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  • Using commit monitors as a form of code review

    - by Jeff Dege
    I'm working in a small company - four developers, working on a variety of projects. We've been looking at what we can do as cost-effective methods of process improvement, and an idea came up. Given what we do, we often have single developers working on parts of a system, independently of the other developers. This can have a number of negative affects: A developer might not be fully aware of the context in which a change is being implemented, and make the change in a way that will meet the current customer's needs, but will break functionality that other customers depend on. A developer might make a change that breaks the current architectural design, introducing a dependency that will cause problems in future development. Other developers might not be aware of how the system has changed, in areas that they have not worked on. We've talked about doing code reviews, as a way of dealing with these issues. But we've not had much success when we tried. It takes a lot of time to prepare a change for a code review, and it takes everybody out of production while the review is being performed. And the benefits of any review we've tried has been minimal. We're using Subversion (with TortioseSVN) as our VCS. I've been looking at the SubVersion CommitMonitor tool, and wondering whether it might work as a sort of poor-man's code review. It lists every commit made on the repository, allowing someone to see the changes that have been made, the log messages made for that change, the files that were included in the change, and the specific lines in each file that were changed. Rather than scheduling a meeting, trying to get everybody together to review every change, we could just have every developer review every other developer's commits, at whatever time was convenient. This would keep every developer abreast of what changes were being made elsewhere in the system, and would have every change reviewed for customer conflicts and design consistency, at a fairly low cost. If someone saw a problem with the code that was being checked in, he could discuss it with the developer who did the commit, or more likely, schedule a meeting to discuss how the new feature could be implemented in a way that would not impact other users or screw up the architecture. Anyone else doing anything like this, using commit monitors for such a purpose?

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  • OSX/Darwin unresolved symbols when linking functions from <math.h>

    - by tbone
    I'm in the process of porting a large'ish (~1M LOC) project from a Window/Visual Studio environment to other platforms, the first of which happens to be Mac OS X. Originally the project was configured as Visual Studio solutions and projects, but now I'm using (the excellent) Premake (http://industriousone.com/premake) to generate project files for multiple platforms (VS, XCode, GMake). I configured, ported and built the first few projects without any significant problems, but having ported the math lib, I ran into this weird linking error that I haven't been able to resolve: Any functions used from math.h will fail to link (causing unresolved symbols). For reference, I'm using Premake v4.2.1 to generate projects for XCode v3.2.1, which is building using gcc v4.2 for the x86_64 architecture. (All this on 64-bit Snow Leopard) I've tried to persuade gcc to link and build everything against a 'known' SDK by adding -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.6 to the build command line. Now under normal circumstances, adding -lm should take care of this, however in Darwin, those math libs are included in libSystem, which, as far as I can tell, gets implicitly linked by gcc/ld. I've tried creating a dummy project from within XCode which just runs: float f = log2(2.0)+log2f(3.f)+log1p(1.1)+log1pf(1.2f)+sin(8.0); std::cout << f << std::endl; and as expected, this builds just fine. However, if I put the same thing in the code inside the Premake generated project, all those math functions end up unresolved. Now comparing the linking command from the 'native' XCode project with my generated XCode project, they seem pretty identical (except that my generated project links other libs as well). 'Native' project: /Developer/usr/bin/g++-4.2 -arch x86_64 -dynamiclib -isysroot /Developer/SDKs/MacOSX10.6.sdk -Lsomepath -Fsomepath -filelist somefile -install_name somename -mmacosx-version-min=10.6 -single_module -compatibility_version 1 -current_version 1 -o somename Generated project: /Developer/usr/bin/g++-4.2 -arch x86_64 -dynamiclib -Lsomepath -Fsomepath -filelist somefile -install_name somename -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.6 somelib.a somelib2.a somelib.dylib somelib2.dylib -single_module -compatibility_version 1 -current_version 1 -o somename Any help or hints about how to proceed would be most appreciated. Are there any gcc flags or other tools that can help me resolve this?

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  • Advice on displaying and allowing editing of data using ASP.NET MVC?

    - by Remnant
    I am embarking upon my first ASP.NET MVC project and I would like to get some input on possible ways to display database data and general best practice. In short, the body of my webpage will show data from my database in a table like format, with each table row showing similar data. For example: Name Age Position Date Joined Jon Smith 23 Striker 18th Mar 2005 John Doe 38 Defender 3rd Jan 1988 In terms of functionality, primarily I’d like to give the user the ability to edit the data and, after the edit, commit the edit to the database and refresh the view.The reason I want to refresh the view is because the data is date ordered and I will need to re-sort if the user edits a date field. My main question is what architecture / tools would be best suited to this fulfil my requirements at a high level? From the research I have done so far my initial conclusions were: ADO.NET for data retrieval. This is something I have used before and feel comfortable with. I like the look of LINQ to SQL but don’t want to make the learning curve any steeper for my first outing into MVC land just yet. Partial Views to create a template and then iterate through a datatable that I have pulled back from my database model. jQuery to allow the user to edit data in the table, error check edited data entries etc. Also, my intial view was that caching the data would not be a key requirement here. The only field a user will be able to update is the field and, if they do, I will need to commit that data to the database immediately and then refresh the view (as the data is date sorted). Any thoughts on this? Alternatively, I have seen some jQuery plug-ins that emulate a datagrid and provide associated functionality. My first thoughts are that I do not need all the functionality that comes with these plug-ins (e.g. zebra striping, ability to sort by column using sort glyph in column headers etc .) and I don’t really see any benefit to this over and above the solution I have outlined above. Again, is there reason to reconsider this view? Finally, when a user edits a date , I will need to refresh the view. In order to do this I had been reading about Html.RenderAction and this seemed like it may be a better option than using Partial Views as I can incorporate application logic into the action method. Am I right to consider Html.RenderAction or have I misunderstood its usage? Hope this post is clear and not too long. I did consider separate posts for each topic (e.g. Partial View vs. Html.RenderAction, when to use jQury datagrid plug-in) but it feels like these issues are so intertwined that they need to be dealt with in contect of each other. Thanks

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  • Winform radiobutton data binding

