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  • JMS Step 6 - How to Set Up an AQ JMS (Advanced Queueing JMS) for SOA Purposes

    - by John-Brown.Evans
    JMS Step 6 - How to Set Up an AQ JMS (Advanced Queueing JMS) for SOA Purposes .jblist{list-style-type:disc;margin:0;padding:0;padding-left:0pt;margin-left:36pt} ol{margin:0;padding:0} .c17_6{vertical-align:top;width:468pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c5_6{vertical-align:top;border-style:solid;border-color:#000000;border-width:1pt;padding:0pt 5pt 0pt 5pt} .c6_6{vertical-align:top;width:156pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c15_6{background-color:#ffffff} .c10_6{color:#1155cc;text-decoration:underline} .c1_6{text-align:center;direction:ltr} .c0_6{line-height:1.0;direction:ltr} .c16_6{color:#666666;font-size:12pt} .c18_6{color:inherit;text-decoration:inherit} .c8_6{background-color:#f3f3f3} .c2_6{direction:ltr} .c14_6{font-size:8pt} .c11_6{font-size:10pt} .c7_6{font-weight:bold} .c12_6{height:0pt} .c3_6{height:11pt} .c13_6{border-collapse:collapse} .c4_6{font-family:"Courier New"} .c9_6{font-style:italic} .title{padding-top:24pt;line-height:1.15;text-align:left;color:#000000;font-size:36pt;font-family:"Arial";font-weight:bold;padding-bottom:6pt} .subtitle{padding-top:18pt;line-height:1.15;text-align:left;color:#666666;font-style:italic;font-size:24pt;font-family:"Georgia";padding-bottom:4pt} li{color:#000000;font-size:10pt;font-family:"Arial"} p{color:#000000;font-size:10pt;margin:0;font-family:"Arial"} h1{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:24pt;font-family:"Arial";font-weight:normal} h2{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:18pt;font-family:"Arial";font-weight:normal} h3{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:14pt;font-family:"Arial";font-weight:normal} h4{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:12pt;font-family:"Arial";font-weight:normal} h5{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:11pt;font-family:"Arial";font-weight:normal} h6{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:10pt;font-family:"Arial";font-weight:normal} This post continues the series of JMS articles which demonstrate how to use JMS queues in a SOA context. The previous posts were: JMS Step 1 - How to Create a Simple JMS Queue in Weblogic Server 11g JMS Step 2 - Using the QueueSend.java Sample Program to Send a Message to a JMS Queue JMS Step 3 - Using the QueueReceive.java Sample Program to Read a Message from a JMS Queue JMS Step 4 - How to Create an 11g BPEL Process Which Writes a Message Based on an XML Schema to a JMS Queue JMS Step 5 - How to Create an 11g BPEL Process Which Reads a Message Based on an XML Schema from a JMS Queue This example leads you through the creation of an Oracle database Advanced Queue and the related WebLogic server objects in order to use AQ JMS in connection with a SOA composite. If you have not already done so, I recommend you look at the previous posts in this series, as they include steps which this example builds upon. The following examples will demonstrate how to write and read from the queue from a SOA process. 1. Recap and Prerequisites In the previous examples, we created a JMS Queue, a Connection Factory and a Connection Pool in the WebLogic Server Console. Then we wrote and deployed BPEL composites, which enqueued and dequeued a simple XML payload. AQ JMS allows you to interoperate with database Advanced Queueing via JMS in WebLogic server and therefore take advantage of database features, while maintaining compliance with the JMS architecture. AQ JMS uses the WebLogic JMS Foreign Server framework. A full description of this functionality can be found in the following Oracle documentation Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server 11g Release 1 (10.3.6) Part Number E13738-06 7. Interoperating with Oracle AQ JMS http://docs.oracle.com/cd/E23943_01/web.1111/e13738/aq_jms.htm#CJACBCEJ For easier reference, this sample will use the same names for the objects as in the above document, except for the name of the database user, as it is possible that this user already exists in your database. We will create the following objects Database Objects Name Type AQJMSUSER Database User MyQueueTable Advanced Queue (AQ) Table UserQueue Advanced Queue WebLogic Server Objects Object Name Type JNDI Name aqjmsuserDataSource Data Source jdbc/aqjmsuserDataSource AqJmsModule JMS System Module AqJmsForeignServer JMS Foreign Server AqJmsForeignServerConnectionFactory JMS Foreign Server Connection Factory AqJmsForeignServerConnectionFactory AqJmsForeignDestination AQ JMS Foreign Destination queue/USERQUEUE eis/aqjms/UserQueue Connection Pool eis/aqjms/UserQueue 2. Create a Database User and Advanced Queue The following steps can be executed in the database client of your choice, e.g. JDeveloper or SQL Developer. The examples below use SQL*Plus. Log in to the database as a DBA user, for example SYSTEM or SYS. Create the AQJMSUSER user and grant privileges to enable the user to create AQ objects. Create Database User and Grant AQ Privileges sqlplus system/password as SYSDBA GRANT connect, resource TO aqjmsuser IDENTIFIED BY aqjmsuser; GRANT aq_user_role TO aqjmsuser; GRANT execute ON sys.dbms_aqadm TO aqjmsuser; GRANT execute ON sys.dbms_aq TO aqjmsuser; GRANT execute ON sys.dbms_aqin TO aqjmsuser; GRANT execute ON sys.dbms_aqjms TO aqjmsuser; Create the Queue Table and Advanced Queue and Start the AQ The following commands are executed as the aqjmsuser database user. Create the Queue Table connect aqjmsuser/aqjmsuser; BEGIN dbms_aqadm.create_queue_table ( queue_table = 'myQueueTable', queue_payload_type = 'sys.aq$_jms_text_message', multiple_consumers = false ); END; / Create the AQ BEGIN dbms_aqadm.create_queue ( queue_name = 'userQueue', queue_table = 'myQueueTable' ); END; / Start the AQ BEGIN dbms_aqadm.start_queue ( queue_name = 'userQueue'); END; / The above commands can be executed in a single PL/SQL block, but are shown as separate blocks in this example for ease of reference. You can verify the queue by executing the SQL command SELECT object_name, object_type FROM user_objects; which should display the following objects: OBJECT_NAME OBJECT_TYPE ------------------------------ ------------------- SYS_C0056513 INDEX SYS_LOB0000170822C00041$$ LOB SYS_LOB0000170822C00040$$ LOB SYS_LOB0000170822C00037$$ LOB AQ$_MYQUEUETABLE_T INDEX AQ$_MYQUEUETABLE_I INDEX AQ$_MYQUEUETABLE_E QUEUE AQ$_MYQUEUETABLE_F VIEW AQ$MYQUEUETABLE VIEW MYQUEUETABLE TABLE USERQUEUE QUEUE Similarly, you can view the objects in JDeveloper via a Database Connection to the AQJMSUSER. 3. Configure WebLogic Server and Add JMS Objects All these steps are executed from the WebLogic Server Administration Console. Log in as the webLogic user. Configure a WebLogic Data Source The data source is required for the database connection to the AQ created above. Navigate to domain > Services > Data Sources and press New then Generic Data Source. Use the values:Name: aqjmsuserDataSource JNDI Name: jdbc/aqjmsuserDataSource Database type: Oracle Database Driver: *Oracle’ Driver (Thin XA) for Instance connections; Versions:9.0.1 and later Connection Properties: Enter the connection information to the database containing the AQ created above and enter aqjmsuser for the User Name and Password. Press Test Configuration to verify the connection details and press Next. Target the data source to the soa server. The data source will be displayed in the list. It is a good idea to test the data source at this stage. Click on aqjmsuserDataSource, select Monitoring > Testing > soa_server1 and press Test Data Source. The result is displayed at the top of the page. Configure a JMS System Module The JMS system module is required to host the JMS foreign server for AQ resources. Navigate to Services > Messaging > JMS Modules and select New. Use the values: Name: AqJmsModule (Leave Descriptor File Name and Location in Domain empty.) Target: soa_server1 Click Finish. The other resources will be created in separate steps. The module will be displayed in the list.   