Planning, Running and measuring tests with Visual Studio 2010 Ultimate and Test and Lab Manager 24 January 2010 Peter-Himschoot VS2010, Team System, .NET Development So what does Visual Studio 2010 bring for testers? A whole lot! Especially the new test environment, where you can create a test plan to validate the quality of the software you’re building. A test plan is a collection of test cases, which you can then run. While running the system keeps track of a whole lot of things, including code coverage and IntelliTrace information. And finally this application allows you to examine the combined results of all tests, to see how your development effort is doing. So again: A test plan is a collection of test suites, used to test a certain iteration in your project. A test suite is a collection of test cases to test a certain part of your project, and a test case is a test for a project feature. A test case is basically an UI test running in a specific environment. To model this, Test and Lab manager also allows you to define a test configuration, which is a certain environment for your code, for example Windows 7 with IE8, or Windows XP SP2 with IE7. Running Test and Lab Manager First time you run this application it will ask for your Team Foundation Server (TFS) and after that, for the Project Collection and Team Project: Ok, next step it will ask you for a test plan; since there are none you will have to create a new one: Then click “Select plan >”. This opens the test plan. if you want you can change some of the properties of this test plan by clicking on the properties tab: Here you can change the iteration for example, or the test settings. With test settings you can change how your tests will be executed. For example in the Local Test Run settings you can change the diagnostic data adapter, which record data from your test run. For example is you want an action recording, event log entries, etc… You can also use it to emulate certain environments, for example running low on memory. You can even create your own data adapter. This first page allows you to change the name, and choose between running a manual or automated test. On the second page you can define the roles. You define a role for each tier to use to run tests and collect data. One the local settings you can only have one role, your own physical machine. If you want to use roles, you will also have to define environments. Here you can define what kind of data you want to gather. For example, the Action Recording will record each action taken during the test, making it easy for another person (typically a developer) to understand what happened during running the test. The Action log is a text version of the recording. IntelliTrace will allow a developer to load the IntelliTrace log and step back in the code, to see how the error came to be. Go back to the Contents tab. Now we’re ready to test some of our user stories (from now on I will be using User Stories, but this could just as easily be called a requirement or anything else to denote a certain needed functionality of your software system). Test cases are grouped into test suites. Per test plan you have a default test suite, but you can also create a test suite for a specific user story, copy a test suite from another test plan, create a nested suite or create one from a query: If you select “Add requirement"to plan” you will need to select a user story. This user story is now associated with this test suite. This will allow reporting to figure out which tests have ran for which user story. Now we’re ready to add a test case, so click the New button. The New Test Case dialog should show: Add the four steps (please note that we’re doing this for the sake of the demo, normally your requirement should not be to crash :) ). Save it. Click on the Tested User Stories tab: the User Story should be there. Save and Close. A couple of other things you can now do is to assign it to a tester, and/or change the configurations: Let’s run the test. First open the Test tab: From here you can see all test cases for a test suite: Select the test case and click on the run button. The Test Runner should open: Check the Create action recording button and hit Start Test. Do as the test case says, and try to use a repeatable way to start the application (for example using the start menu). The first and second step should not be a problem, so click the drop down boxes to the right of each step to indicate success: Now make the third step fail. You’ll need to enter a comment why it failed. Then click the End Test hyperlink button. You’ll see test center gather some information. On top of the test runner window you’ll see a toolbar. Click on the Create Bug button: You’ll see that most of the fields are automatically filled in. You might want to change the Severity for example, and maybe assign it to a certain tester, but that is all… Click Save. Check out the information included in the System Info, and All Links tab. Close it. Remember me asking you to start the application using some repeatable way? Well, try and click on the play button. Your test should replay again. This makes it easier to re-test later. Coming back to Test and Lab Manager. The test case failed so now the UI updates to show this: If you have more than one test, the bar will color depending on how many succeeded, failed or are still in progress. Later you can come back and verify if a bug still exists by using the Verify Bugs tab: Go back to the Plan tab, then open the properties. Now you should see an overview: Back to Visual Studio, so close the Test and Lab Manager. Go to the Team Explorer and open the My Bugs query. You should see the bug we created before. Open it: Go to All Links, and open the IntelliTrace log (.tdlog). With it you can now replay the bug, just like in my previous post on IntelliTrace. If this doesn’t work, go back to the test settings. You might also like the Video feature, so you can replay the user’s actions!
