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lineup is a simple in-memory high-throughput message queue service for Java. It can be used as:

  • As a standalone service accessible via REST services
  • Embedded inside an application


  • In-memory and high-throughput
  • Three different queue types
  • Default: all messages are allowed, including duplicates
  • Reject Duplicates: reject all duplicate messages
  • Priority with Duplicates: a simple priority queue that allows duplicates to be stored
  • Priority without Duplicates: a simple priority queue that rejects duplicates
  • Merging Priority: accept all duplicates and merge them by increasing their priority
  • Accesible via REST API
  • Amazon SQS API compliant (to be done)


The library is currently under development and may not be stable or may not support all features.


The library is released under the terms of Apache Public License Version 2.

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