Documentation/Messaging

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This document was written during the Georgetown Hackfest. In the meantime, a message broker solution has been implemented in the CTK Plugin Framework. A in-process implementation is available and an out-of-process implementation is available for experimentation.

Use cases

Event Management

Each component/application generates many different types of events. A centralized event manager (Hub and Spoke) can be used to aggregate/dispatch events

  1. Synchronization: Window/Leveling events in one window should be synchronized across all viewer windows
  2. Temporal calibration: Different components have different update frequency, a centralized manager can be used to filter UpdateEvents, so the whole system is updating at the same frequency


System Integration

Different system/application have different data format or are running on different physical devices. A event bus can be used for system integration

Solution

  1. UseMessage Broker for event management
  1. Use Message Bus and Publisher/Subscriber design pattern for system integration

Implementation

  1. Message layer: OpenIGTLink
    • OpenIGTLink defines many common data format and message structure
    • It has plain vanilla socket support, might switch to ZeroMQ for transportation
  2. Transportation layer abstraction: ZeroMQ