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Join-patterns provides a way to write concurrent, parallel and distributed computer programs by message passing. Compared to the use of threads and locks, this is a high level programming model using communication constructs model to abstract the complexity of concurrent environment and to allow scalability. Its focus is on the execution of a chord between messages atomically consumed from a group of channels. This template is based on join-calculus and use pattern matching. Concretely, this is done by allowing the join definition of several functions and/or channels by matching concurrent call and messages patterns. It employs the behavioral and the concurrency pattern because it makes easier and more flexible for these entities to communicate and deal with the multi-threaded programming paradigm. == Description == The join-pattern (or a chord in Cω) is like a super pipeline with synchronisation and matching. In fact, this concept is summarise by match and join a set of message available from different message queues, then handles them all simultaneously with one handler. It could be represented by the keywords to specify the first communication that we expected, with the to join/pair other channels and the to run some tasks with the different collected messages. A constructed join pattern typically takes this form: j.When(a1).And(a2). ... .And(an).Do(d) ''Argument a1 of When(a1) may be a synchronous or asynchronous channel or an array of asynchronous channels. Each subsequent argument ai to And(ai) (for i > 1) must be an asynchronous channel.'' More precisely, when a message matches with a chain of linked patterns causes its ''handler'' to run (in a new thread if it's in asynchronous context) otherwise the message is queued until one of its patterns is enabled; if there are several matches, an unspecified pattern is selected.〔(【引用サイトリンク】title=Parallel C# )〕 ''Unlike an event handler, which services one of several alternative events at a time, in conjunction with all other handlers on that event, a join pattern waits for a conjunction of channels and competes for execution with any other enabled pattern.'' Join-pattern is defined by a set of pi-calculus channels x that supports two different operations, sending and receiving, we need two join calculus names to implement it: a channel name x for sending (a message), and a function name x for receiving a value (a request). The meaning of the join definition is that a call to x() returns a value that was sent on an channel x<>. More interestingly, is that each time functions are concurrently, triggers the return process and synchronizes with other joins. J ::= //join patterns | x | x(y) //function call pattern | J | JBIS //synchronization In most of cases, the order of synchronous calls is not guaranteed for performance reasons. Finally, during the match the messages available in the queue could be stolen by some intervening thread; indeed, the awakened thread may have to wait again. 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「Join-pattern」の詳細全文を読む スポンサード リンク
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