItem> SubItems { get; set; } } public class MySubItem { public List<MySubSubItem> SubSubItems { get; set; } } public class MySubSubItem { public string DataValue { get; set; } } public class MyClassDAL { public void InsertMyClass(MyClass myClass) { ctx.MyClasses.InsertOnSubmit(myClass); ctx.SubmitChanges(); } } Sometimes my client will call in with a MyClass that submits only half of the values that it has in the list SubSubItems. Later it calls the insert with the rest of the list. The problem is that when it does this I get a Primary Key violation. The reason is that it is trying to insert the MySubItem again (because there are more items in the SubSubItems owned by the same MySubItem object). How do I deal with this? Do I just call an Update? Do I have to try to separate them out (updates from inserts)? SQL Server 2008 has a really cool Merge functionally. Is there some way to access that from LinqToSQL?

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• How should I go about implementing a points-to analysis in Maude?

  - by reprogrammer

  I'm going to implement a points-to analysis algorithm. I'd like to implement this analysis mainly based on the algorithm by Whaley and Lam. Whaley and Lam use a BDD based implementation of Datalog to represent and compute the points-to analysis relations. The following lists some of the relations that are used in a typical points-to analysis. Note that D(w, z) :- A(w, x),B(x, y), C(y, z) means D(w, z) is true if A(w, x), B(x, y), and C(y, z) are all true. BDD is the data structure used to represent these relations. Relations input vP0 (variable : V, heap : H) input store (base : V, field : F, source : V) input load (base : V, field : F, dest : V) input assign (dest : V, source : V) output vP (variable : V, heap : H) output hP (base : H, field : F, target : H) Rules vP(v, h) :- vP0(v, h) vP(v1, h) :- assign(v1, v2), vP(v2, h) hP(h1, f,h2) :- store(v1, f, v2), vP(v1, h1), vP(v2, h2) vP(v2, h2) :- load(v1, f, v2), vP(v1, h1), hP(h1, f, h2) I need to understand if Maude is a good environment for implementing points-to analysis. I noticed that Maude uses a BDD library called BuDDy. But, it looks like that Maude uses BDDs for a different purpose, i.e. unification. So, I thought I might be able to use Maude instead of a Datalog engine to compute the relations of my points-to analysis. I assume Maude propagates independent information concurrently. And this concurrency could potentially make my points-to analysis faster than sequential processing of rules. But, I don't know the best way to represent my relations in Maude. Should I implement BDD in Maude myself, or Maude's internal unification based on BDD has the same effect?

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• AContext.data can be nil?

  - by waza123

  In this code, as you see on Connect, AContext.Data is filled with something TmyTThreadList = class(TThreadList) id: integer; end; var unique_id:integer; procedure TfrmTestIdTCPServer.IdTCPServerConnect(AContext: TIdContext); begin CS.Enter; try inc(unique_id); finally CS.Leave; end; AContext.Data := myTThreadList.Create; list := myTThreadList(AContext.Data).LockList; try myTThreadList(AContext.Data).id := my_unique_id; list.Add(myTThreadList(AContext.Data)); finally myTThreadList(AContext.Data).UnlockList; end; end; then on disconnect, coder is checking here for Acontext.Data < nil procedure TfrmTestIdTCPServer.IdTCPServerDisconnect(AContext: TIdContext); var begin if AContext.Data <> nil then begin The question is, why he is checking for nil ? Thanks. EDIT: I'm asking this, because when I do the same, onExecute I access AContext.Data , and sometimes (when in same time is connecting many clients) AContext.Data is empty, access violation appears.

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• (C#) Get index of current foreach iteration

  - by Graphain

  Hi, Is there some rare language construct I haven't encountered (like the few I've learned recently, some on Stack Overflow) in C# to get a value representing the current iteration of a foreach loop? For instance, I currently do something like this depending on the circumstances: int i=0; foreach (Object o in collection) { ... i++; } Answers: @bryansh: I am setting the class of an element in a view page based on the position in the list. I guess I could add a method that gets the CSSClass for the Objects I am iterating through but that almost feels like a violation of the interface of that class. @Brad Wilson: I really like that - I've often thought about something like that when using the ternary operator but never really given it enough thought. As a bit of food for thought it would be nice if you could do something similar to somehow add (generically to all IEnumerable objects) a handle on the enumerator to increment the value that an extension method returns i.e. inject a method into the IEnumerable interface that returns an iterationindex. Of course this would be blatant hacks and witchcraft... Cool though... @crucible: Awesome I totally forgot to check the LINQ methods. Hmm appears to be a terrible library implementation though. I don't see why people are downvoting you though. You'd expect the method to either use some sort of HashTable of indices or even another SQL call, not an O(N) iteration... (@Jonathan Holland yes you are right, expecting SQL was wrong) @Joseph Daigle: The difficulty is that I assume the foreach casting/retrieval is optimised more than my own code would be. @Jonathan Holland: Ah, cheers for explaining how it works and ha at firing someone for using it.

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