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Friday 9th August 2002
Microsoft, IBM and BEA Deliver Specifications for Web Service Based Transactions And Process Automation
| ANALYST COMMENT
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This announcement represents another step towards creating a robust, reliable and secure environment for Web Services. We have long commented that existing protocols, particularly WSDL, provide insufficient information to truly communicate how a service should be used. These new protocols go beyond the simple signature expressed in WSDL to provide allow a more complex contract to be described and to document the wider context within which an individual service participates.
The jigsaw puzzle of Web Services protocols that was proposed by IBM and Microsoft last year at a W3C workshop, and which Microsoft went on to label GXA, is gradually being filled out. See the illustration in our CBDI Guide to Web Services (accessible by bronze members) . As well as the WS-Security specification announced recently, we can now fill in the Business Process Orchestration and Message Sequencing pieces. We expect others to be filled in soon, such as Reliable Messaging and Routing, as these are already specified by Microsoft as part of GXA
In the press release, they cite the familiar example of the travel reservation, quote "... a travel agency that exposes its business travel processes -- such as hotel, flight or car rental reservation applications -- as Web services can integrate and transact with the business travel processes of its customers and partners. Using BPEL4WS, WS-Coordination and WS-Transaction, the travel agency's customer could electronically submit a travel itinerary to an agent; the agent's system can automatically procure the appropriate airline, hotel and car reservations from partners to match the customer request; and the system can then send confirmation of all reservations back to the customer once the itinerary processing is complete. In case one of the applications fails, tasks that have already been completed can be automatically undone."
Typically, this scenario is trivialised. Whilst the above demonstrates the need for such protocols, in real life it is never that simple. For example, if having booked the airline and hotel I find there is not a car available, my first action would be to find an alternative car, not un-reserve the airline and hotel and start all over again, possibly loosing the last seat on the airplane in the process. In real life, this scenario requires long running transactions that use compensating transactions that are not necessarily the reverse of the original – the car manufacturer doesn’t unbuild a car when the customer decides not to take delivery. This is where BPEL4WS fits in, describing the overall business process, rather than the atomic transaction within it.
It is good to see that with this announcement BEA have joined with Microsoft and IBM. There is always the possibility that with Microsoft and IBM going it alone when pushing forward the specifications of important protocols they might alienate the rest of the industry. Including others in their efforts from the outset is important if the universal adoption of Web Services is to be kept on track, as is Microsoft and IBM joining in the efforts of others.
Interestingly, BEA recently worked with Intalio, SAP AG, and Sun Microsystems to propose the Web Service Choreography Interface (WSCI), which overlaps with these new proposals. When we reported on WSCI we asked Sun to comment on its relationship to Web Services Flow Language (WSFL), IBM’s precursor to BPEL4WS. Their reply is documented in the news item below. Meanwhile, BEA said that the company would take the knowledge gained in the WSCI effort forward and work with the industry to settle on one common standard. Hopefully this translates into a convergence of WSCI with BPEL4WS and WS-Coordination.
Given the existing investment that Microsoft have in XLANG and IBM in WSFL, it comes as a pleasant surprise to see them coming together in BPEL4WS. This cannot have been easy for Microsoft in particular given that XLANG forms a key part of BizTalk server, and must be seen as a key demonstration of their willingness to work towards open standards.
LW
MORE INFORMATION
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BEA, Intalio, SAP, Sun Publish Web Services Choreography Interface – CBDI News Story
Understanding GXA
Microsoft MSDN Web Services
IBM Web Services
BEA Standards
| Microsoft Corp., IBM Corp. and BEA Systems, Inc. have announced the publication of specifications to collectively describe how to reliably define, create and connect multiple business processes in a Web services environment, and help organizations coordinate business processes and transactions within the enterprise and with partners and customers across heterogeneous systems and within the enterprise. Announced were the new specifications to address transacted communications of Web services (WS-Coordination, WS-Transaction) and a new language to describe business processes (Business Process Execution Language for Web Services, or BPEL4WS).
A business process describes the flow of tasks, the order in which they need to be performed, the type of data shared and how other partners are involved. BPEL4WS allows companies to describe business processes that include multiple Web services and standardize message exchange internally and between partners. WS-Coordination and WS-Transaction provide companies with a reliable and durable way of handling multiple Web services interactions, regardless of the underlying computing infrastructure. In addition, they outline how partners can interact with a collection of Web services and coordinate the outcome of those corresponding activities.
WS-Coordination provides developers with a way to manage the operations related to a business activity. A business process may involve a number of Web services working together to provide a common solution. Each service needs to be able to coordinate its activities with those of the other services for the process to succeed. Coordination involves the sequencing of operations in a process to reach an agreement on the overall outcome of the business process.
WS-Coordination provides the structure under which coordination can take place. The specification supplies standard mechanisms to create and register with transaction protocols that coordinate the execution of distributed operations in a Web services environment. WS-Coordination will help developers control operations that span interoperable Web services.
WS-Transaction allows businesses to monitor the success or failure of each specific, coordinated activity in a business process. It provides businesses with a flexible transaction protocol to help enable consistent and reliable operations across distributed organizations in a Web services environment. The specification also allows the business process to react to faults detected during execution.
WS-Transaction provides for short- and long-running transactions in which resources cannot be locked for the duration of the business process. In both cases, WS-Transaction takes advantage of the structure WS-Coordination provides to enable all participating Web services to end the business process with a shared understanding of its outcome.
For example, a travel reservation process contains a number of activities that must be successfully completed, several of which may run simultaneously, such as airline ticketing, car rental and hotel room booking. The use of WS-Transaction with WS-Coordination helps ensure that these tasks, no matter how they are distributed across programming platforms and companies, all succeed or fail as a unit.
BPEL4WS is an XML-based flow language that defines how business processes interact. This interaction can involve processes contained within or between enterprises. It allows companies to describe complex business processes that can span multiple companies, such as order processing, lead management and claims handling. These business processes can use partner-provided Web services, and can also be offered as Web services business process functions internally or to partners in a reliable and dependable way.
In addition, BPEL4WS helps enable business processes to interoperate within and between companies that use different underlying technologies. This will help companies execute the same business processes in the systems of other vendors, and facilitate message exchange internally and between partners.
BPEL4WS replaces the existing IBM WSFL and Microsoft XLANG efforts by combining and extending the functions of these previous foundation technologies.
Once the business process and the connections with customers, partners and internal entities are defined using BPEL4WS, the next step is to coordinate the various activities that occur within a business process, in order and at the right time for completion. WS-Coordination and WS-Transaction complement BPEL4WS by providing a way for companies to coordinate and integrate a number of distinct Web services and business processes, consistently and reliably, across a variety of implementation environments to ensure the right outcome.
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