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• Azure Grid Computing - Worker Roles as HPC Compute Nodes

  - by JoshReuben

  Overview ·        With HPC 2008 R2 SP1 You can add Azure worker roles as compute nodes in a local Windows HPC Server cluster. ·        The subscription for Windows Azure like any other Azure Service - charged for the time that the role instances are available, as well as for the compute and storage services that are used on the nodes. ·        Win-Win ? - Azure charges the computer hour cost (according to vm size) amortized over a month – so you save on purchasing compute node hardware. Microsoft wins because you need to purchase HPC to have a local head node for managing this compute cluster grid distributed in the cloud. ·        Blob storage is used to hold input & output files of each job. I can see how Parametric Sweep HPC jobs can be supported (where the same job is run multiple times on each node against different input units), but not MPI.NET (where different HPC Job instances function as coordinated agents and conduct master-slave inter-process communication), unless Azure is somehow tunneling MPI communication through inter-WorkerRole Azure Queues. ·        this is not the end of the story for Azure Grid Computing. If MS requires you to purchase a local HPC license (and administrate it), what's to stop a 3rd party from doing this and encapsulating exposing HPC WCF Broker Service to you for managing compute nodes? If MS doesn’t  provide head node as a service, someone else will! Process ·        requires creation of a worker node template that specifies a connection to an existing subscription for Windows Azure + an availability policy for the worker nodes. ·        After worker nodes are added to the cluster, you can start them, which provisions the Windows Azure role instances, and then bring them online to run HPC cluster jobs. ·        A Windows Azure worker role instance runs a HPC compatible Azure guest operating system which runs on the VMs that host your service. The guest operating system is updated monthly. You can choose to upgrade the guest OS for your service automatically each time an update is released - All role instances defined by your service will run on the guest operating system version that you specify. see Windows Azure Guest OS Releases and SDK Compatibility Matrix (http://go.microsoft.com/fwlink/?LinkId=190549). ·        use the hpcpack command to upload file packages and install files to run on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). Requirements ·        assuming you have an azure subscription account and the HPC head node installed and configured. ·        Install HPC Pack 2008 R2 SP 1 -  see Microsoft HPC Pack 2008 R2 Service Pack 1 Release Notes (http://go.microsoft.com/fwlink/?LinkID=202812). ·        Configure the head node to connect to the Internet - connectivity is provided by the connection of the head node to the enterprise network. You may need to configure a proxy client on the head node. Any cluster network topology (1-5) is supported). ·        Configure the firewall - allow outbound TCP traffic on the following ports: 80,       443, 5901, 5902, 7998, 7999 ·        Note: HPC Server  uses Admin Mode (Elevated Privileges) in Windows Azure to give the service administrator of the subscription the necessary privileges to initialize HPC cluster services on the worker nodes. ·        Obtain a Windows Azure subscription certificate - the Windows Azure subscription must be configured with a public subscription (API) certificate -a valid X.509 certificate with a key size of at least 2048 bits. Generate a self-sign certificate & upload a .cer file to the Windows Azure Portal Account page > Manage my API Certificates link. see Using the Windows Azure Service Management API (http://go.microsoft.com/fwlink/?LinkId=205526). ·        import the certificate with an associated private key on the HPC cluster head node - into the trusted root store of the local computer account. Obtain Windows Azure Connection Information for HPC Server ·        required for each worker node template ·        copy from azure portal - Get from: navigation pane > Hosted Services > Storage Accounts & CDN ·        Subscription ID - a 32-char hex string in the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. In Properties pane. ·        Subscription certificate thumbprint - a 40-char hex string (you need to remove spaces). In Management Certificates > Properties pane. ·        Service name - the value of <ServiceName> configured in the public URL of the service (http://<ServiceName>.cloudapp.net). In Hosted Services > Properties pane. ·        Blob Storage account name - the value of <StorageAccountName> configured in the public URL of the account (http://<StorageAccountName>.blob.core.windows.net). In Storage Accounts > Properties pane. Import the Azure Subscription Certificate on the HPC Head Node ·        enable the services for Windows HPC Server  to authenticate properly with the Windows Azure subscription. ·        use the Certificates MMC snap-in to import the certificate to the Trusted Root Certification Authorities store of the local computer account. The certificate must be in PFX format (.pfx or .p12 file) with a private key that is protected by a password. ·        see Certificates (http://go.microsoft.com/fwlink/?LinkId=163918). ·        To open the certificates snapin: Run > mmc. File > Add/Remove Snap-in > certificates > Computer account > Local Computer ·        To import the certificate via wizard - Certificates > Trusted Root Certification Authorities > Certificates > All Tasks > Import ·        After the certificate is imported, it appears in the details pane in the Certificates snap-in. You can open the certificate to check its status. Configure a Proxy Client on the HPC Head Node ·        the following Windows HPC Server services must be able to communicate over the Internet (through the firewall) with the services for Windows Azure: HPCManagement, HPCScheduler, HPCBrokerWorker. ·        Create a Windows Azure Worker Node Template ·        Edit HPC node templates in HPC Node Template Editor. ·        Specify: 1) Windows Azure subscription connection info (unique service name) for adding a set of worker nodes to the cluster + 2)worker node availability policy – rules for deploying / removing worker role instances in Windows Azure o   HPC Cluster Manager > Configuration > Navigation Pane > Node Templates > Actions pane > New à Create Node Template Wizard or Edit à Node Template Editor o   Choose Node Template Type page - Windows Azure worker node template o   Specify Template Name page – template name & description o   Provide Connection Information page – Azure Subscription ID (text) & Subscription certificate (browse) o   Provide Service Information page - Azure service name + blob storage account name (optionally click Retrieve Connection Information to get list of available from azure – possible LRT). o   Configure Azure Availability Policy page - how Windows Azure worker nodes start / stop (online / offline the worker role instance -  add / remove) – manual / automatic o   for automatic - In the Configure Windows Azure Worker Availability Policy dialog -select days and hours for worker nodes to start / stop. ·        To validate the Windows Azure connection information, on the template's Connection Information tab > Validate connection information. ·        You can upload a file package to the storage account that is specified in the template - eg upload application or service files that will run on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). Add Azure Worker Nodes to the HPC Cluster ·        Use the Add Node Wizard – specify: 1) the worker node template, 2) The number of worker nodes   (within the quota of role instances in the azure subscription), and 3)           The VM size of the worker nodes : ExtraSmall, Small, Medium, Large, or ExtraLarge.  ·        to add worker nodes of different sizes, must run the Add Node Wizard separately for each size. ·        All worker nodes that are added to the cluster by using a specific worker node template define a set of worker nodes that will be deployed and managed together in Windows Azure when you start the nodes. This includes worker nodes that you add later by using the worker node template and, if you choose, worker nodes of different sizes. You cannot start, stop, or delete individual worker nodes. ·        To add Windows Azure worker nodes o   In HPC Cluster Manager: Node Management > Actions pane > Add Node à Add Node Wizard o   Select Deployment Method page - Add Azure Worker nodes o   Specify New Nodes page - select a worker node template, specify the number and size of the worker nodes ·        After you add worker nodes to the cluster, they are in the Not-Deployed state, and they have a health state of Unapproved. Before you can use the worker nodes to run jobs, you must start them and then bring them online. ·        Worker nodes are numbered consecutively in a naming series that begins with the root name AzureCN – this is non-configurable. Deploying Windows Azure Worker Nodes ·        To deploy the role instances in Windows Azure - start the worker nodes added to the HPC cluster and bring the nodes online so that they are available to run cluster jobs. This can be configured in the HPC Azure Worker Node Template – Azure Availability Policy -  to be automatic or manual. ·        The Start, Stop, and Delete actions take place on the set of worker nodes that are configured by a specific worker node template. You cannot perform one of these actions on a single worker node in a set. You also cannot perform a single action on two sets of worker nodes (specified by two different worker node templates). ·        ·          Starting a set of worker nodes deploys a set of worker role instances in Windows Azure, which can take some time to complete, depending on the number of worker nodes and the performance of Windows Azure. ·        To start worker nodes manually and bring them online o   In HPC Node Management > Navigation Pane > Nodes > List / Heat Map view - select one or more worker nodes. o   Actions pane > Start – in the Start Azure Worker Nodes dialog, select a node template. o   the state of the worker nodes changes from Not Deployed to track the provisioning progress – worker node Details Pane > Provisioning Log tab. o   If there were errors during the provisioning of one or more worker nodes, the state of those nodes is set to Unknown and the node health is set to Unapproved. To determine the reason for the failure, review the provisioning logs for the nodes. o   After a worker node starts successfully, the node state changes to Offline. To bring the nodes online, select the nodes that are in the Offline state > Bring Online. ·        Troubleshooting o   check node template. o   use telnet to test connectivity: telnet <ServiceName>.cloudapp.net 7999 o   check node status - Deployment status information appears in the service account information in the Windows Azure Portal - HPC queries this -  see  node status information for any failed nodes in HPC Node Management. ·        When role instances are deployed, file packages that were previously uploaded to the storage account using the hpcpack command are automatically installed. You can also upload file packages to storage after the worker nodes are started, and then manually install them on the worker nodes. see hpcpack (http://go.microsoft.com/fwlink/?LinkID=205514). ·        to remove a set of role instances in Windows Azure - stop the nodes by using HPC Cluster Manager (apply the Stop action). This deletes the role instances from the service and changes the state of the worker nodes in the HPC cluster to Not Deployed. ·        Each time that you start a set of worker nodes, two proxy role instances (size Small) are configured in Windows Azure to facilitate communication between HPC Cluster Manager and the worker nodes. The proxy role instances are not listed in HPC Cluster Manager after the worker nodes are added. However, the instances appear in the Windows Azure Portal. The proxy role instances incur charges in Windows Azure along with the worker node instances, and they count toward the quota of role instances in the subscription.

