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  • pointers to member functions in an event dispatcher

    - by derivative
    For the past few days I've been trying to come up with a robust event handling system for the game (using a component based entity system, C++, OpenGL) I've been toying with. class EventDispatcher { typedef void (*CallbackFunction)(Event* event); typedef std::unordered_map<TypeInfo, std::list<CallbackFunction>, hash_TypeInfo > TypeCallbacksMap; EventQueue* global_queue_; TypeCallbacksMap callbacks_; ... } global_queue_ is a pointer to a wrapper EventQueue of std::queue<Event*> where Event is a pure virtual class. For every type of event I want to handle, I create a new derived class of Event, e.g. SetPositionEvent. TypeInfo is a wrapper on type_info. When I initialize my data, I bind functions to events in an unordered_map using TypeInfo(typeid(Event)) as the key that corresponds to a std::list of function pointers. When an event is dispatched, I iterate over the list calling the functions on that event. Those functions then static_cast the event pointer to the actual event type, so the event dispatcher needs to know very little. The actual functions that are being bound are functions for my component managers. For instance, SetPositionEvent would be handled by void PositionManager::HandleSetPositionEvent(Event* event) { SetPositionEvent* s_p_event = static_cast<SetPositionEvent*>(event); ... } The problem I'm running into is that to store a pointer to this function, it has to be static (or so everything leads me to believe.) In a perfect world, I want to store pointers member functions of a component manager that is defined in a script or whatever. It looks like I can store the instance of the component manager as well, but the typedef for this function is no longer simple and I can't find an example of how to do it. Is there a way to store a pointer to a member function of a class (along with a class instance, or, I guess a pointer to a class instance)? Is there an easier way to address this problem?

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  • Multiple domains for different products?

    - by alexandertr
    I have a website with software applications. Is it good for SEO to choose one keyword rich domain name for each of our software products or should we stick to a single domain? From a user's perspective I think it would be easier to remember a domain that is keyword rich as the user will instantly know what this product is for. But I have read articles that the latest trend in SEO is to stick to one domain for all of your products and invest on this single domain website. Is that true? What do you advise? Should I register a separate domain for each of our products or should I use only one single domain? Should I do a 301 redirect with a .htaccess to a single domain? And what about the sitemaps? Should I register all sites in Google Webmaster Tools and post a separate sitemap for each one of them? should my main site sitemap include all pages or should separate domains have their own sitemaps?

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  • Pass User Data to AWS client

    - by bearrito
    Has anyone successful passed user data to the AWS CLI ? I have tried various incantations of the following but it does not work. Docs say string must be base64 encoded : http://docs.aws.amazon.com/cli/latest/reference/ec2/run-instances.html The instance logs never indicate the script is executed and chef is installed. aws ec2 run-instances --image-id ami-a73264ce --count 1 --instance-type t1.micro --key-name scrubbed --iam-instance-profile Arn=arn:aws:iam::scrubbed:instance-profile/scrubbed --user-data $(base64 chef_user_data.sh --wrap=0) chef_user_data.sh #!/bin/bash curl -L https://www.opscode.com/chef/install.sh | sudo bash

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  • What's better for deploying a website + DB on EC2: 2 small VM or a large one?

    - by devguy
    I'm planning the deployment of a mid-sized website with a SQL Server Standard DB. I've chosen Amazon EC2 to deploy it. I now have to choose between these 2 options: 1) get 2 small instances (1 core each, 1.7 GB of ram each): one for the IIS front-end, one for running the DB. Note: these "small instances" can only run the 32-bit version of Win2008 Server 2) a single large instance (4 cores, 7.5 gb of ram) where I'd install both IIS and the SQL Server. Note: this large instance can only run the 64-bit version of Win2008 Server What's better in terms on performance, scalability, ease of management (launch up a new instance while I backup the principal instance) etc. All suggestions and points of view are welcome!

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  • Windows Server 2003 Is there a limit on number of TCP connections per process?

    - by aceinthehole
    We are running into issues with BizTalk host instance intermittently going down. One of the things that we are worried about is the number of FTP connections a single host instance is making which could easily reach into the hundreds perhaps sometimes thousands, depending on traffic. My question is Windows Server 2003 Is there a limit on number of TCP connections per process? If so would putting each application in it's own host instance potentially solve the problem.

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  • Advice for an EC2 Architecture and Deployment Strategy

    - by Mark
    My company is currently migrating several websites and PHP web applications (standard LAMP stack) from three in-house servers to Amazon EC2. Because we had only three servers, we clustered several low-traffic websites with perhaps one high-traffic web application, and served them from the same server. The server admin has pretty much copied the previous architecture wholesale onto the EC2 instances, simply upping the instance size to account for the highest traffic client that occupies that particular instance. This architecture might be okay if it wasn't for deployment. Any time one of these sites/apps changes, it means redeploying the entire instance, along with the 30 sites/apps it hosts, instead of just updating one. How can we architect our cloud in a more modular fashion? Should each app get its own appropriately-sized instance? What is the best strategy for deployment in this type of situation?

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  • Ubuntu package question

    - by Industrial
    Hi everyone, I run Ubuntu, and If i type the following in a terminal, I start a new instance of memcached, right? # memcached -vv How can I target the the current instance of memcached in terminal? It would help me to see the very-verbose mode on my already running instance. Thanks

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  • Efficiency of iterators and alternatives? [migrated]

    - by user48037
    I have the following code for my game tiles: std::vector<GameObject_Tile*>::iterator it; for(int y = 0; y < GAME_TILES_Y; y++) { for(int x = 0; x < GAME_TILES_X; x++) { for (it = gameTiles[x][y].tiles.begin() ; it != gameTiles[x][y].tiles.end(); ++it) {}}} tiles is: struct Game_Tile { // More specific object types will be added here eventually vector<GameObject_Tile*> tiles; }; My problem is that if I change the vector to just be a single GameObject_Tile* instead and remove the iterator line in the loop I go from about 200fps to 450fps. Some context: The vector/pointer only contains one object in both scenarios. I will eventually need to store multiple, but for testing I just set it to a single pointer. The loop goes through 2,300 objects each frame and draws them. I would like to point out that if I remove the Draw (not seen int he example) method, I gain about 30 frames in both scenarios, the issue is the iteration. So I am wondering why having this as a vector being looped through by an iterator (to get at a single object) is costing me over 200 frames when compared to it being a single pointer? The 200+ frames faster code is: std::vector<GameObject_Tile*>::iterator it; for(int y = 0; y < GAME_TILES_Y; y++) { for(int x = 0; x < GAME_TILES_X; x++) { //gameTiles[x][y].tiles is used as a pointer here instead of using *it }} tiles is: struct Game_Tile { // More specific object types will be added here eventually GameObject_Tile* tiles; };

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  • getting database connectivity issue from only one part of my ASP.net project?

    - by Greg
    Hi, Something weird has started happening to my project with Dynamic Data. Suddenly I am now getting connection errors when going to the DD navigation pages, but things work fine on the default DD main page, and also other MVC pages I've added in myself work fine to the database. Any ideas? So in summary if I go to the following web pages: custom URL for my custom controller - this works fine, including getting database data main DD page from root URL - this works fine click on a link to a table maintenance page from the main DD page - GET DATABASE CONNECTIVITY ERROR Some items: * I'm using SQL Server Express 2008 * Doesn't seem to be any debug/error info in VS2010 at all I can see * Web config entry: <add name="Model1Container" connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=GREG\SQLEXPRESS_2008;Initial Catalog=greg_development;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient"/> Error: Server Error in '/' Application. A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) Source Error: Line 39: DropDownList1.Items.Add(new ListItem("[Not Set]", NullValueString)); Line 40: } Line 41: PopulateListControl(DropDownList1); Line 42: // Set the initial value if there is one Line 43: string initialValue = DefaultValue; Source File: U:\My Dropbox\source\ToplogyLibrary\Topology_Web_Dynamic\DynamicData\Filters\ForeignKey.ascx.cs Line: 41 Stack Trace: [SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)] System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +5009598 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +234 System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity) +341 System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, SqlConnection owningObject) +129 System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout) +239 System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, TimeoutTimer timeout, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance) +195 System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance) +232 System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection) +185 System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options) +33 System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject) +524 System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject) +66 System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +479 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +108 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +126 System.Data.SqlClient.SqlConnection.Open() +125 System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure) +52 [EntityException: The underlying provider failed on Open.] System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure) +161 System.Data.EntityClient.EntityConnection.Open() +98 System.Data.Objects.ObjectContext.EnsureConnection() +81 System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) +46 System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +44 System.Data.Objects.ObjectQuery`1.GetEnumeratorInternal() +36 System.Data.Objects.ObjectQuery.System.Collections.IEnumerable.GetEnumerator() +10 System.Web.DynamicData.Misc.FillListItemCollection(IMetaTable table, ListItemCollection listItemCollection) +50 System.Web.DynamicData.QueryableFilterUserControl.PopulateListControl(ListControl listControl) +85 Topology_Web_Dynamic.ForeignKeyFilter.Page_Init(Object sender, EventArgs e) in U:\My Dropbox\source\ToplogyLibrary\Topology_Web_Dynamic\DynamicData\Filters\ForeignKey.ascx.cs:41 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnInit(EventArgs e) +91 System.Web.UI.UserControl.OnInit(EventArgs e) +83 System.Web.UI.Control.InitRecursive(Control namingContainer) +140 System.Web.UI.Control.AddedControl(Control control, Int32 index) +197 System.Web.UI.ControlCollection.Add(Control child) +79 System.Web.DynamicData.DynamicFilter.EnsureInit(IQueryableDataSource dataSource) +200 System.Web.DynamicData.QueryableFilterRepeater.<Page_InitComplete>b__1(DynamicFilter f) +11 System.Collections.Generic.List`1.ForEach(Action`1 action) +145 System.Web.DynamicData.QueryableFilterRepeater.Page_InitComplete(Object sender, EventArgs e) +607 System.EventHandler.Invoke(Object sender, EventArgs e) +0 System.Web.UI.Page.OnInitComplete(EventArgs e) +8871862 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +604 Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1

