Expeditor Developers: Messaging protocols

The micro broker supports two types of messaging for communicating with its clients and with other brokers. The first uses messages built according to the MQTT V3 protocol (details of which are publicly available, see below), while the second uses the Java Messaging Service (JMS) API specification.

Each of these methods has its own strengths and weaknesses. The following is a brief summary their features:

JMS

The micro broker JMS client provides a rich messaging interface for business applications, and contains the following functionality:

Implements the J2EE JMS 1.1 standard interfaces
Supports all of the JMS message payload types (Text, Bytes, Object, Map, Stream)
Supports both persistent and non-persistent delivery modes (equivalent to QoS2 and QoS0 for MQTT – see below)
Provides JMS constructs and transactional models
Supports synchronous and asynchronous consumers
Supports durable subscriptions
Supports JMS selectors
Supports the “No local” property
Supports the JNDI administration model
Does not support XA transactions

MQTT

The micro broker MQTT client is designed for applications that need a lightweight but functional protocol. It includes the following functionality:

Designed to support specialized embedded applications, particularly in constrained environments
Uses the MQTT pervasive messaging protocol
Supports only the publish/subscribe messaging paradigm
Supports asynchronous message delivery only
Supports retained publications
Provides a raw byte message format with no user defined header properties
Offers no support for application control of transactions, “no local” or message selectors
Provides three qualities of service (QoS) for message delivery as per the MQTT specification (see below)
Provides an optimized proprietary programming model
Implements a listener callback pattern for delivery of messages, loss of network connectivity, and so on

The JMS interface is well documented in the Sun specification. The next section provides some further information about the ADD LINK HERE MQTT protocol.