Matrix Client Tutorial

Warning

This book is a work in progress. Most of the information that it contains should be correct, but it is not complete.

Welcome to the Matrix. Matrix is an open protocol for decentralised communication. Matrix allows users on different servers to communicate with each other, similar to how people on different email servers to email each other.

This book is an introduction to creating a client using the Matrix Client-Server API. It will show how to make HTTP calls to a Matrix homeserver, and discuss issues that clients will need to consider, such as reliability and security issues. It does not attempt to be a comprehensive guide to the entire Client-Server API, but will point you to the relevant portions of spec for further details.

You should read this book if:

  • you are creating a Matrix library/SDK,

  • you are writing a Matrix client without the use of a library/SDK, or

  • you want to get a better understanding of how Matrix works.

If you are creating a Matrix client using a library/SDK, some of the information in this book may still be useful, but some things will already be handled by your library/SDK.

We assume that you have:

  • an understanding of JSON encoding,

  • an understanding of HTTP requests, including HTTP status codes, headers, and different types of requests (GET, POST, etc.),

  • experience writing asynchronous code in your preferred programming language.

This book is written in a literate programming style, which interleaves code blocks and text. In short, code blocks are named, and can reference other code blocks using the syntax {{other code block name}}, which will insert the code blocks with the given name in place of the reference. Multiple code blocks can have the same name, in which case they are inserted in the order that they appear in the book (though in many cases, the order does not matter). This allows us to, for example, have a reference such as {{class Foo methods}}, and define the methods of the Foo class in multiple chunks.

The code output of this book will be a library that a Matrix client could use. The actual user interface for a client is out of scope for this book, although for some topics, there may be discussion on how clients may wish to display things to the user.

The code is written in Python using aiohttp, but the rest of the content should apply any other programming languages and most of the code should be easy to port to another language.

Note

The main purpose of the example code here is to illustrate how the Matrix Client-Server API is used, rather than to develop a fully-featured library. While the library generated should be usable for simple situations, it may make some tradeoffs differently from what a “real” Matrix library would make. These tradeoffs will be discussed in the text where appropriate.

The source for this book, including the example code, is available at https://gitlab.com/uhoreg/matrix-tutorial. We will call our Matrix library the very unimaginative name matrixlib.

src/matrixlib/__init__.py:
# {{copyright}}

"""Matrix client library example"""

The main entry point for our library will be a client module. It will contain helper functions and a Client class, representing a client connection.

src/matrixlib/client.py:
# {{copyright}}

"""General Matrix client functionality"""

import aiohttp
import asyncio
import logging
import math
import os
import re
import sys
import time
import typing
from urllib.parse import quote as urlquote, urljoin, urlparse

from . import error
from . import events
from . import pubsub
from . import schema


{{client module classes}}


{{client module functions}}

In the first chapter of this book, we will discover the basics of the Matrix Client-Server API. We will learn how to make requests to the homeserver, log in and out, and send and receive messages. Using this, we will create a simple echo bot.

In the second(?) chapter, we will look at how to perform end-to-end encryption in Matrix. We will extend the echo bot from the previous part so that it works in encrypted rooms. If you do not need encryption, you may skip this part.

Todo

more topics, e.g.

  • media repo

    • URL previews

  • user management

    • registering

    • device management

    • displayname, avatar

    • 3PIDs

  • interacting with rooms

    • create room

    • room versions and upgrades

    • spaces

    • room tags

    • room directory

    • DMs

    • invites, knocking

    • security issues

      • disambiguation, homographs

  • more messaging features

    • reactions

    • edits

    • redactions

    • IM features (mentions, spoilers, etc)

    • typing notifications

    • read receipts

    • presence

  • more on getting events

    • navigating within rooms (backfilling, jumping to a message, how to handle having multiple chunks of timeline)

    • sync filtering, lazy loading

    • push rules/notifications

  • VoIP

  • widgets

  • how to test

  • what client authors need to understand about federation

copyright:
Copyright Hubert Chathi <hubert@uhoreg.ca>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

SPDX-License-Identifier: Apache-2.0

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