WCF and large messages 23 January 2010 Peter-Himschoot WCF, VS2010, .NET Development, Entity Framework This week I’ve been training a couple of people on how to use .NET, WCF4, Entity Framework 4 and other technologies to build an Enterprise Application. One of the things we did was return all rows from a table, and this table contains about 2500 rows. We’re using the Entity Framework 4 self-tracking entities which also serialize all changes made it the objects. And I kept getting this error: The underlying connection was closed: The connection was closed unexpectedly. Server stack trace: at System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException webException, HttpWebRequest request, HttpAbortReason abortReason) at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout) at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout) at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout) At first I thought it was something to do with the maximum message size, another kind of error you get when sending large messages. The maximum message size quota for incoming messages (65536) has been exceeded. To increase the quota, use the MaxReceivedMessageSize property on the appropriate binding element. Server stack trace: at System.ServiceModel.Channels.HttpInput.ThrowMaxReceivedMessageSizeExceeded() at System.ServiceModel.Channels.HttpInput.GetMessageBuffer() at System.ServiceModel.Channels.HttpInput.ReadBufferedMessage(Stream inputStream) This one is easy to fix (although a little confusing because you have to configure the binding of the receiving side of the message, which is most of the time the client: But doing this didn’t help. So what was it? I knew the size of the message couldn’t be the problem, because I’d sent way bigger messages before. Maybe there was something in the contents that made the DataContractSerializer crash? Checking this is easy, I wrote a little code that would make the serializer write everything to a stream and see what happens. Works fine. Hmmm. What could it be? So I went over the list of properties of the DataContractSerializer. I has a MaxItemsInObjectGraph property. Maybe that was it, but how can I change this number? Looking at the behaviors I found it. What you need to do when you send a large number of objects is you have to increate this number, which is easy. At the server side you use the DataContractSerializer service behavior and set its value to a large enough number: At the clients side you use the DataContractSerializer endpoint behavior. That fixed my problem.
Using the Visual Studio 2010 Historical Debugger to save and reproduce bugs 22 January 2010 Peter-Himschoot .NET Development, VS2010 Visual Studio 2010 Ultimate now has IntelliTrace, which is a historical debugging feature. IntelliTrace will keep track of everything your code has been doing and then, when a bug arrives, you can back-track to the possible cause of the bug. You might think this is nothing new, but don’t forget it also tracks the value of any variable at that moment in time. With the usual debugger you will see the latest value, not the value at that moment. You can enable (and it is enabled by default) by going into Options->IntelliTrace->General If you want to try this, build a simple windows forms application with a Button and CheckBox. Then add code as follows: 1: Public Class Form1 2: 3: Private message As String 4: Private flag As Boolean 5: 6: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 7: flag = FlagCheckBox.Checked 8: Doh() 9: End Sub 10: 11: Private Sub Doh() 12: If flag = True Then 13: message = "This should work" 14: Else 15: message = Nothing 16: End If 17: flag = True 18: ShowMessage(message) 19: End Sub 20: 21: Private Sub ShowMessage(ByVal message As String) 22: 23: 24: ' Throw exception if message is empty 25: Dim len As Integer = message.Length 26: 27: End Sub 28: End Class Run it with the checkbox unchecked. This should cause the application to stop in the debugger: Your code should look like this: See those special arraws in the gutter (the gutter is the section where you click to add/remove breakpoints)? These will allow you to backtrack. You should also have a IntelliTrace window looking like this (two views are available): With these you can jump directly to one of your code’s stackframe. Let’s try stepping back to see what happened. Press the back arrow, or better yet, use the keyboard shortcut (on my machine that is Ctrl+Shift+F11): You should now be able to step back in time, for example look how my IDE looks like when stopped at the ShowMessage method: IntelliTrace keeps track of the values of the arguments and such, at each point in time. For example, a little higher in the code I changed the flag variable to true, while the bug is caused because it was false before. IntelliTrace will show me this. 1: Private Sub Doh() 2: If flag = True Then 3: message = "This should work" 4: Else 5: message = Nothing 6: End If 7: flag = True 8: ShowMessage(message) 9: End Sub IntelliTrace will save all of this information in a file (now with an extension called iTrace, notice the naming convention <GRIN>), and because you can open this file afterwards, all kinds of scenario’s can now be implemented. You can send the file to a colleague so he/she can help you debug the problem. So where is this file? Go back to Tools->Options->Advanced and copy the directory for later: Open this directory in file explorer and copy the file to where you like. You will have to stop debugging, otherwise Visual Studio keeps a lock on the file. Don’t stop Visual Studio, because VS throws away the log file when it quits. When you open the file again, Visual Studio will show the log’s summary: Open the Thread Lists and look for the thread you want to see (probably the main thread): Double click it and with a little patience the debugger will open (make sure Visual Studio can find the sources). Or better even, the Visual Studio Test and Lab Manager 2010 can do this for you. So even if you have a non-technical user who is testing some application, and finds a bug, the IntelliTrace file will be attached automatically!