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  • Content Being Echoed Below Footer in Category Post Template

    - by poindexter
    I have created a category template in Wordpress for all posts that are in the 'blog' category. The file name is single-blog.php. There is some conditional code in single.php that checks whether the post is in the 'blog' category and if it is it redirects it to single-blog.php. That seems to be working fine. The problem is that on all the individual 'blog' categorized posts the post title and content are echoed below the footer of the page. I do not know why they are showing up and I haven't been able to stop it or hide it. The Loop is getting closed on the template page, but I'm wondering if the Loop from single.php is somehow also being sent over. You can view an example of the problem here: http://69.20.59.228/2010/03/test-blog-post/ Please let me know if you have any suggestions. I am posting two sections of code below. The first is the conditional call in single.php. The second is the code from the single-blog.php (the category post template). the conditional call in single.php. <?php $post = $wp_query->post; if (in_category('blog')) { include(TEMPLATEPATH.'/single-blog.php'); }?> code from the single-blog.php (the category post template) <?php get_header(); ?> <?php get_sidebar(); ?> <p><h2>The IQNavigator Blog</h2></p> <em><a href="/category/blog">Blog Home</a></em> | <em><a href="/category/blog/feed/">Subscribe via RSS</a></em><p><br></br></p> <?php if (have_posts()) : while (have_posts()) : the_post(); ?> <div <?php post_class() ?> id="post-<?php the_ID(); ?>"> <h1 class="pagetitle"><?php the_title(); ?></h1> <!-- <p class="details">Posted <?php the_time('l, F jS, Y') ?> at <?php the_time() ?></p> --> <div class="entry"> <?php the_content('<p class="serif">Read the rest of this entry &raquo;</p>'); ?> <?php wp_link_pages(array('before' => '<p><strong>Pages:</strong> ', 'after' => '</p>', 'next_or_number' => 'number')); ?> <?php the_tags( '<p>Tags: ', ', ', '</p>'); ?> <p class="postmetadata alt"> <small> -----<br> Posted <?php /* This is commented, because it requires a little adjusting sometimes. You'll need to download this plugin, and follow the instructions: http://binarybonsai.com/wordpress/time-since/ */ /* $entry_datetime = abs(strtotime($post->post_date) - (60*120)); echo time_since($entry_datetime); echo ' ago'; */ ?> on <?php the_time('l, F jS, Y') ?>, filed under <?php the_category(', ') ?>. Follow any responses to this entry through the <?php post_comments_feed_link('RSS'); ?> feed. <?php if ( comments_open() && pings_open() ) { // Both Comments and Pings are open ?> <a href="#respond">Leave your own comment</a>, or <a href="<?php trackback_url(); ?>" rel="trackback">trackback</a> from your own site. <?php } elseif ( !comments_open() && pings_open() ) { // Only Pings are Open ?> Responses are currently closed, but you can <a href="<?php trackback_url(); ?> " rel="trackback">trackback</a> from your own site. <?php } elseif ( comments_open() && !pings_open() ) { // Comments are open, Pings are not ?> You can skip to the end and leave a response. Pinging is currently not allowed. <?php } elseif ( !comments_open() && !pings_open() ) { // Neither Comments, nor Pings are open ?> Both comments and pings are currently closed. <?php } edit_post_link('Edit this entry','','.'); ?> </small> </p> <?php the_tags( '<p>Tagged: ', ', ', '</p>'); ?> </div> </div> <?php comments_template(); ?> <?php endwhile; else: ?> <p>Sorry, no posts matched your criteria.</p> <?php endif; ?> <?php get_footer(); ?>

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  • Using the BAM Interceptor with Continuation

    - by Charles Young
    Originally posted on: http://geekswithblogs.net/cyoung/archive/2014/06/02/using-the-bam-interceptor-with-continuation.aspxI’ve recently been resurrecting some code written several years ago that makes extensive use of the BAM Interceptor provided as part of BizTalk Server’s BAM event observation library.  In doing this, I noticed an issue with continuations.  Essentially, whenever I tried to configure one or more continuations for an activity, the BAM Interceptor failed to complete the activity correctly.   Careful inspection of my code confirmed that I was initializing and invoking the BAM interceptor correctly, so I was mystified.  However, I eventually found the problem.  It is a logical error in the BAM Interceptor code itself. The BAM Interceptor provides a useful mechanism for implementing dynamic tracking.  It supports configurable ‘track points’.  These are grouped into named ‘locations’.  BAM uses the term ‘step’ as a synonym for ‘location’.   Each track point defines a BAM action such as starting an activity, extracting a data item, enabling a continuation, etc.  Each step defines a collection of track points. Understanding Steps The BAM Interceptor provides an abstract model for handling configuration of steps.  It doesn’t, however, define any specific configuration mechanism (e.g., config files, SSO, etc.)  It is up to the developer to decide how to store, manage and retrieve configuration data.  At run time, this configuration is used to register track points which then drive the BAM Interceptor. The full semantics of a step are not immediately clear from Microsoft’s documentation.  They represent a point in a business activity where BAM tracking occurs.  They are named locations in the code.  What is less obvious is that they always represent either the full tracking work for a given activity or a discrete fragment of that work which commences with the start of a new activity or the continuation of an existing activity.  The BAM Interceptor enforces this by throwing an error if no ‘start new’ or ‘continue’ track point is registered for a named location. This constraint implies that each step must marked with an ‘end activity’ track point.  One of the peculiarities of BAM semantics is that when an activity is continued under a correlated ID, you must first mark the current activity as ‘ended’ in order to ensure the right housekeeping is done in the database.  If you re-start an ended activity under the same ID, you will leave the BAM import tables in an inconsistent state.  A step, therefore, always represents an entire unit of work for a given activity or continuation ID.  For activities with continuation, each unit of work is termed a ‘fragment’. Instance and Fragment State Internally, the BAM Interceptor maintains state data at two levels.  First, it represents the overall state of the activity using a ‘trace instance’ token.  This token contains the name and ID of the activity together with a couple of state flags.  The second level of state represents a ‘trace fragment’.   As we have seen, a fragment of an activity corresponds directly to the notion of a ‘step’.  It is the unit of work done at a named location, and it must be bounded by start and end, or continue and end, actions. When handling continuations, the BAM Interceptor differentiates between ‘root’ fragments and other fragments.  Very simply, a root fragment represents the start of an activity.  Other fragments represent continuations.  This is where the logic breaks down.  The BAM Interceptor loses state integrity for root fragments when continuations are defined. Initialization Microsoft’s BAM Interceptor code supports the initialization of BAM Interceptors from track point configuration data.  The process starts by populating an Activity Interceptor Configuration object with an array of track points.  These can belong to different steps (aka ‘locations’) and can be registered in any order.  Once it is populated with track points, the Activity Interceptor Configuration is used to initialise the BAM Interceptor.  The BAM Interceptor sets up a hash table of array lists.  Each step is represented by an array list, and each array list contains an ordered set of track points.  The BAM Interceptor represents track points as ‘executable’ components.  When the OnStep method of the BAM Interceptor is called for a given step, the corresponding list of track points is retrieved and each track point is executed in turn.  Each track point retrieves any required data using a call back mechanism and then serializes a BAM trace fragment object representing a specific action (e.g., start, update, enable continuation, stop, etc.).  The serialised trace fragment is then handed off to a BAM event stream (buffered or direct) which takes the appropriate action. The Root of the Problem The logic breaks down in the Activity Interceptor Configuration.  Each Activity Interceptor Configuration is initialised with an instance of a ‘trace instance’ token.  This provides the basic metadata for the activity as a whole.  It contains the activity name and ID together with state flags indicating if the activity ID is a root (i.e., not a continuation fragment) and if it is completed.  This single token is then shared by all trace actions for all steps registered with the Activity Interceptor Configuration. Each trace instance token is automatically initialised to represent a root fragment.  However, if you subsequently register a ‘continuation’ step with the Activity Interceptor Configuration, the ‘root’ flag is set to false at the point the ‘continue’ track point is registered for that step.   If you use a ‘reflector’ tool to inspect the code for the ActivityInterceptorConfiguration class, you can see the flag being set in one of the overloads of the RegisterContinue method.    This makes no sense.  The trace instance token is shared across all the track points registered with the Activity Interceptor Configuration.  The Activity Interceptor Configuration is designed to hold track points for multiple steps.  The ‘root’ flag is clearly meant to be initialised to ‘true’ for the preliminary root fragment and then subsequently set to false at the point that a continuation step is processed.  Instead, if the Activity Interceptor Configuration contains a continuation step, it is changed to ‘false’ before the root fragment is processed.  This is clearly an error in logic. The problem causes havoc when the BAM Interceptor is used with continuation.  Effectively the root step is no longer processed correctly, and the ultimate effect is that the continued activity never completes!   This has nothing to do with the root and the continuation being in the same process.  It is due to a fundamental mistake of setting the ‘root’ flag to false for a continuation before the root fragment is processed. The Workaround Fortunately, it is easy to work around the bug.  The trick is to ensure that you create a new Activity Interceptor Configuration object for each individual step.  This may mean filtering your configuration data to extract the track points for a single step or grouping the configured track points into individual steps and the creating a separate Activity Interceptor Configuration for each group.  In my case, the first approach was required.  Here is what the amended code looks like: // Because of a logic error in Microsoft's code, a separate ActivityInterceptorConfiguration must be used // for each location. The following code extracts only those track points for a given step name (location). var trackPointGroup = from ResolutionService.TrackPoint tp in bamActivity.TrackPoints                       where (string)tp.Location == bamStepName                       select tp; var bamActivityInterceptorConfig =     new Microsoft.BizTalk.Bam.EventObservation.ActivityInterceptorConfiguration(activityName); foreach (var trackPoint in trackPointGroup) {     switch (trackPoint.Type)     {         case TrackPointType.Start:             bamActivityInterceptorConfig.RegisterStartNew(trackPoint.Location, trackPoint.ExtractionInfo);             break; etc… I’m using LINQ to filter a list of track points for those entries that correspond to a given step and then registering only those track points on a new instance of the ActivityInterceptorConfiguration class.   As soon as I re-wrote the code to do this, activities with continuations started to complete correctly.

