Integations with Spring

What is Spring Integration?

• Framework allows to do the following:
• Allows communication between components within your application, based on in-memory messaging. This allows these application components to be loosely coupled with each other, sharing data through message channels.
•  It allows communication with external systems. You just need to send the information; Spring Integration will handle sending it to the specified external system and bring back a response if necessary. Of course, this works the other way round; Spring Integration will handle incoming calls from the external system to your application. 
• Benefits
• Loose coupling among components.
• Event oriented architecture.
• The integration logic (handled by the framework) is separated from the business logic.
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• Integration is exchange of data between systems(both internal & external)
  
• Integration is a common requirement and rapidly increasing
• Raise of apis has pushed over this requirement of data exchange
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Designed to support enterprise integration patterns

Traditional ways of integration

• Webservices
• File transfer
• Database sharing

Spring provides solution to extract information thru use of trusted enterprise integration patterns. This helps your application to be robust, flexible & consistent.

Common Implementations

• Enterprise Service Bus(ESB)
• Bus between applications. Applications are decoupled 
• Heavy weight
  
• Integration frameworks
• Lightweight
• Point-point connections for simple solutions

Benefits of Spring Integration

• Simplify complex enterprise integrations
• Loosely couple components
• Well defined boundaries between extension points
• Separate integration and business logic

Architecture

• Light weight message driven architecture
• Channels, messages & end points for internal communication
  
• Channels do the routing & end point do the operations(Similar to pipes and filters)
• When communicating with External systems we use special end points called Adapters or Gateways. These sit on the edge of our applications
  
• Adapters facilitate communication between systems
• Available adapters
• Data store
• File store
• HTTP
• Mail
• Messaging
• Twitter
• Webservices
  

Channels

• Pollable
• Subscribable
• MessageChannel(Retains message in buffer until subcriber receives it.
  
• PollableChannel
• Direct
• PublishSubscribe-> one - many
  
• QueueChannel
• PriortyChannel
• DirectChannel

• Router
•  Route message thru channel to end points based on payload type(payload-type-router)
• Route based on Header value
• Route based on Receipent list
• 
  
• Filter
• Splitter
  
• split message into more than one
• Aggregator
• Combines multiple messages into single
  
• Bridge
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Spring Integration

•  Integration Drivers
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Messaging API

External System Integration

Adapter and gateways-

• Adapters are one way communications
• Gateway- two way communication
  

Filesystem integration

FTP Integration

• transfer file from client to server thru established connection
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External System Integration 

• Filesystem - Log aggregation
  
• ftp -
  
• database
• JMS
• http
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