    - by Rajarshi
    I am following the "Presentation Model" design pattern suggested by Martin Fowler for my GUI architecture in a Windows Forms project. "The essence of a Presentation Model is of a fully self-contained class that represents all the data and behavior of the UI window, but without any of the controls used to render that UI on the screen. A view then simply projects the state of the presentation model onto the glass...." - Martin Fowler Read more about this pattern at www.martinfowler.com/eaaDev/PresentationModel.html I am finding the concept very fluid and easy to understand except this one issue of data binding RadioButtons to properties on the Data/Domain object. Suposing I have a Windows Form with 3 radio buttons to depict some "Mode" options as - Auto Manual Import How can I use boolean properties on Data/Domain Objects to DataBind to these buttons? I have tried many ways but to no avail. For example I would like to code like - rbtnAutoMode.DataBindings.Add("Text", myBusinessObject, "IsAutoMode"); rbtnManualMode.DataBindings.Add("Text", myBusinessObject, "IsManualMode"); rbtnImportMode.DataBindings.Add("Text", myBusinessObject, "IsImportMode"); There should be a fourth property like "SelectedMode" on the data/domain object which at the end should depict a single value like "SelectedMode = Auto". I am trying to update this property when any of the "IsAutoMode", "IsManualMode" or "IsImportMode" is changed, e.g. through the property setters. I have INotifyPropertyChanged implemented on my data/domain object so, updating any data/domain object property automatically updates my UI controls, that's not an issue. There is a good example of binding 2 radio buttons here - http://stackoverflow.com/questions/344964/how-do-i-use-databinding-with-windows-forms-radio-buttons but I am missing the link while implementing the same with 3 buttons. I am having very erratic behaviors for the Radio Buttons. I hope I was able to explain reasonably. I am actually in a hurry and could not put a detailed code on post, but any help in this regard is appreciated. There is a simple solution to this issue by exposing a method like - public void SetMode(Modes mode) { this._selectedMode = mode; } which could be called from the "CheckedChanged" event of the Radio Buttons from the UI and would perfectly set the "SelectedMode" on the business object, but I need to stretch the limits to verify whether this can be done by DataBinding.

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  • Visual Studio Express 2012 debug mode doesn't work

    - by user2350086
    I have a project in Visual Studio that I have been working on for a while, and I have used the debugger extensively. Recently I changed some settings and I have lost the ability to stop the program and step through code. I can't figure out what I had changed that might have affected this. If I put a breakpoint in my code and try to have the program stop there, it doesn't. The break point shows up white with a red outline. If I hover the mouse over it, it says "The breakpoint will not currently be hit. No executable code of the debugger's target code type is associated with this line. Possible causes include: conditional compilation, compiler optimizations, or the target architecture of this line is not supported by the current debugger code type." I know for a fact that the program executes the code where the breakpoint is because I put the breakpoint in the beginning of the InitializeComponent method. The program displays the window fine, but does not stop at the breakpoint. Yes, I am running in debug mode. It seems as though there is a disconnect between the compiled code and the source code displayed. Does anyone know what that would be, or know which compiler settings I should check to re-enable debugging? Here are the compiler options: /GS /analyze- /W3 /Zc:wchar_t /I"D:\dev\libcurl-7.19.3-win32-ssl-msvc\include" /Zi /Od /sdl /Fd"Debug\vc110.pdb" /fp:precise /D "WIN32" /D "_DEBUG" /D "_UNICODE" /D "UNICODE" /errorReport:prompt /WX- /Zc:forScope /Oy- /clr /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\mscorlib.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.Data.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.Drawing.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.Windows.Forms.DataVisualization.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.Windows.Forms.dll" /FU"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\System.Xml.dll" /MDd /Fa"Debug\" /EHa /nologo /Fo"Debug\" /Fp"Debug\Prog.pch" The linker options are: /OUT:"D:\dev\Prog\Debug\Prog.exe" /MANIFEST /NXCOMPAT /PDB:"D:\dev\Prog\Debug\Prog.pdb" /DYNAMICBASE "curllib.lib" "winmm.lib" "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" /FIXED:NO /DEBUG /MACHINE:X86 /ENTRY:"Main" /INCREMENTAL /PGD:"D:\dev\Prog\Debug\Prog.pgd" /SUBSYSTEM:WINDOWS /MANIFESTUAC:"level='asInvoker' uiAccess='false'" /ManifestFile:"Debug\Prog.exe.intermediate.manifest" /ERRORREPORT:PROMPT /NOLOGO /LIBPATH:"D:\dev\libcurl-7.19.3-win32-ssl-msvc\lib\Debug" /ASSEMBLYDEBUG /TLBID:1

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  • Mac OS - Built SVN from source, now Apache2 not loading sites

    - by Geuis
    This relates to another question I asked earlier today. I built SVN 1.6.2 from source. In the process, it has completely screwed up my dev environment. After I built SVN, Apache wasn't loading. It was giving me this error: Syntax error on line 117 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec /apache2/mod_dav_svn.so into server: dlopen(/usr/libexec/apache2/mod_dav_svn.so, 10): no suitable image found. Did find:\n\t/usr/libexec/apache2/mod_dav_svn.so: mach-o, but wrong architecture It appears that SVN over-wrote the old mod_dav_svn.so and I am not able to get it to build as FAT, and I can't recover whatever was originally there. I resolved this(temporarily?) by commenting out the line that was loading the mod_dav_svn.so and got Apache to start at this point. However, even though Apache is running I am now getting this error when trying to access my dev sites: Directory index forbidden by Options directive: /usr/share/tomcat6/webapps/ROOT/ I have Apache2 sitting in front of Tomcat6. I access my local dev site using the internal name "http://localthesite". I have had virtual directories set up that have worked until this SVN debacle. Tomcat is installed at /usr/local/apache-tomcat, and webapps is /usr/local/apache-tomcat/webapps. Our production servers deploy tomcat to /usr/share/tomcat6, so I have symlinks setup on my system to replicate this as well. These point back to the actual installation path. This has all been working fine as well. None of our configurations for Apache2, Tomcat, or .htaccess have changed. Over the weekend, I performed a "Repair Disk Permissions" on the system. This was before I discovered the mod_dav_svn.so problem. I have been reading up on this all morning and the most common answer is that there is an Options -Indexes set. We have this in a config file, but it was there before and when I removed it during testing, I still got the same errors from Apache. At this point, I'm assuming I either totally borked the native Apache2 installation on this Mac, or that there is a permissions error somewhere that I'm missing. The permissions error could be from the SVN installation, or from my repair process. Does anyone have any idea what could be the problem? I'm totally blocked right now and have no idea where to check next.

