[[EnterpriseIntegrationPatterns-EnterpriseIntegrationPatterns]]
=== Enterprise Integration Patterns

Camel supports most of the
http://www.eaipatterns.com/toc.html[Enterprise Integration Patterns]
from the excellent book by
http://www.amazon.com/exec/obidos/search-handle-url/105-9796798-8100401?%5Fencoding=UTF8&search-type=ss&index=books&field-author=Gregor%20Hohpe[Gregor
Hohpe] and
http://www.amazon.com/exec/obidos/search-handle-url/105-9796798-8100401?%5Fencoding=UTF8&search-type=ss&index=books&field-author=Bobby%20Woolf[Bobby
Woolf].

If you are new to Camel you might want to try the
Getting Started in the
User Guide before attempting to implement these
patterns.

The EIP icons library is available as a Visio stencil file adapted to
render the icons with the Camel color : sand. Download it
link:enterprise-integration-patterns.data/Hohpe_EIP_camel_20150622.zip?version=1&modificationDate=1435069070000&api=v2[here]
for your presentation, functional and technical analysis documents. The
original EIP stencil is also available in
link:enterprise-integration-patterns.data/Hohpe_EIP_camel_OpenOffice.zip?version=1&modificationDate=1245056975000&api=v2[OpenOffice
3.x Draw] (thanks to Marco Garbelini) ,
http://www.eaipatterns.com/download/EIP_Visio_stencil.zip[Microsoft
Visio], or http://www.graffletopia.com/stencils/137[Omnigraffle].

[[EnterpriseIntegrationPatterns-MessagingSystems]]
==== Messaging Systems

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/ChannelIcon.gif[image]
|Message Channel |How does one application
communicate with another using messaging?

|image:http://www.eaipatterns.com/img/MessageIcon.gif[image]
|Message |How can two applications connected by a
message channel exchange a piece of information?

|image:http://www.eaipatterns.com/img/PipesAndFiltersIcon.gif[image]
|Pipes and Filters |How can we perform
complex processing on a message while maintaining independence and
flexibility?

|image:http://www.eaipatterns.com/img/ContentBasedRouterIcon.gif[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:http://www.eaipatterns.com/img/MessageTranslatorIcon.gif[image]
|Message Translator |How can systems using
different data formats communicate with each other using messaging?

|image:http://www.eaipatterns.com/img/MessageEndpointIcon.gif[image]
|Message Endpoint |How does an application
connect to a messaging channel to send and receive messages?
|=======================================================================

[[EnterpriseIntegrationPatterns-MessagingChannels]]
==== Messaging Channels

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/PointToPointIcon.gif[image]
|Point to Point Channel |How can the
caller be sure that exactly one receiver will receive the document or
perform the call?

|image:http://www.eaipatterns.com/img/PublishSubscribeIcon.gif[image]
|Publish Subscribe Channel |How can
the sender broadcast an event to all interested receivers?

|image:http://www.eaipatterns.com/img/DeadLetterChannelIcon.gif[image]
|Dead Letter Channel |What will the
messaging system do with a message it cannot deliver?

|image:http://www.eaipatterns.com/img/GuaranteedMessagingIcon.gif[image]
|Guaranteed Delivery |How can the sender
make sure that a message will be delivered, even if the messaging system
fails?

|image:http://www.eaipatterns.com/img/MessageBusIcon.gif[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?
|=======================================================================

[[EnterpriseIntegrationPatterns-MessageConstruction]]
==== Message Construction

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/EventMessageIcon.gif[image]
|Event Message |How can messaging be used to
transmit events from one application to another?

|image:http://www.eaipatterns.com/img/RequestReplyIcon.gif[image]
|Request Reply |When an application sends a
message, how can it get a response from the receiver?

|image:http://www.eaipatterns.com/img/CorrelationIdentifierIcon.gif[image]
|Correlation Identifier |How does a
requestor that has received a reply know which request this is the reply
for?

|image:http://www.eaipatterns.com/img/ReturnAddressIcon.gif[image]
|Return Address |How does a replier know where
to send the reply?
|=======================================================================

[[EnterpriseIntegrationPatterns-MessageRouting]]
==== Message Routing

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/ContentBasedRouterIcon.gif[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:http://www.eaipatterns.com/img/MessageFilterIcon.gif[image]
|Message Filter |How can a component avoid
receiving uninteresting messages?

|image:http://www.eaipatterns.com/img/DynamicRouterIcon.gif[image]
|Dynamic Router |How can you avoid the
dependency of the router on all possible destinations while maintaining
its efficiency?

|image:http://www.eaipatterns.com/img/RecipientListIcon.gif[image]
|Recipient List |How do we route a message to
a list of (static or dynamically) specified recipients?

