Integration Styles
File Transfer How can I integrate multiple applications so that they work together and can exchange information?
Shared Database How can I integrate multiple applications so that they work together and can exchange information?
Messaging How can I integrate multiple applications so that they work together and can exchange information?
Messaging Systems
Message Channel How does one application communicate with another using messaging?
Message How can two applications connected by a message channel exchange a piece of information?
Pipes and Filters
How can we perform complex processing on a message while 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 conditions?
Message Translator
How can systems using different data formats communicate with each other using messaging?
Message Endpoint How does an application connect to a messaging channel to send and receive messages?
Messaging Channels
Point-to-Point Channel How can the caller be sure that exactly one receiver will receive the document or perform the call?
Datatype Channel How can the application send a data item such that the receiver will know how to process it?
Guaranteed Delivery How can the sender make sure that a message will be delivered, even if the messaging system fails?
Channel Adapter How can you connect an application to the messaging system so that it can send and receive messages?
Messaging Bridge How can multiple messaging systems be connected so that messages available on one are also available on the others?
Message Bus What is an architecture that enables separate applications to work together, but in a decoupled fashion such that applications can be easily added or removed without affecting the others?
Message Construction
Command Message How can messaging be used to invoke a procedure in another application?
Document Message How can messaging be used to transfer data between applications?
Event Message How can messaging be used to transmit events from one application to another?
Request-Reply When an application sends a message, how can it get a response from the receiver?
Correlation Identifier How does a requestor that has received a reply know which request this is the reply for?
Message Sequence How can messaging transmit an arbitrarily large amount of data?
Message Expiration How can a sender indicate when a message should be considered stale and thus shouldn’t be processed?
Format Indicator How can a message’s data format be designed to allow for possible future changes?
Interlude: Simple Messaging
Message Routing
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 can a component avoid receiving uninteresting messages?
Dynamic Router How can you avoid the dependency of the router on all possible destinations while maintaining its efficiency?
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 may 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 may vary for each message?
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?
Message Broker How can you decouple the destination of a message from the sender and maintain central control over the flow of messages?
Message Transformation
Envelope Wrapper
How can existing systems participate in a messaging exchange that places specific requirements on the message format, such as message header fields or encryption?
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 only in a few data items?
Claim Check
How can we reduce the data volume of message sent across the system without sacrificing information content?
Normalizer How do you process messages that are semantically equivalent, but arrive in a different format?
Canonical Data Model How can you minimize dependencies when integrating applications that use different data formats?
Interlude: Composed Messaging
Messaging Endpoints
Messaging Gateway How do you encapsulate access to the messaging system from the rest of the application?
Messaging Mapper How do you move data between domain objects and the messaging infrastructure while keeping the two independent of each other?
Polling Consumer How can an application consume a message when the application is ready?
Message Dispatcher How can multiple consumers on a single channel coordinate their message processing?
Durable Subscriber How can a subscriber avoid missing messages while it’s not listening for them?
Service Activator How can an application design a service to be invoked both via various messaging technologies and via non-messaging techniques?
System Management
Control Bus
How can we effectively administer a messaging system that is distributed across multiple platforms and a wide geographic area?
Detour How can you route a message through intermediate steps to perform validation, testing or debugging functions?
Wire Tap How do you inspect messages that travel on a point-to-point channel?
Message History
How can we effectively analyze and debug the flow of messages in a loosely coupled system?
Message Store
How can we report against message information without disturbing the loosely coupled and transient nature of a messaging system?
Smart Proxy How can you track messages on a service that publishes reply messages to the Return Address specified by the requestor?
Test Message
What happens, though, if a component is actively processing messages, but garbles outgoing messages due to an internal fault?
Channel Purger How can you keep 'left-over' messages on a channel from disturbing tests or running systems?
Interlude: Systems Management Example
Integration Patterns in Practice
Concluding Remarks
Appendices
Bibliography
Annotated list of references and recommended reading.