Welcome!

Microsoft Cloud Authors: Pat Romanski, Andreas Grabner, Nick Basinger, Kevin Benedict, Liz McMillan

Related Topics: Microsoft Cloud, Java IoT

Microsoft Cloud: Article

What Is Windows Workflow Foundation?

Take control of your processes with WF

Most businesses require processes to function properly. There are different types of processes. Some processes are human-intensive, others machine-intensive, and the last type is a combination of the first two. Some examples of business processes are payroll, new product introductions, new employee hiring, etc. In most cases, these business processes require intervention from multiple entities and thus, are normally long running.

 Workflow is one of the mechanisms used by businesses to express their business processes as a series of self-contained activities. Business Process Management (BPM) systems provided an environment for developers to create, execute, and manage workflows. These workflows are normally expressed using Finite State Machine (FSM), Unified Modeling Language (UML) Activity Diagrams, UML Swim Lanes, or Flow Charts.

Microsoft announced at PDC the unveiling of the Microsoft Windows Workflow Foundation (WF) technology. This technology complements the .NET Framework with a group of workflow-related components that allow developers the ability to define, compile, instantiate, debug, and track workflows. This technology will become part of WinFX together with Windows Presentation Foundation, and Windows Communication Foundation.

Development Paradigm
Using Workflow Foundation (WF) workflows, developers can incorporate concepts like scheduling, task coordination, and escalation into their existing applications for free. WF provides the base platform where ISVs can develop process-rich applications. While Microsoft Visual Studio is not required to develop WF workflows, it provides some really cool capabilities such as a visual designer, Visual Studio workflow templates, and visual debugging, which make it easier to develop workflow-rich applications. WF workflows are developed using markup (XML as shown in Figure 1), just code (C# and Visual Basic.NET as shown in Figure 2), and markup with code separation (C# and Visual Basic.NET as shown in Figure 3). They are packaged into an assembly i.e., workflow library when compiled and require a host application in order to be executed. Host applications can vary from console applications (exe), Windows services, HTTP modules, or server applications like SharePoint Services 12. Other products such as Microsoft BizTalk Server and Microsoft Dynamics AX plan to use the WF platform in future releases.

WF workflows are composed using activities. Activities represent discreet pieces of functionality that are used to run specific business activities. There are two types of activities: composite and individual activities. Composite activities are used to express control statements (i.e., While, For, If-Then-Else, Case, etc.) and for grouping activities that share behavior (i.e., Sequences, Conditioned Activity Groups, etc.). Also, these activities are used to develop reusable sub-processes or sub-workflows. On the opposite side, individual activities provide a mechanism for expressing single pieces of work that need to be executed in the same step in the workflow. Activities in general can have properties and handlers. Handlers are executed synchronously or asynchronously, depending on their definition. Activities represent the smallest building block available to developers to extend the workflow framework. WF provides a base activity library set that can be used by developers to build new applications, or as the baseline for creating new activities. This library represents the minimum set of extensible activities required to build workflows.

The workflow run time is responsible for taking workflow definitions and instantiating them. The life cycle of the workflow instances are managed by the workflow runtime. It is responsible for creating, executing, threading, persisting, tracking, communicating execution events, and coordinating transactions. These functions are managed by the workflow run time via services. There is a set of default services that the run time uses to manage all of its workflow instances, threading, transactions, tracking, state management, etc. Application developers responsible for integrating workflows into their existing applications can overwrite these services. Using this service model, developers are able to expose their existing hosting infrastructure to the workflow library. The framework provides a set of out-of-box services that allow developers to quickly start using the environment without worrying about having to write complicated code. The out-of-box services are instantiated and registered directly with the run time as shown in Figure 4.

Developer Types
These system boundaries give way to three types of developers: host, activity, and workflow developers as shown in Figure 5. Host developers are responsible for providing an execution environment that uses the workflow run-time components to instantiate workflows. Host applications need communication contracts in order to define local protocols between the host application and the workflow library. Also, host developers are responsible for registering workflow services with the workflow run time and for registering out-of-box services with the workflow run time. However, there are situations in which out-of-box services do not suffice for the required needs of host applications. These services establish the quality of services shared by workflow instances. For that reason, the workflow framework provides a mechanism to create new services through inheritance.