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• Part 2: Career development as a Software Developer without becoming a manager.

  - by albertpascual

  Seems like my previous post inspired by the work of Michael “Doc” Norton was a great success for the amount of emails I have received. Yet amazed how many people didn’t want to discuss their questions in the comments  sections. I would encourage people to be more public, still I would like to reply to all of you on this public media. I still welcome those emails. What I found out is that many people feels like me, they want to be developers and still be compensated for their experience without wanting to take a job as a manager. Their perfect day is a full day of coding and learning. Many believe their companies will never pay a manager’s salary to a developer no matter what. Most of you ask how to get the ball rolling. And is the later that I’m addressing here, the previous group, will never try. What companies understand developers value and where can I find them? This is a very difficult question to ask, I don’t have a list of those companies or departments, I have seen in my past signs in companies bending backwards to compensate, in more ways the monetary, a developer that is a good resource to them. Allowing the person to move out of the state and still let them work for the company from home is a sign that company goes by individual cases. Allowing them to go to conference that will not benefit the company is another big sign. Simple signs like flexible hours and letting some people work from home. To see those signs you need to be working in that company for awhile and look at the departments where the manager is taking care of their employees in individual cases. Look for the department where people get quiet extra perks, where some people in the department work from home or remotely. In my experience, but not always true, medium to big companies, are prompt to recognize good developers. Then again, some companies just don’t get it and is when you see many technical people managing developers. For all the people that email me stating that developers can also be very good managers, I do not disagree, I just think that a good developers loves writing code, when you remove that part the better salary isn’t enough to keep a developer happy. Burned out developers appreciate being promoted to managers. How do I know I work in a bad company? In my experience I have been a consultant and seen many companies, a few signs I have learned about companies that will not recognize good developers are: When the turn over is pretty high, when developers are moving out in a big rate, no rocket scientist needs to tap you in the shoulder. When the company is looking always to outsource their development resources. The product is not that interesting nor the company cares too much for their final result and support. Code sweat shops. You’ll know when you start working in one of those. Run for the hills! Where do I start? Disclaimer: I have only based this post on Michael “Doc” Norton, this is just my interpretation and ideas. First thing is to look at Michael “Doc” Norton presentation Take Control of Your Development Career http://docondev.blogspot.com/ That should be the first thing any developer should look and follow like it was a pattern. I would personally recommend to find some language or pattern you are interested with and learn it, learn something that will make you happy. Second, join a User Group and get involve in the community. There are hundreds of user groups, and I’m sure you’ll find one in your city or near you town. Code Camps are Developers Meet Ups are also good resources. Third, I would join a open source project you are interested or better yet, create a new open source project with the new technology that you have learn and get coding. Fourth, create a Twitter account and follow the people that talks about the technology you are interested on. If you follow this 4 steps above I think you’ll be on your way, after they are complete, when you release your Open Source project you can say that you accomplished the first steps. Now, do not expect anything to change in your career life, you are changing and should not expect anything in return, besides borrowing some time from sleeping and your family. Creating a good schedule may help you, I find wasted time in many places that I use. Flying for work is actually one of those that allows me to do my best work on a airplane, don’t need to borrow time from anywhere else. Making sure you always have a light, charged laptop is so important. Next steps following the Michael “Doc” Norton Pattern or my interpretation of. First, help run a user group or better yet, start a new user group. I’ll add, as well, go to one conference a year and free development events around your city; Code Camps, Geek Dinners, etc. There are many free events sponsored by different companies for developers to get to know their products, I highly recommend those as the way to get connected. Second, chose a mentor, this is a very hard thing to do I experienced, find an expert in the technology you are learning that has the time for you, it is difficult, I wish you best of luck. Third, learn another technology or pattern, open your horizons a little bit more. Why not, if you had fun previously, keep doing it. Fourth, get involved in forums to answer and ask questions, getting notice in public forums is rewarding for your ego after such a long journey. Final steps following the Michael “Doc” Norton Pattern Teach what you know, become humble on your knowledge, find as many opportunities to teach and to get involved with the community, bring all that to your day job. Mr. Norton talks about getting naked, expose yourself to others in your knowledge and what you do not know. You are never too important for small opportunities, yet don’t  be afraid to take anything big and learn from the experience. Anytime you have the opportunity to talk to somebody that has reach the point the community knows his or her name, means that you should learn from it. Take opportunities that won’t make you money, yet will make you happy. Sometimes you need to spend money and time. Register talks in Code Camps and Dev Meet Ups, those are free, also go to Conference, Development Summits and Geek Diners for example. One day, people will pay you to attend. When will all these pay off? I don’t know. I’m still in the path, there are a few things that during your journey you may get little acknowledgements that you are in the correct path. In my case I think those are the little signs that tells you about your journey. I got awarded the Microsoft Most Valuable Professional for ASP.NET in 2007, 2008, 2009 and 2010. I got selected to speak at the DevConnections in Las Vegas in 2010 and Orlando 2011. I do believe that I do have a long way to go, yet what I do makes me happy and I hope I can keep doing for years to come. Every year I can see an improvement on my code, and more frameworks and languages are under my belt, I learn to embrace them all as well as in my daily job, I have been able to work in a few projects beyond my department. I’m a learner and believer of the Michael “Doc” Norton pattern. Looking forward to learn more about it to be able to apply it better. In my short journey I now see my mistakes, I did a few things right, I have been listening the intelligent people and not being afraid to move along the technology changes. In my professional life, I have tried to avoid being placed in only one technology and product. I have always share my code and never confused anybody that wanted to take over any of my projects, I didn’t think anything I created as my own nor care too much when politics didn’t see my vision. I stayed flexible, ready and visible, yet humble. I keep my head just below the clouds, and avoided managers meetings. I credit my manager for my success, and I faulted publicly only myself for the failures. Hope this helps. Cheers, Al Follow me in Twitter  Read my previous post tweetmeme_url = 'http://weblogs.asp.net/albertpascual/archive/2010/12/09/part-2-career-development-as-a-software-developer-without-becoming-a-manager.aspx'; tweetmeme_source = 'alpascual';

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• C# 4.0: Alternative To Optional Arguments

  - by Paulo Morgado

  Like I mentioned in my last post, exposing publicly methods with optional arguments is a bad practice (that’s why C# has resisted to having it, until now). You might argument that your method or constructor has to many variants and having ten or more overloads is a maintenance nightmare, and you’re right. But the solution has been there for ages: have an arguments class. The arguments class pattern is used in the .NET Framework is used by several classes, like XmlReader and XmlWriter that use such pattern in their Create methods, since version 2.0: XmlReaderSettings settings = new XmlReaderSettings(); settings.ValidationType = ValidationType.Auto; XmlReader.Create("file.xml", settings); With this pattern, you don’t have to maintain a long list of overloads and any default values for properties of XmlReaderSettings (or XmlWriterSettings for XmlWriter.Create) can be changed or new properties added in future implementations that won’t break existing compiled code. You might now argue that it’s too much code to write, but, with object initializers added in C# 3.0, the same code can be written like this: XmlReader.Create("file.xml", new XmlReaderSettings { ValidationType = ValidationType.Auto }); Looks almost like named and optional arguments, doesn’t it? And, who knows, in a future version of C#, it might even look like this: XmlReader.Create("file.xml", new { ValidationType = ValidationType.Auto });

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• Refactor This (Ugly Code)!

