SERVICE ORCHESTRATION BY USING FLOWS

Presented BySindhu VL

Introduction :

A Flow is a simple yet very flexible mechanism that enables orchestration of services using the sophisticated message flow capabilities of Mule ESB. Using Flow, you may automate integration processes and construct sophisticated integration solutions by simply building them from the connectors provided by Mule. Because of the flexibility of Flow, it is much easier to create solutions that more closely match your requirements. Flow is new in Mule 3.

When to Use a Flow :

Flows are valuable in many situations, including:

Simple integration tasks Scheduled data processing Connecting cloud and on-premise

applications Event processing where multiple

services need to be composed

The Anatomy of a Flow :A flow is in essence just a chain of Message Processors. Think of each Message Processor as a Lego block where a Flow is something you build with them. A flow also has a message source, the source of messages that are processed by the Message Processor chain.

Flow Configuration :A Flow is configured in XML using the <flow> element. Each flow has a name attribute, a message source (unless it’s a private flow), one or more message processors and an optional exception strategy.

Flows seem simple, yet can be quite powerful. In particular, when combined with expressions in Mule, they can allow for very sophisticated processing of the message contents. There are many elements that leverage expressions, including:

Transformers Filters Routing Message Enricher

Example :

Flow Behavior :

When a message is received or generated by the message source the flow is started and the configured message processors are invoked in a chain in the same order as they are configured.

Some message processors accept child message processor elements, in this case these are processed before returning and continuing processing the main list.

Note: When the last element in the flow configuration is a one-way <outbound-endpoint> there’s no result of it’s execution so the returned payload of the message is going to be NullPayload. If the one-way <outbound-endpoint> is followed by another processor, it receives as input the same message that the outbound-endpoint receives instead of NullPayload.

Architecture :

Private Flows :

A private flow is one that cannot be accessed from outside the JVM via a Mule Endpoint because it has no message source defined.

Private Flows are therefore only used if they are referenced from another construct running in the same Mule instance. When configuring Mule using XML the <flow-ref>element is used to include one flow in another.

A private Flow differs from the use of a "Processor Chain" in that a Flow has it’s own context and exception strategy where as when a processor chain is referenced, it is executed in the context of the flow that references it.

Private Flow Example :

ThankYou!!!!!!!!!!