Configure a JMS Foreign Server A foreign server is required in order to reference a 3rd-party JMS provider, in this case the database AQ, within a local WebLogic server JNDI tree. Navigate to Services > Messaging > JMS Modules and select (click on) AqJmsModule to configure it. Under Summary of Resources, select New then Foreign Server. Name: AqJmsForeignServer Targets: The foreign server is targeted automatically to soa_server1, based on the JMS module’s target. Press Finish to create the foreign server. The foreign server resource will be listed in the Summary of Resources for the AqJmsModule, but needs additional configuration steps. Click on AqJmsForeignServer and select Configuration > General to complete the configuration: JNDI Initial Context Factory: oracle.jms.AQjmsInitialContextFactory JNDI Connection URL: <empty> JNDI Properties Credential:<empty> Confirm JNDI Properties Credential: <empty> JNDI Properties: datasource=jdbc/aqjmsuserDataSource This is an important property. It is the JNDI name of the data source created above, which points to the AQ schema in the database and must be entered as a name=value pair, as in this example, e.g. datasource=jdbc/aqjmsuserDataSource, including the “datasource=” property name. Default Targeting Enabled: Leave this value checked. Press Save to save the configuration. At this point it is a good idea to verify that the data source was written correctly to the config file. In a terminal window, navigate to $MIDDLEWARE_HOME/user_projects/domains/soa_domain/config/jms  and open the file aqjmsmodule-jms.xml . The foreign server configuration should contain the datasource name-value pair, as follows:   <foreign-server name="AqJmsForeignServer">         <default-targeting-enabled>true</default-targeting-enabled>         <initial-context-factory>oracle.jms.AQjmsInitialContextFactory</initial-context-factory>         <jndi-property>           <key> datasource </key>           <value> jdbc/aqjmsuserDataSource </value>         </jndi-property>   </foreign-server> </weblogic-jms> Configure a JMS Foreign Server Connection Factory When creating the foreign server connection factory, you enter local and remote JNDI names. The name of the connection factory itself and the local JNDI name are arbitrary, but the remote JNDI name must match a specific format, depending on the type of queue or topic to be accessed in the database. This is very important and if the incorrect value is used, the connection to the queue will not be established and the error messages you get will not immediately reflect the cause of the error. The formats required (Remote JNDI names for AQ JMS Connection Factories) are described in the section Configure AQ Destinations  of the Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server document mentioned earlier. In this example, the remote JNDI name used is   XAQueueConnectionFactory  because it matches the AQ and data source created earlier, i.e. thin with AQ. Navigate to JMS Modules > AqJmsModule > AqJmsForeignServer > Connection Factories then New.Name: AqJmsForeignServerConnectionFactory Local JNDI Name: AqJmsForeignServerConnectionFactory Note: this local JNDI name is the JNDI name which your client application, e.g. a later BPEL process, will use to access this connection factory. Remote JNDI Name: XAQueueConnectionFactory Press OK to save the configuration. Configure an AQ JMS Foreign Server Destination A foreign server destination maps the JNDI name on the foreign JNDI provider to the respective local JNDI name, allowing the foreign JNDI name to be accessed via the local server. As with the foreign server connection factory, the local JNDI name is arbitrary (but must be unique), but the remote JNDI name must conform to a specific format defined in the section Configure AQ Destinations  of the Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server document mentioned earlier. In our example, the remote JNDI name is Queues/USERQUEUE , because it references a queue (as opposed to a topic) with the name USERQUEUE. We will name the local JNDI name queue/USERQUEUE, which is a little confusing (note the missing “s” in “queue), but conforms better to the JNDI nomenclature in our SOA server and also allows us to differentiate between the local and remote names for demonstration purposes. Navigate to JMS Modules > AqJmsModule > AqJmsForeignServer > Destinations and select New.Name: AqJmsForeignDestination Local JNDI Name: queue/USERQUEUE Remote JNDI Name:Queues/USERQUEUE After saving the foreign destination configuration, this completes the JMS part of the configuration. We still need to configure the JMS adapter in order to be able to access the queue from a BPEL processt. 4. Create a JMS Adapter Connection Pool in Weblogic Server Create the Connection Pool Access to the AQ JMS queue from a BPEL or other SOA process in our example is done via a JMS adapter. To enable this, the JmsAdapter in WebLogic server needs to be configured to have a connection pool which points to the local connection factory JNDI name which was created earlier. Navigate to Deployments > Next and select (click on) the JmsAdapter. Select Configuration > Outbound Connection Pools and New. Check the radio button for oracle.tip.adapter.jms.IJmsConnectionFactory and press Next. JNDI Name: eis/aqjms/UserQueue Press Finish Expand oracle.tip.adapter.jms.IJmsConnectionFactory and click on eis/aqjms/UserQueue to configure it. The ConnectionFactoryLocation must point to the foreign server’s local connection factory name created earlier. In our example, this is AqJmsForeignServerConnectionFactory . As a reminder, this connection factory is located under JMS Modules > AqJmsModule > AqJmsForeignServer > Connection Factories and the value needed here is under Local JNDI Name. Enter AqJmsForeignServerConnectionFactory  into the Property Value field for ConnectionFactoryLocation. You must then press Return/Enter then Save for the value to be accepted. If your WebLogic server is running in Development mode, you should see the message that the changes have been activated and the deployment plan successfully updated. If not, then you will manually need to activate the changes in the WebLogic server console.Although the changes have been activated, the JmsAdapter needs to be redeployed in order for the changes to become effective. This should be confirmed by the message Remember to update your deployment to reflect the new plan when you are finished with your changes. Redeploy the JmsAdapter Navigate back to the Deployments screen, either by selecting it in the left-hand navigation tree or by selecting the “Summary of Deployments” link in the breadcrumbs list at the top of the screen. Then select the checkbox next to JmsAdapter and press the Update button. On the Update Application Assistant page, select “Redeploy this application using the following deployment files” and press Finish. After a few seconds you should get the message that the selected deployments were updated. The JMS adapter configuration is complete and it can now be used to access the AQ JMS queue. You can verify that the JNDI name was created correctly, by navigating to Environment > Servers > soa_server1 and View JNDI Tree. Then scroll down in the JNDI Tree Structure to eis and select aqjms. This concludes the sample. In the following post, I will show you how to create a BPEL process which sends a message to this advanced queue via JMS. Best regards John-Brown Evans Oracle Technology Proactive Support Delivery