  - by Alois Kraus

  Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor:         private void HandleMessageCompletion(                                      Message message,                                      TransactionScope tx,                                      OpenedQueue messageQueue,                                      Exception exception,                                      Action<CurrentMessageInformation, Exception> messageCompleted,                                      Action<CurrentMessageInformation> beforeTransactionCommit)         {             var txDisposed = false;             if (exception == null)             {                 try                 {                     if (tx != null)                     {                         if (beforeTransactionCommit != null)                             beforeTransactionCommit(currentMessageInformation);                         tx.Complete();                         tx.Dispose();                         txDisposed = true;                     }                     try                     {                         if (messageCompleted != null)                             messageCompleted(currentMessageInformation, exception);                     }                     catch (Exception e)                     {                         Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);                     }                     return;                 }                 catch (Exception e)                 {                     Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e);                     exception = e;                 }             }             try             {                 if (txDisposed == false && tx != null)                 {                     Trace.TraceWarning("Disposing transaction in error mode");                     tx.Dispose();                 }             }             catch (Exception e)             {                 Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e);             }             if (message == null)                 return;                 try             {                 if (messageCompleted != null)                     messageCompleted(currentMessageInformation, exception);             }             catch (Exception e)             {                 Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);             }               try             {                 var copy = MessageProcessingFailure;                 if (copy != null)                     copy(currentMessageInformation, exception);             }             catch (Exception moduleException)             {                 Trace.TraceError("Module failed to process message failure: " + exception.Message+                                              moduleException);             }               if (messageQueue.IsTransactional == false)// put the item back in the queue             {                 messageQueue.Send(message);             }         }     You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary.  Lets see what the author of this code did intend:          private void HandleMessageCompletion(             TransactionHandler transactionHandler,             MessageCompletionHandler handler,             CurrentMessageInformation messageInfo,             ErrorCollector errors             )         {               // commit current pending transaction             transactionHandler.CallHandlerAndCommit(messageInfo, errors);               // We have an error for a null message do not send completion event             if (messageInfo.CurrentMessage == null)                 return;               // Send completion event in any case regardless of errors             handler.OnMessageCompleted(messageInfo, errors);               // put message back if queue is not transactional             transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors);         }   I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state.          class ErrorCollector          {              List<Exception> _Errors = new List<Exception>();                public void Add(Exception ex, string description)              {                  ex.Data["Description"] = description;                  _Errors.Add(ex);              }                public Exception Last              {                  get                  {                      return _Errors.LastOrDefault();                  }              }                public bool HasError              {                  get                  {                      return _Errors.Count > 0;                  }              }          }   Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures.          class TransactionHandler          {              TransactionScope _Tx;              Action<CurrentMessageInformation> _BeforeCommit;              OpenedQueue _MessageQueue;                public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue)              {                  _Tx = tx;                  _BeforeCommit = beforeCommit;                  _MessageQueue = messageQueue;              }                public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  if (_Tx != null && !errors.HasError)                  {                      try                      {                          if (_BeforeCommit != null)                          {                              _BeforeCommit(currentMessageInfo);                          }                            _Tx.Complete();                          _Tx.Dispose();                      }                      catch (Exception ex)                      {                          errors.Add(ex, "Failed to complete transaction, moving to error mode");                          Trace.TraceWarning("Disposing transaction in error mode");                          try                          {                              _Tx.Dispose();                          }                          catch (Exception ex2)                          {                              errors.Add(ex2, "Failed to dispose of transaction in error mode.");                          }                      }                  }              }                public void ResendMessageOnError(Message message, ErrorCollector errors)              {                  if (errors.HasError && !_MessageQueue.IsTransactional)                  {                      _MessageQueue.Send(message);                  }              }          } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred.            class MessageCompletionHandler          {              Action<CurrentMessageInformation, Exception> _MessageCompletedHandler;              Action<CurrentMessageInformation, Exception> _MessageProcessingFailure;                public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler,                                              Action<CurrentMessageInformation, Exception> messageProcessingFailure)              {                  _MessageCompletedHandler = messageCompletedHandler;                  _MessageProcessingFailure = messageProcessingFailure;              }                  public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageCompletedHandler != null)                      {                          _MessageCompletedHandler(currentMessageInfo, errors.Last);                      }                  }                  catch (Exception ex)                  {                      errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing");                  }                    if (errors.HasError)                  {                      SignalFailedMessage(currentMessageInfo, errors);                  }              }                void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageProcessingFailure != null)                          _MessageProcessingFailure(currentMessageInfo, errors.Last);                  }                  catch (Exception moduleException)                  {                      errors.Add(moduleException, "Module failed to process message failure");                  }              }            }   If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together:   Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo         Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler        TransactionScope tx        OpenedQueue messageQueue        Action<CurrentMessageInformation> beforeTransactionCommit Exception exception,             ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler          Action<CurrentMessageInformation, Exception> messageCompleted          Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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• Metro: Understanding the default.js File

  - by Stephen.Walther

  The goal of this blog entry is to describe — in painful detail — the contents of the default.js file in a Metro style application written with JavaScript. When you use Visual Studio to create a new Metro application then you get a default.js file automatically. The file is located in a folder named \js\default.js. The default.js file kicks off all of your custom JavaScript code. It is the main entry point to a Metro application. The default contents of the default.js file are included below: // For an introduction to the Blank template, see the following documentation: // http://go.microsoft.com/fwlink/?LinkId=232509 (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; app.oncheckpoint = function (eventObject) { // TODO: This application is about to be suspended. Save any state // that needs to persist across suspensions here. You might use the // WinJS.Application.sessionState object, which is automatically // saved and restored across suspension. If you need to complete an // asynchronous operation before your application is suspended, call // eventObject.setPromise(). }; app.start(); })(); There are several mysterious things happening in this file. The purpose of this blog entry is to dispel this mystery. Understanding the Module Pattern The first thing that you should notice about the default.js file is that the entire contents of this file are enclosed within a self-executing JavaScript function: (function () { ... })(); Metro applications written with JavaScript use something called the module pattern. The module pattern is a common pattern used in JavaScript applications to create private variables, objects, and methods. Anything that you create within the module is encapsulated within the module. Enclosing all of your custom code within a module prevents you from stomping on code from other libraries accidently. Your application might reference several JavaScript libraries and the JavaScript libraries might have variables, objects, or methods with the same names. By encapsulating your code in a module, you avoid overwriting variables, objects, or methods in the other libraries accidently. Enabling Strict Mode with “use strict” The first statement within the default.js module enables JavaScript strict mode: 'use strict'; Strict mode is a new feature of ECMAScript 5 (the latest standard for JavaScript) which enables you to make JavaScript more strict. For example, when strict mode is enabled, you cannot declare variables without using the var keyword. The following statement would result in an exception: hello = "world!"; When strict mode is enabled, this statement throws a ReferenceError. When strict mode is not enabled, a global variable is created which, most likely, is not what you want to happen. I’d rather get the exception instead of the unwanted global variable. The full specification for strict mode is contained in the ECMAScript 5 specification (look at Annex C): http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-262.pdf Aliasing the WinJS.Application Object The next line of code in the default.js file is used to alias the WinJS.Application object: var app = WinJS.Application; This line of code enables you to use a short-hand syntax when referring to the WinJS.Application object: for example,  app.onactivated instead of WinJS.Application.onactivated. The WinJS.Application object  represents your running Metro application. Handling Application Events The default.js file contains an event handler for the WinJS.Application activated event: app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; This WinJS.Application class supports the following events: · loaded – Happens after browser DOMContentLoaded event. After this event, the DOM is ready and you can access elements in a page. This event is raised before external images have been loaded. · activated – Triggered by the Windows.UI.WebUI.WebUIApplication activated event. After this event, the WinRT is ready. · ready – Happens after both loaded and activated events. · unloaded – Happens before application is unloaded. The following default.js file has been modified to capture each of these events and write a message to the Visual Studio JavaScript Console window: (function () { "use strict"; var app = WinJS.Application; WinJS.Application.onloaded = function (e) { console.log("Loaded"); }; WinJS.Application.onactivated = function (e) { console.log("Activated"); }; WinJS.Application.onready = function (e) { console.log("Ready"); } WinJS.Application.onunload = function (e) { console.log("Unload"); } app.start(); })(); When you execute the code above, a message is written to the Visual Studio JavaScript Console window when each event occurs with the exception of the Unload event (presumably because the console is not attached when that event is raised).   Handling Different Activation Contexts The code for the activated handler in the default.js file looks like this: app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { if (eventObject.detail.previousExecutionState !== Windows.ApplicationModel.Activation.ApplicationExecutionState.terminated) { // TODO: This application has been newly launched. Initialize // your application here. } else { // TODO: This application has been reactivated from suspension. // Restore application state here. } WinJS.UI.processAll(); } }; Notice that the code contains a conditional which checks the Kind of the event (the value of e.detail.kind). The startup code is executed only when the activated event is triggered by a Launch event, The ActivationKind enumeration has the following values: · launch · search · shareTarget · file · protocol · fileOpenPicker · fileSavePicker · cacheFileUpdater · contactPicker · device · printTaskSettings · cameraSettings Metro style applications can be activated in different contexts. For example, a camera application can be activated when modifying camera settings. In that case, the ActivationKind would be CameraSettings. Because we want to execute our JavaScript code when our application first launches, we verify that the kind of the activation event is an ActivationKind.Launch event. There is a second conditional within the activated event handler which checks whether an application is being newly launched or whether the application is being resumed from a suspended state. When running a Metro application with Visual Studio, you can use Visual Studio to simulate different application execution states by taking advantage of the Debug toolbar and the new Debug Location toolbar.  Handling the checkpoint Event The default.js file also includes an event handler for the WinJS.Application checkpoint event: app.oncheckpoint = function (eventObject) { // TODO: This application is about to be suspended. Save any state // that needs to persist across suspensions here. You might use the // WinJS.Application.sessionState object, which is automatically // saved and restored across suspension. If you need to complete an // asynchronous operation before your application is suspended, call // eventObject.setPromise(). }; The checkpoint event is raised when your Metro application goes into a suspended state. The idea is that you can save your application data when your application is suspended and reload your application data when your application resumes. Starting the Application The final statement in the default.js file is the statement that gets everything going: app.start(); Events are queued up in a JavaScript array named eventQueue . Until you call the start() method, the events in the queue are not processed. If you don’t call the start() method then the Loaded, Activated, Ready, and Unloaded events are never raised. Summary The goal of this blog entry was to describe the contents of the default.js file which is the JavaScript file which you use to kick off your custom code in a Windows Metro style application written with JavaScript. In this blog entry, I discussed the module pattern, JavaScript strict mode, handling first chance exceptions, WinJS Application events, and activation contexts.

