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Python SSE Client

This is a Python client library for iterating over http Server Sent Event (SSE) streams (also known as EventSource, after the name of the Javascript interface inside browsers). The SSEClient class accepts a url on init, and is then an iterator over messages coming from the server.


I (btubbs) haven't been using this library in my own work for years, so I put limited time into maintaining it. I will check in on pull requests and issues once per month. If you are interested in providing more active support for the library, please reach out.


Use pip:

pip install sseclient


from sseclient import SSEClient

messages = SSEClient('')
for msg in messages:

Each message object will have a 'data' attribute, as well as optional 'event', 'id', and 'retry' attributes.

Optional init parameters:

  • last_id: If provided, this parameter will be sent to the server to tell it to return only messages more recent than this ID.
  • retry: Number of milliseconds to wait after disconnects before attempting to reconnect. The server may change this by including a 'retry' line in a message. Retries are handled automatically by the SSEClient object.

You may also provide any additional keyword arguments supported by the Requests library, such as a 'headers' dict and a (username, password) tuple for 'auth'.


Install the library in editable mode:

pip install -e .

Install the test dependencies:

pip install pytest backports.unittest_mock

Run the tests with py.test:

(sseclient)vagrant sseclient $ py.test
===================== test session starts ======================
platform linux2 -- Python 2.7.6 -- py-1.4.30 -- pytest-2.7.2
rootdir: /vagrant/code/sseclient, inifile:
plugins: backports.unittest-mock
collected 11 items ...........

================== 11 passed in 0.19 seconds ===================

There are a couple TODO items in the code for getting the implementation completely in line with the finer points of the SSE spec.

Additional Resources