Building an Enterprise Application with Entity Framework 4 20 January 2010 Peter-Himschoot .NET Development, VS2010, Entity Framework Entity Framework 3 was a bit of a disappointment when it came to supporting enterprise applications. For me the major reason was the fact that entities used by EF required deriving from a class which is part of EF, thus coding the EF requirement into your Business Logic Layer (BLL) and presentation layer. EF 4 is still under development, but already they’re making a lot of compensation for this with their support for POCO (Plain Old Clr Object) and self tracking objects. POCO vs. Self Tracking A self tracking object is an object that has state where you can check what has happened to the object (unmodified, new, modified, deleted). The advantage of this kind of object is simplicity for the user, because the object does all the tracking. Of course this means more work building the object itself, but this can be solved using T4 templates. A POCO is really nothing more than a data carrier object, without any tracking support. Simplicity means maximum portability, especially if you use DataContracts. For the rest of this post I’ll be using self tracking objects, generated through EF 4. I’ll also be using the EF feature CTP 2. Using EF 4 to generate the self tracking objects Start by creating a new WinForms project (of WPF, Silverlight, whatever). Add another library project for your data access layer (DAL) and another one for your entities: Normally I would also add a business logic layer (BLL) but for simplicity I’ll leave it out for now. Now add a new Entity Data Model to your DAL project. Select the Northwind database, then select the Categories and Products tables: This way you end up with this model: Please note that my tables/entities each have an extra column, the Version column. This is a TimeStamp column used to detect concurrent updates. To tell EF to use this column for concurrency, set its Concurrency Mode property to Fixed. This is typically the best way to handle concurrent updates. Right-click your entity model’s background, then select the Add Code Generation Item… menu choice: This alternative code generation will add two T4 templates to the DAL project (using the .tt extension) The ProductsModel.Context.tt is an EF dependent template, so leave it in the DAL project, but the ProductsModel.Types.tt contains the EF independent types which actually are self-tracking entities. Move this template to the Entities project: Watch out, your project will not build until you set following references (diagram made with Visual Studio’s new UML Component Diagram) : This diagram also includes the BLL layer, our solution doesn’t, but if you want, feel free! If you’re using VB.NET, you should also add the Product.Entities namespace to your list of imports of the DAL project: Now you’re ready to implement the DAL layer, so add a ProductsDAL class as follows: 1: Public Class ProductsDAL 2: 3: Public Function GetListOfCategories() As List(Of Category) 4: Using db As New NorthwindEntities 5: Return db.Categories.ToList() 6: End Using 7: End Function 8: 9: Public Sub UpdateCategory(ByVal cat As Category) 10: Using db As New NorthwindEntities 11: db.Categories.ApplyChanges(cat) 12: db.SaveChanges() 13: End Using 14: End Sub 15: 16: End Class Now let’s add some controls and data bind them with Window Forms. For this I use the Data Sources window. Open it and add another data source. Select an object data source: Then select your Category of Product entity, which you should find in the Products.Entities project: Your data source window should now display your entities: Right-click category and select Customize… from the drop-down list. Now you can select Listbox as the control to use. Drag the Category entity to your form to create a listbox and bindingSource: Add two buttons, the Load and Save button. Implement the first button to retrieve the list of categories from the DAL: 1: Dim dal As New ProductsDAL 2: CategoryBindingSource.DataSource = dal.GetListOfCategories() And implement the save button as follows: 1: Dim dal As New ProductsDAL 2: Dim cat As Category = TryCast(CategoryBindingSource.Current, Category) 3: dal.UpdateCategory(cat) Run the solution and click on load. The listbox should fill with categories and the window should look like this (you might first want to copy the connectionstring in the DAL’s project .config to the form’s config): Note the “Change Tracking Enabled”. Check the checkbox if you want to update an object, this will enable the self tracking. Make a change, then click Save. This should update the database. Open two instances of this application. Load in both, then change the same record in both (with tracking enabled). Save both. The second Save should fail because of concurrency checking. Done!