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  • ASP.NET MVC 3: Layouts and Sections with Razor

    - by ScottGu
    This is another in a series of posts I’m doing that cover some of the new ASP.NET MVC 3 features: Introducing Razor (July 2nd) New @model keyword in Razor (Oct 19th) Layouts with Razor (Oct 22nd) Server-Side Comments with Razor (Nov 12th) Razor’s @: and <text> syntax (Dec 15th) Implicit and Explicit code nuggets with Razor (Dec 16th) Layouts and Sections with Razor (Today) In today’s post I’m going to go into more details about how Layout pages work with Razor.  In particular, I’m going to cover how you can have multiple, non-contiguous, replaceable “sections” within a layout file – and enable views based on layouts to optionally “fill in” these different sections at runtime.  The Razor syntax for doing this is clean and concise. I’ll also show how you can dynamically check at runtime whether a particular layout section has been defined, and how you can provide alternate content (or even an alternate layout) in the event that a section isn’t specified within a view template.  This provides a powerful and easy way to customize the UI of your site and make it clean and DRY from an implementation perspective. What are Layouts? You typically want to maintain a consistent look and feel across all of the pages within your web-site/application.  ASP.NET 2.0 introduced the concept of “master pages” which helps enable this when using .aspx based pages or templates.  Razor also supports this concept with a feature called “layouts” – which allow you to define a common site template, and then inherit its look and feel across all the views/pages on your site. I previously discussed the basics of how layout files work with Razor in my ASP.NET MVC 3: Layouts with Razor blog post.  Today’s post will go deeper and discuss how you can define multiple, non-contiguous, replaceable regions within a layout file that you can then optionally “fill in” at runtime. Site Layout Scenario Let’s look at how we can implement a common site layout scenario with ASP.NET MVC 3 and Razor.  Specifically, we’ll implement some site UI where we have a common header and footer on all of our pages.  We’ll also add a “sidebar” section to the right of our common site layout.  On some pages we’ll customize the SideBar to contain content specific to the page it is included on: And on other pages (that do not have custom sidebar content) we will fall back and provide some “default content” to the sidebar: We’ll use ASP.NET MVC 3 and Razor to enable this customization in a nice, clean way.  Below are some step-by-step tutorial instructions on how to build the above site with ASP.NET MVC 3 and Razor. Part 1: Create a New Project with a Layout for the “Body” section We’ll begin by using the “File->New Project” menu command within Visual Studio to create a new ASP.NET MVC 3 Project.  We’ll create the new project using the “Empty” template option: This will create a new project that has no default controllers in it: Creating a HomeController We will then right-click on the “Controllers” folder of our newly created project and choose the “Add->Controller” context menu command.  This will bring up the “Add Controller” dialog: We’ll name the new controller we create “HomeController”.  When we click the “Add” button Visual Studio will add a HomeController class to our project with a default “Index” action method that returns a view: We won’t need to write any Controller logic to implement this sample – so we’ll leave the default code as-is.  Creating a View Template Our next step will be to implement the view template associated with the HomeController’s Index action method.  To implement the view template, we will right-click within the “HomeController.Index()” method and select the “Add View” command to create a view template for our home page: This will bring up the “Add View” dialog within Visual Studio.  We do not need to change any of the default settings within the above dialog (the name of the template was auto-populated to Index because we invoked the “Add View” context menu command within the Index method).  When we click the “Add” Button within the dialog, a Razor-based “Index.cshtml” view template will be added to the \Views\Home\ folder within our project.  Let’s add some simple default static content to it: Notice above how we don’t have an <html> or <body> section defined within our view template.  This is because we are going to rely on a layout template to supply these elements and use it to define the common site layout and structure for our site (ensuring that it is consistent across all pages and URLs within the site).  Customizing our Layout File Let’s open and customize the default “_Layout.cshtml” file that was automatically added to the \Views\Shared folder when we created our new project: The default layout file (shown above) is pretty basic and simply outputs a title (if specified in either the Controller or the View template) and adds links to a stylesheet and jQuery.  The call to “RenderBody()” indicates where the main body content of our Index.cshtml file will merged into the output sent back to the browser. Let’s modify the Layout template to add a common header, footer and sidebar to the site: We’ll then edit the “Site.css” file within the \Content folder of our project and add 4 CSS rules to it: And now when we run the project and browse to the home “/” URL of our project we’ll see a page like below: Notice how the content of the HomeController’s Index view template and the site’s Shared Layout template have been merged together into a single HTML response.  Below is what the HTML sent back from the server looks like: Part 2: Adding a “SideBar” Section Our site so far has a layout template that has only one “section” in it – what we call the main “body” section of the response.  Razor also supports the ability to add additional "named sections” to layout templates as well.  These sections can be defined anywhere in the layout file (including within the <head> section of the HTML), and allow you to output dynamic content to multiple, non-contiguous, regions of the final response. Defining the “SideBar” section in our Layout Let’s update our Layout template to define an additional “SideBar” section of content that will be rendered within the <div id=”sidebar”> region of our HTML.  We can do this by calling the RenderSection(string sectionName, bool required) helper method within our Layout.cshtml file like below:   The first parameter to the “RenderSection()” helper method specifies the name of the section we want to render at that location in the layout template.  The second parameter is optional, and allows us to define whether the section we are rendering is required or not.  If a section is “required”, then Razor will throw an error at runtime if that section is not implemented within a view template that is based on the layout file (which can make it easier to track down content errors).  If a section is not required, then its presence within a view template is optional, and the above RenderSection() code will render nothing at runtime if it isn’t defined. Now that we’ve made the above change to our layout file, let’s hit refresh in our browser and see what our Home page now looks like: Notice how we currently have no content within our SideBar <div> – that is because the Index.cshtml view template doesn’t implement our new “SideBar” section yet. Implementing the “SideBar” Section in our View Template Let’s change our home-page so that it has a SideBar section that outputs some custom content.  We can do that by opening up the Index.cshtml view template, and by adding a new “SiderBar” section to it.  We’ll do this using Razor’s @section SectionName { } syntax: We could have put our SideBar @section declaration anywhere within the view template.  I think it looks cleaner when defined at the top or bottom of the file – but that is simply personal preference.  You can include any content or code you want within @section declarations.  Notice above how I have a C# code nugget that outputs the current time at the bottom of the SideBar section.  I could have also written code that used ASP.NET MVC’s HTML/AJAX helper methods and/or accessed any strongly-typed model objects passed to the Index.cshtml view template. Now that we’ve made the above template changes, when we hit refresh in our browser again we’ll see that our SideBar content – that is specific to the Home Page of our site – is now included in the page response sent back from the server: The SideBar section content has been merged into the proper location of the HTML response : Part 3: Conditionally Detecting if a Layout Section Has Been Implemented Razor provides the ability for you to conditionally check (from within a layout file) whether a section has been defined within a view template, and enables you to output an alternative response in the event that the section has not been defined.  This provides a convenient way to specify default UI for optional layout sections.  Let’s modify our Layout file to take advantage of this capability.  Below we are conditionally checking whether the “SideBar” section has been defined without the view template being rendered (using the IsSectionDefined() method), and if so we render the section.  If the section has not been defined, then we now instead render some default content for the SideBar:  Note: You want to make sure you prefix calls to the RenderSection() helper method with a @ character – which will tell Razor to execute the HelperResult it returns and merge in the section content in the appropriate place of the output.  Notice how we wrote @RenderSection(“SideBar”) above instead of just RenderSection(“SideBar”).  Otherwise you’ll get an error. Above we are simply rendering an inline static string (<p>Default SideBar Content</p>) if the section is not defined.  A real-world site would more likely refactor this default content to be stored within a separate partial template (which we’d render using the Html.RenderPartial() helper method within the else block) or alternatively use the Html.Action() helper method within the else block to encapsulate both the logic and rendering of the default sidebar. When we hit refresh on our home-page, we will still see the same custom SideBar content we had before.  This is because we implemented the SideBar section within our Index.cshtml view template (and so our Layout rendered it): Let’s now implement a “/Home/About” URL for our site by adding a new “About” action method to our HomeController: The About() action method above simply renders a view back to the client when invoked.  We can implement the corresponding view template for this action by right-clicking within the “About()” method and using the “Add View” menu command (like before) to create a new About.cshtml view template.  We’ll implement the About.cshtml view template like below. Notice that we are not defining a “SideBar” section within it: When we browse the /Home/About URL we’ll see the content we supplied above in the main body section of our response, and the default SideBar content will rendered: The layout file determined at runtime that a custom SideBar section wasn’t present in the About.cshtml view template, and instead rendered the default sidebar content. One Last Tweak… Let’s suppose that at a later point we decide that instead of rendering default side-bar content, we just want to hide the side-bar entirely from pages that don’t have any custom sidebar content defined.  We could implement this change simply by making a small modification to our layout so that the sidebar content (and its surrounding HTML chrome) is only rendered if the SideBar section is defined.  The code to do this is below: Razor is flexible enough so that we can make changes like this and not have to modify any of our view templates (nor make change any Controller logic changes) to accommodate this.  We can instead make just this one modification to our Layout file and the rest happens cleanly.  This type of flexibility makes Razor incredibly powerful and productive. Summary Razor’s layout capability enables you to define a common site template, and then inherit its look and feel across all the views/pages on your site. Razor enables you to define multiple, non-contiguous, “sections” within layout templates that can be “filled-in” by view templates.  The @section {} syntax for doing this is clean and concise.  Razor also supports the ability to dynamically check at runtime whether a particular section has been defined, and to provide alternate content (or even an alternate layout) in the event that it isn’t specified.  This provides a powerful and easy way to customize the UI of your site - and make it clean and DRY from an implementation perspective. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • C#/.NET Fundamentals: Choosing the Right Collection Class

