Enterprise Integration Patterns
Camel supports most of the Enterprise Integration Patterns from the excellent book by Gregor Hohpe and Bobby Woolf.
Messaging Systems
 | How does one application communicate with another using messaging? | |
 | How can two applications be connected by a message channel exchange a piece of information? | |
 | How can we perform complex processing on a message while maintaining independence and flexibility? | |
 | How can you decouple individual processing steps so that messages can be passed to different filters depending on a set of conditions? | |
 | How can systems using different data formats communicate with each other using messaging? | |
 | How does an application connect to a messaging channel to send and receive messages? |
Messaging Channels
 | How can the caller be sure that exactly one receiver will receive the document or perform the call? | |
 | How can the sender broadcast an event to all interested receivers? | |
 | What will the messaging system do with a message it cannot deliver? | |
 | How can the sender make sure that a message will be delivered, even if the messaging system fails? | |
 | How can you connect an application to the messaging system so that it can send and receive messages? | |
 | How can multiple messaging systems be connected so that messages available on one are also available on the others?? | |
 | 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? | |
| | Data synchronization by capturing changes made to a database, and apply those changes to another system. |
Message Construction
 | How can messaging be used to transmit events from one application to another? | |
 | When an application sends a message, how can it get a response from the receiver? | |
 | How does a replier know where to send the reply? | |
 | How does a requestor that has received a reply know which request this is the reply for? | |
 | How can a sender indicate when a message should be considered stale and thus shouldn’t be processed? |
Message Routing
| | How do we handle a situation where the implementation of a single logical function (e.g., inventory check) is spread across multiple physical systems? | |
 | How can a component avoid receiving uninteresting messages? | |
 | How can you avoid the dependency of the router on all possible destinations while maintaining its efficiency? | |
 | How do we route a message to a list of (static or dynamically) specified recipients? | |
 | How can we process a message if it contains multiple elements, each of which may have to be processed in a different way? | |
 | How do we combine the results of individual, but related, messages so that they can be processed as a whole? | |
 | How can we get a stream of related but out-of-sequence messages back into the correct order? | |
 | How can you maintain the overall message flow when processing a message consisting of multiple elements, each of which may require different processing? | |
| | 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? | |
 | 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? | |
 | 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? | |
 | How can you decouple the destination of a message from the sender and maintain central control over the flow of messages? | |
 | How can I decouple the continued routing of a message from the current thread? | |
| | 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? | |
 | How can I sample one message out of many in a given period to avoid downstream route does not get overloaded? | |
| | How can I call Kamelets (route templates)? | |
| | How can I delay the sending of a message? | |
 | How can I balance load across a number of endpoints? | |
| | How can I stop calling an external service if the service is broken? | |
| | How can I stop to continue routing a message? | |
 | How can I call a remote service in a distributed system where the service is looked up from a service registry of some sorts? | |
 | 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? | |
| | How can I route a message to a number of endpoints at the same time? | |
 | How can I repeat processing a message in a loop? |
Message Transformation
 | How do we communicate with another system if the message originator does not have all the required data items available? | |
 | How do you simplify dealing with a large message when you are interested only in a few data items? | |
 | How can we reduce the data volume of a message sent across the system without sacrificing information content? | |
 | How do you process messages that are semantically equivalent, but arrive in a different format? | |
| | How can I sort the body of a message? | |
| | How do I execute a script which may not change the message? | |
 | How can I validate a message? |
Messaging Endpoints
| | How do you move data between domain objects and the messaging infrastructure while keeping the two independent of each other? | |
 | How can an application automatically consume messages as they become available? | |
| | How can an application consume a message when the application is ready? | |
 | How can a messaging client process multiple messages concurrently? | |
| | How can multiple consumers on a single channel coordinate their message processing? | |
| | How can a message consumer select which messages it wishes to receive? | |
 | How can a subscriber avoid missing messages while it’s not listening for them? | |
| | How can a message receiver deal with duplicate messages? | |
| | How can a message receiver resume from the last known offset? | |
| | How can a client control its transactions with the messaging system? | |
| | How do you encapsulate access to the messaging system from the rest of the application? | |
| | How can an application design a service to be invoked both via various messaging technologies and via non-messaging techniques? |
System Management
 | How can we effectively administer a messaging system distributed across multiple platforms and a wide geographic area? | |
 | How can you route a message through intermediate steps to perform validation, testing or debugging functions? | |
 | How do you inspect messages that travel on a point-to-point channel? | |
| | How can we effectively analyze and debug the flow of messages in a loosely coupled system? | |
| | How can I log processing a message? | |
| | 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.