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  • How do you handle EF Data Contexts combined with asp.net custom membership/role providers

    - by KallDrexx
    I can't seem to get my head around how to implement a custom membership provider with Entity Framework data contexts into my asp.net MVC application. I understand how to create a custom membership/role provider by itself (using this as a reference). Here's my current setup: As of now I have a repository factory interface that allows different repository factories to be created (right now I only have a factory for EF repositories and and in memory repositories). The repository factory looks like this: public class EFRepositoryFactory : IRepositoryFactory { private EntitiesContainer _entitiesContext; /// <summary> /// Constructor that generates the necessary object contexts /// </summary> public EFRepositoryFactory() { _entitiesContext = new EntitiesContainer(); } /// <summary> /// Generates a new entity framework repository for the specified entity type /// </summary> /// <typeparam name="T">Type of entity to generate a repository for </typeparam> /// <returns>Returns an EFRepository</returns> public IRepository<T> GenerateRepository<T>() where T : class { return new EFRepository<T>(_entitiesContext); } } Controllers are passed an EF repository factory via castle Windsor. The controller then creates all the service/business layer objects it requires and passes in the repository factory into it. This means that all service objects are using the same EF data contexts and I do not have to worry about objects being used in more than one data context (which of course is not allowed and causes an exception). As of right now I am trying to decide how to generate my user and authorization service layers, and have run against a design roadblock. The User/Authization service will be a central class that handles the logic for logging in, changing user details, managing roles and determining what users have access to what. The problem is, using the current methodology the asp.net mvc controllers will initialize it's own EF repository factory via Windsor and the asp.net membership/role provider will have to initialize it's own EF repository factory. This means that each part of the site will then have it's own data context. This seems to mean that if asp.net authenticates a user, that user's object will be in the membership provider's data context and thus if I try to retrieve that user object in the service layer (say to change the user's name) I will get a duplication exception. I thought of making the repository factory class a singleton, but I don't see a way for that to work with castle Windsor. How do other people handle asp.net custom providers in a MVC (or any n-tier) architecture without having object duplication issues?

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  • How do you unit test a unit test?

    - by FlySwat
    I was watching Rob Connerys webcasts on the MVCStoreFront App, and I noticed he was unit testing even the most mundane things, things like: public Decimal DiscountPrice { get { return this.Price - this.Discount; } } Would have a test like: [TestMethod] public void Test_DiscountPrice { Product p = new Product(); p.Price = 100; p.Discount = 20; Assert.IsEqual(p.DiscountPrice,80); } While, I am all for unit testing, I sometimes wonder if this form of test first development is really beneficial, for example, in a real process, you have 3-4 layers above your code (Business Request, Requirements Document, Architecture Document), where the actual defined business rule (Discount Price is Price - Discount) could be misdefined. If that's the situation, your unit test means nothing to you. Additionally, your unit test is another point of failure: [TestMethod] public void Test_DiscountPrice { Product p = new Product(); p.Price = 100; p.Discount = 20; Assert.IsEqual(p.DiscountPrice,90); } Now the test is flawed. Obviously in a simple test, it's no big deal, but say we were testing a complicated business rule. What do we gain here? Fast forward two years into the application's life, when maintenance developers are maintaining it. Now the business changes its rule, and the test breaks again, some rookie developer then fixes the test incorrectly...we now have another point of failure. All I see is more possible points of failure, with no real beneficial return, if the discount price is wrong, the test team will still find the issue, how did unit testing save any work? What am I missing here? Please teach me to love TDD, as I'm having a hard time accepting it as useful so far. I want too, because I want to stay progressive, but it just doesn't make sense to me. EDIT: A couple people keep mentioned that testing helps enforce the spec. It has been my experience that the spec has been wrong as well, more often than not, but maybe I'm doomed to work in an organization where the specs are written by people who shouldn't be writing specs.

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  • SQL Server stored procedures - update column based on variable name..?

    - by ClarkeyBoy
    Hi, I have a data driven site with many stored procedures. What I want to eventually be able to do is to say something like: For Each @variable in sproc inputs UPDATE @TableName SET @variable.toString = @variable Next I would like it to be able to accept any number of arguments. It will basically loop through all of the inputs and update the column with the name of the variable with the value of the variable - for example column "Name" would be updated with the value of @Name. I would like to basically have one stored procedure for updating and one for creating. However to do this I will need to be able to convert the actual name of a variable, not the value, to a string. Question 1: Is it possible to do this in T-SQL, and if so how? Question 2: Are there any major drawbacks to using something like this (like performance or CPU usage)? I know if a value is not valid then it will only prevent the update involving that variable and any subsequent ones, but all the data is validated in the vb.net code anyway so will always be valid on submitting to the database, and I will ensure that only variables where the column exists are able to be submitted. Many thanks in advance, Regards, Richard Clarke Edit: I know about using SQL strings and the risk of SQL injection attacks - I studied this a bit in my dissertation a few weeks ago. Basically the website uses an object oriented architecture. There are many classes - for example Product - which have many "Attributes" (I created my own class called Attribute, which has properties such as DataField, Name and Value where DataField is used to get or update data, Name is displayed on the administration frontend when creating or updating a Product and the Value, which may be displayed on the customer frontend, is set by the administrator. DataField is the field I will be using in the "UPDATE Blah SET @Field = @Value". I know this is probably confusing but its really complicated to explain - I have a really good understanding of the entire system in my head but I cant put it into words easily. Basically the structure is set up such that no user will be able to change the value of DataField or Name, but they can change Value. I think if I were to use dynamic parameterised SQL strings there will therefore be no risk of SQL injection attacks. I mean basically loop through all the attributes so that it ends up like: UPDATE Products SET [Name] = '@Name', Description = '@Description', Display = @Display Then loop through all the attributes again and add the parameter values - this will have the same effect as using stored procedures, right?? I dont mind adding to the page load time since this is mainly going to affect the administration frontend, and will marginly affect the customer frontend.

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  • Java - How to make a set of JInternalFrame independant of each other?