    - by James Michael Hare
    The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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  • What's up with OCFS2?

    - by wcoekaer
    On Linux there are many filesystem choices and even from Oracle we provide a number of filesystems, all with their own advantages and use cases. Customers often confuse ACFS with OCFS or OCFS2 which then causes assumptions to be made such as one replacing the other etc... I thought it would be good to write up a summary of how OCFS2 got to where it is, what we're up to still, how it is different from other options and how this really is a cool native Linux cluster filesystem that we worked on for many years and is still widely used. Work on a cluster filesystem at Oracle started many years ago, in the early 2000's when the Oracle Database Cluster development team wrote a cluster filesystem for Windows that was primarily focused on providing an alternative to raw disk devices and help customers with the deployment of Oracle Real Application Cluster (RAC). Oracle RAC is a cluster technology that lets us make a cluster of Oracle Database servers look like one big database. The RDBMS runs on many nodes and they all work on the same data. It's a Shared Disk database design. There are many advantages doing this but I will not go into detail as that is not the purpose of my write up. Suffice it to say that Oracle RAC expects all the database data to be visible in a consistent, coherent way, across all the nodes in the cluster. To do that, there were/are a few options : 1) use raw disk devices that are shared, through SCSI, FC, or iSCSI 2) use a network filesystem (NFS) 3) use a cluster filesystem(CFS) which basically gives you a filesystem that's coherent across all nodes using shared disks. It is sort of (but not quite) combining option 1 and 2 except that you don't do network access to the files, the files are effectively locally visible as if it was a local filesystem. So OCFS (Oracle Cluster FileSystem) on Windows was born. Since Linux was becoming a very important and popular platform, we decided that we would also make this available on Linux and thus the porting of OCFS/Windows started. The first version of OCFS was really primarily focused on replacing the use of Raw devices with a simple filesystem that lets you create files and provide direct IO to these files to get basically native raw disk performance. The filesystem was not designed to be fully POSIX compliant and it did not have any where near good/decent performance for regular file create/delete/access operations. Cache coherency was easy since it was basically always direct IO down to the disk device and this ensured that any time one issues a write() command it would go directly down to the disk, and not return until the write() was completed. Same for read() any sort of read from a datafile would be a read() operation that went all the way to disk and return. We did not cache any data when it came down to Oracle data files. So while OCFS worked well for that, since it did not have much of a normal filesystem feel, it was not something that could be submitted to the kernel mail list for inclusion into Linux as another native linux filesystem (setting aside the Windows porting code ...) it did its job well, it was very easy to configure, node membership was simple, locking was disk based (so very slow but it existed), you could create regular files and do regular filesystem operations to a certain extend but anything that was not database data file related was just not very useful in general. Logfiles ok, standard filesystem use, not so much. Up to this point, all the work was done, at Oracle, by Oracle developers. Once OCFS (1) was out for a while and there was a lot of use in the database RAC world, many customers wanted to do more and were asking for features that you'd expect in a normal native filesystem, a real "general purposes cluster filesystem". So the team sat down and basically started from scratch to implement what's now known as OCFS2 (Oracle Cluster FileSystem release 2). Some basic criteria were : Design it with a real Distributed Lock Manager and use the network for lock negotiation instead of the disk Make it a Linux native filesystem instead of a native shim layer and a portable core Support standard Posix compliancy and be fully cache coherent with all operations Support all the filesystem features Linux offers (ACL, extended Attributes, quotas, sparse files,...) Be modern, support large files, 32/64bit, journaling, data ordered journaling, endian neutral, we can mount on both endian /cross architecture,.. Needless to say, this was a huge development effort that took many years to complete. A few big milestones happened along the way... OCFS2 was development in the open, we did not have a private tree that we worked on without external code review from the Linux Filesystem maintainers, great folks like Christopher Hellwig reviewed the code regularly to make sure we were not doing anything out of line, we submitted the code for review on lkml a number of times to see if we were getting close for it to be included into the mainline kernel. Using this development model is standard practice for anyone that wants to write code that goes into the kernel and having any chance of doing so without a complete rewrite or.. shall I say flamefest when submitted. It saved us a tremendous amount of time by not having to re-fit code for it to be in a Linus acceptable state. Some other filesystems that were trying to get into the kernel that didn't follow an open development model had a lot harder time and a lot harsher criticism. March 2006, when Linus released 2.6.16, OCFS2 officially became part of the mainline kernel, it was accepted a little earlier in the release candidates but in 2.6.16. OCFS2 became officially part of the mainline Linux kernel tree as one of the many filesystems. It was the first cluster filesystem to make it into the kernel tree. Our hope was that it would then end up getting picked up by the distribution vendors to make it easy for everyone to have access to a CFS. Today the source code for OCFS2 is approximately 85000 lines of code. We made OCFS2 production with full support for customers that ran Oracle database on Linux, no extra or separate support contract needed. OCFS2 1.0.0 started being built for RHEL4 for x86, x86-64, ppc, s390x and ia64. For RHEL5 starting with OCFS2 1.2. SuSE was very interested in high availability and clustering and decided to build and include OCFS2 with SLES9 for their customers and was, next to Oracle, the main contributor to the filesystem for both new features and bug fixes. Source code was always available even prior to inclusion into mainline and as of 2.6.16, source code was just part of a Linux kernel download from kernel.org, which it still is, today. So the latest OCFS2 code is always the upstream mainline Linux kernel. OCFS2 is the cluster filesystem used in Oracle VM 2 and Oracle VM 3 as the virtual disk repository filesystem. Since the filesystem is in the