ActiveMQ: The Open Source Messaging Middleware
In this article, we will delve into the world of ActiveMQ, an open source messaging middleware that provides efficient, scalable, and secure enterprise-class messaging. Developed by the Apache Software Foundation, ActiveMQ is a standard, message-oriented, multi-language messaging middleware application integration that supports a wide range of protocols and features.
Features of ActiveMQ
ActiveMQ is designed to provide a robust and reliable messaging platform that can handle high-performance clustering, client-server, and peer communication. Its key features include:
- Multi-language support: ActiveMQ supports multiple languages, including Java, C, C++, C#, Ruby, Perl, Python, PHP, and more.
- Multiple protocols: ActiveMQ supports various protocols, such as OpenWire, Stomp, AMQP, MQTT, and more.
- Advanced features: ActiveMQ provides features like group communication, message priority, message received with a delay, virtual receivers, persistent messages, and message queue monitoring.
- JMS 1.1 and J2EE 1.4 support: ActiveMQ fully supports JMS 1.1 and J2EE 1.4 specifications, including persistence and distributed transactional messaging.
- Spring framework integration: ActiveMQ can be easily embedded into the Spring configuration file.
- Diverse connection modes: ActiveMQ provides a range of connection modes, including in-VM, TCP, SSL, NIO, UDP, multicast, JGroups, and JXTA.
Messaging Model
ActiveMQ supports two main messaging models:
- Point-to-Point (P2P): In this model, a queue is used as the communication bearer message, where producers and consumers meet mode, and a message can only be used by a consumer. The consumer is not retained until the consumer or the timeout in the queue.
- Publish-Subscribe (Pub/Sub): In this model, a message is used as a communication carrier, similar to a broadcast mode, where the publisher publishes a message, and the message is transmitted to all subscribers. The broadcast message is only received by subscribers who have subscribed to the topic.
Basic Components
When using ActiveMQ, the basic components are the same:
- Broker: The message broker represents the message queue server entity, accepts client connections, and provides the core service messaging.
- Producer: The producer is responsible for producing and transmitting messages to the broker.
- Consumer: The consumer is responsible for getting the message from the broker and processing the business logic.
- Topic: The topic is a unified collection of subscribers, where different producers send a message to the topic, and the broker distributes the message to different subscribers.
- Queue: The queue is an ad-hoc mode specific to a particular producer sends a message queue, where the queue receives the message consumers subscribe to a particular service and processing logic.
- Message: The message is the body of the message, which is defined in a fixed format according to various communication protocols for encoding data packets to achieve transmit messages.
Connector
The ActiveMQ broker provides a communication mechanism for client applications, and the connector mechanism is used to describe the connection mechanism. There are two types of connectors:
- Transport Connector: The transport connector is used to communicate with a client proxy message server (client-to-broker) between a message is used between the proxy server (broker network connector-to-broker) communication (network connector).
- Network Connector: The network connector is used to communicate between the configuration server.
Connection Protocols
ActiveMQ provides a range of connection protocols, including:
- VM: The message server allows the client to communicate directly within the VM, using the Socket connection is not connected, but the direct method is called local virtual machine, avoiding the overhead of the network.
- TCP: The client connects to the remote server through the TCP message.
- UDP: The remote client connects to the message server via UDP.
- Multicast: Allows the use of multicast transmission mode to connect to the message server.
- NIO: The role is the same as TCP, but the use of Java NIO NIO package, which may in some scenarios may provide better performance.
- SSL: Allows the user on the basis of the TCP.
- HTTP: Allows clients to use REST or Ajax way connection, which means you can send messages to ActiveMQ using JavaScript directly.
- WebSockets: Allows clients to connect to the message server via HTML5 WebSocket manner.
- AMQP: Supports since version 5.8.
- MQTT: Supports since version 5.6.
- Stomp: Supports since version 5.6.
Network Connector
ActiveMQ provides a network connector to support high-performance clustering, client-server, and peer communication. The network connector is used to communicate between the configuration server.
Message Store
JMS distribution mode specification has two messages: persistent and non-persistent. JMS implementation for non-persistent messages are required to pledge our best efforts to distribute the message, but the message is not persistent storage; and message persistence, it must distribute the persistent store.
Persistent Messages
Persistent messages are used to send messages that are not lost even if the consumer does not run the current message. These messages are stored in a persistent store, such as a database or a file system.
Non-Persistent Messages
Non-persistent messages are used to send notifications or real-time data, when you compare the value of system performance and even losing messages do not affect the alternative non-persistent messages when normal business operations.
In conclusion, ActiveMQ is a powerful and flexible messaging middleware that provides a wide range of features and protocols to support high-performance clustering, client-server, and peer communication. Its support for persistent and non-persistent messages, as well as its ability to integrate with various languages and protocols, make it an ideal choice for a wide range of applications.