|image:http://www.eaipatterns.com/img/SplitterIcon.gif[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:http://www.eaipatterns.com/img/AggregatorIcon.gif[image]
|Aggregator |How do we combine the results of
individual, but related messages so that they can be processed as a
whole?

|image:http://www.eaipatterns.com/img/ResequencerIcon.gif[image]
|Resequencer |How can we get a stream of related
but out-of-sequence messages back into the correct order?

|image:http://www.eaipatterns.com/img/DistributionAggregateIcon.gif[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:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[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:http://www.eaipatterns.com/img/RoutingTableIcon.gif[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:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[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:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Sampling |How can I sample one message out of many
in a given period to avoid downstream route does not get overloaded?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Delayer |How can I delay the sending of a message?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Load Balancer |How can I balance load across a
number of endpoints?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Hystrix |How can I stop to call an external service if the service is broken?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[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:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[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:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Multicast |How can I route a message to a number
of endpoints at the same time?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|<<loop-eip,Loop>> |How can I repeat processing a message in a loop?
|=======================================================================

[[EnterpriseIntegrationPatterns-MessageTransformation]]
==== Message Transformation

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/DataEnricherIcon.gif[image]
|Content Enricher |How do we communicate
with another system if the message originator does not have all the
required data items available?

|image:http://www.eaipatterns.com/img/ContentFilterIcon.gif[image]
|Content Filter |How do you simplify dealing
with a large message, when you are interested only in a few data items?

|image:http://www.eaipatterns.com/img/StoreInLibraryIcon.gif[image]
|Claim Check |How can we reduce the data volume
of message sent across the system without sacrificing information
content?

|image:http://www.eaipatterns.com/img/NormalizerIcon.gif[image]
|Normalizer |How do you process messages that are
semantically equivalent, but arrive in a different format?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|<<sort-eip,Sort>> |How can I sort the body of a message?

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

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|<<validate-eip,Validate>> |How can I validate a message?
|=======================================================================

[[EnterpriseIntegrationPatterns-MessagingEndpoints]]
==== Messaging Endpoints

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Messaging Mapper |How do you move data
between domain objects and the messaging infrastructure while keeping
the two independent of each other?

|image:http://www.eaipatterns.com/img/EventDrivenConsumerIcon.gif[image]
|Event Driven Consumer |How can an
application automatically consume messages as they become available?

|image:http://www.eaipatterns.com/img/PollingConsumerIcon.gif[image]
|Polling Consumer |How can an application
consume a message when the application is ready?

|image:http://www.eaipatterns.com/img/CompetingConsumersIcon.gif[image]
|Competing Consumers |How can a messaging
client process multiple messages concurrently?

|image:http://www.eaipatterns.com/img/MessageDispatcherIcon.gif[image]
|Message Dispatcher |How can multiple
consumers on a single channel coordinate their message processing?

|image:http://www.eaipatterns.com/img/MessageSelectorIcon.gif[image]
|Selective Consumer |How can a message
consumer select which messages it wishes to receive?

|image:http://www.eaipatterns.com/img/DurableSubscriptionIcon.gif[image]
|Durable Subscriber |How can a subscriber
avoid missing messages while it's not listening for them?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Idempotent Consumer |How can a message
receiver deal with duplicate messages?

|image:http://www.eaipatterns.com/img/TransactionalClientIcon.gif[image]
|Transactional Client |How can a client
control its transactions with the messaging system?

|image:http://www.eaipatterns.com/img/MessagingGatewayIcon.gif[image]
|Messaging Gateway |How do you encapsulate
access to the messaging system from the rest of the application?

|image:http://www.eaipatterns.com/img/MessagingAdapterIcon.gif[image]
|Service Activator |How can an application
design a service to be invoked both via various messaging technologies
and via non-messaging techniques?
|=======================================================================

[[EnterpriseIntegrationPatterns-SystemManagement]]
==== System Management

[width="100%",cols="10%,10%,80%",]
|=======================================================================
|image:http://www.eaipatterns.com/img/ControlBusIcon.gif[image]
|<<controlbus-component,ControlBus>> |How can we effectively administer a
messaging system that is distributed across multiple platforms and a
wide geographic area?

|image:http://www.eaipatterns.com/img/DetourIcon.gif[image]
|Detour |How can you route a message through
intermediate steps to perform validation, testing or debugging
functions?

|image:http://www.eaipatterns.com/img/WireTapIcon.gif[image]
|Wire Tap |How do you inspect messages that travel
on a point-to-point channel?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Message History |How can we effectively
analyze and debug the flow of messages in a loosely coupled system?

|image:http://cwiki.apache.org/confluence/download/attachments/49204/clear.png[image]
|Log |How can I log processing a message?
|=======================================================================