Linux kernel it's released under the GPL v2 The release model has always been that new feature development happened in the mainline kernel and we then built consistent, well tested, snapshots that had versions, 1.2, 1.4, 1.6, 1.8. But these releases were effectively just snapshots in time that were tested for stability and release quality. OCFS2 is very easy to use, there's a simple text file that contains the node information (hostname, node number, cluster name) and a file that contains the cluster heartbeat timeouts. It is very small, and very efficient. As Sunil Mushran wrote in the manual : OCFS2 is an efficient, easily configured, quickly installed, fully integrated and compatible, feature-rich, architecture and endian neutral, cache coherent, ordered data journaling, POSIX-compliant, shared disk cluster file system. Here is a list of some of the important features that are included : Variable Block and Cluster sizes Supports block sizes ranging from 512 bytes to 4 KB and cluster sizes ranging from 4 KB to 1 MB (increments in power of 2). Extent-based Allocations Tracks the allocated space in ranges of clusters making it especially efficient for storing very large files. Optimized Allocations Supports sparse files, inline-data, unwritten extents, hole punching and allocation reservation for higher performance and efficient storage. File Cloning/snapshots REFLINK is a feature which introduces copy-on-write clones of files in a cluster coherent way. Indexed Directories Allows efficient access to millions of objects in a directory. Metadata Checksums Detects silent corruption in inodes and directories. Extended Attributes Supports attaching an unlimited number of name:value pairs to the file system objects like regular files, directories, symbolic links, etc. Advanced Security Supports POSIX ACLs and SELinux in addition to the traditional file access permission model. Quotas Supports user and group quotas. Journaling Supports both ordered and writeback data journaling modes to provide file system consistency in the event of power failure or system crash. Endian and Architecture neutral Supports a cluster of nodes with mixed architectures. Allows concurrent mounts on nodes running 32-bit and 64-bit, little-endian (x86, x86_64, ia64) and big-endian (ppc64) architectures. In-built Cluster-stack with DLM Includes an easy to configure, in-kernel cluster-stack with a distributed lock manager. Buffered, Direct, Asynchronous, Splice and Memory Mapped I/Os Supports all modes of I/Os for maximum flexibility and performance. Comprehensive Tools Support Provides a familiar EXT3-style tool-set that uses similar parameters for ease-of-use. The filesystem was distributed for Linux distributions in separate RPM form and this had to be built for every single kernel errata release or every updated kernel provided by the vendor. We provided builds from Oracle for Oracle Linux and all kernels released by Oracle and for Red Hat Enterprise Linux. SuSE provided the modules directly for every kernel they shipped. With the introduction of the Unbreakable Enterprise Kernel for Oracle Linux and our interest in reducing the overhead of building filesystem modules for every minor release, we decide to make OCFS2 available as part of UEK. There was no more need for separate kernel modules, everything was built-in and a kernel upgrade automatically updated the filesystem, as it should. UEK allowed us to not having to backport new upstream filesystem code into an older kernel version, backporting features into older versions introduces risk and requires extra testing because the code is basically partially rewritten. The UEK model works really well for continuing to provide OCFS2 without that extra overhead. Because the RHEL kernel did not contain OCFS2 as a kernel module (it is in the source tree but it is not built by the vendor in kernel module form) we stopped adding the extra packages to Oracle Linux and its RHEL compatible kernel and for RHEL. Oracle Linux customers/users obviously get OCFS2 included as part of the Unbreakable Enterprise Kernel, SuSE customers get it by SuSE distributed with SLES and Red Hat can decide to distribute OCFS2 to their customers if they chose to as it's just a matter of compiling the module and making it available. OCFS2 today, in the mainline kernel is pretty much feature complete in terms of integration with every filesystem feature Linux offers and it is still actively maintained with Joel Becker being the primary maintainer. Since we use OCFS2 as part of Oracle VM, we continue to look at interesting new functionality to add, REFLINK was a good example, and as such we continue to enhance the filesystem where it makes sense. Bugfixes and any sort of code that goes into the mainline Linux kernel that affects filesystems, automatically also modifies OCFS2 so it's in kernel, actively maintained but not a lot of new development happening at this time. We continue to fully support OCFS2 as part of Oracle Linux and the Unbreakable Enterprise Kernel and other vendors make their own decisions on support as it's really a Linux cluster filesystem now more than something that we provide to customers. It really just is part of Linux like EXT3 or BTRFS etc, the OS distribution vendors decide. Do not confuse OCFS2 with ACFS (ASM cluster Filesystem) also known as Oracle Cloud Filesystem. ACFS is a filesystem that's provided by Oracle on various OS platforms and really integrates into Oracle ASM (Automatic Storage Management). It's a very powerful Cluster Filesystem but it's not distributed as part of the Operating System, it's distributed with the Oracle Database product and installs with and lives inside Oracle ASM. ACFS obviously is fully supported on Linux (Oracle Linux, Red Hat Enterprise Linux) but OCFS2 independently as a native Linux filesystem is also, and continues to also be supported. ACFS is very much tied into the Oracle RDBMS, OCFS2 is just a standard native Linux filesystem with no ties into Oracle products. Customers running the Oracle database and ASM really should consider using ACFS as it also provides storage/clustered volume management. Customers wanting to use a simple, easy to use generic Linux cluster filesystem should consider using OCFS2. To learn more about OCFS2 in detail, you can find good documentation on http://oss.oracle.com/projects/ocfs2 in the Documentation area, or get the latest mainline kernel from http://kernel.org and read the source. One final, unrelated note - since I am not always able to publicly answer or respond to comments, I do not want to selectively publish comments from readers. Sometimes I forget to publish comments, sometime I publish them and sometimes I would publish them but if for some reason I cannot publicly comment on them, it becomes a very one-sided stream. So for now I am going to not publish comments from anyone, to be fair to all sides. You are always welcome to email me and I will do my best to respond to technical questions, questions about strategy or direction are sometimes not possible to answer for obvious reasons.