Activity developers create self-contained logical components that are intended for use by workflow developers to create workflow libraries. Activities can be designed to work on multiple host applications or could be tailored to a specific host. These components can be self-contained (i.e., black boxed) or could allow code-separation handlers to be defined by workflow developers. Activities tailored to a specific host normally take advantage of local communication protocols and specialized services defined by the host application.

Workflow developers leverage the work of activity and host developers to construct workflows. They are responsible for using out-of-box activity libraries and custom activity libraries to create workflow definitions. The majority of these developers leverage graphical tools to construct workflow graphs. However, the types of development environments could range from non-code environments like Microsoft FrontPage to code-rich environments like Microsoft Visual Studio.

Framework Capabilities
Support for long-running workflows is another major feature of Microsoft Windows Workflow. WF provides the required infrastructure to support the execution of long-running workflows. These workflows rely on persistence, transactions, tracking, and host processing to fulfill their tasks. When the workflow is idle, waiting for information from users or systems, it is automatically persisted and removed from memory to reduce resource consumption.

The persistence services provide a default state management services for Microsoft SQL Server (i.e., SqlStatePersistenceService class). Schemas and store procedures are provided for these services and allow the service database to live in another database. The reason for these services is to facilitate the long-running nature of these applications and to provide an automated persistence level to the workflow state.

Timer services are also provided to support management of date-base triggers. Persisting timers ensures that date/time triggers can be relied on for execution if the time hasn't expired. The out-of-box timer services also leverage the Microsoft SQL Server database (i.e., SqlTimerService class). Imagine a scenario where you want to escalate a message after four hours have passed without any intervention and the system goes down before the time has expired. Using persisted timers together with state persistence enables the developer to not have to worry about losing timers and not worry about having to fire events when timers expire.

Tracking provides a default mechanism for generating audit trails and recording historical information. This information can be in-memory or persisted to the database. The out-of-box tracking service also leverages a Microsoft SQL Server database to manipulate the tracking information (SQLTrackingService). The tracking information captures the activity name, times the activity that was executed, and when the various states of the activities are executed. Tracking profiles can be defined to capture a subset of the tracking data. This information can be tailored to capture specific activity status changes, activity property information, and workflow instance data.


More Stories By Israel Hilerio

Israel Hilerio is a program manager at Microsoft in the Windows Workflow Foundation team. He has 15+ years of development experience doing business applications and has a PhD in Computer Science.

Comments (3)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


IoT & Smart Cities Stories
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Druva is the global leader in Cloud Data Protection and Management, delivering the industry's first data management-as-a-service solution that aggregates data from endpoints, servers and cloud applications and leverages the public cloud to offer a single pane of glass to enable data protection, governance and intelligence-dramatically increasing the availability and visibility of business critical information, while reducing the risk, cost and complexity of managing and protecting it. Druva's...
BMC has unmatched experience in IT management, supporting 92 of the Forbes Global 100, and earning recognition as an ITSM Gartner Magic Quadrant Leader for five years running. Our solutions offer speed, agility, and efficiency to tackle business challenges in the areas of service management, automation, operations, and the mainframe.
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, compared the Jevons Paradox to modern-day enterprise IT, examin...
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, @CloudEXPO and DXWorldEXPO are two of the most important technology events of the year. Since its launch over eight years ago, @CloudEXPO and DXWorldEXPO have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, we provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading...
DSR is a supplier of project management, consultancy services and IT solutions that increase effectiveness of a company's operations in the production sector. The company combines in-depth knowledge of international companies with expert knowledge utilising IT tools that support manufacturing and distribution processes. DSR ensures optimization and integration of internal processes which is necessary for companies to grow rapidly. The rapid growth is possible thanks, to specialized services an...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Scala Hosting is trusted by 50 000 customers from 120 countries and hosting 700 000+ websites. The company has local presence in the United States and Europe and runs an internal R&D department which focuses on changing the status quo in the web hosting industry. Imagine every website owner running their online business on a fully managed cloud VPS platform at an affordable price that's very close to the price of shared hosting. The efforts of the R&D department in the last 3 years made that pos...