Aleksander Slominski, IU Extreme! Lab (Editor)
Kenneth Chiu, IU Extreme! Lab
Sriram Krishnan, IU Extreme! Lab
Copyright 2004 by Indiana University Extreme! Lab All rights reserved.
Indiana University Extreme! Lab (collectively, the "Authors") hereby grant you permission to copy and display the WS-Performance Specification, in any medium without fee or royalty, provided that you include the following on ALL copies of the WS-Performance Specification, or portions thereof, that you make:
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The WS-Performance Specification may change before final release and you are cautioned against relying on the content of this specification.
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No other rights are granted by implication, estoppel or otherwise.
This document defines a new kind of policy assertions [WS-Policy] which apply to both Web Services and other Web Services specifications.
WS-Performance is provided as-is and for review and evaluation only. IU Extreme! Lab hopes to solicit your contributions and suggestions in the near future. IU Extreme! Lab makes no warrantees or representations regarding the specifications in any manner whatsoever.
By using XML, SOAP and related standards it is possible not only to leverage WS* specifications but to compose them together. However there is important missing information not available to WS architects: what are performance implications of various specifications and their parameters. WS-Performance allows to attach such metadata to description of specifications and Web Services.
This WS-Performance Specification is an initial public draft release and is provided for review and evaluation only. IU Extreme! Lab hopes to solicit your contributions and suggestions in the near future. IU Extreme! Lab makes no warrantees or representations regarding the specification in any manner whatsover.
1.1. Notational Conventions
2. Policy Assertions for Performance
2.3. PerformanceToken Assertion
3. Security Considerations
WS-Performance provides a neutral and Web Services friendly mechanism to indicate performance characteristics of Web Services specifications.
We have noticed that one of the most important concern when composing Web Services is impact on performance of each specification. Therefore if there could be a synthetic indicator of performance impact of each specification it could help to automate estimation of composed Web Services.
Initially we considered calling this compositional effect of Web Serviced a 'slowness' factor (or simply 'WS-Slowness') but as we firmly believe Web Services performance will improve due to Moore's Law we have chosen to concentrate on positive performance outlook for Web Services.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [KEYWORDS].
When describing abstract data models, this specification uses the notational convention used by the XML Infoset [XmlInfoset].
This specification uses a number of namespace prefixes throughout; they are listed in Table 1. Note that the choice of any namespace prefix is arbitrary and not semantically significant.
Table 1 Prefixes and Namespaces used in this specification
WS-Performance is defined in terms of the XML Information Set [XmlInfoset]. WS-Performance is designed to work with general Web Services framework including WSDL service descriptions and be conformant to the SOAP 1.2 processing model; SOAP 1.2 is not a requirement for using the constructs defined in this specification. The examples in this specification use an XML 1.0 representation but this is not a requirement.
All information items defined by WS-Performance are identified by the XML namespace URI [XML-ns] "http://www.extreme.indiana.edu/xgws/schemas/2004/04/performance". A normative XML Schema document MAY be obtained by dereferencing the XML namespace URI.
We introduce following terms we use throughout this document:
The [WS-Policy] specification defines a framework to indicate a service's requirements and policies. We extend this framework to allow making statements not only about services but also about WS* service specifications.
To indicate support for this specification the following policy assertion SHOULD be used:
<wsp:SpecVersion wsp:Usage="wsp:Required" URI="http://www.extreme.indiana.edu/xgws/schemas/2004/04/performance" />
<pi:PerformanceToken> element is used to describe what are
performance indicators provided by Web Service or WS specification.
<PerformanceToken wsp:Preference="..." wsp:Usage="..." > <TokenType>...</TokenType> <TokenIssuer>...</TokenIssuer> <Claims>...Token type-specific claims...</Claims> ... (TokenType-specific details) </PerformanceToken>
The following describes the attributes and tags listed in the schema outlined above:
|pi:PeakMessagesPerSecond||Maximum number of messages that service can process
NOTE: not applicable to WS specifications
|pi:AverageTimeToProcessMessageInMs||Average time to process input message in milliseconds|
How many times slower (expressed in xsd:double) is using particular
feature when compared to some baseline|
NOTE: this is further defined by additional specification, for example we expect to have WS-Security specific set of claims to describe impact of message encryption and signing
|QName||Additional token types can easily be added|
It is strongly RECOMMENDED that policies and assertions about WS specifications will be signed by all specifications authors
It is strongly RECOMMENDED that policies and assertions about Web Services endpoints be signed by service designers and implementators.
This work was done under influence of Global XML Web Services Specification Architecture.
[KEYWORDS] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, Harvard University, March 1997
[WS-Policy] "Web Services Policy Framework", BEA, IBM, Microsoft, SAP, December 2002 (see http://msdn.microsoft.com/webservices/default.aspx?pull=/library/en-us/dnglobspec/html/ws-policy.asp )
[XmlInfoset] W3C Recommendation "XML Information Set", John Cowan, Richard Tobin, 24 October 2001 (see http://www.w3.org/TR/2001/REC-xml-infoset-20011024/ )
[XML-ns] W3C Recommendation "Namespaces in XML", Tim Bray et al., 14 January 1999 (see http://www.w3.org/TR/1999/REC-xml-names-19990114/ )