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• Wrong perspective is showing in Eclipse plugin project [closed]

  - by Arun Kumar Choudhary

  I am working in Eclipse Modeling Framework (Eclipse plugin development) in my project the tool(project i am working) provides three perspectives. 1.Accelerator Analyst perspective 2.Contract Validation and 3.Underwriter rules Editor... By default it starts with Contract validation perspective (As we define it within the plugin_customization.ini). However after switching to other perspective does not change the perspective shown... As all perspective (Class, Id and Name) is define only inside Plugin.XML as it is the task of org.eclipse.ui.perspective that that perspective name should be come forefront. Out of 10 7 times it is working fine but I am not getting why this is not working in that 3 cases. I am pasting my plugin.XML file <?xml version="1.0" encoding="UTF-8"?> <?eclipse version="3.0"?> <plugin> <extension id="RuleEditor.application" name="Accelerator Tooling" point="org.eclipse.core.runtime.applications"> <application> <run class="com.csc.fs.underwriting.product.UnderWritingApplication"> </run> </application> </extension> <extension point="org.eclipse.ui.perspectives"> <perspective class="com.csc.fs.underwriting.product.ContractValidationPerspective" icon="icons/javadevhov_obj.gif" id="com.csc.fs.underwriting.product.ContractValidationPerspective" name="Contract Validation"> </perspective> </extension> <extension point="org.eclipse.ui.perspectives"> <perspective class="com.csc.fs.underwriting.product.UnderwritingPerspective" icon="icons/javadevhov_obj.gif" id="com.csc.fs.underwriting.product.UnderwritingPerspective" name="Underwriting"> </perspective> </extension> <extension id="product" point="org.eclipse.core.runtime.products"> <product application="com.csc.fs.nba.underwriting.application.RuleEditor.application" name="Rule Configurator Workbench" description="%AppName"> <property name="introTitle" value="Welcome to Accelerator Tooling"/> <property name="introVer" value="%version"/> <property name="introBrandingImage" value="product:csclogo.png"/> <property name="introBrandingImageText" value="CSC FSG"/> <property name="preferenceCustomization" value="plugin_customization.ini"/> <property name="appName" value="Rule Configurator Workbench"> </property> </product> </extension> <extension point="org.eclipse.ui.intro"> <intro class="org.eclipse.ui.intro.config.CustomizableIntroPart" icon="icons/Welcome.gif" id="com.csc.fs.nba.underwriting.intro"/> <introProductBinding introId="com.csc.fs.nba.underwriting.intro" productId="com.csc.fs.nba.underwriting.application.product"/> <intro class="org.eclipse.ui.intro.config.CustomizableIntroPart" id="com.csc.fs.nba.underwriting.application.intro"> </intro> <introProductBinding introId="com.csc.fs.nba.underwriting.application.intro" productId="com.csc.fs.nba.underwriting.application.product"> </introProductBinding> </extension> <extension name="Accelerator Tooling" point="org.eclipse.ui.intro.config"> <config content="$nl$/intro/introContent.xml" id="org.eclipse.platform.introConfig.mytest" introId="com.csc.fs.nba.underwriting.intro"> <presentation home-page-id="news"> <implementation kind="html" os="win32,linux,macosx" style="$nl$/intro/css/shared.css"/> </presentation> </config> <config content="introContent.xml" id="com.csc.fs.nba.underwriting.application.introConfigId" introId="com.csc.fs.nba.underwriting.application.intro"> <presentation home-page-id="root"> <implementation kind="html" os="win32,linux,macosx" style="content/shared.css"> </implementation> </presentation> </config> </extension> <extension point="org.eclipse.ui.intro.configExtension"> <theme default="true" id="org.eclipse.ui.intro.universal.circles" name="%theme.name.circles" path="$nl$/themes/circles" previewImage="themes/circles/preview.png"> <property name="introTitle" value="Accelerator Tooling"/> <property name="introVer" value="%version"/> </theme> </extension> <extension point="org.eclipse.ui.ide.resourceFilters"> <filter pattern="*.dependency" selected="true"/> <filter pattern="*.producteditor" selected="true"/> <filter pattern="*.av" selected="true"/> <filter pattern=".*" selected="true"/> </extension> <extension point="org.eclipse.ui.splashHandlers"> <splashHandler class="com.csc.fs.nba.underwriting.application.splashHandlers.InteractiveSplashHandler" id="com.csc.fs.nba.underwriting.application.splashHandlers.interactive"> </splashHandler> <splashHandler class="com.csc.fs.underwriting.application.splashHandlers.InteractiveSplashHandler" id="com.csc.fs.underwriting.application.splashHandlers.interactive"> </splashHandler> <splashHandlerProductBinding productId="com.csc.fs.nba.underwriting.application" splashId="com.csc.fs.underwriting.application.splashHandlers.interactive"> </splashHandlerProductBinding> </extension> <extension id="com.csc.fs.pa.security" point="com.csc.fs.pa.security.implementation.secure"> <securityImplementation class="com.csc.fs.pa.security.PASecurityImpl"> </securityImplementation> </extension> <extension id="productApplication.security.pep" name="com.csc.fs.pa.producteditor.application.security.pep" point="com.csc.fs.pa.security.implementation.authorize"> <authorizationManager class="com.csc.fs.pa.security.authorization.PAAuthorizationManager"> </authorizationManager> </extension> <extension point="org.eclipse.ui.editors"> <editor class="com.csc.fs.underwriting.product.editors.PDFViewer" extensions="pdf" icon="icons/pdficon_small.gif" id="com.csc.fs.pa.producteditor.application.editors.PDFViewer" name="PDF Viewer"> </editor> </extension> <extension point="org.eclipse.ui.views"> <category id="com.csc.fs.pa.application.viewCategory" name="%category"> </category> </extension> <extension point="org.eclipse.ui.newWizards"> <category id="com.csc.fs.pa.application.newWizardCategory" name="%category"> </category> <category id="com.csc.fs.pa.application.newWizardInitialize" name="%initialize" parentCategory="com.csc.fs.pa.application.newWizardCategory"> </category> </extension> <extension point="com.csc.fs.pa.common.usability.addNewCategory"> <addNewCategoryId id="com.csc.fs.pa.application.newWizardCategory"> </addNewCategoryId> </extension> <!--extension point="org.eclipse.ui.activities"> <activity description="View Code Generation Option" id="com.csc.fs.pa.producteditor.application.viewCodeGen" name="ViewCodeGen"> </activity> <activityPatternBinding activityId="com.csc.fs.pa.producteditor.application.viewCodeGen" pattern="com.csc.fs.pa.bpd.vpms.codegen/com.csc.fs.pa.bpd.vpms.codegen.bpdCodeGenActionId"> </activityPatternBinding> Add New Product Definition Extension </extension--> </plugin> class="com.csc.fs.underwriting.product.editors.PDFViewer" extensions="pdf" icon="icons/pdficon_small.gif" id="com.csc.fs.pa.producteditor.application.editors.PDFViewer" name="PDF Viewer"> </editor> </extension> <extension point="org.eclipse.ui.views"> <category id="com.csc.fs.pa.application.viewCategory" name="%category"> </category> </extension> <extension point="org.eclipse.ui.newWizards"> <category id="com.csc.fs.pa.application.newWizardCategory" name="%category"> </category> <category id="com.csc.fs.pa.application.newWizardInitialize" name="%initialize" parentCategory="com.csc.fs.pa.application.newWizardCategory"> </category> </extension> <extension point="com.csc.fs.pa.common.usability.addNewCategory"> <addNewCategoryId id="com.csc.fs.pa.application.newWizardCategory"> </addNewCategoryId> </extension> <!--extension point="org.eclipse.ui.activities"> <activity description="View Code Generation Option" id="com.csc.fs.pa.producteditor.application.viewCodeGen" name="ViewCodeGen"> </activity> <activityPatternBinding activityId="com.csc.fs.pa.producteditor.application.viewCodeGen" pattern="com.csc.fs.pa.bpd.vpms.codegen/com.csc.fs.pa.bpd.vpms.codegen.bpdCodeGenActionId"> </activityPatternBinding> Add New Product Definition Extension </extension--> </plugin> Inside each class(the qualified classes in above xml) i did only hide and show the view according to perspective and that is working very fine.. Please provide any method that Eclipse provide so that I can override it in each classed so that it can work accordingly.