    - by Amokrane
    Hello, I'm programming a short Paint program like and I'm trying to make an MDI architecture for it. To make that happen, I used JInternalFrame inside a JDesktopPane. Although I kind of obtain multiple frames, there are not really working properly. Basically, if I have 2 JInternalFrame I can draw only on the last one. The other one seems to be disabled. Here is a short video illustrating the problem. http://bit.ly/9ydiwM Here are some part of the code. Panneau.java public class Panneau extends JDesktopPane { /** La liste de fenêtres ouvertes */ private static ArrayList<Cadre> cadres; /** Le pannel comportant la liste des formes à dessiner*/ private Pannel pannel; /** La barre d'outils */ private ToolBox toolBox; public Panneau() { this.setLayout(new BorderLayout()); // Initialisations des listes de cadres cadres = new ArrayList<Cadre>(); // En haut ToolBox toolBox = new ToolBox(); this.add(toolBox, BorderLayout.NORTH); **// Intialisation de la première internal frame Cadre cadre = new Cadre(); this.add(cadre, BorderLayout.CENTER);** cadres.add(cadre); // Ajout du pannel à gauche pannel = new Pannel(); this.add(pannel, BorderLayout.WEST); } /** * Crée une nouvelle fenêtre de dessin * */ **public void createNewInternalFrame() { Cadre cadre = new Cadre(); this.add(cadre, BorderLayout.CENTER); cadres.add(cadre); }** } public class Cadre extends JInternalFrame { /** Largeur par d'une fenêtre interne */ private int width; /** Hauteur d'une fenêtre interne */ private int height; /** Titre d'une fenêtre interne */ private String title; /** Toile associée à la fenêtre interne */ private Toile toile; public Cadre() { width = 400; height = 400; title = "Form"; toile = new Toile(); this.setTitle(title); this.setSize(width, height); this.setEnabled(true); this.setResizable(true); this.setAutoscrolls(true); this.setClosable(true); this.setIconifiable(true); this.setDoubleBuffered(true); this.setContentPane(toile); this.setVisible(true); this.pack(); } } Basically, Panneau is the main Window that contains all the differents parts of the GUI. I can create as much JInternalFrame that I want, using : Panneau.createNewInternalFrame(). Toile is basically where I draw my shapes. Any idea ? Thanks

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  • Am I using EJBs properly?

    - by kgrad
    I am using a JEE6 stack including JPA 2.0, JSF 2.0, EJB 3.1 etc. The way my architecture is setup is the following: I have JPA annotated DAOs using hibernate as my JPA provider. I have JSF Managed beans which correspond to my facelet/xhtml pages. I have EJBs that handle all of my database requests. My XHTML pages have JSF EL which make calls to my Managed beans. My managed beans contain references to my DAO entities which are managed by EJBs. For example, I have a user entity which is mapped to a db table. I have a user EJB which handles all CRUD operations that return Users. I have a page that edits a user. The highlevel workflow would be: navigate to user edit page - EL calls a method located in the managed bean that loads a user. The method calls userEJB.loadUser(user) from the EJB to get the user from the database. The user is edited and submit - a function is called in the managed bean which calls a function in the EJB to save the user. etc. I am running into issues accessing my data within my JSF pages using EJBs. I am having a lot of problems with lazy initialization errors, which I believe is due to how I have set things up. For example, I have a Client entity that has a List of users which are lazily loaded. In order to get a client I call a method in my EJB which goes to the database, finds a client and returns it. Later on i wish to access this clients list of users, in order to do so i have to go back to the EJB by calling some sort of method in order to load those users (since they are lazily loaded). This means that I have to create a method such as public List<User> getUserListByClient(Client c) { c = em.merge(c); return c.getUserList(); } The only purpose of this method is to load the users (and I'm not even positive this approach is good or works). If i was doing session management myself, I would like just leave the session open for the entire request and access the property directly, this would be fine as the session would be open anyway, there seems to be this one extra layer of indirection in EJBs which is making things difficult for me. I do like EJBs as I like the fact that they are controlled by the container, pooled, offer transaction management for free etc. However, I get the feeling that I am using them incorrectly, or I have set up my JSF app incorrectly. Any feedback would be greatly appreciated. thanks,

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  • How to avoid this PDO exception: Cannot execute queries while other unbuffered queries are active

    - by Vittorio Vittori
    Hi, I'd like to print a simple table in my page with 3 columns, building name, tags and architecture style. If I try to retrieve the list of building names and arch. styles there is no problem: SELECT buildings.name, arch_styles.style_name FROM buildings INNER JOIN buildings_arch_styles ON buildings.id = buildings_arch_styles.building_id INNER JOIN arch_styles ON arch_styles.id = buildings_arch_styles.arch_style_id LIMIT 0, 10 My problem starts on retreaving the first 5 tags for every building of the query I've just wrote. SELECT DISTINCT name FROM tags INNER JOIN buildings_tags ON buildings_tags.tag_id = tags.id AND buildings_tags.building_id = 123 LIMIT 0, 5 The query itself works perfectly, but not where I thought to use it: <?php // pdo connection allready active, i'm using mysql $pdo_conn->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true); $sql = "SELECT buildings.name, buildings.id, arch_styles.style_name FROM buildings INNER JOIN buildings_arch_styles ON buildings.id = buildings_arch_styles.building_id INNER JOIN arch_styles ON arch_styles.id = buildings_arch_styles.arch_style_id LIMIT 0, 10"; $buildings_stmt = $pdo_conn->prepare ($sql); $buildings_stmt->execute (); $buildings = $buildings_stmt->fetchAll (PDO::FETCH_ASSOC); $sql = "SELECT DISTINCT name FROM tags INNER JOIN buildings_tags ON buildings_tags.tag_id = tags.id AND buildings_tags.building_id = :building_id LIMIT 0, 5"; $tags_stmt = $pdo_conn->prepare ($sql); $html = "<table>"; // i'll use it to print my table foreach ($buildings as $building) { $name = $building["name"]; $style = $building["style_name"]; $id = $building["id"]; $tags_stmt->bindParam (":building_id", $id, PDO::PARAM_INT); $tags_stmt->execute (); // the problem is HERE $tags = $tags_stmt->fetchAll (PDO::FETCH_ASSOC); $html .= "... $name ... $style"; foreach ($tags as $current_tag) { $tag = $current_tag["name"]; $html .= "... $tag ..."; // let's suppose this is an area of the table where I print the first 5 tags per building } } $html .= "...</table>"; print $html; I'm not experienced on queries, so i though something like this, but it throws the error: PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute. What can I do to avoid this? Should I change all and search a different way to get this kind of queries?

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  • Where to put a glossary of important terms and patterns in documentation?

