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More about BPEL 

Enterprise Application Integration
Most organizations have a highly disparate application infrastructure comprising a variety of applications from multiple vendors, running on different platforms, and created with completely different technologies. Traditional enterprise application integration (EAI) products have emerged in the last decade to tackle these integration challenges.

Over the last few years, many organizations have made significant investments in these EAI solutions. As a result, business integrations in the EAI space tend to be locked into a single vendor and the integration components are tightly coupled. The cost of maintaining these proprietary integration links is a significant burden. Specialized skills are required, exacerbating the cost and stability concerns. Furthermore, ripping-and-replacing existing EAI solutions is not a plausible alternative for an organization protecting massive investments in EAI.

BPEL
BPEL, which stands for Business Process Execution Language, addresses all these problems by delivering a standards-based, platform-neutral solution. BPEL is an industry-standard, XML-based workflow definition language that allows businesses to describe business processes that are connected via web services.

BPEL provides an XML-based grammar for describing the logic to control and coordinate Web services participating in a process flow. This grammar can be interpreted and executed by a BPEL orchestration engine. The engine coordinates all of the activities in the process, and controls the system's corrective activities when exceptions occur. BPEL builds on and extends XML and Web Services specifications.The loosely coupled BPEL process eliminates vendor lock-in, reduces integration costs, and provides interoperability; it also adds a sophisticated layer of security, exception management, and logging. Most important, companies can leverage their existing infrastructure, service-enable it, and orchestrate it using BPEL.

BPEL Limitations
The BPEL standard does not address human involvement in business processes. As a result, BPEL compliant products, such as Oracle BPEL Server, IBM Websphere and Microsoft BizTalk, are primarily focussed on composing business processes that integrate web services and legacy applications. It is true that all of these products have some form of human workflow extensions, but these are limited in functionality and cover only a small set of scenarios.

BPEL4PEOPLE
In August 2005, IBM and SAP released a whitepaper that addresses the fact that human interactions are not covered by BPEL and proposes a BPEL extension called BPEL4PEOPLE. The paper describes business scenarios where users are involved in business processes and defines appropriate extensions to BPEL to address these.

However, no formal specification has been released so far and it remains to be seen if this initiative will be supported. It is also not part of the latest draft of BPEL 2.0.