Request-response
Encyclopedia
Request-response or request-reply is one of the basic methods computers use to talk to each other. When using request-response, the first computer requests some data and the second computer responds to the request. Usually there is a series of such interchanges until the complete message is sent. Browsing a web page is an example of request-response communication. One can think of request-response as being like a telephone call, where you call someone and they answer the call. Compare this with one-way computer communication, which is like the push-to-talk or "barge in" feature found on some phones and two-way radios, where a message is sent without waiting for a response. Sending an email is an example of one-way communication.
in which a requestor sends a request message to a replier system which receives and processes the request, ultimately returning a message in response. This is a simple, but powerful messaging pattern which allows two applications to have a two-way conversation with one another over a channel. This pattern is especially common in client-server architectures.
For simplicity's sake, this pattern is typically implemented in a purely synchronous fashion, as in web service
calls over HTTP, which holds a connection open and waits until the response is delivered or the timeout
period expires. However, request-response may also be implemented asynchronously
, with a response being returned at some unknown later time. This is often referred to as "sync over async", or "sync/async", and is common in enterprise application integration
(EAI) implementations where slow aggregations
, time-intensive functions, or human workflow
must be performed before a response can be constructed and delivered.
Technical details
Request-response, also known as request-reply, is a message exchange patternMessage Exchange Pattern
In software architecture, a messaging pattern is a network-oriented architectural pattern which describes how two different parts of a message passing system connect and communicate with each other....
in which a requestor sends a request message to a replier system which receives and processes the request, ultimately returning a message in response. This is a simple, but powerful messaging pattern which allows two applications to have a two-way conversation with one another over a channel. This pattern is especially common in client-server architectures.
For simplicity's sake, this pattern is typically implemented in a purely synchronous fashion, as in web service
Web service
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
calls over HTTP, which holds a connection open and waits until the response is delivered or the timeout
Timeout (telecommunication)
In telecommunication and related engineering , the term timeout or time-out has several meanings, including...
period expires. However, request-response may also be implemented asynchronously
Asynchronous communication
In telecommunications, asynchronous communication is transmission of data without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream. Any timing required to recover data from the communication symbols is encoded within the symbols...
, with a response being returned at some unknown later time. This is often referred to as "sync over async", or "sync/async", and is common in enterprise application integration
Enterprise application integration
Enterprise Application Integration is defined as the use of software and computer systems architectural principles to integrate a set of enterprise computer applications.- Overview :...
(EAI) implementations where slow aggregations
Aggregate function
In computer science, an aggregate function is a function where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning or measurement such as a set, a bag or a list....
, time-intensive functions, or human workflow
Workflow
A workflow consists of a sequence of connected steps. It is a depiction of a sequence of operations, declared as work of a person, a group of persons, an organization of staff, or one or more simple or complex mechanisms. Workflow may be seen as any abstraction of real work...
must be performed before a response can be constructed and delivered.