Why use BPEL
The advantages of using WS-BPEL include:
Provides industry standard language for expressing business processes: As with its rich and comprehensive semantics, WS-BPEL represents a standard which has undergone rigorous development by the industry toward addressing complex requirements, resulting in a comprehensive orchestration solution.
Leverage a common skill set and language: Standards enable lower total cost of ownership through knowledge portability - instead of using complex proprietary technologies, WS-BPEL enables best practices, patterns, experience and training to be leveraged from a variety of vendors, as well as access to resources knowledgeable in the WS-BPEL model and technology.
Abstracts business logic and responsibility: Application and business services can be designed to be process-agnostic and reusable. The business process assumes the management and coordination of state, freeing constituent services from a number of design constraints. Additionally, the business process logic is centralized in one location, as opposed to being distributed across and embedded within multiple services.
Designed to fit naturally into the Web services stack: In WS-BPEL a business processes interact with services through Web services invocations, and are themselves externalized as Web services. This recursive composition enables a BPEL process to leverage the interoperability provided by the lower levels of the Web Services stack, such as WSDL, SOAP, and WS-Addressing.
Expressed entirely in XML: As WS-BPEL business processes are expressed in XML, they are human-readable and can be used by any XML processing facilities, enabling them to be produced and consumed within the XML stack.
Uses and extends WSDL 1.1: WS-BPEL uses and extends WSDL to both provide and consume Web services in an abstract way, using WSDL to define service interfaces.
Uses XML Schema 1.0 type definitions for the data model
Portable across platform and vendor: WS-BPEL provides for standards-based platforms which reduce vendor lock-in and facilitate migration from one vendor platform to another. WS-BPEL processes will run on any WS-BPEL-compliant engine.
Interoperable between interacting processes: Many deployments will have multiple orchestration platforms due to embedding in tools and applications, organizational purchases, etc. WS-BPEL provides a common standard which provides for interoperability between the different platforms and the processes that execute on them.