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• Notes on Oracle BPM PS6 Adaptive Case Management

  - by gcolman

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} I have recently been looking at the  latest release of the BPM Case Management feature in the Oracle BPM PS6 release. I had put together some notes to help me gain a better understanding of the context of the PS6 BPM Case Management. Hopefully, this along with the other resources will enable you to gain a clear picture of the flexibility of this feature. Oracle BPM PS6 release includes Case Management capability. This initial release aims to provide: Case Management Framework Integration of Case Management with BPM & SOA suite It is best to regard the current PS6 case management feature as a case management framework. The framework provides the building blocks for creating a case management system that is fully integrated into Oracle BPM suite. As of the current PS6 release, no UI tooling exists to help manage cases or the case lifecycle. Mark Foster has written a good blog which outlines Case Management within PS6 in the following link. I wanted to provide more context on Case Management from my perspective in this blog. PS6 Case Management - High level View BPM PS6 includes “Case” as a first class component in a SOA Suite composite. The Case components (added to the SOA Composite) are created when a BPM process is assigned to a case in JDveloper. The SOA Case component is defined and configured within JDevloper, which allows us to specify the case data structures and metadata such as stakeholders, outcomes, milestones, document stores etc. "Activities" are associated with a case, and become available to be executed via the case apis. Activities are BPM processes, Human Activities or Java call outs. The PS6 release includes some additional database tables to store the case metadata and case instance data (data object, comments, etc…). These new tables are created within the SOA_INFRA schema and the documents associated with that case into a document repository that is configured with the case. One of the main features of Case Management is the control of the case logic through case events and case business rules. A PS6 Case has an associated business rule component, which can be configured to control the availability and execution of activities within the case. The business rules component is able to act upon events that the PS6 Case Management framework generates during the lifecycle of that case. Events are fired during the lifetime of the case (e.g. Case created, activity started, activity ended, note added, document uploaded.) Internal Case state The internal state of a case is represented by the diagram below. This shows the internal states and the transition paths for a Case from one state to the next Each transition in state will create an event that can be enacted upon via the Case rules engine. The internal case state lifecycle is defined as follows Defining a case A Case is created and defined as a component of a JDeveloper BPM project. When you create a Case as part of a BPM project, JDeveloper, creates the following components within the SCA composite: Case component Case component interfaces (WSDL etc) Case Rules component (Oracle Business Rules) Adds the Case Component and Case Rules Component to the BPM SOA composite Case Configuration The following section gives a high level overview of the items that can be configured for a BPM Case. Case Activities A Case is associated with a set of activities that are to be performed as part of that Case. Case activities can be: SOA Human Tasks BPM processes Custom Task (Java Class) Case activities are created from pre-existing BPM process or human tasks, which, once defined, can be configured additionally as Case activities in JDeveloper and made available within the lifecycle of a case. I've described the following configurable components of a case (very!) briefly as: Milestones Milestones are (optional) user defined logical milestones that can be achieved within a case. No activities are associates with a milestone, but milestone attainment can be programmatically set and events raised when milestones are reached Outcomes User defined status of a completed case. An event is fired when an outcome is attained. Case Data Defines the data that will be stored with a case XML schemas define the data that is stored with the case. Case Documents Defines the location of documents that are attached to a case (e.g. WebCenter Content) User Defined Events Optional user defined events that can be fired or captured to drive case processing rules Stakeholders Defines the actors who can participate in the case (roles, users, groups) Defines permissions for individual case permissions (read case, create document etc…) Business Rules Business rules are the main component controlling the flow of a Case Each case has an associated business ruleset Rules are fired on receiving Case events (or User defined events) Life cycle events Milestone events Activity events Data events Document events Comment events User event Managing the Case Managing the lifecycle of a case is achieved in two ways: Managing case logic with Business Rules Managing the case lifecycle via the Case APIs. A BPM Case can be viewed as a set of case data & documents along with the activities that can be performed within a case and also the case lifecycle state expressed as milestones and internal lifecycle state. The management of the case life is achieved though both the configuration of business rules and the “manual” interaction with a case instance through the Case APIs. Business Rules and Case Events A key component within the Case management framework is the event model. The BPM Case Management solution internally utilizes Oracle EDN (Event Delivery Network) to publish and subscribe to events generated by the Case framework. Events are generated by the Case framework on each of the processes and stages that a case instance will travel on its lifetime. The following case events are part of the BPM Case: Life cycle events Milestone events Activity events Data events Document events Comment events User event The Case business rules are configured to listen for these events, and business logic can be coded into the Case rules component to enact upon an event being received. Case API & Interaction Along with the business rules component, Cases can be managed via the Case API interfaces. These interfaces allow for the building of custom applications to integrate into case management framework. The API’s allow for updating case comments & documents, executing case activities, updating milestones etc. As there is no in built case management UI functions within the PS6 release, Cases need to be managed via a custom built UI, interacting with selected case instances, launching case activities, closing cases etc. (There is expected to be a UI component within subsequent releases) Logical Case Flow The diagram below is intended to depict a logical view of the case steps for a typical case. A UI or other service calls the Case interface to create a Case instance The case instance is created & database data inserted A lifecycle event is raised indicating a case activity (created) event The case business rules capture the event and decide on an action to take Additionally other parties can subscribe to Case events via EDN The business rules may handle the event, e.g. configured to execute a case activity on case creation event The BPM/Human Workflow/Custom activity is executed A case activity event is raised on the execute activity A case work UI or business service can inspect the case instance and call other actions to progress that case, such as: Execute activity Add Note Add document Add case data Update Milestone Raise user defined event Suspend case Resume case Close Case Summary Having had a little time to play around with the APIs and the case configuration, I really like the flexibility and power of combining Oracle Business Rules and the BPM Case Management event model. Creating something this flexible and powerful without BPM Case Management would take a lot of time and effort. This is hopefully going to save my customers a lot of time and effort! I may make amendments to this post as my understanding of Case Management increases! Take a look at the following links for official documentation etc. http://docs.oracle.com/cd/E28280_01/doc.1111/e15176/case_mgmt_bpmpd.htm https://blogs.oracle.com/bpm/entry/just_in_case 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";}

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• links for 2010-05-06

  - by Bob Rhubart

  Podcast: Collaborate 10 Wrap-Up - Conclusion #c10 More Collaborate 2010 Las Vegas highlights and hijinks from this ten-member panel, including OAUG and ODTUG board members, members of the Oracle ACE program, and OAUG President Dave Ferguson. (tags: otn oracle collaborate2010) Peter Scott: Realtime Data Warehouse Loading Rittman-Mead's Peter Scott looks at putting data in to a data warehouse in real time. (tags: oracle datawarehousing businessintelligence) Live Webcast: Social BPM - Integrating Enterprise 2.0 with Business Applications - May 12, 2010 at 11:00 a.m. PT Business Process Management with integrated Enterprise 2.0 collaboration can improve business responsiveness and enhance overall enterprise productivity. Learn how to take your business to the next level with a unified solution that fosters process-based collaboration between employees, partners, and customers. (tags: oracle otn bpm enterprise2.0 webcast) Management Pack for Identity Management Viewlet A screencast produced by the Grid Control team showing the features of the Identity Management Pack for Grid Control 11g. Grid Control 11g now works with Oracle Virtual Directory 11g. (tags: oracle otn security identitymanagement) @pevansgreenwood: Having too much SOA is a bad thing (and what we might do about it) "The problem is usually too much flexibility, as flexibility creates complexity, and complexity exponentially increases the effort required to manage and deliver the software." -- Peter Evans-Greenwood (tags: soa complexity flexibility) @vampbenepe: Integration patterns for social data: the Open Social Data Bus "The main point is about defining the right integration pattern for social data: is it a 'message bus' pattern or a 'shared database' pattern?" -- William Vampbenepe (tags: oracle otn enterprise2.0 enterprisearchitecture)

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• Oracle Solaris 11 ZFS Lab for Openworld 2012

