Web Service Broker

See Core J2EE Patterns, 2nd Edition for full description of this pattern and its strategies.

Problem

You want to provide access to one or more services using XML and web protocols.

Forces

• You want to reuse and expose existing services to clients.
• You want to monitor and potentially limit the usage of exposed services, based on your business requirements and system resource usage.
• Your services must be exposed using open standards to enable integration of heterogeneous applications.
• You want to bridge the gap between business requirements and existing service capabilities

Solution

Use a Web Service Broker to expose and broker one or more services using XML and web protocols.

Class Diagram

Sequence Diagram

Strategies

• Custom XML Messaging Strategy
• Java Binder Strategy
• JAX-RPC Strategy

Consequences

• Introduces a layer between client and service
• Existing remote Session Façades (341) need be refactored to support local access
• Network performance may be impacted due to web protocols

Related Patterns

• Aggregator [EIP]
• Application Service
  Application Service components can be called from Web Service Broker components.
• Session Façade
  Session Façade components can be called from Web Service Broker components.
• Mediator [POSA1]
  Mediator is a hub for interaction like Web Service Broker
• Message Router [EIP]

Excerpted from Core J2EE Patterns, 2nd Edition. See the book for full description of the pattern including class diagrams, sequence diagrams and sample code.