Windows Communication Foundation - the New Technology for Service Oriented Application - Essay Example

Name: Prof: Subj: Date: Windows Communication Foundation: The New Technology for Service Oriented Application The introduction of standard protocols for application-to-application communication specifically in web services has altered the way software are developed and used. Since these services are now capable of providing reliable and secured communication, software developers must be able to keep pace with the rapid transformation and ensure development tools and technologies are supporting service-oriented applications. WCF or Windows Communication Foundation is a new technology introduced by Microsoft as part of the WinFX platform in Windows Vista release. WCF is getting good reviews and gaining acceptance in the software development circle. This paper will going the discuss WCF’s functionality in relation with Service-Oriented Architecture and Web Services including business benefits and future development. Service Oriented Architecture The Service Oriented Architecture or SOA, a technology developed a few years ago, is a concept promoting software reusability, longer life span, and straightforward updating. Similar to Enterprise Architecture, SOA is also primarily giving emphasis to business process. However, SOA does require both business and IT transformation. This means not only replacing or installing IT infrastructure but also changing customary business management and organizational models with a new flexible methodology. The SOA system enables full control of business information and operational strategies to attain organizational objectives such as better product quality and enhanced customer satisfaction (Durvasala et. al. 12). The concept of SOA may vary from one organization to another but in general application; it is a solution independent of domain, technology, existing standards, and implementations. Its sovereignty over business aspects that are continuously changing and often problematic provides growth, reuse, and interoperability. This is the description of SOA’s Reference Model. A model that can be implemented modestly in general form to allow various changes in business services and architecture. The seven main concept of a reference model according to Shipe (2006) page 2, are service, visibility, interaction, real-world effect, service description, policies and contracts, and execution context, which are usually group according to their functionality helpful to SOA. To support these concepts, a simpler approach to support service-oriented architectures is vital for software developers and therefore Microsoft Corporation developed a technology specifically designed for SOA. WCF - Windows Communication Foundation WCF or Windows Communication Foundation, which is originally code named “Indigo” by Microsoft developers, is intended to be the groundwork for service-oriented application development on the Windows environment and it will serve as an extension of the Microsoft .NET Framework 2.0. A runtime and a set of Advance Programmers Interface (API) for building systems that can send messages between services and clients (MSDN-1 1). Since SOA is an architectural pattern that contains various styles, WCF provides a layered architecture that would expose a channel that will provide asynchronous and untyped messages. Right at the upper layer, are protocol facilities providing secured and reliable communication, data exchange, and variety of transport and encoding preference. WCF has two significant features: interoperability with other platforms and interoperability with other Microsoft technologies that were developed before WCF (Peiris and Mulder 18). To understand the real function of WCF, imagine a car rental firm requiring a new application for car reservations to run on the Windows environment. Since the company is already using Windows, they decided to create the application on a .NET version 2.0 Framework. Aware that this application should be accessible by other application in and out of the company, the developer decided to build it following SOA style; with the application logic visible to other application through a clear set of services. In order to implement these services and enable communication with other application, the new application will need to use WC (Chappell 3). Since WCF is primarily a set of classes implemented on top of .NET’s Common Language Runtime (CLR), it enables object-oriented developers to build service-oriented applications with ease in a familiar environment. WCF is part of the WinFX developer’s platform in Windows Vista release and will be available on Windows XP and Server 2003. Figure 1.0 (Chappell 5) showing interaction between WCF client and service thru SOAP (Simple Object Access Protocol). A lightweight, XML based protocol that allows exchange of information in a decentralized and distributed environment. WCF is unifying communication technologies built with .NET framework and support cross-vendor interoperability with open service-orientation. WCF - Unifying Microsoft Technology Considering the unification of distributed computing technologies of Microsoft using the car rental scenario in the previous page, the development team assigned to do build the application will surely have a hard time choosing the proper distributed technology from the numerous choices offered by .NET framework. Furthermore, a car reservation application as this will need more than just one and most probably will end up using available multiple .NET technologies. As a result, the completed application would be too complex to implement and maintain. Take for instance ASP.NET Web Service as a means of communicating with existing J2EE (JAVA 2 Enterprise Edition) based car reservation application and other application over the Internet. A developer, who is in need of a web service supported on most platforms, would likely to adopt this service in order to achieve cross-vendor interoperability. However, this is only applicable for that purpose and