  - by user12626122

  Preface This is the content from the Oracle Openworld 2012 ZFS lab. It was well attended - the feedback was that it was a little short - thats probably because in writing it I bacame very time-concious after the ASM/ACFS on Solaris extravaganza I ran last year which was almost too long for mortal man to finish in the 1 hour session. Enjoy. Table of Contents Exercise Z.1: ZFS Pools Exercise Z.2: ZFS File Systems Exercise Z.3: ZFS Compression Exercise Z.4: ZFS Deduplication Exercise Z.5: ZFS Encryption Exercise Z.6: Solaris 11 Shadow Migration Introduction This set of exercises is designed to briefly demonstrate new features in Solaris 11 ZFS file system: Deduplication, Encryption and Shadow Migration. Also included is the creation of zpools and zfs file systems - the basic building blocks of the technology, and also Compression which is the compliment of Deduplication. The exercises are just introductions - you are referred to the ZFS Adminstration Manual for further information. From Solaris 11 onward the online manual pages consist of zpool(1M) and zfs(1M) with further feature-specific information in zfs_allow(1M), zfs_encrypt(1M) and zfs_share(1M). The lab is easily carried out in a VirtualBox running Solaris 11 with 6 virtual 3 Gb disks to play with. Exercise Z.1: ZFS Pools Task: You have several disks to use for your new file system. Create a new zpool and a file system within it. Lab: You will check the status of existing zpools, create your own pool and expand it. Your Solaris 11 installation already has a root ZFS pool. It contains the root file system. Check this: root@solaris:~# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT rpool 15.9G 6.62G 9.25G 41% 1.00x ONLINE - root@solaris:~# zpool status pool: rpool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM rpool ONLINE 0 0 0 c3t0d0s0 ONLINE 0 0 0 errors: No known data errors Note the disk device the root pool is on - c3t0d0s0 Now you will create your own ZFS pool. First you will check what disks are available: root@solaris:~# echo | format Searching for disks...done AVAILABLE DISK SELECTIONS: 0. c3t0d0 <ATA-VBOX HARDDISK-1.0 cyl 2085 alt 2 hd 255 sec 63> /pci@0,0/pci8086,2829@d/disk@0,0 1. c3t2d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@2,0 2. c3t3d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@3,0 3. c3t4d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@4,0 4. c3t5d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@5,0 5. c3t6d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@6,0 6. c3t7d0 <ATA-VBOX HARDDISK-1.0 cyl 1534 alt 2 hd 128 sec 32> /pci@0,0/pci8086,2829@d/disk@7,0 Specify disk (enter its number): Specify disk (enter its number): The root disk is numbered 0. The others are free for use. Try creating a simple pool and observe the error message: root@solaris:~# zpool create mypool c3t2d0 c3t3d0 'mypool' successfully created, but with no redundancy; failure of one device will cause loss of the pool So destroy that pool and create a mirrored pool instead: root@solaris:~# zpool destroy mypool root@solaris:~# zpool create mypool mirror c3t2d0 c3t3d0 root@solaris:~# zpool status mypool pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c3t2d0 ONLINE 0 0 0 c3t3d0 ONLINE 0 0 0 errors: No known data errors Back to topExercise Z.2: ZFS File Systems Task: You have to create file systems for later exercises. You can see that when a pool is created, a file system of the same name is created: root@solaris:~# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 86.5K 2.94G 31K /mypool Create your filesystems and mountpoints as follows: root@solaris:~# zfs create -o mountpoint=/data1 mypool/mydata1 The -o option sets the mount point and automatically creates the necessary directory. root@solaris:~# zfs list mypool/mydata1 NAME USED AVAIL REFER MOUNTPOINT mypool/mydata1 31K 2.94G 31K /data1 Back to top Exercise Z.3: ZFS Compression Task:Try out different forms of compression available in ZFS Lab:Create 2nd filesystem with compression, fill both file systems with the same data, observe results You can see from the zfs(1) manual page that there are several types of compression available to you, set with the property=value syntax: compression=on | off | lzjb | gzip | gzip-N | zle Controls the compression algorithm used for this dataset. The lzjb compression algorithm is optimized for performance while providing decent data compression. Setting compression to on uses the lzjb compression algorithm. The gzip compression algorithm uses the same compression as the gzip(1) command. You can specify the gzip level by using the value gzip-N where N is an integer from 1 (fastest) to 9 (best compression ratio). Currently, gzip is equivalent to gzip-6 (which is also the default for gzip(1)). Create a second filesystem with compression turned on. Note how you set and get your values separately: root@solaris:~# zfs create -o mountpoint=/data2 mypool/mydata2 root@solaris:~# zfs set compression=gzip-9 mypool/mydata2 root@solaris:~# zfs get compression mypool/mydata1 NAME PROPERTY VALUE SOURCE mypool/mydata1 compression off default root@solaris:~# zfs get compression mypool/mydata2 NAME PROPERTY VALUE SOURCE mypool/mydata2 compression gzip-9 local Now you can copy the contents of /usr/lib into both your normal and compressing filesystem and observe the results. Don't forget the dot or period (".") in the find(1) command below: root@solaris:~# cd /usr/lib root@solaris:/usr/lib# find . -print | cpio -pdv /data1 root@solaris:/usr/lib# find . -print | cpio -pdv /data2 The copy into the compressing file system takes longer - as it has to perform the compression but the results show the effect: root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.35G 1.59G 31K /mypool mypool/mydata1 1.01G 1.59G 1.01G /data1 mypool/mydata2 341M 1.59G 341M /data2 Note that the available space in the pool is shared amongst the file systems. This behavior can be modified using quotas and reservations which are not covered in this lab but are covered extensively in the ZFS Administrators Guide. Back to top Exercise Z.4: ZFS Deduplication The deduplication property is used to remove redundant data from a ZFS file system. With the property enabled duplicate data blocks are removed synchronously. The result is that only unique data is stored and common componenents are shared. Task:See how to implement deduplication and its effects Lab: You will create a ZFS file system with deduplication turned on and see if it reduces the amount of physical storage needed when we again fill it with a copy of /usr/lib. root@solaris:/usr/lib# zfs destroy mypool/mydata2 root@solaris:/usr/lib# zfs set dedup=on mypool/mydata1 root@solaris:/usr/lib# rm -rf /data1/* root@solaris:/usr/lib# mkdir /data1/2nd-copy root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02M 2.94G 31K /mypool mypool/mydata1 43K 2.94G 43K /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1 2142768 blocks root@solaris:/usr/lib# zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.02G 1.99G 31K /mypool mypool/mydata1 1.01G 1.99G 1.01G /data1 root@solaris:/usr/lib# find . -print | cpio -pd /data1/2nd-copy 2142768 blocks root@solaris:/usr/lib#zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 1.99G 1.96G 31K /mypool mypool/mydata1 1.98G 1.96G 1.98G /data1 You could go on creating copies for quite a while...but you get the idea. Note that deduplication and compression can be combined: the compression acts on metadata. Deduplication works across file systems in a pool and there is a zpool-wide property dedupratio: root@solaris:/usr/lib# zpool get dedupratio mypool NAME PROPERTY VALUE SOURCE mypool dedupratio 4.30x - Deduplication can also be checked using "zpool list": root@solaris:/usr/lib# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT mypool 2.98G 1001M 2.01G 32% 4.30x ONLINE - rpool 15.9G 6.66G 9.21G 41% 1.00x ONLINE - Before moving on to the next topic, destroy that dataset and free up some space: root@solaris:~# zfs destroy mypool/mydata1 Back to top Exercise Z.5: ZFS Encryption Task: Encrypt sensitive data. Lab: Explore basic ZFS encryption. This lab only covers the basics of ZFS Encryption. In particular it does not cover various aspects of key management. Please see the ZFS Adminastrion Manual and the zfs_encrypt(1M) manual page for more detail on this functionality. Back to top root@solaris:~# zfs create -o encryption=on mypool/data2 Enter passphrase for 'mypool/data2': ******** Enter again: ******** root@solaris:~# Creation of a descendent dataset shows that encryption is inherited from the parent: root@solaris:~# zfs create mypool/data2/data3 root@solaris:~# zfs get -r encryption,keysource,keystatus,checksum mypool/data2 NAME PROPERTY VALUE SOURCE mypool/data2 encryption on local mypool/data2 keysource passphrase,prompt local mypool/data2 keystatus available - mypool/data2 checksum sha256-mac local mypool/data2/data3 encryption on inherited from mypool/data2 mypool/data2/data3 keysource passphrase,prompt inherited from mypool/data2 mypool/data2/data3 keystatus available - mypool/data2/data3 checksum sha256-mac inherited from mypool/data2 You will find the online manual page zfs_encrypt(1M) contains examples. In particular, if time permits during this lab session you may wish to explore the changing of a key using "zfs key -c mypool/data2". Exercise Z.6: Shadow Migration Shadow Migration allows you to migrate data from an old file system to a new file system while simultaneously allowing access and modification to the new file system during the process. You can use Shadow Migration to migrate a local or remote UFS or ZFS file system to a local file system. Task: You wish to migrate data from one file system (UFS, ZFS, VxFS) to ZFS while mainaining access to it. Lab: Create the infrastructure for shadow migration and transfer one file system into another. First create the file system you want to migrate root@solaris:~# zpool create oldstuff c3t4d0 root@solaris:~# zfs create oldstuff/forgotten Then populate it with some files: root@solaris:~# cd /var/adm root@solaris:/var/adm# find . -print | cpio -pdv /oldstuff/forgotten You need the shadow-migration package installed: root@solaris:~# pkg install shadow-migration Packages to install: 1 Create boot environment: No Create backup boot environment: No Services to change: 1 DOWNLOAD PKGS FILES XFER (MB) Completed 1/1 14/14 0.2/0.2 PHASE ACTIONS Install Phase 39/39 PHASE ITEMS Package State Update Phase 1/1 Image State Update Phase 2/2 You then enable the shadowd service: root@solaris:~# svcadm enable shadowd root@solaris:~# svcs shadowd STATE STIME FMRI online 7:16:09 svc:/system/filesystem/shadowd:default Set the filesystem to be migrated to read-only root@solaris:~# zfs set readonly=on oldstuff/forgotten Create a new zfs file system with the shadow property set to the file system to be migrated: root@solaris:~# zfs create -o shadow=file:///oldstuff/forgotten mypool/remembered Use the shadowstat(1M) command to see the progress of the migration: root@solaris:~# shadowstat EST BYTES BYTES ELAPSED DATASET XFRD LEFT ERRORS TIME mypool/remembered 92.5M - - 00:00:59 mypool/remembered 99.1M 302M - 00:01:09 mypool/remembered 109M 260M - 00:01:19 mypool/remembered 133M 304M - 00:01:29 mypool/remembered 149M 339M - 00:01:39 mypool/remembered 156M 86.4M - 00:01:49 mypool/remembered 156M 8E 29 (completed) Note that if you had created /mypool/remembered as encrypted, this would be the preferred method of encrypting existing data. Similarly for compressing or deduplicating existing data. The procedure for migrating a file system over NFS is similar - see the ZFS Administration manual. That concludes this lab session.

