Enterprise Service Bus (ESB)

• The infrastructure of a SOA landscape that enables the interoperability of services.
• Its core task is to provide connectivity, data transformations, and (intelligent) routing so that systems can communicate via services.
• ESB is just a piece of software, hardware is not part of ESB.

ESB Responsibilities

• Providing connectivity
• Data transformation
• (Intelligent) routing
• Dealing with security
• Dealing with reliability
• Service management
• Monitoring and logging

Interoperability through transformation

• May transfer any protocol to any protocol
• May change the formats or mappings
• May contain transformation logic
• Should not contain business logic

Routing

• There must be some way of sending a service call from a consumer to a provider, and then sending an answer back from the provider to the consumer
• Depending on the technology used, and the level of intelligence provided, this task may be trivial, or may require very complicated processing

Interceptors

Protocol-Driven Versus API-Driven ESB

Other Important Concepts

• Point-to-Point Connections Versus Mediation
• Data Mapping
• Security
• Reliability (message delivery and queueing)
• Service Management (replaces UDDI)
• Monitoring and Logging

Business Activity Monitoring (BAM)

• Shows the state of your business on the fly
• Analyses activity rather than data (compare data warehouse and data mining)