Welcome to the Zaqar Developer 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.

Note

This documentation is generated by the Sphinx toolkit and lives in the Zaqar project source tree. Additional draft and project documentation regarding Zaqar and other components of OpenStack can be found on the OpenStack Wiki, as well as in the user guides found on docs.openstack.org.

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

Concepts

• Glossary

Modules reference

Zaqar is composed of two layers:

• Transport
• Storage Layer

The transport drivers are responsible for interacting with Zaqar clients. Every query made by clients is processed by the transport layer, which is in charge of passing this information to the backend and then returning the response in a format understandable by the client.

The storage drivers are responsible for interacting with the storage backends and, that way, store or retrieve the data coming from the transport layer.

In order to keep these layers decoupled, we have established that checks should be performed in the appropriate layer. In other words, transport drivers must guarantee that the incoming data is well-formed and storage drivers must enforce their data model stays consistent.

Setting up Zaqar in development environment

• Setting up a development environment

Welcome new contributors

• Welcome new contributors
• Your first patch
• Your first review

Running and writing tests

• Running tests
• Test suite structure

Reviewing

• Reviewer Guide

Tutorials

• Running benchmark
• Writing stages for the storage pipelines

Other resources

• Project hosting with Launchpad
  • Launchpad credentials
  • Mailing list
  • Bug tracking
  • Feature requests (Blueprints)
  • Technical support (Answers)
• Code reviews with Gerrit
• Continuous integration with Jenkins

Internal API reference

• The zaqar.api.handler module
• The zaqar.api.v1.request module
• The zaqar.api.v1.response module
• The zaqar.api.v1_1.request module
• The zaqar.api.v1_1.response module
• The zaqar.api.v2.endpoints module
• The zaqar.api.v2.request module
• The zaqar.api.v2.response module
• The zaqar.bootstrap module
• The zaqar.cmd.gc module
• The zaqar.cmd.server module
• The zaqar.common.access module
• The zaqar.common.api.api module
• The zaqar.common.api.errors module
• The zaqar.common.api.request module
• The zaqar.common.api.response module
• The zaqar.common.api.schemas.flavors module
• The zaqar.common.api.schemas.pools module
• The zaqar.common.api.utils module
• The zaqar.common.cli module
• The zaqar.common.configs module
• The zaqar.common.decorators module
• The zaqar.common.errors module
• The zaqar.common.pipeline module
• The zaqar.common.storage.select module
• The zaqar.common.transport.wsgi.helpers module
• The zaqar.common.urls module
• The zaqar.common.utils module
• The zaqar.context module
• The zaqar.i18n module
• The zaqar.notification.notifier module
• The zaqar.notification.tasks.mailto module
• The zaqar.notification.tasks.webhook module
• The zaqar.storage.base module
• The zaqar.storage.errors module
• The zaqar.storage.mongodb.catalogue module
• The zaqar.storage.mongodb.claims module
• The zaqar.storage.mongodb.controllers module
• The zaqar.storage.mongodb.driver module
• The zaqar.storage.mongodb.flavors module
• The zaqar.storage.mongodb.messages module
• The zaqar.storage.mongodb.options module
• The zaqar.storage.mongodb.pools module
• The zaqar.storage.mongodb.queues module
• The zaqar.storage.mongodb.subscriptions module
• The zaqar.storage.mongodb.utils module
• The zaqar.storage.pipeline module
• The zaqar.storage.pooling module
• The zaqar.storage.redis.claims module
• The zaqar.storage.redis.controllers module
• The zaqar.storage.redis.driver module
• The zaqar.storage.redis.messages module
• The zaqar.storage.redis.models module
• The zaqar.storage.redis.options module
• The zaqar.storage.redis.queues module
• The zaqar.storage.redis.scripting module
• The zaqar.storage.redis.subscriptions module
• The zaqar.storage.redis.utils module
• The zaqar.storage.sqlalchemy.catalogue module
• The zaqar.storage.sqlalchemy.controllers module
• The zaqar.storage.sqlalchemy.driver module
• The zaqar.storage.sqlalchemy.options module
• The zaqar.storage.sqlalchemy.pools module
• The zaqar.storage.sqlalchemy.queues module
• The zaqar.storage.sqlalchemy.tables module
• The zaqar.storage.sqlalchemy.utils module
• The zaqar.storage.utils module
• The zaqar.transport.auth module
• The zaqar.transport.base module
• The zaqar.transport.utils module
• The zaqar.transport.validation module
• The zaqar.transport.websocket.driver module
• The zaqar.transport.websocket.factory module
• The zaqar.transport.websocket.protocol module
• The zaqar.transport.wsgi.driver module
• The zaqar.transport.wsgi.errors module
• The zaqar.transport.wsgi.utils module
• The zaqar.transport.wsgi.v1_0.claims module
• The zaqar.transport.wsgi.v1_0.health module
• The zaqar.transport.wsgi.v1_0.homedoc module
• The zaqar.transport.wsgi.v1_0.messages module
• The zaqar.transport.wsgi.v1_0.metadata module
• The zaqar.transport.wsgi.v1_0.pools module
• The zaqar.transport.wsgi.v1_0.queues module
• The zaqar.transport.wsgi.v1_0.stats module
• The zaqar.transport.wsgi.v1_1.claims module
• The zaqar.transport.wsgi.v1_1.flavors module
• The zaqar.transport.wsgi.v1_1.health module
• The zaqar.transport.wsgi.v1_1.homedoc module
• The zaqar.transport.wsgi.v1_1.messages module
• The zaqar.transport.wsgi.v1_1.ping module
• The zaqar.transport.wsgi.v1_1.pools module
• The zaqar.transport.wsgi.v1_1.queues module
• The zaqar.transport.wsgi.v1_1.stats module
• The zaqar.transport.wsgi.v2_0.claims module
• The zaqar.transport.wsgi.v2_0.flavors module
• The zaqar.transport.wsgi.v2_0.health module
• The zaqar.transport.wsgi.v2_0.homedoc module
• The zaqar.transport.wsgi.v2_0.messages module
• The zaqar.transport.wsgi.v2_0.ping module
• The zaqar.transport.wsgi.v2_0.pools module
• The zaqar.transport.wsgi.v2_0.queues module
• The zaqar.transport.wsgi.v2_0.stats module
• The zaqar.transport.wsgi.v2_0.subscriptions module
• The zaqar.transport.wsgi.v2_0.urls module
• The zaqar.transport.wsgi.version module
• The zaqar.version module

Indices and tables

• Index
• Module Index
• Search Page