Using the Visual Studio 2010 layer diagram to verify your solution 17 January 2010 Peter-Himschoot .NET Development, Team System Visual Studio 2010 adds a whole new series of modeling tools to the product, including UML modeling. In this post I want to discuss the Layer diagram and its relation to building enterprise applications. The Layer Diagram Visual studio 2010 now comes with new modeling tools, which you can reach through the architecture menu from Visual Studio 2010 (I’m using the Ultimate edition): This will open the Add New Diagram dialog: Select Layer Diagram. If you don’t yet have a Modeling Project in your solution, another dialog will open so you can name your new modeling project. You should now see an empty layer diagram, so let’s add some layers. Open the toolbox: Double click the Layer item in the toolbox (doing this will lock the toolbox into adding layers, if you single click it you will need to go back to the toolbox for each layer) and click the layer diagram three times to add three layers, stacked vertically. Name the top one Presentation, the middle one BLL (Business Logic Layer) and the bottom one DAL (Data Access Layer). So now we have three layers. Now let’s add a couple of dependencies. I want the presentation layer to use the BLL layer, but not reversed, so let’s model this by adding a dependency from the Presentation layer to the BLL. Let’s also do the same for the BLL to the DAL: The Enterprise Application Skeleton Having a layer diagram is nice, but how can it help you with your development? The layer diagram can help by verifying your solution and projects comply with the layer diagram. As an example I want to use the Enterprise Skeleton solution I use for enterprise development. In its simple version there are 4 projects (excluding the modeling project): one for the presentation layer, one for the BLL and one for the DAL. The fourth project contains the data carrier objects that travel between layers; the DAL is responsible for retrieving and storing these objects, the BLL will check these objects using the business rules and the presentation layer will display these objects. Let’s use this solution with the layer diagram. Adding layer verification to your solution Open Visual Studio with this kind of solution and with your layer diagram (part of a modeling project in your solution). Now drag and drop each project to its appropriate layer. Drop the Products.Common onto the DAL layer (this is a mistake which we’ll discover soon with the verification feature). Each time you do this you will see a counter appear on the layer, counting the number of projects mapped to the layer… However, you cannot see here which project is mapped to each layer. Back to the architecture menu. Open “Windows –> Layer Explorer”, which displays the mappings: If you select a specific layer in the layer diagram, this window will show only projects mapped to it. You can do the same by: right-click on a layer, select View Links. Validation the solution Right-click the layer diagram and select Validate Architecture: Visual studio will start to analyze your code and may return a bunch of validation errors: Open the error list window to see these errors: From here you can do several things: create a work item to correct the error, suppress the error, or investigate the error: The screenshot illustrates the last action. With this you can go to the method or type involved in the validation error. The problem we are facing here is actually because I put the Products.Common project into the DAL. But the presentation layer also needs the types in this project, but we’re not allowing referencing the DAL from the presentation layer. We could add this dependency (please don’t), or we can fix the problem. Fixing the problem Add another layer to the layer diagram, calling it Common. This layer will contain all types common to the other layers, so add dependencies from these layers to the common layer. Finally drag the Products.Common project to the common layer. One more thing: we need to remove the Products.Common project from the DAL layer. Select this layer, in the Layer Explorer you should see two projects. Remove the common project. Now verify again. You should have 0 errors. Automating Validation This validation is a powerful tool to prevent layering mistakes from creeping into your solution. So can we automatically run this whenever we build? Yes we can! One way is to set the Validate Architecture property of the modeling project to true. Then each time you build the solution the layer diagram will verify. This can take same time for each build, so it is better to do this using Team build. You can enable validation using the /p:ValidateArchitecture=true option. To do this, open your build definition and set the “MSBuild Arguments” property like this: Generating dependencies from your solution Another thing you can do is to add the layer dependencies from your solution. Right-click the layer diagram after adding your layer (and which you mapped to your projects). Then select the Generate Dependencies menu. What else is there? What else can you do with the layer diagram? Look at the previous screen shot. If you’re connected to VSTS you can link and create work items.
