Enterprise Integration Patterns
Messaging Patterns
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Shared DatabaseShared DatabaseMessaging Patterns » Integration Styles

An enterprise has multiple applications that are being built independently, with different languages and platforms. The enterprise needs information to be shared rapidly and consistently.

How can I integrate multiple applications so that they work together and can exchange information?

Integrate applications by having them store their data in a single Shared Database.

If a family of integrated applications all rely on the same database, then you can be pretty sure that they are always consistent all of the time. If you do get simultaneous updates to a single piece of data from different sources, then you have transaction management systems that handle that about as gracefully as it ever can be managed. Since the time between updates is so small, any errors are much easier to find and fix.

One of the biggest difficulties with Shared Database is coming up with a suitable design for the shared database. Coming up with a unified schema that can meet the needs of multiple applications is a very difficult exercise, often resulting in a schema that application programmers find difficult to work with.

If the technical difficulties of designing a unified schema aren't enough, there are also severe political difficulties. If a critical application is likely to suffer delays in order to work with a unified schema, then often there is irresistable pressure to separate. Human conflicts between departments often exacerbate this problem.

... Read the entire pattern in the book Enterprise Integration Patterns

Related patterns: Remote Procedure Invocation, File Transfer, Messaging


Table of Contents
Preface
Introduction
Solving Integration Problems using Patterns
Integration Styles
File Transfer
Shared Database
Remote Procedure Invocation
Messaging
Messaging Systems
Message Channel
Message
Pipes and Filters
Message Router
Message Translator
Message Endpoint
Messaging Channels
Point-to-Point Channel
Publish-Subscribe Channel
Datatype Channel
Invalid Message Channel
Dead Letter Channel
Guaranteed Delivery
Channel Adapter
Messaging Bridge
Message Bus
Message Construction
Command Message
Document Message
Event Message
Request-Reply
Return Address
Correlation Identifier
Message Sequence
Message Expiration
Format Indicator
Interlude: Simple Messaging
JMS Request/Reply Example
.NET Request/Reply Example
JMS Publish/Subscribe Example
Message Routing
Content-Based Router
Message Filter
Dynamic Router
Recipient List
Splitter
Aggregator
Resequencer
Composed Msg. Processor
Scatter-Gather
Routing Slip
Process Manager
Message Broker
Message Transformation
Envelope Wrapper
Content Enricher
Content Filter
Claim Check
Normalizer
Canonical Data Model
Interlude: Composed Messaging
Synchronous (Web Services)
Asynchronous (MSMQ)
Asynchronous (TIBCO)
Messaging Endpoints
Messaging Gateway
Messaging Mapper
Transactional Client
Polling Consumer
Event-Driven Consumer
Competing Consumers
Message Dispatcher
Selective Consumer
Durable Subscriber
Idempotent Receiver
Service Activator
System Management
Control Bus
Detour
Wire Tap
Message History
Message Store
Smart Proxy
Test Message
Channel Purger
Interlude: Systems Management Example
Instrumenting Loan Broker
Integration Patterns in Practice
Case Study: Bond Trading System
Concluding Remarks
Emerging Standards
Appendices
Bibliography
Revision History
Creative Commons Attribution License

You can reuse the following elements under the Creative Commons Attribution license: pattern icon, pattern name, problem and solution statements (in bold), and the sketch. Other portions are protected by copyright.

Enterprise Integration Patterns

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