Windows Communication Foundation (Indigo) FAQ

Windows Communication Foundation is Microsoft's unified programming model for building service-oriented applications with managed code. It extends the .NET Framework to enable developers to build secure and reliable transacted Web services that integrate across platforms and interoperate with existing investments. Windows Communication Foundation combines and extends the capabilities of existing Microsoft distributed systems technologies, including Enterprise Services, System.Messaging, Microsoft .NET Remoting, ASMX, and WSE to deliver a unified development experience across multiple axes, including distance (cross-process, cross-machine, cross-subnet, cross-intranet, cross-Internet), topologies (farms, fire-walled, content-routed, dynamic), hosts (ASP.NET, EXE, Windows Presentation Foundation, Windows Forms, NT Service, COM+), protocols (TCP, HTTP, cross-process, custom), and security models (SAML, Kerberos, X509, username/password, custom).

Windows Communication Foundation radically simplifies development of distributed applications in several ways. First, Windows Communication Foundation reduces complexity by unifying the silos that exist with today's distributed technology stacks (Enterprise Services, System.Messaging, .NET Remoting, ASMX, and WSE). This enables developers to compose distributed applications using the best features of each of today's stacks. Second, Windows Communication Foundation maximizes developer productivity through an attribute-based programming model. Finally, Windows Communication Foundation is the first development framework built from the ground up on the principle of service-orientation—enabling developers to build loosely coupled applications that interoperate securely and reliably across platforms.

Windows Communication Foundation is the first programming model built from the ground up to provide implicit service-oriented application development, enabling developers to work autonomously and build applications that are more version independent, thereby increasing application resilience to change.

Find out about Windows Communication Foundation by starting with David Chappell's Introducing Indigo white paper. Also, download the Beta 1 bits and start learning your way around the object model.

Our goal is to release a great product to customers. We plan to ship the final version in 2006 as part of Windows Vista, the next version of Windows.

No. Windows Communication Foundation will also be available on Windows XP and Windows Server 2003 as a part of a .NET Framework 3.0 (formerly WinFX) Runtime Components.

Since Windows Communication Foundation is an extension of the .NET Framework, the delivery mechanism for Windows Communication Foundation will be similar to the current .NET Framework delivery method.

Subsequent CTP releases will be announced at a later date.

Visual Studio 2005 is the next release of the .NET Framework and Visual Studio development tools. Windows Communication Foundation is a set of additional managed class libraries that provide a unified framework for building advanced Web services. Windows Communication Foundation extends the .NET Framework and is fully compatible with Visual Studio 2005, meaning that developers using Visual Studio 2005 will be able to program against the Windows Communication Foundation class libraries using the language of their choice, their existing skills, and a familiar environment.

No, Windows Communication Foundation will ship separately from Visual Studio 2005 as a part of a .NET Framework 3.0 (formerly WinFX) Runtime Components.

BizTalk and Windows Communication Foundation are complementary technologies. BizTalk provides business process orchestration, message transformation, business activity monitoring, and more through designers and visual tools. Windows Communication Foundation provides a unified framework for building secure and reliable transacted Web services. When Windows Communication Foundation ships, BizTalk will provide a Windows Communication Foundation adapter that enables Windows Communication Foundation services to be incorporated into business process orchestration. In future versions of BizTalk, the integration between the technologies will be even more seamless, with Windows Communication Foundation providing the core messaging and Web service capabilities of BizTalk.

Windows Communication Foundation represents the next logical version for each of today's distributed systems stacks. As such, developers using today's technologies will be able to apply their existing skills to Windows Communication Foundation application development. In addition, Windows Communication Foundation will enable side-by-side operation of applications built with existing technologies and Windows Communication Foundation-based applications. Finally, Microsoft will provide guidance for developers upgrading existing code from ASMX, .NET Remoting, .NET Enterprise services, WSE, System.Messaging to Windows Communication Foundation.

The current plan is for Windows Communication Foundation to provide wire-level interoperability with WSE3, System.Messaging, .NET Enterprise Services, and ASMX applications. With minimal or no changes to code, applications built with these technologies will be able to call Windows Communication Foundation services and be callable by Windows Communication Foundation services.

Customers can continue running applications built with today's technologies and these applications can peacefully coexist with Windows Communication Foundation applications side-by-side. Upgrading existing code is optional and can be done on an incremental basis.

While upgrading to Windows Communication Foundation is not required, many developers may choose to upgrade code in order to take advantage of the unified programming model and new features that Windows Communication Foundation offers. Windows Communication Foundation is being designed to enable smooth upgrading of existing applications and provides the flexibility to upgrade applications incrementally. Microsoft will provide guidance (released to MSDN at a later date) on how to upgrade existing code to Windows Communication Foundation.

Developers using today's distributed systems technologies will be immediately familiar with the Windows Communication Foundation programming model. They will be able to take advantage of the programming model because it is designed to fit naturally with existing .NET Framework programming concepts and is accessible using any .NET language (C#, VB.NET, J#, C++, etc).