Project Management: Planning an iteration with Team System 2010 11 January 2010 Peter-Himschoot .NET Development, Team System, VS2010 In my previous post I talked about planning a whole project. Now I want to blog about planning a single iteration using the new Team System 2010 iteration with Excel and Project. After creating the user stories, the next step is to break each user story into detailed tasks. To facilitate this, the MSF agile template has a special Excel sheet under Documents->Shared Documents->Iteration <X>: Double-click to open it. Before you edit, click the Edit Workbook button beneath the ribbon: To split up a user story into (linked) tasks, you want to create child work items beneath your user story. Do this using the “Add Child” button on the ribbon: Pressing the Add Child will add another row to the sheet, and also adds another Title column. This is used to detect/indicate the parent/child relation between two work items. So here I’ve added a couple of child tasks to the user story. Now we can start planning the iteration. First you will want to fill in the “Assigned To”, “"Remaining Work”, “Area” and “Iteration” columns with some data. Choose a team member for the Assigned To column, and choose your iteration for the Iteration column. Here’s an example: Next you want to plan the iteration, so go to the Settings tab. In this tab you set the iteration start and end date. The Excel sheet will use this together with the interruptions sheet to determine the amount of work that can be done in this iteration. Once you fill out this sheet you can go to the Capacity sheet, where you can balance the work load for each team member. Start by providing the hours/day and number of days in the iteration for each team member. Now you can see the workload for each team member. April has way too much work (and Abu too little) so go back to the backlog sheet and move some work to Abu. Go back to the capacity sheet and see the now work load: Imagine Doris being called over to help with another project. How will this affect capacity? Start by filling in the interruptions tab: And go back to capacity. Whew. Not a problem!