still, the developer should look for another service capable of managing object lifetimes and could define distributed transaction such as Enterprise Services. Again, ES is still not enough since it only supports a few set of communication protocols. This kind of predicament facing developers whenever they tried to build an additional application should be address by a single but versatile solution (Chappell 6-7). WCF provides optimal performance when both communicating parties and services are built with WCF (Fig. 1). Since messages data encoding is a binary version of SOAP rather than the standard text-based format of XML, it is also capable of high performance communication with call center client application. In other areas of concern, managing object lifetimes, distributed transactions, and other aspect of ES are now provided by WCF. This means that a WCF based applications can use these services to communicate with any remote application they wish reliably and secured. Unification of these services provides better functionality and significantly simplifies the process. Moreover, since WCF helps applications solve their communication dilemma, it could probably support even the most complex scenario (Chappell 7). WCF- Interoperability with other Technologies The design of WCF is not only to operate within technologies built by Microsoft but designed with functionalities to support and interoperate with non-WCF environment. Long before WCF, there were already web services technology specifications defined jointly by Microsoft, IBM, and other leading vendors to allow basic communication. These are basic messaging, security, reliability, transactions, and services metadata. Enterprise applications nowadays are commonly purchased from different vendors, written in various language, and running in different operating system. This is a reality that many organizations should know and be able to resolve in the near future. WCF’s fundamental communication mechanism enables WCF-based applications to communicate with various enterprise applications running in different platform and environment. It can interact with applications running in a diverse process on the same Windows platform or another Windows machine. Furthermore, it can also communicate effectively with J2EE applications running on Sun Solaris, OS2, and Linux. WCF practically supports almost all SOAP’s specifications on Messaging such as WS-Addressing, Message Transmission Optimization Mechanism (MTOM), and XML-Binary Optimized Packaging (XOP). It is also capable of dealing with Metadata specifications such as Web Services Description Language (WSDL). Enable security through WS-Security, WS-Trust, and WS-SecureConversation. Ensure Reliability through WS-ReliableMessaging, and conduct transactions through WS-Coordination and WS-Atomic Transaction with SOAP-based exchange (Chappell 10). WCF- Interoperability with Pre-WCF Technologies Microsoft made sure that its customer’s investment would not go to waste and there is no need to change existing Microsoft applications to use WCF. It will relatively enhance interoperability and reliability of existing technology. WCF will have no problem operating with earlier technologies such as ASMX (Active Server Method) file extensions using SOAP and since WCF persistent queuing depends on MSMQ (Microsoft Message Queue); it can easily interact with non-WCF applications built in similar interface. However, nobody is perfect and interoperability has its limitations. Web Services Enhancements (WSE 1.0 and 2.0) operates on the same WS.* specifications similar to WCF but they do not allow interoperability. This is because version 1.0 and 2.0 are using earlier version of the WS.* specs. On the other hand, later version like WSE 3.0 does allow interoperability (Chappell 10-11). WCF – Open Support for SOD One of the most important objectives of WCF is to promote Service-Oriented Development, and very soon all platforms with provide support for building service-oriented software. Applications with a clear focus on services instead of objects will become the fundamental goals of software developers. WCF’s design is clearly for sharing schema and not class as in object-oriented development. The interaction of services are limited only through well defined XML interface, and OOD style passing of classes and methods outside services limits are not permitted. In WCF, services and client remains independent of each other. They can come and interact no matter what language they are written or running in a dissimilar environment. Unlike object-oriented technologies, services do not hide distribution between local and remote objects. The interactions between services and clients are always visible and unambiguous. In addition, the ability of a client to use a service depends on the availability of what the clients and services can support. SOA is slowly becoming the default approach in the creation of new enterprise applications and WCF will be the common foundation of SOA (Chappell 12). Creating and Consuming a WCF Service To create a WCF service, a developer should be aware of three basic things. The service class, host environment, and service endpoints (see Fig, 2.0). The service class will come from C# or Visual basic or any other language compatible with .NET’s CLR (Common Language Runtime). The host environment in which the service will actually run and one or more endpoints where clients will access the service (Chappell 13). An endpoint is a construct where messages are sent and received (MSDN-1 1). Creating a WCF service class is similar with any other class but with few added definition. These additions allow the creator to specify a single or multiple service contracts that the WCF class will implement. A minimum of one contract; it can be a service or a data contract. A contract is an attribute with properties similar to other file extensions in .NET where access to services are influenced by the defined instructions associated with the file attributes. The .NET framework is known to use attributes for