Messaging service overview
The Message service is multi-tenant, fast, reliable, and scalable. It allows
developers to share data between distributed application components performing
different tasks, without losing messages or requiring each component to be
always available.
The service features a RESTful API and a Websocket API, which developers can
use to send messages between various components of their SaaS and mobile
applications, by using a variety of communication patterns.
Key features
The Messaging service provides the following key features:
- Choice between two communication transports. Both with Identity service
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, its firewall-friendly nature, and its 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 Identity service IDs.
- Support for several common patterns including event broadcasting, task
distribution, and point-to-point messaging.
- Component-based architecture with support for custom back ends and message
filters.
- Efficient reference implementation with an eye toward low latency and high
throughput (dependent on back end).
- Highly-available and horizontally scalable.
- Support for subscriptions to queues. Several notification types are
available:
- Email notifications
- Webhook notifications
- Websocket notifications
Layers of the Messaging service
The Messaging service has following layers:
- The transport layer (Messaging application) which can provide these APIs:
- HTTP RESTful API (via
wsgi
driver).
- Websocket API (via
websocket
driver).
- The storage layer which keeps all the data and metadata about queues and
messages. It has two sub-layers:
- The management store database (Catalog). Can be
MongoDB
database (or
MongoDB
replica-set) or SQL database.
- The message store databases (Pools). Can be
MongoDB
database (or
MongoDB
replica-set) or Redis
database.