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In computer science, message queues and mailboxes are software-engineering components used for inter-process communication (IPC), or for inter-thread communication within the same process. They use a queue for messaging – the passing of control or of content. Group communication systems provide similar kinds of functionality. ==Overview== Message queues provide an asynchronous communications protocol, meaning that the sender and receiver of the message do not need to interact with the message queue at the same time. Messages placed onto the queue are stored until the recipient retrieves them. Message queues have implicit or explicit limits on the size of data that may be transmitted in a single message and the number of messages that may remain outstanding on the queue. Many implementations of message queues function internally: within an operating system or within an application. Such queues exist for the purposes of that system only.〔Win32 system message queues. 〕〔Linux and POSIX message queues. (Overview of POSIX message queues ) at linux.die.net〕〔Using Linux Message Queues. (Linux message queue functions ) at www.civilized.com〕 Other implementations allow the passing of messages between different computer systems, potentially connecting multiple applications and multiple operating systems.〔For example, the MSMQ product. 〕 These message queueing systems typically provide enhanced resilience functionality to ensure that messages do not get "lost" in the event of a system failure. Examples of commercial implementations of this kind of message queueing software (also known as message-oriented middleware) include IBM WebSphere MQ (formerly MQ Series) and Oracle Advanced Queuing (AQ). There is a Java standard called Java Message Service, which has several proprietary and free software implementations. Implementations exist as proprietary software, provided as a service, open source software, or a hardware-based solution. Proprietary options have the longest history, and include products from the inception of message queuing, such as IBM WebSphere MQ (formerly MQ Series), and those tied to specific operating systems, such as Microsoft Message Queuing. There are also cloud-based message queuing service options, such as Amazon Simple Queue Service (SQS), StormMQ and IronMQ. There are a number of open source choices of messaging middleware systems, including JBoss Messaging, JORAM, Apache ActiveMQ, Sun Open Message Queue, Apache Qpid,〔(Apache Qpid Project, an implementation of AMQP ).〕 RabbitMQ, Beanstalkd, Tarantool and HTTPSQS.〔(HTTPSQS, a message queue based on HTTP GET/POST protocol. )〕 In addition to open source systems, hardware-based messaging middleware exists with vendors like Solace Systems, Sonoa / Apigee and Tervela offering queuing through silicon or silicon/software datapaths. Most real-time operating systems (RTOSes), such as VxWorks and QNX, encourage the use of message queueing as the primary inter-process or inter-thread communication mechanism. The resulting tight integration between message passing and CPU scheduling is attributed as a main reason for the usability of RTOSes for real time applications. Early examples of commercial RTOSes that encouraged a message-queue basis to inter-thread communication also include VRTX and pSOS+, both of which date to the early 1980s. The Erlang programming language uses ''processes'' to provide concurrency; these processes communicate asynchronously using message queuing. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Message queue」の詳細全文を読む スポンサード リンク
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