Skip to main content

Callosum RPC Library

Project description


An RPC Transport Library

It provides an asynchronous multi-channel order-preserving message and data streaming transport for upper RPC layers (e.g., Apache Thrift) by wrapping lower transport implementations (e.g., ZeroMQ).

It aims to follow the latest coding style and conventions in Python asyncio.

Corpus callosum is a bundle of neuron fibers that connects two cerebral hemispheres of a human brain.


Python 3.8 or higher.


  • RPC
    • Native timeout and cancellation support
    • Explicit server-to-client error propagation including stringified tracebacks
    • Order preserving based on user-defined keys while keeping executions asynchronous
  • Streaming
    • Broadcast & shared pipelines
  • Optional client authentication and encrypted communication
    • Currently supported for only ZeroMQ with its CURVE library
  • Optional message compression using snappy
  • Replacible and combinable lower/upper layers (ZeroMQ/Redis + JSON/msgpack/Thrift)

Planned features

  • Managed streaming (with acks)
  • Tunneling to bundle other channels and generic network traffic in a single connection
  • Bidirectional RPC
  • Chunked transfer of large messages


To install the core:

$ pip install -U pip setuptools
$ pip install callosum

You may add extra dependencies like:

$ pip install 'callosum[zeromq,redis,thrift,snappy]'


Please check out the examples directory.


Use the editable installation of Python setuptools.

$ pip install -U pip setuptools
$ pip install -U -e '.[dev,build,test,zeromq,redis,thrift,snappy]'


.. towncrier release notes start

v0.9.7 (2020-12-22)


  • Provide repr() of exceptions in RPC user/internal errors for better application-level error logging (#15)

v0.9.6 (2020-06-05)


  • upper.rpc: Support server-side cancellation and propagation to clients by adding the CANCELLED RPC message type (#14)


  • Drop use of aiojobs in favor of native semaphores for limiting the task concurrency and less clutters on job scheduling semantics (#14)


  • Stability updates for the RPC layer: (#14)
    • Fix wrong message sequence calcuation with SEQ_BITS and clarify the roles of cleanup() and cancel() methods in the schedulers.
    • Now we use the exit-ordered scheduler by default.

v0.9.5 (2020-05-12)


  • lower.zeromq: Use destroy() for zmq context termination to improve stability and shutdown open socekts cleanly (#13)

v0.9.4 (2020-04-10)


  • Fix a race condition due to overlapping RPC message sequence IDs by separating server/client message sequence IDs (#12)


  • Adopt towncrier for changelog management (#11)

v0.9.3 (2020-03-20)

  • FIX: Mitigate bogus KeyError when cleaning up task futures in RPC servers that has caused event loop spinning.

v0.9.2 (2020-02-28)

  • MAINTENANCE: Update dependencies and only specify the minimum versions since Callosum is a library.

v0.9.1 (2020-01-05)

  • FIX: wrong typing of RPCMessage.body field

  • IMPROVE: Add debug_rpc option to rpc.Peer for logging exceptions in RPC scheduler and user-defined handlers explicitly.

  • Update dependencies and remove unused ones.

v0.9.0 (2019-12-06)

  • First public release with a working RPC based on ZeroMQ DEALER/ROUTER sockets.


  • Started the project.

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for callosum, version 0.9.7
Filename, size File type Python version Upload date Hashes
Filename, size callosum-0.9.7-py3-none-any.whl (29.8 kB) File type Wheel Python version py3 Upload date Hashes View
Filename, size callosum-0.9.7.tar.gz (23.9 kB) File type Source Python version None Upload date Hashes View

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring DigiCert DigiCert EV certificate Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page