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• CQRS without using others patterns

  - by John Smith

  I would like to explain CQRS to my team of developers. I just can't figure out how to explain it in the simplest way so they can implement the pattern rapidly without any others frameworks. I've read a lot of resources including video and articles but I don't find how to implement CQRS without using others patterns like a service Bus, event sourcing pattern, domain driven design. I know the purpose of these pattern but for the first step, I don't want them to think CQRS and theses patterns must be tied together. My first idea is to say that CQRS is about separating the read part and the write part. The read part is composed only of the UI project, and DAL project. Then the write part is composed of a typical multilayer architecture: UI/BLL/DAL. Then, does CQRS say we must also have two datastore ? What about the notion of commands which reveal the user's intention, is it also something part of CQRS or DDD ? Basically, how to implement CQRS without using others patterns. I concede it's also not that clear in my mind because I've used to work with NCQRS/DDD/Event Sourcing/ServiceBus in my personal project. Thanks

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• Developing a feature which sole purpose to be taken out?

  - by adib

  What is the name of the pattern in which individual contributors (programmers/designers) developed an artifact for the sole purpose is to serve as a diversion so that management can remove that feature in the final product? This is a folklore I heard from an ex-colleague who used to work at a large game development company. At that company, it is well known that middle management is pressurized to "give inputs" and "make changes" to the product otherwise they risk being seen as not contributing to the project. This situation have delayed many projects because of these superfluous "management inputs". In one project at the above company, the artists and developers created a supernumerary animated character that appears in every cutscene and sticks out like a sore thumb. They designed it in such a way that it can be easily removed before the game is shipped (this was when games were still sold in physical media and not a downloadable product). Obviously the management then voted to remove the animation. On the positive side, management didn't introduced any unnecessary changes that would have delayed the project because they have shown that they provided constructive inputs to the product. This process pattern has a name among game programmers that work in corporates, but I forgot what was the actual name. I believe it's duck-something. Anybody can help pointing out the name and perhaps some rather credible reference to how the pattern develops?.

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• New features for Expression Blend 4 Release Candidate

  - by kaleidoscope

  With Microsoft Expression Blend 4, you can create websites and applications based on Microsoft Silverlight 3 and Microsoft Silverlight 4, and desktop applications based on Windows Presentation Foundation (WPF) 3.5 with Service Pack 1 (SP1) and WPF4. Expression Blend provides new support for prototyping, interactivity through behaviors, special Silverlight functionality, and on-the-fly sample data generation. Expression Blend includes new behaviors that are quickly and easily configured Expression Blend offers new sample data, behaviors, and features of project templates to support the Model-View-ViewModel (MVVM) pattern The MVVM pattern is a way to structure a Silverlight or WPF application so that user interface (UI) objects are as decoupled as possible from the application's data and behavior. This makes it easier for design tasks and development tasks to be performed independently and without breaking each other. Essentially, your UI is the View. You bind objects in the View to properties and commands of the ViewModel, and the View can also call methods on the ViewModel. Compatible with Silverlight 3 and WPF 3.5 with Service Pack 1 (SP1) Interoperate able with Visual Studio. Included New Shapes: The Assets panel in Expression Blend contains a new Shapes category, including presets for the easy creation of arcs, arrows, callouts, and polygons. New Controls: Expression Blend has tooling support for the RichTextBox control in Silverlight. XAML cleanliness :Expression Blend generates less XAML with respect to animations and animation-related properties. MVVM project template: Expression Blend includes a new project template that offers a basic starting point for Model-View-ViewModel pattern applications. Run project with CTRL+F5:To improve consistency with Visual Studio, you can now invoke the Run Project command by pressing either CTRL+F5 or F5 Technorati Tags: Rituraj,Features of Expression Blend4 RC

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• JavaScript Class Patterns Revisited: Endgame

  - by Liam McLennan

  I recently described some of the patterns used to simulate classes (types) in JavaScript. But I missed the best pattern of them all. I described a pattern I called constructor function with a prototype that looks like this: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); and I mentioned that the problem with this pattern is that it does not provide any encapsulation, that is, it does not allow private variables. Jan Van Ryswyck recently posted the solution, obvious in hindsight, of wrapping the constructor function in another function, thereby allowing private variables through closure. The above example becomes: var Person = (function() { // private variables go here var name,age; function constructor(n, a) { name = n; age = a; } constructor.prototype = { toString: function() { return name + " is " + age + " years old."; } }; return constructor; })(); var john = new Person("John Galt", 50); console.log(john.toString()); Now we have prototypal inheritance and encapsulation. The important thing to understand is that the constructor, and the toString function both have access to the name and age private variables because they are in an outer scope and they become part of the closure.

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• How does this ruby error handling module code work

  - by Michael Durrant

  Trying to get a better handle on ruby exception handling. I have this code (from a book): def err_with_msg(pattern) m = Module.new (class << m; self; end).instance_eval do define_method(:===) do |e| pattern === e.msg end end m end So ok this is a method. We're creating a new Module. I think of module as mix-ins. Not sure what it's doing here. Not we add the module to the class. Fair enough. Then we have self on its own. What that for? I guess we have a little anonymouse method this is just about self. hmmm ok, now for each of the above, check the pattern match. but for each, I thought the above for for a new Module, did the module get to use instance's by being included? A better explanation of what's going on here would be most helpful.

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• Design for object with optional and modifiable attributtes?

  - by Ikuzen

  I've been using the Builder pattern to create objects with a large number of attributes, where most of them are optional. But up until now, I've defined them as final, as recommended by Joshua Block and other authors, and haven't needed to change their values. I am wondering what should I do though if I need a class with a substantial number of optional but non-final (mutable) attributes? My Builder pattern code looks like this: public class Example { //All possible parameters (optional or not) private final int param1; private final int param2; //Builder class public static class Builder { private final int param1; //Required parameters private int param2 = 0; //Optional parameters - initialized to default //Builder constructor public Builder (int param1) { this.param1 = param1; } //Setter-like methods for optional parameters public Builder param2(int value) { param2 = value; return this; } //build() method public Example build() { return new Example(this); } } //Private constructor private Example(Builder builder) { param1 = builder.param1; param2 = builder.param2; } } Can I just remove the final keyword from the declaration to be able to access the attributes externally (through normal setters, for example)? Or is there a creational pattern that allows optional but non-final attributes that would be better suited in this case?

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• TODO Formatting

  - by charlie.mott

  Article Source: http://geekswithblogs.net/charliemott TODO's should only be used for a short period of time to remind you that something needs to be done. They should then be addressed as soon as possible. In order to know who owns a TODO task and how long it’s been outstanding, my company uses the following standard for TODO formatting: Format:     // TODO : Owner Initials – Date Created – Description of task. Sample:     // TODO: CM – 2012/01/20 – Move this class to a new location so it can be reused. Using this pattern makes it easy to use the Resharper TODO explorer. The Carrot In order to make it easy for developers to apply this rule, a code snippet can be created in Visual Studio. Even better, I created a Resharper template. This gives the facility to use the current user name and current date macros. image This actually makes the formatting look like this. Sample:     // TODO: cmott – 2012/01/20 – Move this class to a new location so it can be reused. The Stick How to you enforce such a rule? I tried to create a custom Resharper Highlighting Pattern to perform custom code analysis inspection for deviations from this pattern. However, I did not have any success. The find dialog would not accept // text. If I work it out, I will update this blog post. StyleCop Instead I created a custom StyleCop rule. I followed the approach used with the StyleCop Contrib project. This provides a simple to use base class and easy to use unit testing framework. I will upload this todo format analyzer as a patch to that project. image

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• Can higher-order functions in FP be interpreted as some kind of dependency injection?

  - by Giorgio

  According to this article, in object-oriented programming / design dependency injection involves a dependent consumer, a declaration of a component's dependencies, defined as interface contracts, an injector that creates instances of classes that implement a given dependency interface on request. Let us now consider a higher-order function in a functional programming language, e.g. the Haskell function filter :: (a -> Bool) -> [a] -> [a] from Data.List. This function transforms a list into another list and, in order to perform its job, it uses (consumes) an external predicate function that must be provided by its caller, e.g. the expression filter (\x -> (mod x 2) == 0) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] selects all even numbers from the input list. But isn't this construction very similar to the pattern illustrated above, where the filter function is the dependent consumer, the signature (a -> Bool) of the function argument is the interface contract, the expression that uses the higher-order is the injector that, in this particular case, injects the implementation (\x -> (mod x 2) == 0) of the contract. More in general, can one relate higher-order functions and their usage pattern in functional programming to the dependency injection pattern in object-oriented languages? Or in the inverse direction, can dependency injection be compared to using some kind of higher-order function?