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  • Java Cloud Service Integration using Web Service Data Control

    - by Jani Rautiainen
    Java Cloud Service (JCS) provides a platform to develop and deploy business applications in the cloud. In Fusion Applications Cloud deployments customers do not have the option to deploy custom applications developed with JDeveloper to ensure the integrity and supportability of the hosted application service. Instead the custom applications can be deployed to the JCS and integrated to the Fusion Application Cloud instance.This series of articles will go through the features of JCS, provide end-to-end examples on how to develop and deploy applications on JCS and how to integrate them with the Fusion Applications instance.In this article a custom application integrating with Fusion Application using Web Service Data Control will be implemented. v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} Pre-requisites Access to Cloud instance In order to deploy the application access to a JCS instance is needed, a free trial JCS instance can be obtained from Oracle Cloud site. To register you will need a credit card even if the credit card will not be charged. To register simply click "Try it" and choose the "Java" option. The confirmation email will contain the connection details. See this video for example of the registration. Once the request is processed you will be assigned 2 service instances; Java and Database. Applications deployed to the JCS must use Oracle Database Cloud Service as their underlying database. So when JCS instance is created a database instance is associated with it using a JDBC data source. The cloud services can be monitored and managed through the web UI. For details refer to Getting Started with Oracle Cloud. JDeveloper JDeveloper contains Cloud specific features related to e.g. connection and deployment. To use these features download the JDeveloper from JDeveloper download site by clicking the “Download JDeveloper 11.1.1.7.1 for ADF deployment on Oracle Cloud” link, this version of JDeveloper will have the JCS integration features that will be used in this article. For versions that do not include the Cloud integration features the Oracle Java Cloud Service SDK or the JCS Java Console can be used for deployment. For details on installing and configuring the JDeveloper refer to the installation guide. For details on SDK refer to Using the Command-Line Interface to Monitor Oracle Java Cloud Service and Using the Command-Line Interface to Manage Oracle Java Cloud Service. Create Application In this example the “JcsWsDemo” application created in the “Java Cloud Service Integration using Web Service Proxy” article is used as the base. Create Web Service Data Control In this example we will use a Web Service Data Control to integrate with Credit Rule Service in Fusion Applications. The data control will be used to query data from Fusion Applications using a web service call and present the data in a table. To generate the data control choose the “Model” project and navigate to "New -> All Technologies -> Business Tier -> Data Controls -> Web Service Data Control" and enter following: Name: CreditRuleServiceDC URL: https://ic-[POD].oracleoutsourcing.com/icCnSetupCreditRulesPublicService/CreditRuleService?WSDL Service: {{http://xmlns.oracle.com/apps/incentiveCompensation/cn/creditSetup/creditRule/creditRuleService/}CreditRuleService On step 2 select the “findRule” operation: Skip step 3 and on step 4 define the credentials to access the service. Do note that in this example these credentials are only used if testing locally, for JCS deployment credentials need to be manually updated on the EAR file: Click “Finish” and the proxy generation is done. Creating UI In order to use the data control we will need to populate complex objects FindCriteria and FindControl. For simplicity in this example we will create logic in a managed bean that populates the objects. Open “JcsWsDemoBean.java” and add the following logic: Map findCriteria; Map findControl; public void setFindCriteria(Map findCriteria) { this.findCriteria = findCriteria; } public Map getFindCriteria() { findCriteria = new HashMap(); findCriteria.put("fetchSize",10); findCriteria.put("fetchStart",0); return findCriteria; } public void setFindControl(Map findControl) { this.findControl = findControl; } public Map getFindControl() { findControl = new HashMap(); return findControl; } Open “JcsWsDemo.jspx”, navigate to “Data Controls -> CreditRuleServiceDC -> findRule(Object, Object) -> result” and drag and drop the “result” node into the “af:form” element in the page: On the “Edit Table Columns” remove all columns except “RuleId” and “Name”: On the “Edit Action Binding” window displayed enter reference to the java class created above by selecting “#{JcsWsDemoBean.findCriteria}”: Also define the value for the “findControl” by selecting “#{JcsWsDemoBean.findControl}”. Deploy to JCS For WS DC the authentication details need to be updated on the connection details before deploying. Open “connections.xml” by navigating “Application Resources -> Descriptors -> ADF META-INF -> connections.xml”: Change the user name and password entry from: <soap username="transportUserName" password="transportPassword" To match the access details for the target environment. Follow the same steps as documented in previous article ”Java Cloud Service ADF Web Application”. Once deployed the application can be accessed with URL: https://java-[identity domain].java.[data center].oraclecloudapps.com/JcsWsDemo-ViewController-context-root/faces/JcsWsDemo.jspx When accessed the first 10 rules in the system are displayed: Summary In this article we learned how to integrate with Fusion Applications using a Web Service Data Control in JCS. In future articles various other integration techniques will be covered. 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  • How to Achieve OC4J RMI Load Balancing

