Enterprise Integration Patterns

Camel supports most of the Enterprise Integration Patterns from the excellent book by Gregor Hohpe and Bobby Woolf.

Messaging Systems

image

Message Channel

How does one application communicate with another using messaging?

image

Message

How can two applications be connected by a message channel exchange a piece of information?

image

Pipes and Filters

How can we perform complex processing on a message while maintaining independence and flexibility?

image

Message Router

How can you decouple individual processing steps so that messages can be passed to different filters depending on a set of conditions?

image

Message Translator

How can systems using different data formats communicate with each other using messaging?

image

Message Endpoint

How does an application connect to a messaging channel to send and receive messages?

Messaging Channels

image

Point to Point Channel

How can the caller be sure that exactly one receiver will receive the document or perform the call?

image

Publish Subscribe Channel

How can the sender broadcast an event to all interested receivers?

image

Dead Letter Channel

What will the messaging system do with a message it cannot deliver?

image

Guaranteed Delivery

How can the sender make sure that a message will be delivered, even if the messaging system fails?

image

Channel Adapter

How can you connect an application to the messaging system so that it can send and receive messages?

image

Messaging Bridge

How can multiple messaging systems be connected so that messages available on one are also available on the others??

image

Message Bus

What is an architecture that enables separate applications to work together, but in a de-coupled fashion such that applications can be easily added or removed without affecting the others?

image

Change Data Capture

Data synchronization by capturing changes made to a database, and apply those changes to another system.

Message Construction

image

Event Message

How can messaging be used to transmit events from one application to another?

image

Request Reply

When an application sends a message, how can it get a response from the receiver?

image

Return Address

How does a replier know where to send the reply?

image

Correlation Identifier

How does a requestor that has received a reply know which request this is the reply for?

image

Message Expiration

How can a sender indicate when a message should be considered stale and thus shouldn’t be processed?

Message Routing

image

Content Based Router

How do we handle a situation where the implementation of a single logical function (e.g., inventory check) is spread across multiple physical systems?

image

Message Filter

How can a component avoid receiving uninteresting messages?

image

Dynamic Router

How can you avoid the dependency of the router on all possible destinations while maintaining its efficiency?

image

Recipient List

How do we route a message to a list of (static or dynamically) specified recipients?

image

Splitter

How can we process a message if it contains multiple elements, each of which may have to be processed in a different way?

image

Aggregator

How do we combine the results of individual, but related messages so that they can be processed as a whole?

image

Resequencer

How can we get a stream of related but out-of-sequence messages back into the correct order?

image

Composed Message Processor

How can you maintain the overall message flow when processing a message consisting of multiple elements, each of which may require different processing?

image

Scatter-Gather

How do you maintain the overall message flow when a message needs to be sent to multiple recipients, each of which may send a reply?

image

Routing Slip

How do we route a message consecutively through a series of processing steps when the sequence of steps is not known at design-time and may vary for each message?

image

Process Manager

How do we route a message through multiple processing steps when the required steps may not be known at design-time and may not be sequential?

image

Message Broker

How can you decouple the destination of a message from the sender and maintain central control over the flow of messages?

image

Throttler

How can I throttle messages to ensure that a specific endpoint does not get overloaded, or we don’t exceed an agreed SLA with some external service?

image

Sampling

How can I sample one message out of many in a given period to avoid downstream route does not get overloaded?

image

Kamelet

How can I call Kamelets (route templates).

image

Delayer

How can I delay the sending of a message?

image

Load Balancer

How can I balance load across a number of endpoints?

image

Circuit Breaker

How can I stop to call an external service if the service is broken?

image

Stop

How can I stop continue routing a message?

image

Service Call

How can I call a remote service in a distributed system where the service is looked up from a service registry of some sorts?

image

Saga

How can I define a series of related actions in a Camel route that should be either completed successfully (all of them) or not-executed/compensated?

image

Multicast

How can I route a message to a number of endpoints at the same time?

image

Loop

How can I repeat processing a message in a loop?

Message Transformation

image

Content Enricher

How do we communicate with another system if the message originator does not have all the required data items available?

image

Content Filter

How do you simplify dealing with a large message, when you are interested only in a few data items?

image

Claim Check

How can we reduce the data volume of message sent across the system without sacrificing information content?

image

Normalizer

How do you process messages that are semantically equivalent, but arrive in a different format?

image

Sort

How can I sort the body of a message?

image

Script

How do I execute a script which may not change the message?

image

Validate

How can I validate a message?

Messaging Endpoints

image

Messaging Mapper

How do you move data between domain objects and the messaging infrastructure while keeping the two independent of each other?

image

Event Driven Consumer

How can an application automatically consume messages as they become available?

image

Polling Consumer

How can an application consume a message when the application is ready?

image

Competing Consumers

How can a messaging client process multiple messages concurrently?

image

Message Dispatcher

How can multiple consumers on a single channel coordinate their message processing?

image

Selective Consumer

How can a message consumer select which messages it wishes to receive?

image

Durable Subscriber

How can a subscriber avoid missing messages while it’s not listening for them?

image

Idempotent Consumer

How can a message receiver deal with duplicate messages?

image

Transactional Client

How can a client control its transactions with the messaging system?

image

Messaging Gateway

How do you encapsulate access to the messaging system from the rest of the application?

image

Service Activator

How can an application design a service to be invoked both via various messaging technologies and via non-messaging techniques?

System Management

image

ControlBus

How can we effectively administer a messaging system that is distributed across multiple platforms and a wide geographic area?

image

Detour

How can you route a message through intermediate steps to perform validation, testing or debugging functions?

image

Wire Tap

How do you inspect messages that travel on a point-to-point channel?

image

Message History

How can we effectively analyze and debug the flow of messages in a loosely coupled system?

image

Log

How can I log processing a message?

image

Step

Groups together a set of EIPs into a composite logical unit for metrics and monitoring.

EIP Icons

The EIP icons library is available as a Visio stencil file adapted to render the icons with the Camel color. Download it here for your presentation, functional and technical analysis documents.

The original EIP stencil is also available in OpenOffice 3.x Draw, Microsoft Visio, or Omnigraffle.