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📎 #eip

channel_adapter

Background​

  • Problem: connecting an application to send / receive messages

eip_channel_adapter.png

Pattern​

TLDR

Use a Channel Adapter to decouple logic for interacting with a messageChannel

QUOTE

Example: Stock Trading​

  • A stock trading system may wish to keep a log of all of a stock's prices in a database table
  • Channel-to-RDBMS
    • relational database adapter that logs each message from a channel to a specified table and schema
  • Internet-to-channel adapter
    • The system may also be able to:
      • Recieve external quote requests from the Internet (TCP/IP or HTTP)
      • Send them on its internal quote-request channel with the internal quote requests

Example: Commercial EAI Tools​

  • Commercial EAI vendors provide a collection of Channel Adapters as part of their offerings
  • Having adapters to all major application packages available simplifies development of an integration solution greatly
  • Most vendors also provide more generic database adapters as well as software development kits (SDK's) to develop custom adapters

Example: Legacy Platform Adapters​

  • A number of vendors provide adapters from common messaging system to legacy systems executing on platforms such as as UNIX, MVS, OS/2, AS/400, Unisys, and VMS
  • Most of these adapters are specific to a certain messaging system
  • For example, Envoy Technologies' EnvoyMQ is a Channel Adapter that connects many legacy platforms with MSMQ
    • Components:
      • Client that runs on the legacy computer
      • Server that runs on a Windows computer with MSMQ

References

  • Enterprise Integration Patterns by Gregor Hohpe, Bobby Woolf