Frequently asked questions (FAQ)
1 What does ASAP stand for?
Asynchronous Service Access Protocol
2 What does Asynchronous mean?
ASAP uses the term asynchronous to mean that the requests and responses are not synchronized. In a synchronous exchange, the client asks A and the server answers A, client asks B and the server answers B, and so forth. In an asynchronous exchange, the client can ask A, B then C, and the server can answer B, C then A. For an asynchronous exchange to work, the client must have some means for correlating the responses to the requests. The need for asynchronous interaction arises when the server takes a long time to create its responses.
3 Why do we need asynchronous services?
Most everything on the Internet is currently based on instant gratification. A client requests a resource; if the server does not respond with the resource within 60 seconds, then the request fails. With the expansion of the Internet to electronic commerce and most notably webservices, there have arisen classes of resources that cannot be created within 60 seconds. Some of these resources take several minutes or even days to create. What we need is an ability for a webservice to respond to client, "The resource you requested is not ready yet. Where do you want me to send it when it's done?"
4 What types of webservices are asynchronous?
Any service that takes more than 60 seconds to respond is a likely asynchronous webservice. Business processes are often asynchronous, especially if they require human intervention or approval. Large data mining queries will often be asynchronous. Remote mobile devices that move in and out of coverage areas are also well suited for asynchronous webservices. Chained webservices, that is webservices that rely on other webservices, can also be asynchronous because, although each service in the chain my respond by itself in less than 60 seconds, the sum of their response times in sequence exceeds 60 seconds.
5 What is the objective of ASAP?
The objective of ASAP is to provide the minimum functionality necessary to handle an asynchronous exchange in Simple Object Access Protocol (SOAP).
6 If asynchronous services are so common, why form a separate technical committee for ASAP?
Many standards efforts face an asynchronous challenge or have an asynchronous requirement. Without ASAP, each of these standards efforts would be forced to create their own means of handling an asynchronous exchange in SOAP. There would arise a multitude of systems having a multitude of ways of accomplishing essentially the same task. Is that not what we adopted XML and SOAP to avoid? The objective of ASAP is to provide the minimum functionality necessary to handle an asynchronous exchange in SOAP that other standards efforts can employ in achieving their particular business requirements.
7 What is Wf-XML 2.0?
ASAP can be used with any kind of service – the internal workings of that service are not exposed. Wf-XML extends the protocol with additional information for the special case that the service is a BPM engine. Such engines have the property that their process can be examined by being retrieved in a standard form, such as XPDL or BPEL. It provides an interface to send new or updated process definitions to the BPM engine. Also, for any engine that implements the process as a sequence of activities, it provides a call to find out what the current activities are running, which is a finer grained indication of the status than you could get from ASAP alone.
8 What would Wf-XML be used for?
Wf-XML is an ideal way for a BPM engine to invoke a process in another BPM engine, and to wait for it to completed.
9 How can Wf-XML be used by BP Design Tools?
Wf-XML provides a standard way to retrieve a process definition from a BPM engine, and to provide an updated one to the BPM engine. A process design tool could used this standard web services based protocol to browse processes on remote BPM server. It provides an interface between such a design tool and the BPM engine; this is the traditional WfMC Interface 1 for getting and setting the process definition. There is no other effort known to be proposed for standardizing this interaction.
10 Where did ASAP and Wf-XML come from?
The roots of the current effort began in 1997 with the Internet Engineering Task Force (IETF) effot named Simple Workflow Access Protocol (SWAP) lead by Netscape, Oracle and others. SWAP was implemented by a number of commercial products. For example, an office supply company used SWAP to allow its 1300 corporate customers to order equipment over the Internet, and to allow the conclusion of the request to return some number of minutes or hours later.
The WfMC took the ideas of SWAP, and reduced the scope in order to produce a somewhat more limited, but more rigorously defined standard that became known as Wf-XML.
Because SWAP was invented before SOAP, it does not use SOAP message structures. ASAP is an effort to move the same capability to be on top of SOAP messages, and to conform to other web standards that have come into existence in the mean time. Similarly, Wf-XML 2.0 is an attempt to move the existing Wf-XML to this ASAP basis because it is based on SOAP.
More than 20 individuals have contributed to the creation of ASAP so far. The current technical committee includes individuals from Amberpoint, British Telecom, Cisco, Computer Associates, Fujitsu, Iway, Lockheed Martin, Research in Motion and The University of Hong Kong.
11 Who is sponsoring the Demonstration of Wf-XML and ASAP?
The Workflow Management Coalition (WfMC) is making the arrangements for the demonstration, and the publication of the results.
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