Project Management: Hierarchical Work Items with Visual Studio and Project in Team System 2010 11 January 2010 Peter-Himschoot Team System, VS2010, .NET Development In my previous posts I talked about high level project management, and detailed iteration planning. Both created work items, mainly user stories with child task work items. How does this work in Visual Studio? And what about MS Project? Visual Studio and hierarchical work items Let’s start with Visual Studio. Open your team project and expand the Team Queries, then Workbook Queries: You’ll notice that for each iteration VSTS creates an iteration backlog query, showing you the work items for the iteration. Pay attention to the icon: this means that this is a hierarchical query which will use indentation to show the parent child relation. Execute one of the iteration backlog queries. You should get a list user stories: Notice the + sign before the user story title: with this you can expand the the child tasks. In the toolbar you can also see an + and – icon. These will expand/contract all user stories with their children: Should you see a task assigned to the wrong user story, you can simple drag it to the correct one, and Visual Studio will automatically move it, and indicate your changes using bold. Here I’ve moved tasks #48 to user story #11: You can also use the green arrows in the toolbar to change the level of a work item, for example to make it a child work item. Be careful: this only works if your work items is below a user story. Otherwise drag it to the parent like before. You can also directly create a child work item by right-clicking on a work item and adding a New Linked Work Item. Linking to other work items has been greatly extended. You can now choose from a variety of links: Note the predecessor link. We will revisit this when we look at MS Project and TFS. Scheduling tasks with MS Project When using MS Project with TFS 2008, dependencies added with MS Project would not be saved back to TFS. With TFS 2010 you can now easily plan tasks in project using Gantt charts, add dependencies and publish back to TFS without losing these dependencies. Start MS Project using the “Open in Microsoft XXX” feature in Visual Studio: Let’s say you have two tasks: Now you want to indicate that the first task assigned to April must be done before April can start the second task. Do to this Alt-drag the first task to the second task to create a predecessor relation. Your Gantt chart should now look like this: Note the Predecessors column which contains the row number of the first task. This is not the work item id, it is the number of the row in Project. Now you can publish this back to TFS. After that, go back to Visual Studio and open the first work item. Go to the links tab. You should now see a successor link to the next task:
Project Management: Planning a project with Team System 2010 08 January 2010 Peter-Himschoot .NET Development, VS2010, Team System Project management has changed. Changed towards SCRUM based project management where you start by building a list of User Stories, also known as the backlog... This list of user stories allows you to plan the project by selecting the highest priority user stories, adding them to an iteration, planning the iteration and implementing it. User stories are assigned story points which is an abstract unit for measuring the amount of work. Let’ start by creating a new Team Project. Nothing has changed in the “New Team Project” wizard except that the team project templates have been modified (to better support SCRUM like project management). Again you can choose between an agile template and the CMMI template. The CMMI (Capability Maturity Model Integration) template is more formal; in this post I’ll be using the agile template. Creating user stories A newly created team project will now be empty of work items; the intent is that you start by creating User Stories. These user stories describe the user’s needs. Then you prioritize the user stories and assign story points to them to estimate the work required. A user story is a very slim and high-level user requirement. For example: “The delegate can pay by credit card to confirm reserving the course” (Personally I see user stories as short-hand versions of use cases). To create a new user story with Team System you can choose between Visual Studio, Excel or Team Web Access. Using Excel To create user stories you’ll probably want to use Excel. Previously I found the workbook that came with team foundation 2008 a little lacking, but now you get all you need to perform high level planning. So let’s set out and try this. Open Team Project explorer, and drill down to Documents->Shared Documents. Double click on Project Backlog.xlsm to open Microsoft Excel. Ignore the security warnings if you get some... The Product Backlog is a new workbook that enables you to manage your product backlog of work items from within Microsoft Excel. Start by refreshing from the server by clicking the Refresh button. This will synchronize your workbook with changes made to the server. From Excel you can also edit your areas and iterations, access Team Web Access, and create reports. But also take notice to the sheets in this workbook: First one is for editing the backlog, second one is for high-level iteration planning and the third one is for planning interruptions. The workbook takes very good care of synchronizing changes from one sheet in the other. Let’s start with the first one: the product backlog. The workbook is open in read-only mode by default, so start by clicking on the “Edit workbook“ button: Then you can start adding user stories: Prioritize your user stories by assigning a rank. Prioritizing user stories can be done in many ways, for example Karl Wiegers Kano model. You also need to assign story points as an estimate for the amount of work required (story points don’t generally use precise estimates, like hours or something). Using Visual Studio You can also use Visual Studio to add a new user story; then you’ll get this window inside