NET's System. Transactions namespace. The Transaction class offers a lightweight, auto-enlisting, and promotable transaction. The transaction can start as a local transaction, and later the runtime can promote the transaction to a heavyweight, distributed transaction if needed. Instead, the runtime can persist the state of the workflow to a durable store and unload the instance from memory. In 30 days or hopefully, less , the runtime can reload the workflow instance and resume processing.
The WF runtime will automatically persist a workflow that is idle or suspended when a persistence service is present. Of course, we'll need a database schema that the persistence service understands. A tracking service will tell the runtime the type of information it wants to know about workflows using a tracking profile.
Once the service establishes a profile, the service can open a tracking channel to receive events and data. Chapter 5 includes more details on tracking profiles and channels. The runtime does not start a tracking service by default, but we can programmatically add a tracking service or configure a tracking service with an application configuration file for the runtime to use.
Maybe you've had one of those product managers who is always at your desk, asking "are you done, yet? The sample isn't meant to demonstrate all the capabilities of the platform, but give a general feel for creating and running a workflow with WF.
Supported development tools for the. The extensions are not compatible with the Express editions of Visual Studio We'll choose C as our language and select the Sequential Workflow Console Application template see the screenshot on the next page.
The template gives us a project with references to all the correct WF assemblies, an empty workflow, and a Program. Right-click the workflow and select Delete so we can start a workflow from scratch. If we click to expand the node containing Workflow1. As we mentioned earlier, the partial class will combine with the class generated from the XAML to produce a single type. Let's modify the class in Workflow1. If we double-click the. We can drag a While activity from the Toolbox and drop the activity between the start and end point of our workflow.
The While Activity executes a child task until some condition is met. Our next step is to drag a Code activity from the Toolbox into the center of the While activity. At this point, our designer should resemble the following screenshot:. Notice both activities display a red exclamation point. The activities are failing their validation checks.
We can hover the mouse cursor over the exclamation points and open a smart tag to view the validation error. If we tried to compile the program we'd see these same validation errors as compilation errors. We'll fix these errors now. The Code activity requires us to assign an event handler for the ExecuteCode event. We can set the event by opening the Properties window F4 and clicking the Code activity to set focus. Double-clicking in the empty space beside the ExecuteCode property will send us into the code-beside file and generate a new event handler.
We can place the following code into the event handler. This code will ask the user if a bug is fixed, and then read a key press. The Code activity should now pass validation, so we can turn our attention to the While activity. A While activity requires a valid Condition property. Several activities in the base activity library work with conditions, including the IfElse, ConditionedActivityGroup , and Replicator activities.
These choices represent the two techniques available to express a condition, the first being with code a method that returns a Boolean value , the second being with a rule. Let's select the RuleConditionReference. A rule condition is a named expression that evaluates to true or false, and can live in an external.
A plus sign appears beside the Condition property, and we can click the sign to expand the property editor. When the Condition property expands, the Property window gives us the ability to set a ConditionName and an Expression. Clicking on the ellipsis … button in the Condition name will launch a Select Condition dialog box. We want the While activity to loop until the bug is fixed. Our rule is! Once we've entered the condition notice the editor provides IntelliSense , we can click OK.
We should select Condition1 and press OK. The While activity should now have a ConditionName and Expression set, and pass validation. Now we need to open the Program. We need to host the WF runtime and ask the runtime to execute our workflow. The item template for a workflow project provides all the boilerplate code we need. Let's review the code:. The code wires up event handlers to the runtime so we know if a workflow terminates because of an exception , or completes successfully. The code instantiates our bug-fixing workflow using the CreateWorkflow method, passing the type of our workflow.
Since the workflow engine executes our workflow asynchronously, we need to block our thread on an AutoResetEvent object and wait for the workflow to complete otherwise, the console mode program would exit before the workflow gets an opportunity to run.
An AutoResetEvent object will block a thread until the object is in a signaled state, which we do with the Set event in the event handlers. Software developers have been implementing workflows to model business processes since the beginning of time. During this time, we've learned that workflows can be long-running and often require input from humans. Building a robust workflow to meet these challenges is a daunting task. An ideal paradigm for building workflows is to separate the workflow definition from the engine that executes the workflow.
Windows Workflow brings a workflow engine and workflow development tools to Microsoft platforms. The instructions for the WF engine are activities, and we can arrange these activities using a graphical designer, XAML, code, or a combination of the three. WF provides the services we need for a workflow engine, including persistence, threading, and transaction services. The future looks bright for building workflow solutions.
Living in Hagerstown, Maryland, Scott tries to play as much softball as possible during the summer. Contact K. Scott Allen. About this book Windows Workflow Foundation WF is a technology for defining, executing, and managing workflows. Publication date: December Publisher Packt. Pages ISBN Chapter 1. Hello, Workflow. Building Workflow Solutions. Note The C code we saw earlier is an example of imperative programming. A Windows Workflow Tour. Custom Activities. Note C , VB. Visual Studio Extensions.