    - by fip
    This is an old, Oracle SOA and OC4J 10G topic. In fact this is not even a SOA topic per se. Questions of RMI load balancing arise when you developed custom web applications accessing human tasks running off a remote SOA 10G cluster. Having returned from a customer who faced challenges with OC4J RMI load balancing, I felt there is still some confusions in the field how OC4J RMI load balancing work. Hence I decide to dust off an old tech note that I wrote a few years back and share it with the general public. Here is the tech note: Overview A typical use case in Oracle SOA is that you are building web based, custom human tasks UI that will interact with the task services housed in a remote BPEL 10G cluster. Or, in a more generic way, you are just building a web based application in Java that needs to interact with the EJBs in a remote OC4J cluster. In either case, you are talking to an OC4J cluster as RMI client. Then immediately you must ask yourself the following questions: 1. How do I make sure that the web application, as an RMI client, even distribute its load against all the nodes in the remote OC4J cluster? 2. How do I make sure that the web application, as an RMI client, is resilient to the node failures in the remote OC4J cluster, so that in the unlikely case when one of the remote OC4J nodes fail, my web application will continue to function? That is the topic of how to achieve load balancing with OC4J RMI client. Solutions You need to configure and code RMI load balancing in two places: 1. Provider URL can be specified with a comma separated list of URLs, so that the initial lookup will land to one of the available URLs. 2. Choose a proper value for the oracle.j2ee.rmi.loadBalance property, which, along side with the PROVIDER_URL property, is one of the JNDI properties passed to the JNDI lookup.(http://docs.oracle.com/cd/B31017_01/web.1013/b28958/rmi.htm#BABDGFBI) More details below: About the PROVIDER_URL The JNDI property java.name.provider.url's job is, when the client looks up for a new context at the very first time in the client session, to provide a list of RMI context The value of the JNDI property java.name.provider.url goes by the format of a single URL, or a comma separate list of URLs. A single URL. For example: opmn:ormi://host1:6003:oc4j_instance1/appName1 A comma separated list of multiple URLs. For examples:  opmn:ormi://host1:6003:oc4j_instanc1/appName, opmn:ormi://host2:6003:oc4j_instance1/appName, opmn:ormi://host3:6003:oc4j_instance1/appName When the client looks up for a new Context the very first time in the client session, it sends a query against the OPMN referenced by the provider URL. The OPMN host and port specifies the destination of such query, and the OC4J instance name and appName are actually the “where clause” of the query. When the PROVIDER URL reference a single OPMN server Let's consider the case when the provider url only reference a single OPMN server of the destination cluster. In this case, that single OPMN server receives the query and returns a list of the qualified Contexts from all OC4Js within the cluster, even though there is a single OPMN server in the provider URL. A context represent a particular starting point at a particular server for subsequent object lookup. For example, if the URL is opmn:ormi://host1:6003:oc4j_instance1/appName, then, OPMN will return the following contexts: appName on oc4j_instance1 on host1 appName on oc4j_instance1 on host2, appName on oc4j_instance1 on host3,  (provided that host1, host2, host3 are all in the same cluster) Please note that One OPMN will be sufficient to find the list of all contexts from the entire cluster that satisfy the JNDI lookup query. You can do an experiment by shutting down appName on host1, and observe that OPMN on host1 will still be able to return you appname on host2 and appName on host3. When the PROVIDER URL reference a comma separated list of multiple OPMN servers When the JNDI propery java.naming.provider.url references a comma separated list of multiple URLs, the lookup will return the exact same things as with the single OPMN server: a list of qualified Contexts from the cluster. The purpose of having multiple OPMN servers is to provide high availability in the initial context creation, such that if OPMN at host1 is unavailable, client will try the lookup via OPMN on host2, and so on. After the initial lookup returns and cache a list of contexts, the JNDI URL(s) are no longer used in the same client session. That explains why removing the 3rd URL from the list of JNDI URLs will not stop the client from getting the EJB on the 3rd server. About the oracle.j2ee.rmi.loadBalance Property After the client acquires the list of contexts, it will cache it at the client side as “list of available RMI contexts”.  This list includes all the servers in the destination cluster. This list will stay in the cache until the client session (JVM) ends. The RMI load balancing against the destination cluster is happening at the client side, as the client is switching between the members of the list. Whether and how often the client will fresh the Context from the list of Context is based on the value of the  oracle.j2ee.rmi.loadBalance. The documentation at http://docs.oracle.com/cd/B31017_01/web.1013/b28958/rmi.htm#BABDGFBI list all the available values for the oracle.j2ee.rmi.loadBalance. Value Description client If specified, the client interacts with the OC4J process that was initially chosen at the first lookup for the entire conversation. context Used for a Web client (servlet or JSP) that will access EJBs in a clustered OC4J environment. If specified, a new Context object for a randomly-selected OC4J instance will be returned each time InitialContext() is invoked. lookup Used for a standalone client that will access EJBs in a clustered OC4J environment. If specified, a new Context object for a randomly-selected OC4J instance will be created each time the client calls Context.lookup(). Please note the regardless of the setting of oracle.j2ee.rmi.loadBalance property, the “refresh” only occurs at the client. The client can only choose from the "list of available context" that was returned and cached from the very first lookup. That is, the client will merely get a new Context object from the “list of available RMI contexts” from the cache at the client side. The client will NOT go to the OPMN server again to get the list. That also implies that if you are adding a node to the server cluster AFTER the client’s initial lookup, the client would not know it because neither the server nor the client will initiate a refresh of the “list of available servers” to reflect the new node. About High Availability (i.e. Resilience Against Node Failure of Remote OC4J Cluster) What we have discussed above is about load balancing. Let's also discuss high availability. This is how the High Availability works in RMI: when the client use the context but get an exception such as socket is closed, it knows that the server referenced by that Context is problematic and will try to get another unused Context from the “list of available contexts”. Again, this list is the list that was returned and cached at the very first lookup in the entire client session.

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  • SQL SERVER – Data Sources and Data Sets in Reporting Services SSRS

    - by Pinal Dave
    This example is from the Beginning SSRS by Kathi Kellenberger. Supporting files are available with a free download from the www.Joes2Pros.com web site. This example is from the Beginning SSRS. Supporting files are available with a free download from the www.Joes2Pros.com web site. Connecting to Your Data? When I was a child, the telephone book was an important part of my life. Maybe I was just a nerd, but I enjoyed getting a new book every year to page through to learn about the businesses in my small town or to discover where some of my school acquaintances lived. It was also the source of maps to my town’s neighborhoods and the towns that surrounded me. To make a phone call, I would need a telephone number. In order to find a telephone number, I had to know how to use the telephone book. That seems pretty simple, but it resembles connecting to any data. You have to know where the data is and how to interact with it. A data source is the connection information that the report uses to connect to the database. You have two choices when creating a data source, whether to embed it in the report or to make it a shared resource usable by many reports. Data Sources and Data Sets A few basic terms will make the upcoming choses make more sense. What database on what server do you want to connect to? It would be better to just ask… “what is your data source?” The connection you need to make to get your reports data is called a data source. If you connected to a data source (like the JProCo database) there may be hundreds of tables. You probably only want data from just a few tables. This means you want to write a specific query against this data source. A query on a data source to get just the records you need for an SSRS report is called a Data Set. Creating a local Data Source You can connect embed a connection from your report directly to your JProCo database which (let’s say) is installed on a server named Reno. If you move JProCo to a new server named Tampa then you need to update the Data Set. If you have 10 reports in one project that were all pointing to the JProCo database on the Reno server then they would all need to be updated at once. It’s possible to make a project level Data Source and have each report use that. This means one change can fix all 10 reports at once. This would be called a Shared Data Source. Creating a Shared Data Source The best advice I can give you is to create shared data sources. The reason I recommend this is that if a database moves to a new server you will have just one place in Report Manager to make the server name change. That one change will update the connection information in all the reports that use that data source. To get started, you will start with a fresh project. Go to Start > All Programs > SQL Server 2012 > Microsoft SQL Server Data Tools to launch SSDT. Once SSDT is running, click New Project to create a new project. Once the New Project dialog box appears, fill in the form, as shown in. Be sure to select Report Server Project this time – not the wizard. Click OK to dismiss the New Project dialog box. You should now have an empty project, as shown in the Solution Explorer. A report is meant to show you data. Where is the data? The first task is to create a Shared Data Source. Right-click on the Shared Data Sources folder and choose Add New Data Source. The Shared Data Source Properties dialog box will launch where you can fill in a name for the data source. By default, it is named DataSource1. The best practice is to give the data source a more meaningful name. It is possible that you will have projects with more than one data source and, by naming them, you can tell one from another. Type the name JProCo for the data source name and click the Edit button to configure the database connection properties. If you take a look at the types of data sources you can choose, you will see that SSRS works with many data platforms including Oracle, XML, and Teradata. Make sure SQL Server is selected before continuing. For this post, I am assuming that you are using a local SQL Server and that you can use your Windows account to log in to the SQL Server. If, for some reason you must use SQL Server Authentication, choose that option and fill in your SQL Server account credentials. Otherwise, just accept Windows Authentication. If your database server was installed locally and with the default instance, just type in Localhost for the Server name. Select the JProCo database from the database list. At this point, the connection properties should look like. If you have installed a named instance of SQL Server, you will have to specify the server name like this: Localhost\InstanceName, replacing the InstanceName with whatever your instance name is. If you are not sure about the named instance, launch the SQL Server Configuration Manager found at Start > All Programs > Microsoft SQL Server 2012 > Configuration Tools. If you have a named instance, the name will be shown in parentheses. A default instance of SQL Server will display MSSQLSERVER; a named instance will display the name chosen during installation. Once you get the connection properties filled in, click OK to dismiss the Connection Properties dialog box and OK again to dismiss the Shared Data Source properties. You now have a data source in the Solution Explorer. What’s next I really need to thank Kathi Kellenberger and Rick Morelan for sharing this material for this 5 day series of posts on SSRS. To get really comfortable with SSRS you will get to know the different SSDT windows, Build reports on your own (without the wizards),  Add report headers and footers, Accept user input,  create levels, charts, or even maps for visual appeal. You might be surprise to know a small 230 page book starts from the very beginning and covers the steps to do all these items. Beginning SSRS 2012 is a small easy to follow book so you can learn SSRS for less than $20. See Joes2Pros.com for more on this and other books. If you want to learn SSRS in easy to simple words – I strongly recommend you to get Beginning SSRS book from Joes 2 Pros. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Reporting Services, SSRS

