WS enumeration

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WS-Enumeration ( English enumeration , enumeration ') is a submitted in 2006 a proposal from the group of WS- * specifications. Since April 2011 this "Member Submission" (suggestions from members) has the status "Candidate Recommendation" (possible future standard). The WS- * specifications are industrial standards of the World Wide Web Consortium (W3C).

The aim of the specification is to standardize the block-by-block transmission of larger amounts of data. However, this involves any type of enumerable data such as the data lines of a database query or the elements of a queue . It is not necessary that the entire amount of data is transferred immediately in one go. By transmitting the data in blocks, the sender can process the next data while the receiver processes the data sent last. This overlapping preparation or processing of the data enables a higher speed to be achieved than if the data were transmitted all at once.

functionality

A data transfer between the data sink (receiver) and the data source typically takes place as follows:

  1. The data sink sends a request to the data source ( enumerate ).
  2. The data source sends back a response ( EnumerateResponse ). This also contains the so-called enumeration context ( EnumerationContext ).
  3. Based on the enumeration context, the data sink now sends one or more requests ( pull ) to the source.
  4. The data source responds to every pull request with a pull response . The item element contains the actual data, the structure and format of which is application-specific. If the element EndofSequence is contained in this PullResponse , then all data is transferred and no further pull requests for this enumeration are necessary.

There are further protocol elements, for example for a status query and the premature termination of data transmission.

Specifics and restrictions

WS-Enumeration does not determine whether the enumeration context ( EnumerationContext ) is stored by the data source or the recipient. It is also possible to change responsibility for storage with each request.

Furthermore, the WS enumeration does not determine

  • whether the data can be transferred in full,
  • in which order the data is transmitted and
  • whether the same data is returned for each request.

All of these points are application specific.

Classification in the context of WS- *

WS enumeration is based on WS addressing ; the format of the messages exchanged and the definition of the endpoints correspond to this specification. This also makes it possible for the data to be transmitted over a longer period of time. For security reasons, the use of WS-Security (encryption and signing) is also recommended. In order to avoid certain types of attacks, the specification also suggests using WS-SecureConversation and WS-SecurityPolicy . This then also makes WS policy mandatory for all participants.

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