zaqar/doc/source/index.rst
wanghao fad3fa1416 [community goal] Update contributor documentation
This patch updates/adds the contributor documentation to follow
the guidelines of the Ussuri cycle community goal[1].

[1] https://governance.openstack.org/tc/goals/selected/ussuri/project-ptl-and-contrib-docs.html

Change-Id: I4407ab803cf3dfd66ab3c5b25f8f0db85147cdc5
2021-06-15 16:28:28 +08:00

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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.
=====================================
Welcome to the Zaqar's Documentation!
=====================================
Zaqar is a multi-tenant cloud messaging and notification service for web
and mobile developers.
The service features a REST API, which developers can use to send messages
between various components of their SaaS and mobile applications, by using a
variety of communication patterns. Underlying this API is an efficient
messaging engine designed with scalability and security in mind. The Websocket
API is also available.
Other OpenStack components can integrate with Zaqar to surface events to end
users and to communicate with guest agents that run in the "over-cloud" layer.
Key features
------------
Zaqar provides the following key features:
* Choice between two communication transports. Both with Keystone support:
* Firewall-friendly, **HTTP-based RESTful API**. Many of today's developers
prefer a more web-friendly HTTP API. They value the simplicity and
transparency of the protocol, it's firewall-friendly nature, and it's huge
ecosystem of tools, load balancers and proxies. In addition, cloud
operators appreciate the scalability aspects of the REST architectural
style.
* **Websocket-based API** for persistent connections. Websocket protocol
provides communication over persistent connections. Unlike HTTP, where
new connections are opened for each request/response pair, Websocket can
transfer multiple requests/responses over single TCP connection. It saves
much network traffic and minimizes delays.
* Multi-tenant queues based on Keystone project IDs.
* Support for several common patterns including event broadcasting, task
distribution, and point-to-point messaging.
* Component-based architecture with support for custom backends and message
filters.
* Efficient reference implementation with an eye toward low latency and high
throughput (dependent on backend).
* Highly-available and horizontally scalable.
* Support for subscriptions to queues. Several notification types are
available:
* Email notifications.
* Webhook notifications.
* Websocket notifications.
Project scope
-------------
The Zaqar API is data-oriented. That is, it does not provision message brokers
and expose those directly to clients. Instead, the API acts as a bridge between
the client and one or more backends. A provisioning service for message
brokers, however useful, serves a somewhat different market from what Zaqar is
targeting today. With that in mind, if users are interested in a broker
provisioning service, the community should consider starting a new project to
address that need.
Design principles
-----------------
Zaqar, as with all OpenStack projects, is designed with the following
guidelines in mind:
* **Component-based architecture.** Quickly add new behaviors
* **Highly available and scalable.** Scale to very serious workloads
* **Fault tolerant.** Isolated processes avoid cascading failures
* **Recoverable.** Failures should be easy to diagnose, debug, and rectify
* **Open standards.** Be a reference implementation for a community-driven
Contents
--------
.. toctree::
:maxdepth: 2
user/index
admin/index
install/index
configuration/index
contributor/contributing
contributor/index
cli/index
.. toctree::
:maxdepth: 1
glossary