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  • The SPARC SuperCluster

    - by Karoly Vegh
    Oracle has been providing a lead in the Engineered Systems business for quite a while now, in accordance with the motto "Hardware and Software Engineered to Work Together." Indeed it is hard to find a better definition of these systems.  Allow me to summarize the idea. It is:  Build a compute platform optimized to run your technologies Develop application aware, intelligently caching storage components Take an impressively fast network technology interconnecting it with the compute nodes Tune the application to scale with the nodes to yet unseen performance Reduce the amount of data moving via compression Provide this all in a pre-integrated single product with a single-pane management interface All these ideas have been around in IT for quite some time now. The real Oracle advantage is adding the last one to put these all together. Oracle has built quite a portfolio of Engineered Systems, to run its technologies - and run those like they never ran before. In this post I'll focus on one of them that serves as a consolidation demigod, a multi-purpose engineered system.  As you probably have guessed, I am talking about the SPARC SuperCluster. It has many great features inherited from its predecessors, and it adds several new ones. Allow me to pick out and elaborate about some of the most interesting ones from a technological point of view.  I. It is the SPARC SuperCluster T4-4. That is, as compute nodes, it includes SPARC T4-4 servers that we learned to appreciate and respect for their features: The SPARC T4 CPUs: Each CPU has 8 cores, each core runs 8 threads. The SPARC T4-4 servers have 4 sockets. That is, a single compute node can in parallel, simultaneously  execute 256 threads. Now, a full-rack SPARC SuperCluster has 4 of these servers on board. Remember the keyword demigod.  While retaining the forerunner SPARC T3's exceptional throughput, the SPARC T4 CPUs raise the bar with single performance too - a humble 5x better one than their ancestors.  actually, the SPARC T4 CPU cores run in both single-threaded and multi-threaded mode, and switch between these two on-the-fly, fulfilling not only single-threaded OR multi-threaded applications' needs, but even mixed requirements (like in database workloads!). Data security, anyone? Every SPARC T4 CPU core has a built-in encryption engine, that is, encryption algorithms cast into silicon.  A PCI controller right on the chip for customers who need I/O performance.  Built-in, no-cost Virtualization:  Oracle VM for SPARC (the former LDoms or Logical Domains) is not a server-emulation virtualization technology but rather a serverpartitioning one, the hypervisor runs in the server firmware, and all the VMs' HW resources (I/O, CPU, memory) are accessed natively, without performance overhead.  This enables customers to run a number of Solaris 10 and Solaris 11 VMs separated, independent of each other within a physical server II. For Database performance, it includes Exadata Storage Cells - one of the main reasons why the Exadata Database Machine performs at diabolic speed. What makes them important? They provide DB backend storage for your Oracle Databases to run on the SPARC SuperCluster, that is what they are built and tuned for DB performance.  These storage cells are SQL-aware.  That is, if a SPARC T4 database compute node executes a query, it doesn't simply request tons of raw datablocks from the storage, filters the received data, and throws away most of it where the statement doesn't apply, but provides the SQL query to the storage node too. The storage cell software speaks SQL, that is, it is able to prefilter and through that transfer only the relevant data. With this, the traffic between database nodes and storage cells is reduced immensely. Less I/O is a good thing - as they say, all the CPUs of the world do one thing just as fast as any other - and that is waiting for I/O.  They don't only pre-filter, but also provide data preprocessing features - e.g. if a DB-node requests an aggregate of data, they can calculate it, and handover only the results, not the whole set. Again, less data to transfer.  They support the magical HCC, (Hybrid Columnar Compression). That is, data can be stored in a precompressed form on the storage. Less data to transfer.  Of course one can't simply rely on disks for performance, there is Flash Storage included there for caching.  III. The low latency, high-speed backbone network: InfiniBand, that interconnects all the members with: Real High Speed: 40 Gbit/s. Full Duplex, of course. Oh, and a really low latency.  RDMA. Remote Direct Memory Access. This technology allows the DB nodes to do exactly that. Remotely, directly placing SQL commands into the Memory of the storage cells. Dodging all the network-stack bottlenecks, avoiding overhead, placing requests directly into the process queue.  You can also run IP over InfiniBand if you please - that's the way the compute nodes can communicate with each other.  IV. Including a general-purpose storage too: the ZFSSA, which is a unified storage, providing NAS and SAN access too, with the following features:  NFS over RDMA over InfiniBand. Nothing is faster network-filesystem-wise.  All the ZFS features onboard, hybrid storage pools, compression, deduplication, snapshot, replication, NFS and CIFS shares Storageheads in a HA-Cluster configuration providing availability of the data  DTrace Live Analytics in a web-based Administration UI Being a general purpose application data storage for your non-database applications running on the SPARC SuperCluster over whichever protocol they prefer, easily replicating, snapshotting, cloning data for them.  There's a lot of great technology included in Oracle's SPARC SuperCluster, we have talked its interior through. As for external scalability: you can start with a half- of full- rack SPARC SuperCluster, and scale out to several racks - that is, stacking not separate full-rack SPARC SuperClusters, but extending always one large instance of the size of several full-racks. Yes, over InfiniBand network. Add racks as you grow.  What technologies shall run on it? SPARC SuperCluster is a general purpose scaleout consolidation/cloud environment. You can run Oracle Databases with RAC scaling, or Oracle Weblogic (end enjoy the SPARC T4's advantages to run Java). Remember, Oracle technologies have been integrated with the Oracle Engineered Systems - this is the Oracle on Oracle advantage. But you can run other software environments such as SAP if you please too. Run any application that runs on Oracle Solaris 10 or Solaris 11. Separate them in Virtual Machines, or even Oracle Solaris Zones, monitor and manage those from a central UI. Here the key takeaways once again: The SPARC SuperCluster: Is a pre-integrated Engineered System Contains SPARC T4-4 servers with built-in virtualization, cryptography, dynamic threading Contains the Exadata storage cells that intelligently offload the burden of the DB-nodes  Contains a highly available ZFS Storage Appliance, that provides SAN/NAS storage in a unified way Combines all these elements over a high-speed, low-latency backbone network implemented with InfiniBand Can grow from a single half-rack to several full-rack size Supports the consolidation of hundreds of applications To summarize: All these technologies are great by themselves, but the real value is like in every other Oracle Engineered System: Integration. All these technologies are tuned to perform together. Together they are way more than the sum of all - and a careful and actually very time consuming integration process is necessary to orchestrate all these for performance. The SPARC SuperCluster's goal is to enable infrastructure operations and offer a pre-integrated solution that can be architected and delivered in hours instead of months of evaluations and tests. The tedious and most importantly time and resource consuming part of the work - testing and evaluating - has been done.  Now go, provide services.   -- charlie  

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  • Developing Schema Compare for Oracle (Part 1)