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  • What is the differnce between DataTemplate and DataContext in WPF?

    - by Ashish Ashu
    I can set the relationship b/w View Model and view through following DataContext syntax: <UserControl.DataContext> <view_model:MainMenuModel /> </UserControl.DataContext> And I can also set the relationship b/w View Model and view through following DataTemplate syntax: <DataTemplate DataType="{x:Type viewModel:UserViewModel}"> <view:UserView /> </DataTemplate> Please let me know what is the difference between the two ? Is the second XAML does not set the data context of a view ?

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  • Git-windows case sensitive file names not handled properly

    - by dhanasekar79
    We have the git bare repository in unix that has files with same name that differs only in cases. Example: GRANT.sql grant.sql When we clone the bare repository from unix in to a windows box, git status detecs the file as modified. The working tree is loaded only with grant.sql, but git status compares grant.sql and GRANT.sql and shows the file as modified in the working tree. I tried using the core.ignorecase false but the result is the same. Is there any way to rix this issue.

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  • Soapui & Xpath : Problem with assertion for a simple node

    - by mada
    Hi, i'm currently using SoapUI Free edition 3.2-beta 2. And i have a weird problem with a Xpath assertion: I have this in response: (...) And i'm using this xpath to assert that the "niveau" with id='2' is in the response: Xpath expression; //*:niveau[@id='2'] & the expected result is : but i have this error message: XPathContains comparison failed, expecting [ ], actual was [null] but if i try this : exitsts(//*:niveau[@id='2']) & the expected result is : True it works !!? But this syntax is quite difficult to read & lmaintain & i would like to use the 1st syntax (i ve tried to ignore namespace, add them.. stil doesnt work). Any idea ? Regards

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  • Design for a machine learning artificial intelligence framework

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • Is there any good reason to use <rtexprvalue>false</rtexprvalue> in JSP tags?

    - by Superfilin
    Is there any good reason to disallow scriptlet or EL expression to be inserted as attribute value? Let's say we have tag: <tag> <name>mytag</name> <tag-class>org.apache.beehive.netui.tags.tree.Tree</tag-class> <attribute> <name>attr</name> <required>false</required> <rtexprvalue>false</rtexprvalue> <type>boolean</type> </attribute> </tag> What could be a good reason for dissallowing the below? <my:mytag attr="${setting}" />

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  • WPF TreeView drag and drop using preview

    - by imekon
    I'm handling drag and drop events in a TreeView using PreviewMouseDown, PreviewMouseMove and PreviewMouseUp, however, there is an issue. In my PreviewMouseDown handler, I set everything ready in case there's a drag started (detected in the Move event), however I set e.Handled = true. This means that standard selection events don't get generated on my tree! What I want to be able to do in my Up event is to invoke the standard treeview selection changed event - except I cannot call events outside of the tree. So what's the correct way to do this? I have tried using the standard MouseDown, MouseMove and MouseUp events however there's an issue with messing up my multiple selection feature that means I need to use the Preview version of those events.

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  • Powerpoint Add-In: Add a Button to PPT to SyntaxHighlight a Textbox

    - by Tigraine
    Hi Guys, I am trying to write an Add-In to Powerpoint that does basically one thing: Give users a Button somewhere to click, once they click on it the currently selected TextField should get syntax highlighted. The Syntax highlighting part is easy, I'm just having a real hard time finding some good information on how to successfully interact with Powerpoint from code. There are some MSDN articles highlighting how to add controls on document start or AddSlide, but no good information on how to extend the UI. Has anyone had some experience in this field and could point me to some resource that may help? Also, I am running Powerpoint 2007 while my customer may end up running PPT2003. How is the backwards compatibility of the Add-ins? greetings Daniel

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  • Design for a machine learning artificial intelligence framework (community wiki)

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • Getting Started with UDK

    - by Sean Edwards
    I've been trying for a couple of days now to learn UDK, but I seem to be stuck at making that leap to understanding how everything works together. I understand the syntax, that's all well and good, and I pretty much get how classes and .ini files interact. As for the API, I have the entire reference as pretty decent Doxygen-style HTML output. What I'm looking for is a sort of intermediate tutorial on game creation from scratch (as opposed to modding UT3 itself), more advanced than just learning language syntax, but not yet to the level of going through the API step by step. I'm looking for some guide to the structure of the internals - how GameInfo and PlayerController interact, where Pawn comes in, etc. - a way to visualize the big picture. Does anyone have a particular favorite intermediate-level tutorials (or set of tutorials) that they used when first learning UDK?