    - by Tetha
    Greetings. I want to document certain patterns in the code in order to build up a consistent terminology (in order to easen communication about the software). I am, however, unsure, where to define the terms given. In order to get on the same level, an example: I have a code generator. This code generator receives a certain InputStructure from the Parser (yes, the name InputStructure might be less than ideal). This InputStructure is then transformed into various subsequent datastructures (like an abstract description of the validation process). Each of these datastructures can be either transformed into another value of the same datastructure or it can be transformed into the next datastructure. This should sound like Pipes and Filters to some degree. Given this, I call an operation which takes a datastructures and constructs a value of the same datastructure a transformation, while I call an operation which takes a datastructure and produces a different follow-up datastructure a derivation. The final step of deriving a string containing code is called emitting. (So, overall, the codegenerator takes the input-structure and transforms, transforms, derives, transforms, derives and finally emits). I think emphasizing these terms will be benefitial in communications, because then it is easy to talk about things. If you hear "transformation", you know "Ok, I only need to think about these two datastructures", if you hear "emitting", you know "Ok, I only need to know this datastructure and the target language.". However, where do I document these patterns? The current code base uses visitors and offers classes called like ValidatorTransformationBase<ResultType> (or InputStructureTransformationBase<ResultType>, and so one and so on). I do not really want to add the definition of such terms to the interfaces, because in that case, I'd have to repeat myself on each and every interface, which clearly violates DRY. I am considering to emphasize the distinction between Transformations and Derivations by adding further interfaces (I would have to think about a better name for the TransformationBase-classes, but then I could do thinks like ValidatorTransformation extends ValidatorTransformationBase<Validator>, or ValidatorDerivationFromInputStructure extends InputStructureTransformation<Validator>). I also think I should add a custom page to the doxygen documentation already existing, as in "Glossary" or "Architecture Principles", which contains such principles. The only disadvantage of this would be that a contributor will need to find this page in order to actually learn about this. Am I missing possibilities or am I judging something wrong here in your opinion? -- Regards, Tetha

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  • QT vs. Net - REAL comparisons for R.A.D. projects

    - by Pirate for Profit
    Man in all these Qt vs. .NET discussions 90% these people argue about the dumbest crap. Trying to get a real comparison chart here, because I know a little about both frameworks but I don't know everything. I believe Qt and .NET both have strengths and weaknesses. This is to make a comparison that highlights these so people can make more informed decisions before embarking on a project, in the spirit of R.A.D. Event Handling In Qt the event handling system is very simple. You just emit signals when something cool happens and then catch them in slots. ie. // run some calculations, then emit valueChanged(30, false, 20.2); and then catching it, any object can make a slot to recieve that message easily void MyObj::valueChanged(int percent, bool ok, float timeRemaining). It's easy to "block" an event or "disconnect" when needed, and works seamlessly across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, void valueChanged(object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET anonymous delegates are the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down for the simplest yet still flexible event handling system ever i m o. Plugins and such I do love some of the ease of C# compared to C++, as well as .NET's assembly architecture, even though it leads to a bunch of .dll's (there's ways to combine everything into a single exe though). That is a big bonus for modular projects, which are a PITA to import stuff in C++ as far as RAD is concerned. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. QConcurrent is the simplest threading mechanism I've ever played with. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? Doesn't the just-in-time compiler make native code that is pretty good, like and that only happens the first time the program is run? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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  • Qt vs .NET - a few comparisons [closed]

    - by Pirate for Profit
    Event Handling In Qt the event handling system you just emit signals when something cool happens and then catch them in slots, for instance emit valueChanged(int percent, bool something); and void MyCatcherObj::valueChanged(int p, bool ok){} blocking them and disconnecting them when needed, doing it across threads... once you get the hang of it, it just seems a lot more natural and intuitive than the way the .NET event handling is set up (you know, object sender, CustomEventArgs e). And I'm not just talking about syntax, because in the end the .NET delegate crap is the bomb. I'm also talking about in more than just reflection (because, yes, .NET obviously has much stronger reflection capabilities). I'm talking about in the way the system feels to a human being. Qt wins hands down i m o. Basically, the footprints make more sense and you can visualize the project easier without the clunky event handling system. I wish I could it explain it better. The only thing is, I do love some of the ease of C# compared to C++ and .NET's assembly architecture. That is a big bonus for modular projects, which are a PITA to do in C++. Database Ease of Doing Crap Also what about datasets and database manipulations. I think .net wins here but I'm not sure. Threading/Conccurency How do you guys think of the threading? In .NET, all I've ever done is make like a list of master worker threads with locks. I like QConcurrentFramework, you don't worry about locks or anything, and with the ease of the signal slot system across threads it's nice to get notified about the progress of things. Memory Usage Also what do you think of the overall memory usage comparison. Is the .NET garbage collector pretty on the ball and quick compared to the instantaneous nature of native memory management? Or does it just let programs leak up a storm and lag the computer then clean it up when it's about to really lag? However, I am a n00b who doesn't know what I'm talking about, please school me on the subject.

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  • Microsoft Access and Java JDBC-ODBC Error

    - by user1638362
    Trying to insert some values in a Microsoft access database using java. I can an error however, java.sql.SQLException: [Microsoft][ODBC Driver Manager] The specified DSN contains an architecture mismatch between the Driver and Application Exception in thread "main" java.lang.NullPointerException To create the data source im using SysWoW64 odbcad32 and adding it the datasource to system DNS. I say this as i have seen else where there are problems which occur with 64bit systems. However it still doesn't work for me. Microsoft Office 32bit. import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; public class RMIAuctionHouseJDBC { /** * @param args */ public static void main(String[] args) { String theItem = "Car"; String theClient="KHAN"; String theMessage="1001"; Connection conn =null; // Create connection object try{ Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); System.out.println("Driver Found"); } catch(Exception e) { System.out.println("Driver Not Found"); System.err.println(e); } // connecting to database try{ String database ="jdbc:odbc:Driver={Microsoft Access Driver (*.accdb)};DBQ=AuctionHouseDatabase.accdb;"; conn = DriverManager.getConnection(database,"",""); System.out.println("Conn Found"); } catch(SQLException se) { System.out.println("Conn Not Found"); System.err.println(se); } // Create select statement and execute it try{ /*String insertSQL = "INSERT INTO AuctionHouse VALUES ( " +"'" +theItem+"', " +"'" +theClient+"', " +"'" +theMessage+"')"; */ Statement stmt = conn.createStatement(); String insertSQL = "Insert into AuctionHouse VALUES ('Item','Name','Price')"; stmt.executeUpdate(insertSQL); // Retrieve the results conn.close(); } catch(SQLException se) { System.out.println("SqlStatment Not Found"); System.err.println(se); } } } java.sql.SQLException: [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified at sun.jdbc.odbc.JdbcOdbc.createSQLException(Unknown Source) at sun.jdbc.odbc.JdbcOdbc.standardError(Unknown Source) at sun.jdbc.odbc.JdbcOdbc.SQLDriverConnect(Unknown Source) at sun.jdbc.odbc.JdbcOdbcConnection.initialize(Unknown Source)

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  • Is it too early to start designing for Task Parallel Library?