    - by Simon Cooper
    SQL Compare is one of Red Gate's most successful SQL Server tools; it allows developers and DBAs to compare and synchronize the contents of their databases. Although similar tools exist for Oracle, they are quite noticeably lacking in the usability and stability that SQL Compare is known for in the SQL Server world. We could see a real need for a usable schema comparison tools for Oracle, and so the Schema Compare for Oracle project was born. Over the next few weeks, as we come up to release of v1, I'll be doing a series of posts on the development of Schema Compare for Oracle. For the first post, I thought I would start with the main pitfalls that we stumbled across when developing the product, especially from a SQL Server background. 1. Schemas and Databases The most obvious difference is that the concept of a 'database' is quite different between Oracle and SQL Server. On SQL Server, one server instance has multiple databases, each with separate schemas. There is typically little communication between separate databases, and most databases are no more than about 1000-2000 objects. This means SQL Compare can register an entire database in a reasonable amount of time, and cross-database dependencies probably won't be an issue. It is a quite different scene under Oracle, however. The terms 'database' and 'instance' are used interchangeably, (although technically 'database' refers to the datafiles on disk, and 'instance' the running Oracle process that reads & writes to the database), and a database is a single conceptual entity. This immediately presents problems, as it is infeasible to register an entire database as we do in SQL Compare; in my Oracle install, using the standard recommended options, there are 63975 system objects. If we tried to register all those, not only would it take hours, but the client would probably run out of memory before we finished. As a result, we had to allow people to specify what schemas they wanted to register. This decision had quite a few knock-on effects for the design, which I will cover in a future post. 2. Connecting to Oracle The next obvious difference is in actually connecting to Oracle – in SQL Server, you can specify a server and database, and off you go. On Oracle things are slightly more complicated. SIDs, Service Names, and TNS A database (the files on disk) must have a unique identifier for the databases on the system, called the SID. It also has a global database name, which consists of a name (which doesn't have to match the SID) and a domain. Alternatively, you can identify a database using a service name, which normally has a 1-to-1 relationship with instances, but may not if, for example, using RAC (Real Application Clusters) for redundancy and failover. You specify the computer and instance you want to connect to using TNS (Transparent Network Substrate). The user-visible parts are a config file (tnsnames.ora) on the client machine that specifies how to connect to an instance. For example, the entry for one of my test instances is: SC_11GDB1 = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = simonctest)(PORT = 1521)) ) (CONNECT_DATA = (SID = 11gR1db1) ) ) This gives the hostname, port, and SID of the instance I want to connect to, and associates it with a name (SC_11GDB1). The tnsnames syntax also allows you to specify failover, multiple descriptions and address lists, and client load balancing. You can then specify this TNS identifier as the data source in a connection string. Although using ODP.NET (the .NET dlls provided by Oracle) was fine for internal prototype builds, once we released the EAP we discovered that this simply wasn't an acceptable solution for installs on other people's machines. Due to .NET assembly strong naming, users had to have installed on their machines the exact same version of the ODP.NET dlls as we had on our build server. We couldn't ship the ODP.NET dlls with our installer as the Oracle license agreement prohibited this, and we didn't want to force users to install another Oracle client just so they can run our program. To be able to list the TNS entries in the connection dialog, we also had to locate and parse the tnsnames.ora file, which was complicated by users with several Oracle client installs and intricate TNS entries. After much swearing at our computers, we eventually decided to use a third party Oracle connection library from Devart that we could ship with our program; this could use whatever client version was installed, parse the TNS entries for us, and also had the nice feature of being able to connect to an Oracle server without having any client installed at all. Unfortunately, their current license agreement prevents us from shipping an Oracle SDK, but that's a bridge we'll cross when we get to it. 3. Running synchronization scripts The most important difference is that in Oracle, DDL is non-transactional; you cannot rollback DDL statements like you can on SQL Server. Although we considered various solutions to this, including using the flashback archive or recycle bin, or generating an undo script, no reliable method of completely undoing a half-executed sync script has yet been found; so in this case we simply have to trust that the DBA or developer will check and verify the script before running it. However, before we got to that stage, we had to get the scripts to run in the first place... To run a synchronization script from SQL Compare we essentially pass the script over to the SqlCommand.ExecuteNonQuery method. However, when we tried to do the same for an OracleConnection we got a very strange error – 'ORA-00911: invalid character', even when running the most basic CREATE TABLE command. After much hair-pulling and Googling, we discovered that Oracle has got some very strange behaviour with semicolons at the end of statements. To understand what's going on, we need to take a quick foray into SQL and PL/SQL. PL/SQL is not T-SQL In SQL Server, T-SQL is the language used to interface with the database. It has DDL, DML, control flow, and many other nice features (like Turing-completeness) that you can mix and match in the same script. In Oracle, DDL SQL and PL/SQL are two completely separate languages, with different syntax, different datatypes and different execution engines within the instance. Oracle SQL is much more like 'pure' ANSI SQL, with no state, no control flow, and only the basic DML commands. PL/SQL is the Turing-complete language, but can only do DML and DCL (i.e. BEGIN TRANSATION commands). Any DDL or SQL commands that aren't recognised by the PL/SQL engine have to be passed back to the SQL engine via an EXECUTE IMMEDIATE command. In PL/SQL, a semicolons is a valid token used to delimit the end of a statement. In SQL, a semicolon is not a valid token (even though the Oracle documentation gives them at the end of the syntax diagrams) . When you execute the command CREATE TABLE table1 (COL1 NUMBER); in SQL*Plus the semicolon on the end is a command to SQL*Plus to execute the preceding statement on the server; it strips off the semicolon before passing it on. SQL Developer does a similar thing. When executing a PL/SQL block, however, the syntax is like so: BEGIN INSERT INTO table1 VALUES (1); INSERT INTO table1 VALUES (2); END; / In this case, the semicolon is accepted by the PL/SQL engine as a statement delimiter, and instead the / is the command to SQL*Plus to execute the current block. This explains the ORA-00911 error we got when trying to run the CREATE TABLE command – the server is complaining about the semicolon on the end. This also means that there is no SQL syntax to execute more than one DDL command in the same OracleCommand. Therefore, we would have to do a round-trip to the server for every command we want to execute. Obviously, this would cause lots of network traffic and be very slow on slow or congested networks. Our first attempt at a solution was to wrap every SQL statement (without semicolon) inside an EXECUTE IMMEDIATE command in a PL/SQL block and pass that to the server to execute. One downside of this solution is that we get no feedback as to how the script execution is going; we're currently evaluating better solutions to this thorny issue. Next up: Dependencies; how we solved the problem of being unable to register the entire database, and the knock-on effects to the whole product.

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  • Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors

