what is synchronous web services?

what is synchronous web services?

Postby mohsinazeema » Sat Jun 16, 2012 2:57 am

what is synchronous web services?
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Re: what is synchronous web services?

Postby mohsinazeema » Tue Jun 26, 2012 9:34 pm

Synchronous services are characterized by the client invoking a service and then waiting for a response to the request.

Read the following article for further clarification

http://java.sun.com/blueprints/webservi ... rvbp3.html
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Re: what is synchronous web services?

Postby rao-h2kinfosys » Thu Dec 13, 2012 9:49 pm

No stop in synchronous communication , Data will be send from sender to receiver and get the response back same time. the client connection remains open from the time the request is submitted to the server .

In Asynchronous communication , Sender send the request and provider can send the response later time.
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Asynchronous vs. Synchronous

In a synchronous implementation of a Web Service, the client connection remains open from the time the request is submitted to the server. The client will wait until the server sends back the response message. The advantage of using the synchronous RPC communication is that the client application knows the status of the Web Service operation in a very short time (either it receives a response or it times out). A serious limitation of using synchronous messaging is that the server may have to deal with a large number of concurrent connections because each concurrent client maintains an open to connection while waiting for the results. This causes the server application to become increasingly complex. If one of the invocations to a synchronous service provider fails, the server application has to provide the mechanism to trap the failure and recover and re-route the processing or flag an error before continuing with the other synchronous invocations.

At the present time, most Web Services toolkits only support synchronous messaging by default. However, using existing standards and tools such as asynchronous message queuing frameworks, some vendors have emulated asynchronous messaging for Web Services. Several organizations, companies and the Web Services working groups have recognized the need to have asynchronous messaging support and have been moving towards defining standards (e.g. WS-ReliableMessaging).


synchronous
In the context of Web services, the term "synchronous" is used informally to describe certain message exchange patterns (MEPs).

In principle, MEPs may be arbitrarily complex, and may include various temporal relationships between messages. In practice, there is a small number of patterns for which the temporal relationships are well (if informally) understood. MEPs which describe temporally coupled or "lock-step" interactions are frequently referred to as "synchronous". Examples include RPC-style request-response interactions and some kinds of transactional exchanges. Other MEPs allow messages to be sent without precise sequencing, and these are described as "asynchronous". Examples include a flow of sensor event messages which need not be individually acknowledged, and an auction in which parties may submit bids at any time during the auction.

The terms "synchronous" and "asynchronous" are descriptive, and do not correspond precisely to properties of MEPs. Occasionally the terms may be associated with particular message transport features, such as the re-use of a session. While specific implementations may support such notions, a dependency on such a feature would violate protocol independence, and therefore be problematic.

It is also worth noting that in some computing platforms or message transport systems the terms "synchronous" and "asynchronous" are perfectly well defined. For example many APIs include "asynchronous I/O" support, and certain message-oriented middleware systems offer synchronous and asynchronous notification and delivery modes. However, Web services are defined as platform- and transport- independent, and relying on implementation-specific terms is likely to result in confusion.

Many (most?) Web services do not use published MEP's, but instead rely on more or less informal patterns and techniques. In such cases, the terms "synchronous" and "asynchronous" are sometimes used to indicate the type of informal pattern being used. They may indicate whether or not coordination and synchronization techniques such as correlation data and particular transport bindings are to be used.

In view of the informal way that the terms are used, it is recommended that documents should not rely upon the use of "synchronous" or "asynchronous" in any normative
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Re: what is synchronous web services?

Postby rao-h2kinfosys » Thu Dec 13, 2012 9:50 pm

See more in
http://www.h2kinfosys.com/forums/viewtopic.php?f=26&t=1389
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