    - by Joe Erickson
    I have been following the development of the .NET Task Parallel Library (TPL) with great interest since Microsoft first announced it. There is no doubt in my mind that we will eventually take advantage of TPL. What I am questioning is whether it makes sense to start taking advantage of TPL when Visual Studio 2010 and .NET 4.0 are released, or whether it makes sense to wait a while longer. Why Start Now? The .NET 4.0 Task Parallel Library appears to be well designed and some relatively simple tests demonstrate that it works well on today's multi-core CPUs. I have been very interested in the potential advantages of using multiple lightweight threads to speed up our software since buying my first quad processor Dell Poweredge 6400 about seven years ago. Experiments at that time indicated that it was not worth the effort, which I attributed largely to the overhead of moving data between each CPU's cache (there was no shared cache back then) and RAM. Competitive advantage - some of our customers can never get enough performance and there is no doubt that we can build a faster product using TPL today. It sounds fun. Yes, I realize that some developers would rather poke themselves in the eye with a sharp stick, but we really enjoy maximizing performance. Why Wait? Are today's Intel Nehalem CPUs representative of where we are going as multi-core support matures? You can purchase a Nehalem CPU with 4 cores which share a single level 3 cache today, and most likely a 6 core CPU sharing a single level 3 cache by the time Visual Studio 2010 / .NET 4.0 are released. Obviously, the number of cores will go up over time, but what about the architecture? As the number of cores goes up, will they still share a cache? One issue with Nehalem is the fact that, even though there is a very fast interconnect between the cores, they have non-uniform memory access (NUMA) which can lead to lower performance and less predictable results. Will future multi-core architectures be able to do away with NUMA? Similarly, will the .NET Task Parallel Library change as it matures, requiring modifications to code to fully take advantage of it? Limitations Our core engine is 100% C# and has to run without full trust, so we are limited to using .NET APIs.

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  • Binding functions of derived class with luabind

    - by Anamon
    I am currently developing a plugin-based system in C++ which provides a Lua scripting interface, for which I chose to use luabind. I'm using Lua 5 and luabind 0.9, both statically linked and compiled with MSVC++ 8. I am now having trouble binding functions with luabind when they are defined in a derived class, but not its parent class. More specifically, I have an abstract base class called 'IPlugin' from which all plugin classes inherit. When the plugin manager initialises, it registers that class and its functions like this: luabind::open(L); luabind::module(L) [ luabind::class_("IPlugin") .def("start", (void(IPlugin::*)())&IPlugin::start) ]; As it is only known at runtime what effective plugin classes are available, I had to solve loading plugins in a kind of roundabout way. The plugin manager exposes a factory function to Lua, which takes the name of a plugin class and a desired object name. The factory then creates the object, registers the plugin's class as inheriting from the 'IPlugin' base class, and immediately calls a function on the created object that registers itself as a global with the Lua state, like this: void PluginExample::registerLuaObject(lua_State *L, string a_name) { luabind::globals(L)[a_name] = (PluginExample*)this; } I initially did this because I had problems with Lua determining the most derived class of the object, as if I register it from the StreamManager it is only known as a subtype of 'IPlugin' and not the specific subtype. I'm not sure anymore if this is even necessary though, but it works and the created object is subsequently accessible from Lua under 'a_name'. The problem I have, though, is that functions defined in the derived class, which were not declared at all in the parent class, cannot be used. Virtual functions defined in the base class, such as 'start' above, work fine, and calling them from Lua on the new object runs the respective redefined code from the 'PluginExample' class. But if I add a new function to 'PluginExample', here for example a function taking no arguments and returning void, and register it like this: luabind::module(L) [ luabind::class_("PluginExample") .def(luabind::constructor()) .def("func", &PluginExample::func) ]; calling 'func' on the new object yields the following Lua runtime error: No matching overload found, candidates: void func(PluginExample&) I am correctly using the ':' syntax so the 'self' argument is not needed and it seems suddenly Lua cannot determine the derived type of the object anymore. I am sure I am doing something wrong, probably having to do with the two-step binding required by my system architecture, but I can't figure out where. I'd much appreciate some help =)

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  • In a DDD approach, is this example modelled correctly?

    - by Tag
    Just created an acc on SO to ask this :) Assuming this simplified example: building a web application to manage projects... The application has the following requirements/rules. 1) Users should be able to create projects inserting the project name. 2) Project names cannot be empty. 3) Two projects can't have the same name. I'm using a 4-layered architecture (User Interface, Application, Domain, Infrastructure). On my Application Layer i have the following ProjectService.cs class: public class ProjectService { private IProjectRepository ProjectRepo { get; set; } public ProjectService(IProjectRepository projectRepo) { ProjectRepo = projectRepo; } public void CreateNewProject(string name) { IList<Project> projects = ProjectRepo.GetProjectsByName(name); if (projects.Count > 0) throw new Exception("Project name already exists."); Project project = new Project(name); ProjectRepo.InsertProject(project); } } On my Domain Layer, i have the Project.cs class and the IProjectRepository.cs interface: public class Project { public int ProjectID { get; private set; } public string Name { get; private set; } public Project(string name) { ValidateName(name); Name = name; } private void ValidateName(string name) { if (name == null || name.Equals(string.Empty)) { throw new Exception("Project name cannot be empty or null."); } } } public interface IProjectRepository { void InsertProject(Project project); IList<Project> GetProjectsByName(string projectName); } On my Infrastructure layer, i have the implementation of IProjectRepository which does the actual querying (the code is irrelevant). I don't like two things about this design: 1) I've read that the repository interfaces should be a part of the domain but the implementations should not. That makes no sense to me since i think the domain shouldn't call the repository methods (persistence ignorance), that should be a responsability of the services in the application layer. (Something tells me i'm terribly wrong.) 2) The process of creating a new project involves two validations (not null and not duplicate). In my design above, those two validations are scattered in two different places making it harder (imho) to see whats going on. So, my question is, from a DDD perspective, is this modelled correctly or would you do it in a different way?

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  • Square Peg Web: Gets you the traffic to where it matters most: Your Website!