    - by SeanMcAlinden
    Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design For the latest code go to http://rapidioc.codeplex.com/ When building our proxy type, the first thing we need to do is build the constructors. There needs to be a corresponding constructor for each constructor on the passed in base type. We also want to create a field to store the interceptors and construct this list within each constructor. So assuming the passed in base type is a User<int, IRepository> class, were looking to generate constructor code like the following:   Default Constructor public User`2_RapidDynamicBaseProxy() {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }     Parameterised Constructor public User`2_RapidDynamicBaseProxy(IRepository repository1) : base(repository1) {     this.interceptors = new List<IInterceptor<User<int, IRepository>>>();     DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>();     this.interceptors.Add(item); }   As you can see, we first populate a field on the class with a new list of the passed in base type. Construct our DefaultInterceptor class. Add the DefaultInterceptor instance to our interceptor collection. Although this seems like a relatively small task, there is a fair amount of work require to get this going. Instead of going through every line of code – please download the latest from http://rapidioc.codeplex.com/ and debug through. In this post I’m going to concentrate on explaining how it works. TypeBuilder The TypeBuilder class is the main class used to create the type. You instantiate a new TypeBuilder using the assembly module we created in part 1. /// <summary> /// Creates a type builder. /// </summary> /// <typeparam name="TBase">The type of the base class to be proxied.</typeparam> public static TypeBuilder CreateTypeBuilder<TBase>() where TBase : class {     TypeBuilder typeBuilder = DynamicModuleCache.Get.DefineType         (             CreateTypeName<TBase>(),             TypeAttributes.Class | TypeAttributes.Public,             typeof(TBase),             new Type[] { typeof(IProxy) }         );       if (typeof(TBase).IsGenericType)     {         GenericsHelper.MakeGenericType(typeof(TBase), typeBuilder);     }       return typeBuilder; }   private static string CreateTypeName<TBase>() where TBase : class {     return string.Format("{0}_RapidDynamicBaseProxy", typeof(TBase).Name); } As you can see, I’ve create a new public class derived from TBase which also implements my IProxy interface, this is used later for adding interceptors. If the base type is generic, the following GenericsHelper.MakeGenericType method is called. GenericsHelper using System; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Types.Helpers {     /// <summary>     /// Helper class for generic types and methods.     /// </summary>     internal static class GenericsHelper     {         /// <summary>         /// Makes the typeBuilder a generic.         /// </summary>         /// <param name="concrete">The concrete.</param>         /// <param name="typeBuilder">The type builder.</param>         public static void MakeGenericType(Type baseType, TypeBuilder typeBuilder)         {             Type[] genericArguments = baseType.GetGenericArguments();               string[] genericArgumentNames = GetArgumentNames(genericArguments);               GenericTypeParameterBuilder[] genericTypeParameterBuilder                 = typeBuilder.DefineGenericParameters(genericArgumentNames);               typeBuilder.MakeGenericType(genericTypeParameterBuilder);         }           /// <summary>         /// Gets the argument names from an array of generic argument types.         /// </summary>         /// <param name="genericArguments">The generic arguments.</param>         public static string[] GetArgumentNames(Type[] genericArguments)         {             string[] genericArgumentNames = new string[genericArguments.Length];               for (int i = 0; i < genericArguments.Length; i++)             {                 genericArgumentNames[i] = genericArguments[i].Name;             }               return genericArgumentNames;         }     } }       As you can see, I’m getting all of the generic argument types and names, creating a GenericTypeParameterBuilder and then using the typeBuilder to make the new type generic. InterceptorsField The interceptors field will store a List<IInterceptor<TBase>>. Fields are simple made using the FieldBuilder class. The following code demonstrates how to create the interceptor field. FieldBuilder interceptorsField = typeBuilder.DefineField(     "interceptors",     typeof(System.Collections.Generic.List<>).MakeGenericType(typeof(IInterceptor<TBase>)),       FieldAttributes.Private     ); The field will now exist with the new Type although it currently has no data – we’ll deal with this in the constructor. Add method for interceptorsField To enable us to add to the interceptorsField list, we are going to utilise the Add method that already exists within the System.Collections.Generic.List class. We still however have to create the methodInfo necessary to call the add method. This can be done similar to the following: Add Interceptor Field MethodInfo addInterceptor = typeof(List<>)     .MakeGenericType(new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) })     .GetMethod     (        "Add",        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) },        null     ); So we’ve create a List<IInterceptor<TBase>> type, then using the type created a method info called Add which accepts an IInterceptor<TBase>. Now in our constructor we can use this to call this.interceptors.Add(// interceptor); Building the Constructors This will be the first hard-core part of the proxy building process so I’m going to show the class and then try to explain what everything is doing. For a clear view, download the source from http://rapidioc.codeplex.com/, go to the test project and debug through the constructor building section. Anyway, here it is: DynamicConstructorBuilder using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; using Rapid.DynamicProxy.Interception; using Rapid.DynamicProxy.Types.Helpers; namespace Rapid.DynamicProxy.Types.Constructors {     /// <summary>     /// Class for creating the proxy constructors.     /// </summary>     internal static class DynamicConstructorBuilder     {         /// <summary>         /// Builds the constructors.         /// </summary>         /// <typeparam name="TBase">The base type.</typeparam>         /// <param name="typeBuilder">The type builder.</param>         /// <param name="interceptorsField">The interceptors field.</param>         public static void BuildConstructors<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 MethodInfo addInterceptor             )             where TBase : class         {             ConstructorInfo interceptorsFieldConstructor = CreateInterceptorsFieldConstructor<TBase>();               ConstructorInfo defaultInterceptorConstructor = CreateDefaultInterceptorConstructor<TBase>();               ConstructorInfo[] constructors = typeof(TBase).GetConstructors();               foreach (ConstructorInfo constructorInfo in constructors)             {                 CreateConstructor<TBase>                     (                         typeBuilder,                         interceptorsField,                         interceptorsFieldConstructor,                         defaultInterceptorConstructor,                         addInterceptor,                         constructorInfo                     );             }         }           #region Private Methods           private static void CreateConstructor<TBase>             (                 TypeBuilder typeBuilder,                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ConstructorInfo defaultInterceptorConstructor,                 MethodInfo AddDefaultInterceptor,                 ConstructorInfo constructorInfo             ) where TBase : class         {             Type[] parameterTypes = GetParameterTypes(constructorInfo);               ConstructorBuilder constructorBuilder = CreateConstructorBuilder(typeBuilder, parameterTypes);               ILGenerator cIL = constructorBuilder.GetILGenerator();               LocalBuilder defaultInterceptorMethodVariable =                 cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase)));               ConstructInterceptorsField(interceptorsField, interceptorsFieldConstructor, cIL);               ConstructDefaultInterceptor(defaultInterceptorConstructor, cIL, defaultInterceptorMethodVariable);               AddDefaultInterceptorToInterceptorsList                 (                     interceptorsField,                     AddDefaultInterceptor,                     cIL,                     defaultInterceptorMethodVariable                 );               CreateConstructor(constructorInfo, parameterTypes, cIL);         }           private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         }           private static void AddDefaultInterceptorToInterceptorsList             (                 FieldBuilder interceptorsField,                 MethodInfo AddDefaultInterceptor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Ldfld, interceptorsField);             cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);             cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor);         }           private static void ConstructDefaultInterceptor             (                 ConstructorInfo defaultInterceptorConstructor,                 ILGenerator cIL,                 LocalBuilder defaultInterceptorMethodVariable             )         {             cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);             cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable);         }           private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         }           private static ConstructorBuilder CreateConstructorBuilder(TypeBuilder typeBuilder, Type[] parameterTypes)         {             return typeBuilder.DefineConstructor                 (                     MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName                     | MethodAttributes.HideBySig, CallingConventions.Standard, parameterTypes                 );         }           private static Type[] GetParameterTypes(ConstructorInfo constructorInfo)         {             ParameterInfo[] parameterInfoArray = constructorInfo.GetParameters();               Type[] parameterTypes = new Type[parameterInfoArray.Length];               for (int p = 0; p < parameterInfoArray.Length; p++)             {                 parameterTypes[p] = parameterInfoArray[p].ParameterType;             }               return parameterTypes;         }           private static ConstructorInfo CreateInterceptorsFieldConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(List<>),                     new Type[] { typeof(IInterceptor<TBase>) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           private static ConstructorInfo CreateDefaultInterceptorConstructor<TBase>() where TBase : class         {             return ConstructorHelper.CreateGenericConstructorInfo                 (                     typeof(DefaultInterceptor<>),                     new Type[] { typeof(TBase) },                     BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic                 );         }           #endregion     } } So, the first two tasks within the class should be fairly clear, we are creating a ConstructorInfo for the interceptorField list and a ConstructorInfo for the DefaultConstructor, this is for instantiating them in each contructor. We then using Reflection get an array of all of the constructors in the base class, we then loop through the array and create a corresponding proxy contructor. Hopefully, the code is fairly easy to follow other than some new types and the dreaded Opcodes. ConstructorBuilder This class defines a new constructor on the type. ILGenerator The ILGenerator allows the use of Reflection.Emit to create the method body. LocalBuilder The local builder allows the storage of data in local variables within a method, in this case it’s the constructed DefaultInterceptor. Constructing the interceptors field The first bit of IL you’ll come across as you follow through the code is the following private method used for constructing the field list of interceptors. private static void ConstructInterceptorsField             (                 FieldBuilder interceptorsField,                 ConstructorInfo interceptorsFieldConstructor,                 ILGenerator cIL             )         {             cIL.Emit(OpCodes.Ldarg_0);             cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor);             cIL.Emit(OpCodes.Stfld, interceptorsField);         } The first thing to know about generating code using IL is that you are using a stack, if you want to use something, you need to push it up the stack etc. etc. OpCodes.ldArg_0 This opcode is a really interesting one, basically each method has a hidden first argument of the containing class instance (apart from static classes), constructors are no different. This is the reason you can use syntax like this.myField. So back to the method, as we want to instantiate the List in the interceptorsField, first we need to load the class instance onto the stack, we then load the new object (new List<TBase>) and finally we store it in the interceptorsField. Hopefully, that should follow easily enough in the method. In each constructor you would now have this.interceptors = new List<User<int, IRepository>>(); Constructing and storing the DefaultInterceptor The next bit of code we need to create is the constructed DefaultInterceptor. Firstly, we create a local builder to store the constructed type. Create a local builder LocalBuilder defaultInterceptorMethodVariable =     cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); Once our local builder is ready, we then need to construct the DefaultInterceptor<TBase> and store it in the variable. Connstruct DefaultInterceptor private static void ConstructDefaultInterceptor     (         ConstructorInfo defaultInterceptorConstructor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor);     cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } As you can see, using the ConstructorInfo named defaultInterceptorConstructor, we load the new object onto the stack. Then using the store local opcode (OpCodes.Stloc), we store the new object in the local builder named defaultInterceptorMethodVariable. Add the constructed DefaultInterceptor to the interceptors field collection Using the add method created earlier in this post, we are going to add the new DefaultInterceptor object to the interceptors field collection. Add Default Interceptor private static void AddDefaultInterceptorToInterceptorsList     (         FieldBuilder interceptorsField,         MethodInfo AddDefaultInterceptor,         ILGenerator cIL,         LocalBuilder defaultInterceptorMethodVariable     ) {     cIL.Emit(OpCodes.Ldarg_0);     cIL.Emit(OpCodes.Ldfld, interceptorsField);     cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable);     cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } So, here’s whats going on. The class instance is first loaded onto the stack using the load argument at index 0 opcode (OpCodes.Ldarg_0) (remember the first arg is the hidden class instance). The interceptorsField is then loaded onto the stack using the load field opcode (OpCodes.Ldfld). We then load the DefaultInterceptor object we stored locally using the load local opcode (OpCodes.Ldloc). Then finally we call the AddDefaultInterceptor method using the call virtual opcode (Opcodes.Callvirt). Completing the constructor The last thing we need to do is complete the constructor. Complete the constructor private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL)         {             cIL.Emit(OpCodes.Ldarg_0);               if (parameterTypes.Length > 0)             {                 LoadParameterTypes(parameterTypes, cIL);             }               cIL.Emit(OpCodes.Call, constructorInfo);             cIL.Emit(OpCodes.Ret);         }           private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL)         {             for (int i = 1; i <= parameterTypes.Length; i++)             {                 cIL.Emit(OpCodes.Ldarg_S, i);             }         } So, the first thing we do again is load the class instance using the load argument at index 0 opcode (OpCodes.Ldarg_0). We then load each parameter using OpCode.Ldarg_S, this opcode allows us to specify an index position for each argument. We then setup calling the base constructor using OpCodes.Call and the base constructors ConstructorInfo. Finally, all methods are required to return, even when they have a void return. As there are no values on the stack after the OpCodes.Call line, we can safely call the OpCode.Ret to give the constructor a void return. If there was a value, we would have to pop the value of the stack before calling return otherwise, the method would try and return a value. Conclusion This was a slightly hardcore post but hopefully it hasn’t been too hard to follow. The main thing is that a number of the really useful opcodes have been used and now the dynamic proxy is capable of being constructed. If you download the code and debug through the tests at http://rapidioc.codeplex.com/, you’ll be able to create proxies at this point, they cannon do anything in terms of interception but you can happily run the tests, call base methods and properties and also take a look at the created assembly in Reflector. Hope this is useful. The next post should be up soon, it will be covering creating the private methods for calling the base class methods and properties. Kind Regards, Sean.

