willdot.net
An experimental pub/sub client and server project.
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## Message broker is my attempt at building client / server pub/sub system written in Go using plain `net.Conn`.
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# Message Broker
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Message broker is my attempt at building client / server pub/sub system written in Go using plain `net.Conn`.
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I decided to try to build one to further my understanding of how such a common tool is used in software engineering.
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I realised that I took for granted how complicated other pub / sub message brokers were such as NATs, RabbitMQ and Kafka. By creating my own, I hope to dive into and understand more of how message brokers work.
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## Concept
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The server accepts TCP connections. When a connection is first established, the client will send an "action" message which determines what type of client it is; subscribe or publish.
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### Subscribing
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Once a connection has declared itself as a subscribing connection, it will need to then send the list of topics it wishes to initally subscribe to. After that the connection will enter a loop where it can then send a new action; subscribe to new topic(s) or unsubscribe from topic(s).
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### Publishing
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Once a subscription has declared itself as a publisher, it will enter a loop where it can then send a message for a topic. Once a message has been received, the server will then send it to all connections that are subscribed to that topic.
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### Sending data via a connection
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When sending a message representing an action (subscribe, publish etc) then a uint8 binary message is sent.
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When sending any other data, the length of the data is to be sent first using a binary uint32 and then the actual data sent afterwards.