Web Services Enhancements (WSE) augments ASP.NET Web services support with key WS-* features; Windows Communication Foundation is the next-generation Web services infrastructure for Windows. The version of WSE that ships prior to Windows Communication Foundation will be wire-level compatible and Microsoft will provide guidance to customers and developers on upgrading WSE code to Windows Communication Foundation.

• Build services using the ASP.NET (ASMX) Web service model.
• Enhance your ASMX service with WSE if you need the WSE feature set (including end-to-end security).
• Use object technology in a service's implementation.
• Use System.Messaging if you need the reliable messaging and queuing features in MSMQ.
• ASMX-avoid or abstract using low-level extensibility such as the HTTP Context object.
• .NET Remoting-avoid or abstract using low-level extensibility such as .NET Remoting sinks and channels.
• Enterprise services-avoid passing object references inside of ES.
• Do not use COM+ APIs-use System.EnterpriseServices.
• Do not use MSMQ APIs-use System.Messaging.

A service class, implemented in C# or VB.NET or another CLR-based language that implements one or more methods;
A host environment—an application domain and process—in which the service runs;
One or more endpoints that allow clients to access the service.

A class implementing a Windows Communication Foundation service is typically compiled into a library. By definition, all libraries need a host application domain and Windows process to run in. Windows Communication Foundation provides two options for hosting libraries that implement services. One is to use a host application domain and process provided by the Windows Activation Service (WAS), while the other allows a service to be hosted in any application domain running in an arbitrary process (such as a Windows Forms application, a console application, an NT Service, etc).

By default, Windows Communication Foundation uses SOAP (perhaps with some WS-* extensions), represented on the wire in its usual text-based XML encoding. When two Windows Communication Foundation-based services communicate with each other, however, it makes sense to optimize this communication. All of the same features are provided, including reliable messaging, security, and transactions, but the wire encoding used is an optimized binary version of SOAP. Messages still conform to the data structure of a SOAP message, referred to as its Infoset, but their encoding uses a binary representation of that Infoset rather than the standard angle-brackets-and-text format of XML.

Yes. Windows Communication Foundation services can be hosted in a variety of application types, including desktop applications (built with Windows Presentation Foundation or Windows Forms), COM+ components, Windows Services, etc. This enables developers to simply build service endpoints and have Windows Communication Foundation handle the communication between them.

Yes. Windows Communication Foundation supports multiple message patterns, including one-way, request/response, two-way (duplex), and queued.

Yes. Windows Communication Foundation will plug into the Microsoft Distributed Transaction Coordinator (MSDTC) extensibility model and will support WS-AtomicTransaction as well as WS-Coordination to enable coordinated transactions across platforms.

SOAP Message Transmission Optimization Mechanism (MTOM) will be the attachment technology supported in Windows Communication Foundation.

For more information on Windows Communication Foundation's features and capabilities, read David Chappell's Introducing Indigo white paper.

Service Orientation is a specific set of architectural principles for building loosely coupled services that help developers maximize the return on your application investments over time. The services have explicit boundaries, are autonomous, share schema and contracts, and determine compatibility based on policy. Applications based on these principles provide benefits in maintainability, reusability, and manageability of connected systems. Windows Communication Foundation is the first programming model built from the ground up for building service-oriented applications.

Loosely-coupled applications built on the tenets of service orientation yield benefits in maintainability, reusability, and manageability of connected systems. Service-oriented applications also more closely reflect real-world processes and relationships. Microsoft sees service orientation as a means to an end—that end being a set of connected systems that optimize communications across a business—connecting people, information, and devices.

No. Service-oriented development complements object-oriented (OO) development. Object-oriented development continues to fulfill an important role in the internal design of services. Service-orientation deals with how to interconnect services to build connected systems. To use an architecture analogy, OO development addresses the architecture within a single building (a service), while service-orientation addresses the issues around city planning (a system).

Today, it is difficult to build service-oriented applications due to the lack of an intuitive service-oriented programming model. Web services provide a great start, but lack support for more advanced communication, including secure and reliable transacted services. Windows Communication Foundation provides both an intuitive service-oriented programming model and the advanced functionality to create service-oriented applications that interoperate across organizational and platform boundaries.

Yes. By default, services built with Windows Communication Foundation will communicate with other services based on the interoperable Web services specifications. This means that Windows Communication Foundation services will communicate with any application built on an infrastructure that also conforms to these standards. Microsoft is deeply committed to platform interoperability and is an active member of key standards organizations defining the latest Web services standards. Microsoft also continues to engage in public interoperability workshops to help ensure cross-platform communication with other vendors.

Windows Communication Foundation will support a broad range of Web services standards, including basic standards (XML, XSD, XPath, SOAP, WSDL) and advanced standards and specifications that comprise the WS-* architecture. These include WS-Addressing, WS-Policy, WS-Security, WS-Trust, WS-SecureConversation, WS-ReliableMessaging, WS-AtomicTransaction, WS-Coordination, WS-Policy, and MTOM.