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  • Using Cloud OER to Find Fusion Applications On-Premise Service Concrete WSDL URL by Rajesh Raheja

    - by JuergenKress
    In my previous post on Fusion Applications Integration, the Fusion Applications OER white paper explains Oracle Enterprise Repository (OER) usage in the applications context, assuming a dedicated OER for your Fusion Applications instance (whether cloud/SaaS or on-premise). Having a dedicated OER instance is recommended as it can provide customized service metadata and can be used for overall SOA governance in addition to simple service discovery. One of the common queries I get is how on-premise customers without a dedicated OER can find a concrete service WSDL URL for their specific environment using the cloud hosted OER instance. Read the full article here. SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit  www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Technorati Tags: OER,SOA Governance,SOA Community,Oracle SOA,Oracle BPM,BPM,Community,OPN,Jürgen Kress

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  • Setting up SSO in ADF Security-enabled application

    - by Dmitry Nefedkin
    I'm continuing a series of post/videos regarding  the setting up ADF applications in the real world. This time I'm going to present how to set up Single Sign-On (SSO) and Single Logout (SLO) for ADF application using Oracle Access Manager 11g.  In this 40-min video we are going to explore the following topics: Review the demo environment; Install Oracle HTTP Server 11g (OHS) instance as a reverse proxy for Oracle Weblogic Server; Install OAM 11g Web Gate inside OHS; Modify and redeploy the ADF application for use with OAM; Configure OAM Identity Asserter in ADF domain; Configure single logout (SLO); Test SSO and SLO  

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  • Using idle time in turn-based (RPG) games for updating

    - by The Communist Duck
    If you take any turn based RPG game there will be large periods of time when nothing is happening because the game is looping over 'wait_for_player_input'. Naturally it seems sensible to use this time to update things. However, this immediately seems to suggest that it would need to be threaded. Is this sort of design possible in a single thread? loop: if not check_something_pressed: update_a_very_small_amount else keep going But if we says 'a_very_small_amount' is only updating a single object each loop, it's going to be very slow at updating. How would you go about this, preferably in a single thread? EDIT: I've tagged this language-agnostic as that seems the sensible thing, though anything more specific to Python would be great. ;-)

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  • Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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  • Multiple Object Instantiation

    - by Ricky Baby
    I am trying to get my head around object oriented programming as it pertains to web development (more specifically PHP). I understand inheritance and abstraction etc, and know all the "buzz-words" like encapsulation and single purpose and why I should be doing all this. But my knowledge is falling short with actually creating objects that relate to the data I have in my database, creating a single object that a representative of a single entity makes sense, but what are the best practises when creating 100, 1,000 or 10,000 objects of the same type. for instance, when trying to display a list of the items, ideally I would like to be consistent with the objects I use, but where exactly should I run the query/get the data to populate the object(s) as running 10,000 queries seems wasteful. As an example, say I have a database of cats, and I want a list of all black cats, do I need to set up a FactoryObject which grabs the data needed for each cat from my database, then passes that data into each individual CatObject and returns the results in a array/object - or should I pass each CatObject it's identifier and let it populate itself in a separate query.

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  • What are the downsides of implementing a singleton with Java's enum?

    - by irreputable
    Traditionally, a singleton is usually implemented as public class Foo1 { private static final Foo1 INSTANCE = new Foo1(); public static Foo1 getInstance(){ return INSTANCE; } private Foo1(){} public void doo(){ ... } } With Java's enum, we can implement a singleton as public enum Foo2 { INSTANCE; public void doo(){ ... } } As awesome as the 2nd version is, are there any downsides to it? (I gave it some thoughts and I'll answer my own question; hopefully you have better answers)

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  • Storing Attendance Data in database

    - by Ali Abbas
    So i have to store daily attendance of employees of my organisation from my application . The part where I need some help is, the efficient way to store attendance data. After some research and brain storming I came up with some approaches . Could you point me out which one is the best and any unobvious ill effects of the mentioned approaches. The approaches are as follows Create a single table for whole organisation and store empid,date,presentstatus as a row for every employee everyday. Create a single table for whole organisation and store a single row for each day with a comma delimited string of empids which are absent. I will generate the string on my application. Create different tables for each department and follow the 1 method. Please share your views and do mention any other good methods

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  • A Basic Thread

    - by Joe Mayo
    Most of the programs written are single-threaded, meaning that they run on the main execution thread. For various reasons such as performance, scalability, and/or responsiveness additional threads can be useful. .NET has extensive threading support, from the basic threads introduced in v1.0 to the Task Parallel Library (TPL) introduced in v4.0. To get started with threads, it's helpful to begin with the basics; starting a Thread. Why Do I Care? The scenario I'll use for needing to use a thread is writing to a file.  Sometimes, writing to a file takes a while and you don't want your user interface to lock up until the file write is done. In other words, you want the application to be responsive to the user. How Would I Go About It? The solution is to launch a new thread that performs the file write, allowing the main thread to return to the user right away.  Whenever the file writing thread completes, it will let the user know.  In the meantime, the user is free to interact with the program for other tasks. The following examples demonstrate how to do this. Show Me the Code? The code we'll use to work with threads is in the System.Threading namespace, so you'll need the following using directive at the top of the file: using System.Threading; When you run code on a thread, the code is specified via a method.  Here's the code that will execute on the thread: private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written."); } The call to Thread.Sleep(1000) delays thread execution. The parameter is specified in milliseconds, and 1000 means that this will cause the program to sleep for approximately 1 second.  This method happens to be static, but that's just part of this example, which you'll see is launched from the static Main method.  A thread could be instance or static.  Notice that the method does not have parameters and does not have a return type. As you know, the way to refer to a method is via a delegate.  There is a delegate named ThreadStart in System.Threading that refers to a method without parameters or return type, shown below: ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); I'll show you the whole program below, but the ThreadStart instance above goes in the Main method. The thread uses the ThreadStart instance, fileWriterHandlerDelegate, to specify the method to execute on the thread: Thread fileWriter = new Thread(fileWriterHandlerDelegate); As shown above, the argument type for the Thread constructor is the ThreadStart delegate type. The fileWriterHandlerDelegate argument is an instance of the ThreadStart delegate type. This creates an instance of a thread and what code will execute, but the new thread instance, fileWriter, isn't running yet. You have to explicitly start it, like this: fileWriter.Start(); Now, the code in the WriteFile method is executing on a separate thread. Meanwhile, the main thread that started the fileWriter thread continues on it's own.  You have two threads running at the same time. Okay, I'm Starting to Get Glassy Eyed. How Does it All Fit Together? The example below is the whole program, pulling all the previous bits together. It's followed by its output and an explanation. using System; using System.Threading; namespace BasicThread { class Program { static void Main() { ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); Thread fileWriter = new Thread(fileWriterHandlerDelegate); Console.WriteLine("Starting FileWriter"); fileWriter.Start(); Console.WriteLine("Called FileWriter"); Console.ReadKey(); } private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written"); } } } And here's the output: Starting FileWriter Called FileWriter File Written So, Why are the Printouts Backwards? The output above corresponds to Console.Writeline statements in the program, with the second and third seemingly reversed. In a single-threaded program, "File Written" would print before "Called FileWriter". However, this is a multi-threaded (2 or more threads) program.  In multi-threading, you can't make any assumptions about when a given thread will run.  In this case, I added the Sleep statement to the WriteFile method to greatly increase the chances that the message from the main thread will print first. Without the Thread.Sleep, you could run this on a system with multiple cores and/or multiple processors and potentially get different results each time. Interesting Tangent but What Should I Get Out of All This? Going back to the main point, launching the WriteFile method on a separate thread made the program more responsive.  The file writing logic ran for a while, but the main thread returned to the user, as demonstrated by the print out of "Called FileWriter".  When the file write finished, it let the user know via another print statement. This was a very efficient use of CPU resources that made for a more pleasant user experience. Joe

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