different things and a good example of that is the Webmethod attribute in an ASMX technology specifically created to indicate a SOAP callable web service. WCF embraced this idea to define and control its services and the most basic attribute in WCF is the ServiceContract. (Chappell 14) Creating a WCF Client is easy and even much simpler since it only requires the creation of local stand-in or a proxy for the service, which is connected to a specific endpoint on the target service. It is important to know exactly what the contract is in the endpoint since the contract definition will be use to create the proxy. A utility called svcutil in WCF can perform this task by accessing the services DLL, learn the contract, and generate a proxy and a client configuration file. Other features of WCF include support for the old remote procedure call (RPC) style client/service interface. Since SOAP is a message-oriented protocol, it can accommodate other programming models. WCF designers consider these possibilities and consequently include support for the following; Asynchronous RPC with non-blocking paired calls carrying lists of typed parameters, Traditional messaging with non-blocking call carrying a single parameter with each channel providing send and receive method, and direct manipulation of SOAP messages thru WCF’s MessageContract attribute (Chappell 31). WCF and Security WCF’s security is based on the existing SOAP’s security infrastructure and standards. It also integrates with HTTPS, and Windows Integrated Security. WCF is a realization of existing security system with the main benefit of using SOAP as the protocol in support to the current protocols. Take for instance credentials such as user name and password containing interoperable XML-based SOAP profiles. Messages are delivered securely using these profiles and taking advantage XML digital signatures and encryption. Similar to open XML, a Component Object Model (COM) on Windows also delivers secure, distributed applications since it has a complete security mechanism that impose reliability, privacy, and verification. However, it cannot do cross-platform secure messaging like WCF. With Windows Communication Foundation, it is possible to create services and clients beyond the boundaries of the Windows domains and across the Internet. The interoperable messages of WCF are indispensable for creating dynamic and secured business-driven services (MSDN-3 1). The following illustrates some common threats that WCF can help prevent when sending and receiving messages between various points: A bank scenario where malevolent user intercepts the message and later carries out a fund transfer using compromised account number and password. A phishing attack where rogue entities posing as a legitimate online service intercepting sensitive client information and transferring funds using compromised accounts. Another is message modification to acquire a different result away from the actual caller instruction and divert funds to a rogue account. A hacker replaying transactions repeatedly thus creating duplicate orders or purchases. This kind of intrusion will eventually destroy accounts integrity and reliability. With WCF message transfer security, messages are authenticated at the service endpoint and perform client principal authentication ensuring message integrity and confidentiality. Finally, WCF detects hacker replays thus minimizing the risk of data duplication (MSDN-3 1). Conclusion The worldwide recognition of web services has changed how software application components are design and built. This is in relation with vendor’s settlements on standards and proven interoperability that helps set web services separately from other integrated technologies. WCF or Windows Communication Foundation is Microsoft’s integrated framework for building dependable, secure, and interoperable distributed applications. WCF symbolizes a new step in distributed programming for .NET Framework developers. Offering a new way and convenient approach to distributed computing, extensive interoperability, and complete support for service orientation. WCF serves as a strong foundation for the .NET Framework for scripting codes capable of communicating across various components, applications, and systems. The real beauty behind WCF is its capability to communicate beyond the limitations of the operating systems. The fact the WCF uses SOAP framework, applications in written for other OS can still communicate thru messages. Furthermore, applications written with WCF do not need to worry about shared memory and OS restricted message queues implementation. Clearly, it is only a matter of time when all communication related .NET codes would be written with WCF. Consequently, object-oriented developers will soon start building service-oriented applications for the enterprise. Finally, with the development and adoption of WCF by the global software community, the idea of software reuse, longer application life span, and easy integration will be completely realize and would bring great benefits to businesses and end users. Work Cited List Chappell David, Introducing Windows Communication Foundation: An Early Look, Chappell and Associates, San Francisco California, U.S.A., www.davidchappell.com, September 2005 MSDN-1, Fundamental Microsoft Communication Foundation Concept, Microsoft Corporation 2007, online at http://msdn2.microsoft.com/en-us/library/ms731079.aspx MSDN-2, What is Windows Communication Foundation?,,. Microsoft Corporation 2007, online at http://msdn2.microsoft.com/en-us/library/ms731082.aspx MSDN-3, WCF Security Overview, Microsoft Corporation 2007, online at http://msdn2.microsoft.com/en-us/library/ms735093.aspx Peiris and Mulder, Practical Microsoft SOA Implementation, Apress, 2560 Ninth Street, Suite 219, Berkeley, CA 94710, ISBN-13 (pbk): 978-1-59059-702-6, 2007 Shipe Brian, Service Oriented Architecture: Final Paper, University of Minnesota, U.S.A., 2006 Durvasula et. al., SOA Practitioners Guide Part 1: Why Service Oriented Architecture?, September 2006 Read More