    - by demetriusalwyn
    Have you decided to start your business online or is your business not reaching the targeted audience? Come to Square Peg Web; where you will find what you want to make your business reach new heights. The team at Square Peg Web is professionals who understand what you want and make sure you get it right. Our confidence stems from the fact of thousands of satisfied clients who keep referring friends and business associates to us and we do not let our clients down. Many companies promise the sky but how far is does their work live up to the promises? We do not know about the others however, we are sure that we strive to put together all our ideas and thoughts to make your website rank among the top. Web hosting is something that needs to have a personal touch; Square Peg Web customizes everything to suit your requirements so that you do not have to look further. With Square Peg Web you have a host of features to make your Business go viral. Some of the product details that are offered with Square Peg Web are unlimited product options/ variants/ properties giving you an option on price modifiers. You get unlimited customized input fields for your products and you can also Customer-define the prices. Square Peg Web provides you an option of using multiple product images with zoom features and one can also list a particular product in several categories. There are other aspects which make Square Peg Web the best choice for your website needs; every sale of yours’ is important to you and to us. We make sure that each sale is tracked by the product and also the list of bestsellers that appeal to the audience. Other comprehensive statistics of Square Peg Web includes searchable order data, an interface for shipments and order fulfillments, export sales & customer data for usage in a spreadsheet and the ability to export orders to QuickBooks format. With Square Peg Web; Admin Panel is a lot simpler. Administrative access is completely password protected and any changes done are all in real-time. You can have absolute control on the cart from anywhere around the world using your web browser and the topping on the cake is the unlimited amount of admin accounts that can be created for you. Square Peg Web offers you a world of experience with the options of choosing from marketing websites to e-commerce and from customized applications to community oriented sites. Some of the projects which appear in the portfolio of Square Peg Web are Online Marketing Web Sites, E-Commerce Web Sites, customized web applications, Blog designing and programming, video sharing and the option of downloading web sites, online advertisements, flash animation, customer and product support web sites, web site re-designing and planning and complete information architecture.

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  • Make a compiled binary run at native speed flawlessly without recompiling from source on a another system?

    - by unknownthreat
    I know that many people, at a first glance of the question, may immediately yell out "Java", but no, I know Java's qualities. Allow me to elaborate my question first. Normally, when we want our program to run at a native speed on a system, whether it be Windows, Mac OS X, or Linux, we need to compile from source codes. If you want to run a program of another system in your system, you need to use a virtual machine or an emulator. While these tools allow you to use the program you need on the non-native OS, they sometimes have problems of performance and glitches. We also have a newer compiler called "JIT Compiler", where the compiler will parse the bytecode program to native machine language before execution. The performance may increase to a very good extent with JIT Compiler, but the performance is still not the same as running it on a native system. Another program on Linux, WINE, is also a good tool for running Windows program on Linux system. I have tried running Team Fortress 2 on it, and tried experiment with some settings. I got ~40 fps on Windows at its mid-high setting on 1280 x 1024. On Linux, I need to turn everything low at 1280 x 1024 to get ~40 fps. There are 2 notable things though: Polygon model settings do not seem to affect framerate whether I set it low or high. When there are post-processing effects or some special effects that require manipulation of drawn pixels of the current frame, the framerate will drop to 10-20 fps. From this point, I can see that normal polygon rendering is just fine, but when it comes to newer rendering methods that requires graphic card to the job, it slows down to a crawl. Anyway, this question is rather theoretical. Is there anything we can do at all? I see that WINE can run STEAM and Team Fortress 2. Although there are flaws, they can run at lower setting. Or perhaps, I should also ask, "is it possible to translate one whole program on a system to another system without recompiling from source and get native speed?" I see that we also have AOT Compiler, is it possible to use it for something like this? Or there are so many constraints (such as DirectX call or differences in software architecture) that make it impossible to have a flawless and not native to the system program that runs at native speed?

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  • Hide a base class method from derived class, but still visible outside of assembly

    - by clintp
    This is a question about tidyness. The project is already working, I'm satisfied with the design but I have a couple of loose ends that I'd like to tie up. My project has a plugin architecture. The main body of the program dispatches work to the plugins that each reside in their own AppDomain. The plugins are described with an interface, which is used by the main program (to get the signature for invoking DispatchTaskToPlugin) and by the plugins themselves as an API contract: namespace AppServer.Plugin.Common { public interface IAppServerPlugin { void Register(); void DispatchTaskToPlugin(Task t); // Other methods omitted } } In the main body of the program Register() is called so that the plugin can register its callback methods with the base class, and then later DispatchTaskToPlugin() is called to get the plugin running. The plugins themselves are in two parts. There's a base class that implements the framework for the plugin (setup, housekeeping, teardown, etc..). This is where DispatchTaskToPlugin is actually defined: namespace AppServer.Plugin { abstract public class BasePlugin : MarshalByRefObject, AppServer.Plugin.Common.IAppServerPlugin { public void DispatchTaskToPlugin(Task t) { // ... // Eventual call to actual plugin code // } // Other methods omitted } } The actual plugins themselves only need to implement a Register() method (to give the base class the delegates to call eventually) and then their business logic. namespace AppServer.Plugin { public class Plugin : BasePlugin { override public void Register() { // Calls a method in the base class to register itself. } // Various callback methods, business logic, etc... } } Now in the base class (BasePlugin) I've implemented all kinds of convenience methods, collected data, etc.. for the plugins to use. Everything's kosher except for that lingering method DispatchTaskToPlugin(). It's not supposed to be callable from the Plugin class implementations -- they have no use for it. It's only needed by the dispatcher in the main body of the program. How can I prevent the derived classes (Plugin) from seeing the method in the base class (BasePlugin/DispatchTaskToPlugin) but still have it visible from outside of the assembly? I can split hairs and have DispatchTaskToPlugin() throw an exception if it's called from the derived classes, but that's closing the barn door a little late. I'd like to keep it out of Intellisense or possibly have the compiler take care of this for me. Suggestions?

