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Chapter 1. Overview
Rhea is a library for developing messaging applications. It enables you to write JavaScript applications that send and receive AMQP messages.
Red Hat build of Rhea is part of AMQ Clients, a suite of messaging libraries supporting multiple languages and platforms. For information on available clients, see AMQ Clients.
Red Hat build of Rhea is based on the Rhea messaging library. For detailed API documentation, see the Rhea API reference.
1.1. Key features
- An event-driven API that simplifies integration with existing applications
- SSL/TLS for secure communication
- Flexible SASL authentication
- Automatic reconnect and failover
- Seamless conversion between AMQP and language-native data types
- Access to all the features and capabilities of AMQP 1.0
1.2. Supported standards and protocols
Red Hat build of Rhea supports the following industry-recognized standards and network protocols:
- Version 1.0 of the Advanced Message Queueing Protocol (AMQP)
- Versions 1.0, 1.1, 1.2, and 1.3 of the Transport Layer Security (TLS) protocol, the successor to SSL
- Simple Authentication and Security Layer (SASL) mechanisms ANONYMOUS, PLAIN, and EXTERNAL
- Modern TCP with IPv6
1.3. Supported configurations
Refer to Red Hat AMQ Supported Configurations on the Red Hat Customer Portal for current information regarding Red Hat build of Rhea supported configurations.
1.4. Terms and concepts
This section introduces the core API entities and describes how they operate together.
| Entity | Description |
|---|---|
| Container | A top-level container of connections. |
| Connection | A channel for communication between two peers on a network. It contains sessions. |
| Session | A context for sending and receiving messages. It contains senders and receivers. |
| Sender | A channel for sending messages to a target. It has a target. |
| Receiver | A channel for receiving messages from a source. It has a source. |
| Source | A named point of origin for messages. |
| Target | A named destination for messages. |
| Message | An application-specific piece of information. |
| Delivery | A message transfer. |
Red Hat build of Rhea sends and receives messages. Messages are transferred between connected peers over senders and receivers. Senders and receivers are established over sessions. Sessions are established over connections. Connections are established between two uniquely identified containers. Though a connection can have multiple sessions, often this is not needed. The API allows you to ignore sessions unless you require them.
A sending peer creates a sender to send messages. The sender has a target that identifies a queue or topic at the remote peer. A receiving peer creates a receiver to receive messages. The receiver has a source that identifies a queue or topic at the remote peer.
The sending of a message is called a delivery. The message is the content sent, including all metadata such as headers and annotations. The delivery is the protocol exchange associated with the transfer of that content.
To indicate that a delivery is complete, either the sender or the receiver settles it. When the other side learns that it has been settled, it will no longer communicate about that delivery. The receiver can also indicate whether it accepts or rejects the message.
1.5. Document conventions
The sudo command
In this document, sudo is used for any command that requires root privileges. Exercise caution when using sudo because any changes can affect the entire system. For more information about sudo, see Using the sudo command.
File paths
In this document, all file paths are valid for Linux, UNIX, and similar operating systems (for example, /home/andrea). On Microsoft Windows, you must use the equivalent Windows paths (for example, C:\Users\andrea).
Variable text
This document contains code blocks with variables that you must replace with values specific to your environment. Variable text is enclosed in arrow braces and styled as italic monospace. For example, in the following command, replace <project-dir> with the value for your environment:
$ cd <project-dir>