WF Validation and Debugging. Designer Looks. The Windows Workflow Runtime. Hosting the Windows Workflow Runtime.
Runtime Services. I can't resist: You may need WF only if any of the following are true: false. You will probably regret it: Steep learning curve Difficult to debug Difficult to maintain Doesn't provide enough power, flexibility, or productivity gain to justify its use Can and will corrupt application state that cannot be recovered The only time I could ever conceive of using WF is if I wanted to host the designer for an end-user and probably not even then.
Of course, this is only my opinion, but I think it's a damn good one. Stephen Kennedy Ronnie Overby Ronnie Overby I wrote this answer on a day that I was angry at WF4. I'll update my answer with the issues I have faced. We inherited a half completed project from a consultant which used WF as its backbone. It was prone to errors, corrupted workflows that can't be restarted, an archaic versioning system that requires a complete duplicate of the workflow for any minor changes, horrific generated code, and such a delicate code that you have to handle it with kid gloves.
After 6 months of yellow screens of death we scrapped the entire WF and used xml instead. Best decision we ever made. The phrase: "Doesn't provide enough power, flexibility, or productivity gain to justify its use" says plenty enough for me.
Thank you for that. Haters need to explain their hate. Show 4 more comments. Here are the advantages and disadvantages of Workflow Foundation I gathered from my experience: Advantages Persistence: If you're going to have many long running processes think days, weeks, months , then Workflows are great for this.
Idle workflow instances are persisted to the database so it doesn't use up memory. As a developer, I prefer to write code rather than snapping things together visually.
And when you have a non-developer making workflows, you often end up with a huge confusing mess. Disadvantages Programming Model: You're really limited in programming features.
Think about all the great features you have in C , then forget about them. Simple one or two line statements in C becomes a fairly large block activities. This is particularly a pain for input validation. Having said that, if you're really careful to keep only high-level logic in workflows, and everything else in C , then it might not be a problem.
Performance: Workflows use up a large amount of memory. If you're deploying a lot of workflows on a server, make sure you have tons of memory.
Also be aware that workflows are much slower than normal C code. Steep learning curve, hard to debug: As mentioned above. You're going to spend a lot of time figuring out how to get things to work, and figuring out the best way to do something. Workflow Version Incompatibility: If you deploy a workflow with persistence, and you need to make updates to the workflow, the old workflow instances are no longer compatible. Supposedly this is fixed in. NET 4. You have to use VB expressions.
Not flexible: If you need some special or specific functionality not provided by Workflow Foundation, prepare for a lot of pain. In some cases, it might not even be possible. Who knows until you try? There's a lot of risk here. You don't even need to define an interface. Mas Mas 4, 5 5 gold badges 35 35 silver badges 54 54 bronze badges.
Most of your disadvantages are simply not true, maybe you are not familiar enough with WF. Take action: Organizations interested in using a low-code or no-code framework should start by following these steps:. NET any time soon. CoreWF is a community, open-source runtime of WF spearheaded by the. NET Foundation. But CoreWF has some potential issues:.
WF still works. If you have no reason to stop using it, your business can revisit this issue in a few years when CoreWF is further in development. If the time comes where you need to move to. We do not recommend planning to target CoreWF, as it may never be production ready.
But there is no reason not to keep an eye on it. But many businesses already make large applications made up of small parts arranged in a flexible order without a workflow. They do it by using microservices. Microservices development is when you break down your application into discreet services and develop each independently. It's the same strategy as WF: you make each business action a service, then combine them into one process.
Keep these things in mind when considering microservices:. By taking away the workflow framework, you take away the ability for non-developers to make changes on their own. If that is something your business needs, the other alternatives are better fits. Take action: Organizations interested in replacing WF with microservices should follow these steps:.
The good news about WF is that it is not going anywhere. There is plenty of time to decide if it is the best solution for your problems and whether any alternatives would work better.
Starting the planning process now saves you from the risks of hasty decision-making later. Get your copy today! Maximize developer time, minimize release risk, and empower stakeholders to bring their vision to life faster, all with the people and technology you have right now. In this article, we will answer the questions: What is happening with WF?
What problems does WF solve? What are alternatives to WF? What is Happening with Workflow Foundation? WF is now a legacy technology, and that comes with some complications: It will be harder to find developers.
Given a choice, most developers want to work with newer technologies and learn skills they can apply to many different opportunities, not legacy applications.
Legacy applications increase in cost over time. The longer you stay on WF, the more expensive changing or migrating becomes. For one thing, finding talent to maintain your WF apps will be difficult and costly.
For another, even with less experienced developers who learn WF as they go, it will take more time and incur more risk to make changes. When support ends, security will be a significant issue. WF is going to be supported for a long time but not forever. Once support ends, exposed vulnerabilities will require you to migrate quickly or find a way to patch the issue yourself.
WF makes the whole application legacy, not just a component. WF is designed to work with. Keeping WF locks you into using additional legacy components for your whole application.
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