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• Sharding / indexing strategy for multi-faceted search

  - by Graham

  I'm currently thinking about our database structure and how we modify it for scale. Specifically, we're thinking about using ElasticSearch to provide our search functionality. One common pattern with ElasticSearch seems to be the 'user-routing' pattern; that is, using routing to ensure that any one user's data resides on the same shard. This is great for client-specific search e.g. Gmail. Our application has a constraint such that any user will have a maximum of a few thousand documents, so this pattern seems like a good candidate. However, our search needs to work across all users, as well as targeting a specific user (so I might search my content, Alice's content, or all content). Similarly, we need to provide full-text search across any timeframe; recent months to several years ago. I'm thinking of combining the 'user-routing' and 'index-per-time-interval' patterns: I create an index for each month By default, searches are aliased against the most recent X months If no results are found, we can search against previous X months As we grow, we can reduce the interval X Each document is routed by the user ID So, this should let us do the following: search by user. This will search all indeces across 1 shard search by time. This will search ~2 indeces (by default) across all shards Is this a reasonable approach, considering we may scale to multi-million+ documents? Or should I be denormalizing the data somehow, so that user searches are performed on a totally seperate index from date searches? Thanks for any pros-cons of the above scenario.

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• Database Driven Web Application, C# Front-End and F# Back-End meaning

  - by user1473053

  Hi I am an intern working with ASP.NET. My current task is to make a website which will incorporate some jquery viewing features. This project seems to me will be primarily dealing with reading data from a database and making graphs out of them. This will require me to make custom queries from whatever the client is looking at. I think it is going to be what this guy calls an Ad Hoc Query tool My plan for this is to make it a database-driven website. So I can utilize the jquery dynamic viewing capabilities. I stumbled upon the functional programming paradigm and found F#. I read that because of it's functional programming paradigm, it makes it a good language to do asynchronous functions. I read about how you can use this with LINQ to SQL and how easy it is to make queries without actually putting the query language in. I understand the concept of the MVC design pattern. But I don't understand what they mean about C# being the front-end and F# being the back-end. Can someone clarify this to me? Also what are your thoughts about doing this project in this way? Any comments and thoughts are greatly appreciated. I feel as if learning F# will be a great learning experience for me. My guess is that the F# back-end is like the part where it controls the calls to the database. F# is possibly the model part of the design pattern. And C# is the controller. So HTML, Javascript and Jquery stuff will be my View design pattern. Clarify please?

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• Are DDD Aggregates really a good idea in a Web Application?

  - by Mystere Man

  I'm diving in to Domain Driven Design and some of the concepts i'm coming across make a lot of sense on the surface, but when I think about them more I have to wonder if that's really a good idea. The concept of Aggregates, for instance makes sense. You create small domains of ownership so that you don't have to deal with the entire domain model. However, when I think about this in the context of a web app, we're frequently hitting the database to pull back small subsets of data. For instance, a page may only list the number of orders, with links to click on to open the order and see its order id's. If i'm understanding Aggregates right, I would typically use the repository pattern to return an OrderAggregate that would contain the members GetAll, GetByID, Delete, and Save. Ok, that sounds good. But... If I call GetAll to list all my order's, it would seem to me that this pattern would require the entire list of aggregate information to be returned, complete orders, order lines, etc... When I only need a small subset of that information (just header information). Am I missing something? Or is there some level of optimization you would use here? I can't imagine that anyone would advocate returning entire aggregates of information when you don't need it. Certainly, one could create methods on your repository like GetOrderHeaders, but that seems to defeat the purpose of using a pattern like repository in the first place. Can anyone clarify this for me?

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• TechEd 2012: MVVM In XAML

  - by Tim Murphy

  Paul Sheriff was a real character at the start of his MVVM in XAML session.  There was a lot of sarcasm and self deprecation going on prior to the .  That is never a bad way to get things rolling right after lunch.  Then things got semi-serious. The presentation itself had a number of surprises, but not all of them had to do with XAML.  When he flipped over his company’s code generation tool it took me off guard.  I am used to generator that create code for a whole project, but his tools were able to create different types of constructs on demand.  It also made it easier to follow what he was doing than some of the other demos I have seen this week where people were using code snippets. Getting to the heart of the topic I found myself thinking that I may have found my utopia for application development in MVVM.  Yes, I know there is no such thing, but this comes closer than any other pattern I have learned about.  This pattern allows the application to have better separation of concerns than I have seen before.  This is especially true since you can leverage data binding.  I’m not sure why it has taken me so long to find time for this subject. As Paul demonstrated using this pattern with XAML gives you multi-platform reusable code when you leverage common utility classes and ModelView classes.  The one drawback I see is that you have to go to the lowest common denominator between the platforms you want to support, but you always have to weigh the trade offs. And finally, the Visual Studio nuggets just keep coming.  Even though it has been available for several generations of Visual Studio I have never seen someone use linked files within a solution.  It just goes to show that I should spend more time exploring the deeper features of each dialog. del.icio.us Tags: TechEd,TechEd 2012,MVVM,Paul Sheriff,Patterns,Visual Studio 2012

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• Single complex or multiple simple autoload functions [on hold]

  - by Tyson of the Northwest

  Using the spl_autoload_register(), should I use a single autoload function that contains all the logic to determine where the include files are or should I break each include grouping into it's own function with it's own logic to include the files for the called function? As the places where include files may reside expands so too will the logic of a single function. If I break it into multiple functions I can add functions as new groupings are added, but the functions will be copy/pastes of each other with minor alterations. Currently I have a tool with a single registered autoload function that picks apart the class name and tries to predict where it is and then includes it. Due to naming conventions for the project this has been pretty simple. if has namespace if in template namespace look in Root\Templates else look in Root\Modules\Namespace else look in Root\System if file exists include But we are starting to include Interfaces and Traits into our codebase and it hurts me to include the type of a thing in it's name. So we are looking at instead of a single autoload function that digs through the class name and looks for the file and has increasingly complex logic to it, we are looking at having multiple autoload functions registered. But each one follows the same pattern and any time I see that I get paranoid about code copying. function systemAutoloadFunc logic to create probable filename if filename exists in system include it and return true else return false function moduleAutoloadFunc logic to create probable filename if filename exists in modules include it and return true else return false Every autoload function will follow that pattern and the last of each function if filename exists, include return true else return false is going to be identical code. This makes me paranoid about having to update it later across the board if the file_exists include pattern we are using ever changes. Or is it just that, paranoia and the multiple functions with some identical code is the best option?

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• MVC design patterns

  - by insane-36

  I have an application and it does not use a very good structure. However it seems to me that I have tried to stick to mvc design pattern but a senior engineer claims that I have no design patterns and code are mesh. How I have structured the code : I have couple of nsmanagedobject model classes which represents model in my case and a reskit library which encapsulates the nsurlconnection and url request. I fetch the request from the view controller itself and then when the request get completed I create predicate and then populate it in tableview. Wherever I need custom view either I create it in nib or create in a custom subclass of UIView. I have use delegation pattern and notification to communication to view controller, views and block callback with restkit. But, the senior engineer is very new to ios. He has been doing it for 2 months now but he is a good java programmer. So, what is mvc pattern ? Is core data model not working as a model objects, view controller as controller and views. I dont seem to find any other places or any other cases to create my own model object since the most of the models are used as NSManagedObject subclass.

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• Storing a pass-by-reference parameter as a pointer - Bad practice?

  - by Karl Nicoll

  I recently came across the following pattern in an API I've been forced to use: class SomeObject { public: // Constructor. SomeObject(bool copy = false); // Set a value. void SetValue(const ComplexType &value); private: bool m_copy; ComplexType *m_pComplexType; ComplexType m_complexType; }; // ------------------------------------------------------------ SomeObject::SomeObject(bool copy) : m_copy(copy) { } // ------------------------------------------------------------ void SomeObject::SetValue(const ComplexType &value) { if (m_copy) m_complexType.assign(value); else m_pComplexType = const_cast<ComplexType *>(&value); } The background behind this pattern is that it is used to hold data prior to it being encoded and sent to a TCP socket. The copy weirdness is designed to make the class SomeObject efficient by only holding a pointer to the object until it needs to be encoded, but also provide the option to copy values if the lifetime of the SomeObject exceeds the lifetime of a ComplexType. However, consider the following: SomeObject SomeFunction() { ComplexType complexTypeInstance(1); // Create an instance of ComplexType. SomeObject encodeHelper; encodeHelper.SetValue(complexTypeInstance); // Okay. return encodeHelper; // Uh oh! complexTypeInstance has been destroyed, and // now encoding will venture into the realm of undefined // behaviour! } I tripped over this because I used the default constructor, and this resulted in messages being encoded as blank (through a fluke of undefined behaviour). It took an absolute age to pinpoint the cause! Anyway, is this a standard pattern for something like this? Are there any advantages to doing it this way vs overloading the SetValue method to accept a pointer that I'm missing? Thanks!

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• Is this JS code a good way for defining class with private methods?

  - by tigrou

  I was recently browsing a open source JavaScript project. The project is a straight port from another project in C language. It mostly use static methods, packed together in classes. Most classes are implemented using this pattern : Foo = (function () { var privateField = "bar"; var publicField = "bar";     function publicMethod() { console.log('this is public');     } function privateMethod() { console.log('this is private'); } return {   publicMethod : publicMethod, publicField : publicField }; })(); This was the first time I saw private methods implemented that way. I perfectly understand how it works, using a anonymous method. Here is my question : is this pattern a good practice ? What are the actual limitations or caveats ? Usually i declare my JavaScript classes like that : Foo = new function () { var privateField = "test"; this.publicField = "test";     this.publicMethod = function()     { console.log('this method is public'); privateMethod();     } function privateMethod() { console.log('this method is private'); } }; Other than syntax, is there any difference with the pattern show above ?

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