VS: Please note the format of the title. This makes it a lot easier to think about user stories. Using VS for a single user story works like a charm, but for lists of users stories you’ll want to use Excel. Using Team Web Access Another option, which I think is quite realistic for project managers (and even end users), is to use a web site for editing work items. That is why Team System comes with Team Web Access. You can find the site from your team project portal. Then you can add any work item directly like this: Select User Story from the drop down and you get this: Again, you can add all necessary information directly. Planning Iterations Once you have a good idea about your user stories, you can start iteration planning. In this phase you will assign user stories to iterations. Each iteration will have room for a number of story points (this number is called project velocity, which is the average number of story points your team can do in a single iteration). Iteration planning is done with the Iteration planning worksheet. Note the help above. Once you’re familiar with this sheet you can hide the help. In here you plan your iterations. First you enter start and end date. The sheet will calculate the number of days for the iteration, taking into consideration any planned interruptions you entered into the interruptions sheet. Next you can start to assign user stories to iterations. The sheet will update again with a simple bar chart, making it easier to load balance your work over iterations: The interruptions sheet is just that, simply fill out any dates when no work can be done on the project because of holidays, special events, etc… The Planned Iterations sheet will automatically update nr of days with it. So for example, if we plan a team building meeting in Hawai on the 01/13/2010, the iteration will have 4 days: That’s it for now. In my next post I’ll discuss detailed iteration planning with Visual Studio 2010. Trying this yourself If you want to try this yourself, I recommend you download the virtual machine from Microsoft (comes with sample data and all, and a bunch of labs). The one using Virtual PC 2007 The one for Windows 7 Virtual PC The one for Hyper-V Windows Server 2008
Blogging Frenzy 21 October 2009 Peter-Himschoot .NET Development Looks like I started to blog a lot more lately, and so do a couple of my colleagues. Check out Nick’s blog: http://blogs.u2u.be/Nick/ And of course Kris’s blog: http://blogs.u2u.be/Kris/ Both of them have gone crazy with Extension methods… So should I?
Workflow 4 parallel and compensation activities 15 October 2009 Peter-Himschoot .NET Development, WF 4 So I’m looking into workflow foundation 4 (using Visual Studio 2010 Beta 2). Let’s look at the parallel activity included within. The parallel activity will schedule all of its child activities asynchronously and then wait until all children have completed or the CompletionCondition evaluates to True. Let’s do a little experiment: Start Visual Studio and create a new workflow console application. Drag a Sequence activity to the designer. In it add a WriteLine activity and a Parallel activity. Drag a sequence activity inside the parallel activity. It will automatically split up to allow other branches: Rename this sequence to left, then add a WriteLine activity, a Delay and another WriteLine activity. Repeat this for the right branch, calling it Right. Now we only need to add two variables to time the delays. Select the Start sequence, and on the bottom of the designer click on the variables button. This will open the variables window: In here define two variables leftDelay and rightDelay and make them of type TimeSpan using the dropdown combobox and select “Browse for Types…”. This should open the “Browse and Select a .NET Type” dialog. One of the new things I like about this window is that you can search for a type: Finally we should end up with this: Run and you should get this: As you can see the parallel activity will now execute both left and right branches. But what if you want one of the branches to stop because another branch has done all that is needed? For that we can use the Parallel’s activity CompletionCondition. When one of the branches of the parallel activity completes, the parallel activity will check its CompletionCondition. If set to false, it will allow other braches to continue. Otherwise it will cancel the other, still running, branches. So let’s test this. Click on the parallel activity and add a new boolean variable called stopProcessing (I’ve renamed the parallel activity Race, so that’s set as the stopProcessing variable’s scope): Now set the parallel activity CompletionCondition to this variable by clicking the activity and using the property window: Next add to each branch an assignment activity after the last writeline to set the stopProcessing to true: Run: you should see one branch complete while the other never does: And what about doing something when you get cancelled? To do this we need to use a CancellationScope. A CancellationScope allows you to define what needs to be done when a branch gets cancelled, for example in a parallel activity because another branch completed with the CompletionCondition set to True. Let’s try this. Inside the parallel activity drag a CancellationScope. Then drag the left branch in it. Repeat with a new CancellationScope for the right branch. Drag a WriteLine activity into each CancellationScope’s CancellationHandler. For example the left side should write “Left was cancelled” in the CancellationHandler: Run again: You should now see one side complete, and the other being cancelled: WARNING: Although you might think it is a good idea to schedule as much work as possible in parallel, this will not make your orchestration faster. WF will still schedule all activities on the same thread, so if your activities never go idle, it will take the same amount of time as if you’re using a sequence. Only if each branch in the parallel activity needs to wait on some response will using the parallel activity make a difference.