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  • Serialize struct with pointers to NSData

    - by leolobato
    Hey guys, I need to add some kind of archiving functionality to a Objective-C Trie implementation (NDTrie on github), but I have very little experience with C and it's data structures. struct trieNode { NSUInteger key; NSUInteger count, size; id object; __strong struct trieNode ** children; __strong struct trieNode * parent; }; @interface NDTrie (Private) - (struct trieNode*)root; @end What I need is to create an NSData with the tree structure from that root - or serialize/deserialize the whole tree some other way (conforming to NSCoding?), but I have no clue how to work with NSData and a C struct containing pointers. Performance on deserializing the resulting object would be crucial, as this is an iPhone project and I will need to load it in the background every time the app starts. What would be the best way to achieve this? Thanks!

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  • MYSQL stored function - create function (function definition) problem using FORMAT

    - by Jason Fonseca
    Hi all, I keep receiving an error with the following code. I am trying to make a function that will format a field (content=0.0032) into a varchar/percent (content=0.32%). At the moment i'm just trying to get format to work, and it throws up an error "Error Code : 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 'len);" The function definition for "Format" is "Format(X,d)" where x is the number and d is the number of decimal places to round too. It then should output a string ###,###,###.## etc. My code is as follows: DROP FUNCTION IF EXISTS percent; DELIMITER $$ CREATE /*[DEFINER = { user | CURRENT_USER }]*/ FUNCTION `auau7859_aba`.`percent`(num DOUBLE, len INT) RETURNS VARCHAR(10) DETERMINISTIC BEGIN RETURN FORMAT(num,len); END$$ DELIMITER ; Save me...Luke

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  • VS2010 add-in custom menu item in files of Solution Explorer

    - by NewProgrammer
    Hey guys, I need to create a custom menu item for Visual Studio 2010 Add-in in C#, but I have had no luck in coming with a solution anytime soon. I am aware that there was a similar post: http://stackoverflow.com/questions/2486818/visual-studio-add-in-adding-a-context-menu-item-to-solution-explorer But it did not help, as the blog follows the process through the integration package, and the video is done through VB. I had attempted to convert the VB syntax to the C# syntax, but about half way through the video, the Add-in methods has significantly changed from 2005 to 2010, as some of the methods have removed or changed. Is there any good tutorials on making a custom menu item on the Solution Explorer in the lastest Visual Studio in C#, and is there a good website that could be used as a reference for looking over the VS add-in API? I've used Microsoft's main website, however it is confusing and wordy, which is difficult to understand and find the methods, properties, or commands that I am looking for. Any help would be appreicated, Thanks in advance.

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  • Apache </Location> Errors

    - by Eddie
    Hi there! I am having real trouble with this installation - Basically this is the erro that I am getting: apache2: Syntax error on line 234 of /etc/apache2/apache2.conf: Syntax error on line 10 of /etc/apache2/conf.d/amberdms-bs.conf: Expected </Location\xc2\xa0/billing_system> but saw </Location> and this is the code that is being used in that modules file: #  # Amberdms Billing System is an open source accounting, service billing and time keeping web application.  #  Alias /billing_system /usr/share/amberdms/billing_system  <Location /billing_system>  Order deny,allow  Allow from all  AllowOverride all    Please help me! I need this software to be installed, but this error has stumped me.

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  • Excel - Looping through data till it finds the right one

    - by DanoK
    I'm pulling data from one Excel table into another using an IF statement. I want it to check two fields and if it is a match I want it to print something and if it doesn't then I want it to continue searching. If there is no absolute match then leave the field blank. I believe I'm running into an syntax issue but after numerous iterations I can't get it to pull everything over. Here is my current syntax. =IF(BM5<>"External","",IF(AND(S5=VLOOKUP(A5,ExternalOnly,5,FALSE),A5=VLOOKUP(A5,ExternalOnly,1,FALSE)),S5,"")

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  • MySQL died during the night on a 12.04.1 Ubuntu

    - by Olivier
    I can't explain why, but somehow during the night, one of my MySQL running on an Ubuntu 12.04.1 box broke. The service is running but I can't login anymore (to SQL), the previous password is not working anymore. It does not looks like the server has been compromised (nothing in /var/auth.log) It looks like some automatic security upgrade (server is configured to perform those) has occured and broke something. The MySQL server has restarted a couple of times in the logs at the time errors started to happen (I get email when CRON task fail). In the logs it complains about an unset root password (I do have cron job running all day using SQL so the password was set & working for months). Anyway I can't login without password either! Do you have any idea of what could have happened? How do I get my databases back? This line looks strange : Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 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 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Here is the full log below : Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER ! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: To do so, start the server, then issue the following commands: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysqladmin -u root -h ns398758.ovh.net password 'new-password' Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Alternatively you can run: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: /usr/bin/mysql_secure_installation Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: which will also give you the option of removing the test Nov 6 06:36:06 ns398758 mysqld_safe[6586]: databases and anonymous user created by default. This is Nov 6 06:36:06 ns398758 mysqld_safe[6586]: strongly recommended for production servers. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: See the manual for more instructions. Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Please report any problems with the /usr/scripts/mysqlbug script! Nov 6 06:36:06 ns398758 mysqld_safe[6586]: Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: Completed initialization of buffer pool Nov 6 06:36:06 ns398758 mysqld_safe[6632]: 121106 6:36:06 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:07 ns398758 mysqld_safe[6632]: 121106 6:36:07 InnoDB: Waiting for the background threads to start Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:08 ns398758 mysqld_safe[6632]: 121106 6:36:08 InnoDB: Starting shutdown... Nov 6 06:36:09 ns398758 mysqld_safe[6632]: 121106 6:36:09 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Completed initialization of buffer pool Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:11 ns398758 mysqld_safe[6676]: 121106 6:36:11 InnoDB: Waiting for the background threads to start Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: ERROR: 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 'ALTER TABLE user ADD column Show_view_priv enum('N','Y') CHARACTER SET utf8 NOT ' at line 1 Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 [ERROR] Aborting Nov 6 06:36:12 ns398758 mysqld_safe[6676]: Nov 6 06:36:12 ns398758 mysqld_safe[6676]: 121106 6:36:12 InnoDB: Starting shutdown... Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:13 ns398758 mysqld_safe[6676]: 121106 6:36:13 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:13 ns398758 mysqld_safe[6676]: Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Completed initialization of buffer pool Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:13 ns398758 mysqld_safe[6697]: 121106 6:36:13 InnoDB: Waiting for the background threads to start Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:14 ns398758 mysqld_safe[6697]: 121106 6:36:14 InnoDB: Starting shutdown... Nov 6 06:36:15 ns398758 mysqld_safe[6697]: 121106 6:36:15 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 [Note] Plugin 'FEDERATED' is disabled. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: The InnoDB memory heap is disabled Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Mutexes and rw_locks use GCC atomic builtins Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Compressed tables use zlib 1.2.3.4 Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Initializing buffer pool, size = 128.0M Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Completed initialization of buffer pool Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: highest supported file format is Barracuda. Nov 6 06:36:15 ns398758 mysqld_safe[6718]: 121106 6:36:15 InnoDB: Waiting for the background threads to start Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: 1.1.8 started; log sequence number 29276459701 Nov 6 06:36:16 ns398758 mysqld_safe[6718]: ERROR: 1050 Table 'plugin' already exists Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 [ERROR] Aborting Nov 6 06:36:16 ns398758 mysqld_safe[6718]: Nov 6 06:36:16 ns398758 mysqld_safe[6718]: 121106 6:36:16 InnoDB: Starting shutdown... Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 InnoDB: Shutdown completed; log sequence number 29276459701 Nov 6 06:36:17 ns398758 mysqld_safe[6718]: 121106 6:36:17 [Note] /usr/sbin/mysqld: Shutdown complete Nov 6 06:36:17 ns398758 mysqld_safe[6718]: Nov 6 06:36:19 ns398758 /etc/mysql/debian-start[6816]: Upgrading MySQL tables if necessary. Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: /usr/bin/mysql_upgrade: the '--basedir' option is always ignored Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysql' as: /usr/bin/mysql Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Looking for 'mysqlcheck' as: /usr/bin/mysqlcheck Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: Running 'mysqlcheck' with connection arguments: '--port=3306' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' '--host=localhost' '--socket=/var/run/mysqld/mysqld.sock' Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.acos OK Nov 6 06:36:20 ns398758 /etc/mysql/debian-start[6819]: col_digitas.aros OK ...

