96 lines
3.7 KiB
ReStructuredText
96 lines
3.7 KiB
ReStructuredText
===============
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Message service
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===============
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.. toctree::
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:maxdepth: 1
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message/zaqar-conf.rst
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message/api.rst
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message/zaqar-drivers.rst
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message/zaqar-storage-drivers.rst
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message/zaqar-transport-drivers.rst
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message/zaqar-notifications.rst
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message/zaqar-authentication.rst
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message/zaqar-pooling.rst
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message/logs.rst
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tables/conf-changes/zaqar.rst
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The Message service is multi-tenant, fast, reliable, and scalable. It allows
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developers to share data between distributed application components performing
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different tasks, without losing messages or requiring each component to be
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always available.
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The service features a RESTful API, which developers can use to send messages
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between various components of their SaaS and mobile applications, by using a
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variety of communication patterns.
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Key features
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~~~~~~~~~~~~
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The Message service provides the following key features:
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* Choice between two communication transports. Both with Identity service
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support:
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* Firewall-friendly, **HTTP-based RESTful API**. Many of today's developers
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prefer a more web-friendly HTTP API. They value the simplicity and
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transparency of the protocol, its firewall-friendly nature, and its huge
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ecosystem of tools, load balancers and proxies. In addition, cloud
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operators appreciate the scalability aspects of the REST architectural
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style.
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* **Websocket-based API** for persistent connections. Websocket protocol
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provides communication over persistent connections. Unlike HTTP, where
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new connections are opened for each request/response pair, Websocket can
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transfer multiple requests/responses over single TCP connection. It saves
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much network traffic and minimizes delays.
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* Multi-tenant queues based on Identity service IDs.
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* Support for several common patterns including event broadcasting, task
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distribution, and point-to-point messaging.
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* Component-based architecture with support for custom back ends and message
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filters.
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* Efficient reference implementation with an eye toward low latency and high
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throughput (dependent on back end).
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* Highly available and horizontally scalable.
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* Support for subscriptions to queues. Several notification types are
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available:
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* Email notifications.
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* Webhook notifications.
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* Websocket notifications.
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Components
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~~~~~~~~~~
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The Message service contains the following components:
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* **Transport back end**. The Message service requires the selection of a
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transport specification responsible of the communication between the
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endpoints. In addition to the base driver implementation, the Message
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service also provides the means to add support for other transport
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mechanisms. The default option is WSGI.
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* **Storage back end**. The Message service depends on a storage engine for
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message persistence. In addition to the base driver implementation, the
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Message service also provides the means to add support for other storage
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solutions. The default storage option is MongoDB.
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To configure your Message service installation, you must define configuration
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options in these files:
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* ``zaqar.conf``. Contains most of the Message service configuration options.
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Resides in the ``/etc/zaqar`` directory. If there is a file ``zaqar.conf``
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in ``~/.zaqar`` directory, it is used instead of the one in ``/etc/zaqar``
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directory.
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* ``policy.json``. Contains RBAC policy for all actions. Only applies to API
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v2. Resides in the ``/etc/zaqar`` directory. If there is a file
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``policy.json`` in ``~/.zaqar`` directory, it is used instead of the one in
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``/etc/zaqar`` directory. See :doc:`../policy-json-file`.
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.. note::
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The common configurations for shared service and libraries,
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such as database connections and RPC messaging,
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are described at :doc:`common-configurations`.
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