Wednesday, June 27, 2012

What Is A Messagequeue And How Is It Used?

You may have heard the term messagequeue when you were learning about the internet. But what exactly is it and how is it used? Basically, a taskqueue is an asynchronous communication protocol. Simply put, this means that when a message is sent, the sender and the receiver of the specific message don't need to work with the queue at the same time. A message is basically placed within the queue and they are stored here until the receiver of the message retrieves it. There are normally limits on the size of the data that can be sent through each message. These limits are either explicit or implicit.
There are generally also limits on the number of messages that can be outstanding within the queue. The vast majority of message queues have an internal function. They are stored within either an application or an operating system and these messages only exist for that specific system. There are other implementations for this as well, such as the java messaging service. Basically, different implementations allow for messages to be passed from one computer system to another. In doing so, the message queue connects multiple operating systems across multiple applications. These systems give greater resilience functionality. In doing so, they may sure that a message is never lost should the system fail for whatever reason. There are a number of examples of this system in practice. This software is commonly referred to as message orientated middleware. It can be found in IBM's Websphere MQ. This was previously known as the MQ series. We have already mentioned the Java messaging service standard, but there is also the Oracle Advanced Queuing service.
The service offered by Java is a free software implementation with various proprietary implementations.You could also opt for open source. There are a range of middleware systems that fit into this. For instance, JORAM, JBoss Messaging, Apache Active MQ, Apache Qpic, Sun Open Message Queue, Beanstalk'd, RabbitMQ and HTTPSQS. These are all terms you will frequently come across if you start studying internet processes.However, there is more than just an open source system. Messagequeue and other hardware based messaging middleware are becoming increasingly popular. They can be found from a range of different software vendors, such as Sonoa / Apigee, Solace Systems as well as Tervela.
These all offer queuing options through data paths that are either silicon/software or fully silicon.It is generally recommended by RTOSes that a taskqueue is used as the primary IPC. This is certainly the case with operating systems such as QNX or VxWorks. This type of queue is meant to be the primary inter-thread communication mechanism. Because of this, there is a very tight integration between the CPU scheduling and the message actually passing. This is why RTOSes is so usable in real time applications. There are some early examples of RTOSes that have been using this since inter computer communication started to become possible, dating back as far as the early 1980s.
If you want to learn more about computers and how they communicate with one another, you need to learn about messagequeue. This is the system that is used to ensure messages get to where they are supposed to be, even if the recipient is away.

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