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  • Setting treeview background color in VB6 has a flaw - help?

    - by RenMan
    I have successfully implemented this method of using the Win32 API to set the background color of a treeview in VB 6: http://support.microsoft.com/kb/178491 However, one thing goes wrong: when you expand the tree nodes more than two levels deep, the area to the left of (and sometimes under) the inner plus [+] and minus [-] signs is still white. Does anyone know how to get this area to the correct background color, too? Note: I'm also setting the BackColor of each node, and also the BackColor of the treeview's imagelist. Here's my version of the code: Public Sub TreeView_SetBackgroundColor(TreeView As MSComctlLib.TreeView, BackgroundColor As Long) Dim lStyle As Long, Node As MSComctlLib.Node For Each Node In TreeView.Nodes Node.BackColor = BackgroundColor Next TreeView.ImageList.BackColor = BackgroundColor Call SendMessage( _ TreeView.hwnd, _ TVM_SETBKCOLOR, _ 0, _ ByVal BackgroundColor) 'Now reset the style so that the tree lines appear properly. lStyle = GetWindowLong(TreeView.hwnd, GWL_STYLE) Call SetWindowLong(TreeView.hwnd, GWL_STYLE, lStyle - TVS_HASLINES) Call SetWindowLong(TreeView.hwnd, GWL_STYLE, lStyle) End Sub

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  • Install mod_jk with Apache 2.2

    - by peter
    I have downloaded mod_jk-1.2.28-httpd-2.2.X.so for Apache 2.2 running on CentOS, and set up as per http://tomcat.apache.org/connectors-doc/webserver_howto/apache.html. When I try to start httpd it fails with the following error: "Starting httpd: httpd: Syntax error on line 993 of /etc/httpd/conf/httpd.conf: Syntax error on line 2 of /opt/apache-tomcat-6.0.26/conf/jk/mod_jk.conf-auto: Cannot load /etc/httpd/modules/mod_jk-1.2.28-httpd-2.2.X.so into server: /etc/httpd/modules/mod_jk-1.2.28-httpd-2.2.X.so: wrong ELF class: ELFCLASS32" Does that mean that mod_jk-1.2.28-httpd-2.2.X.so has not been properly compiled?. What can I do about that? Thanks Peter

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  • Delphi Prism getting Unknown Identifier "DllImport" error

    - by Robo
    I'm trying to call Window's SendMessage method in Delphi Prism, I've declared the class as follow: type MyUtils = public static class private [DllImport("user32.dll", CharSet := CharSet.Auto)] method SendMessage(hWnd:IntPtr; Msg:UInt32; wParam:IntPtr; lParam:IntPtr):IntPtr; external; protected public end; When I tried to compile, I get the error Unknown identifier "DllImport" I used this as an example, http://stackoverflow.com/questions/2708520/how-to-call-function-createprocess-in-delphi-prism and the syntax looks the same. Is there a setting I need to enable, or do I have a syntax error?

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  • Google Appengine and Python exceptions

    - by Jim
    In my Google Appengine application I have defined a custom exception InvalidUrlException(Exception) in the module 'gvu'. Somewhere in my code I do: try: results = gvu.article_parser.parse(source_url) except gvu.InvalidUrlException as e: self.redirect('/home?message='+str(e)) ... which works fine in the local GAE development server, but raises <type 'exceptions.SyntaxError'>: invalid syntax (translator.py, line 18) when I upload it. (line 18 is the line starting with 'except') The problem seems to come from the 'as e' part: if I remove it I don't get this exception anymore. However I would like to be able to access the raised exception. Have you ever encountered this issue? Is there an alternative syntax?

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  • VBA for Access 2003 - DDL help with creating access file: setting the Autonumber data type

    - by Justin
    So I have the below VB that creates an access file in the default workspace, creates a table, create some fields in that table...just need to know the syntax for setting the first data type/field to autonumber...GUID, Counter, etc will not work as in Access SQL ' error handling usually goes here dim ws as workspace dim dbExample as database dim tblMain as TableDef dim fldMain as Field dim idxMain as Index set ws = workspace(0) set dbExample = ws.CreateDatabase('string file path') set tblMain = dbExample.CreateTableDef("tblMain") set fldMain = tblMain.CreateField("ID", 'right here I do not know what to substitute for dbInteger to get the autonumber type to work ) tblMain.Fields.Append fldMain etc to create other fields and indexes so in this line: set fldMain = tblMain.CreateField("ID", dbInteger) i need to replace the dbInteger with something that VB reconizes as the autonumber property. i have tried GUID, Counter, Autonumber, AutoIncrement....unfortunately none of these work anyone know the syntax I am missing here? Thanks, Justin

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  • Integer in MySQL Subqueries in store procedure

    - by confiq
    I made simple procedure just to demonstrate CREATE PROCEDURE `demo`(demo_int int) BEGIN DECLARE minid INT; SELECT min(id) FROM (SELECT id FROM events LIMIT demo_int,9999999999999999) as hoo INTO minid; END$$ The problem is with demo_int, if i change it to LIMIT 1,9999999999999999 it works but LIMIT demo_int,9999999999999999 Does not... It gives error 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 'demo_int,9999999999999999) as hoo INTO minid; END' at line 4 (errno: 1064) Any clues?

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