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  • WLI domain with 3 servers - issues on JPD process startup

    - by XpiritO
    Hi there. I'm currently working on a clustered WLI environment which comprehends 3 servers: 1 admin server ("AdminServer") and 2 managed servers ("mn1" and "mn2") grouped as a cluster, as follows: Architecture diagram: http://img72.imageshack.us/img72/4112/clusterdiagram.jpg I've developed a JPD process to execute some scheduled tasks, invoked using a Message Broker. I've deployed this project into a single-server WLI domain (with AdminServer only) and it works as expected: the JPD process is invoked (I've configured a Timer Event Generator instance to start it up). Message broker: http://img532.imageshack.us/img532/1443/wlimessagebroker.jpg Timer event generator: http://img408.imageshack.us/img408/7358/wlitimereventgenerator.jpg In order to achieve fail-over and load-balancing capabilities, I'm currently trying to deploy this JPD process into this clustered WLI environment. Although, I'm having some issues with this, as I cannot get it to work properly, even if it still works. Here is a screenshot of the "WLI Process Instance Monitor" (with AdminServer and mn1 instances up and running): http://img710.imageshack.us/img710/8477/wliprocessinstancemonit.jpg According to this screen the process seems to be running, as it shows in this instance monitor screen. However, I don't see any output coming out neither at AdminServer console or mn1 console. In single-server domain it was visible output from JPD process "timeout" callback method, wich implementation is shown below: @com.bea.wli.control.broker.MessageBroker.StaticSubscription(xquery = "", filterValueMatch = "", channelName = "/SamplePrefix/Samples/SampleStringChannel", messageBody = "{x0}") public void subscription(java.lang.String x0) { String toReturn=""; try { Context myCtx = new InitialContext(); MBeanHome mbeanHome = (MBeanHome)myCtx.lookup("weblogic.management.home.localhome"); toReturn=mbeanHome.getMBeanServer().getServerName(); System.out.println("**** executed at **** " + System.currentTimeMillis() + " by: " + toReturn); } catch (Exception e) { System.out.println("Exception!"); e.printStackTrace(); } } (...) @org.apache.beehive.controls.api.events.EventHandler(field = "myT", eventSet = com.bea.control.WliTimerControl.Callback.class, eventName = "onTimeout") public void myT_onTimeout(long time, java.io.Serializable data) { // #START: CODE GENERATED - PROTECTED SECTION - you can safely add code above this comment in this method. #// // input transform System.out.println("**** published at **** " + System.currentTimeMillis()); publishControl.publish("aaaa"); // parameter assignment // #END : CODE GENERATED - PROTECTED SECTION - you can safely add code below this comment in this method. #// } and here is the output visible at "AdminServer" console in single-server domain testing: **** published at **** 1273238090713 **** executed at **** 1273238132123 by: AdminServer **** published at **** 1273238152462 **** executed at **** 1273238152562 by: AdminServer (...) What may be wrong with my clustered configuration? Am I missing something to accomplish clustered deployment? Thanks in advance for your help.

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  • Error building C program

    - by John
    Here are my 2 source files: main.c: #include <stdio.h> #include "part2.c" extern int var1; extern int array1[]; int main() { var1 = 4; array1[0] = 2; array1[1] = 4; array1[2] = 5; array1[3] = 7; display(); printf("---------------"); printf("Var1: %d", var1); printf("array elements:"); int x; for(x = 0;x < 4;++x) printf("%d: %d", x, array1[x]); return 0; } part2.c #include <stdio.h> int var1; int array1[4]; void display(void); void display(void) { printf("Var1: %d", var1); printf("array elements:"); int x; for(x = 0;x < 4;++x) printf("%d: %d", x, array1[x]); } When i try to compile the program this is what i get: Ld /Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Products/Debug/Test normal x86_64 cd /Users/John/Xcode/Test setenv MACOSX_DEPLOYMENT_TARGET 10.7 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.7.sdk -L/Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Products/Debug -F/Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Products/Debug -filelist /Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Intermediates/Test.build/Debug/Test.build/Objects-normal/x86_64/Test.LinkFileList -mmacosx-version-min=10.7 -o /Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Products/Debug/Test ld: duplicate symbol _display in /Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Intermediates/Test.build/Debug/Test.build/Objects-normal/x86_64/part2.o and /Users/John/Library/Developer/Xcode/DerivedData/Test-blxrdmnozbbrbwhcekmouessaprf/Build/Intermediates/Test.build/Debug/Test.build/Objects-normal/x86_64/main.o for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) I am using Xcode and both files are inside of a C project called Test What is causing the error and how do i fix it?

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  • Which network protocol to use for lightweight notification of remote apps?

    - by Chris Thornton
    I have this situation.... Client-initiated SOAP 1.1 communication between one server and let's say, tens of thousands of clients. Clients are external, coming in through our firewall, authenticated by certificate, https, etc.. They can be anywhere, and usually have their own firewalls, NAT routers, etc... They're truely external, not just remote corporate offices. They could be in a corporate/campus network, DSL/Cable, even Dialup. Client uses Delphi (2005 + SOAP fixes from 2007), and the server is C#, but from an architecture/design standpoint, that shouldn't matter. Currently, clients push new data to the server and pull new data from the server on 15-minute polling loop. The server currently does not push data - the client hits the "messagecount" method, to see if there is new data to pull. If 0, it sleeps for another 15 min and checks again. We're trying to get that down to 7 seconds. If this were an internal app, with one or just a few dozen clients, we'd write a cilent "listener" soap service, and would push data to it. But since they're external, sit behind their own firewalls, and sometimes private networks behind NAT routers, this is not practical. So we're left with polling on a much quicker loop. 10K clients, each checking their messagecount every 10 seconds, is going to be 1000/sec messages that will mostly just waste bandwidth, server, firewall, and authenticator resources. So I'm trying to design something better than what would amount to a self-inflicted DoS attack. I don't think it's practical to have the server send soap messages to the client (push) as this would require too much configuration at the client end. But I think there are alternatives that I don't know about. Such as: 1) Is there a way for the client to make a request for GetMessageCount() via Soap 1.1, and get the response, and then perhaps, "stay on the line" for perhaps 5-10 minutes to get additional responses in case new data arrives? i.e the server says "0", then a minute later in response to some SQL trigger (the server is C# on Sql Server, btw), knows that this client is still "on the line" and sends the updated message count of "5"? 2) Is there some other protocol that we could use to "ping" the client, using information gathered from their last GetMessageCount() request? 3) I don't even know. I guess I'm looking for some magic protocol where the client can send a GetMessageCount() request, which would include info for "oh by the way, in case the answer changes in the next hour, ping me at this address...". Also, I'm assuming that any of these "keep the line open" schemes would seriously impact the server sizing, as it would need to keep many thousands of connections open, simultaneously. That would likely impact the firewalls too, I think. Is there anything out there like that? Or am I pretty much stuck with polling? TIA, Chris

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