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Mediation flows
Mediation is a way of mediating or intervening dynamically between services. A mediation flow implements a mediation.
Mediation has several useful functions.
For example, you can use mediation when you need to transform data from one service into an acceptable format for a subsequent service. You can use logging to log messages from a service before they are sent to the next service.
You can use routing to route data from one service into an appropriate service determined by the mediation flow.
A mediation can also be used to map interfaces.
For example, two components can have methods that perform basically the same action but have different names such as getCredit and getCreditRating. They can also have different operation names and the operations can have different parameter types. An interface map maps the operations and parameters of these methods so that the differences are resolved and the two components may interact. An interface map is like a bridge between the interfaces of two components allowing them to be wired together despite differences.
A mediation operates independently of the services that it connects. A mediation in the assembly editor appears as a mediation flow component between exports and imports.
In the following diagram, three service requesters or exports send their output data to the interface of the mediation flow component. The mediation flow component then routes the appropriate data to two service providers or imports.
A mediation flow is a flow-like construct created with the mediation flow editor. When you select a mediation flow component in the assembly editor, you automatically open the mediation flow editor. In the mediation flow editor, an operation from one service, the service requester or export, is mapped to the operation of another service, the service provider or import, along with functions provided by the mediation flow editor. These functions are called mediation primitives and are wired in a mediation flow as shown in the following diagram.
You can use mediation primitives supplied by IBM, or you can create your own custom primitives. Mediation primitives can act on both message content and message context, where context is binding-specific information such as Simple Object Access Protocol (SOAP) or Java Message Service (JMS) headers, or user-defined properties.
In the diagram that follows an operation, applyforLoan, sends a message first to a logging primitive, Log, that records the message. Log sends the message to the Filter primitive, which, depending on the message, routes the message to either a processBusinessLoan operation or a processPersonalLoan operation.
Both types of modules can contain mediation flow components and Java components that augment the mediation flow component. For more information, see the Modules section.
Related concepts:
Java objects
BPEL process
State machines
Business rules
Selectors
Human tasks
Stand-alone references