Hermes

ZMQ-based framework for building simple Pub-Sub Systems, written in Python 3.

It offers thread-based wrappers for zmq’s SUB and PUB sockets, a pre-configured proxy device and a Node class to pull it all together.

Hermes allows you to quickly build a cluster of publishers which can support arbitrary numbers of subscribers via single address.

Since the project was birthed with a financial use-case in mind, it supplies some basic data structures (called Message) to transport data via hermes. These are optional, but are used by other parts of our system to efficiently process incoming data streams.

Design

There as several basic components that interact in a hermes-based system: On the processing layer, we have:

• the Node object, which may consist of any number of Receiver and Publisher objects.

• the Proxy object, which aggregates data streams from several Node objects and allows subscribers to subscribe to them from a single address.

On the transport layer, we have:

• the Envelope object, which is just a wrapper data structure to send around messages with some meta data attached (time stamp of creation, origin, topic, etc)

• the Message object, which is usually sent by assigning it to an Envelope (although the usage of a Message object is optional - Envelope takes any kind of serializable data).

Motivation

Hermes is the base for our Crypto trading system, and allows us to set up new node clusters in a convenient and maintainable way, without our contributors having to worry too much about the inner workings of ZMQ.

Usage

install via pip install hermes-zmq and import with import hermes.