Chapter 3. Introducing Enterprise Integration Patterns
Abstract
3.1. Overview of the Patterns
Enterprise Integration Patterns book
Messaging systems
Table 3.1. Messaging Systems
Icon | Name | Use Case |
---|---|---|
![]() | Message | How can two applications connected by a message channel exchange a piece of information? |
![]() | Message Channel | How does one application communicate with another application using messaging? |
![]() | Message Endpoint | How does an application connect to a messaging channel to send and receive messages? |
![]() | Pipes and Filters | How can we perform complex processing on a message while still maintaining independence and flexibility? |
![]() | Message Router | How can you decouple individual processing steps so that messages can be passed to different filters depending on a set of defined conditions? |
![]() | Message Translator | How do systems using different data formats communicate with each other using messaging? |
Messaging channels
Table 3.2. Messaging Channels
Icon | Name | Use Case |
---|---|---|
![]() | Point to Point Channel | How can the caller be sure that exactly one receiver will receive the document or will perform the call? |
![]() | Publish Subscribe Channel | How can the sender broadcast an event to all interested receivers? |
![]() | Dead Letter Channel | What will the messaging system do with a message it cannot deliver? |
![]() | Guaranteed Delivery | How does the sender make sure that a message will be delivered, even if the messaging system fails? |
![]() | Message Bus | What is an architecture that enables separate, decoupled applications to work together, such that one or more of the applications can be added or removed without affecting the others? |
Message construction
Table 3.3. Message Construction
Icon | Name | Use Case |
---|---|---|
![]() | Correlation Identifier | How does a requestor identify the request that generated the received reply? |
![]() | Return Address | How does a replier know where to send the reply? |
Message routing
Table 3.4. Message Routing
Icon | Name | Use Case |
---|---|---|
![]() | 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? |
![]() | Message Filter | How does a component avoid receiving uninteresting messages? |
![]() | Recipient List | How do we route a message to a list of dynamically specified recipients? |
![]() | Splitter | How can we process a message if it contains multiple elements, each of which might have to be processed in a different way? |
![]() | Aggregator | How do we combine the results of individual, but related messages so that they can be processed as a whole? |
![]() | Resequencer | How can we get a stream of related, but out-of-sequence, messages back into the correct order? |
![]() | 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? |
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? | |
![]() | 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 might vary for each message? |
Throttler | How can I throttle messages to ensure that a specific endpoint does not get overloaded, or that we don't exceed an agreed SLA with some external service? | |
Delayer | How can I delay the sending of a message? | |
Load Balancer | How can I balance load across a number of endpoints? | |
Multicast | How can I route a message to a number of endpoints at the same time? | |
Loop | How can I repeat processing a message in a loop? | |
Sampling | How can I sample one message out of many in a given period to avoid downstream route does not get overloaded? |
Message transformation
Table 3.5. Message Transformation
Icon | Name | Use Case |
---|---|---|
![]() | Content Enricher | How do we communicate with another system if the message originator does not have all the required data items available? |
![]() | Content Filter | How do you simplify dealing with a large message, when you are interested in only a few data items? |
![]() | Claim Check | How can we reduce the data volume of messages sent across the system without sacrificing information content? |
![]() | Normalizer | How do you process messages that are semantically equivalent, but arrive in a different format? |
Sort | How can I sort the body of a message? |
Messaging endpoints
Table 3.6. Messaging Endpoints
Icon | Name | Use Case |
---|---|---|
Messaging Mapper | How do you move data between domain objects and the messaging infrastructure while keeping the two independent of each other? | |
![]() | Event Driven Consumer | How can an application automatically consume messages as they become available? |
![]() | Polling Consumer | How can an application consume a message when the application is ready? |
![]() | Competing Consumers | How can a messaging client process multiple messages concurrently? |
![]() | Message Dispatcher | How can multiple consumers on a single channel coordinate their message processing? |
![]() | Selective Consumer | How can a message consumer select which messages it wants to receive? |
![]() | Durable Subscriber | How can a subscriber avoid missing messages when it's not listening for them? |
Idempotent Consumer | How can a message receiver deal with duplicate messages? | |
![]() | Transactional Client | How can a client control its transactions with the messaging system? |
![]() | Messaging Gateway | How do you encapsulate access to the messaging system from the rest of the application? |
![]() | Service Activator | How can an application design a service to be invoked both via various messaging technologies and via non-messaging techniques? |
System management
Table 3.7. System Management
Icon | Name | Use Case |
---|---|---|
![]() | Wire Tap | How do you inspect messages that travel on a point-to-point channel? |