ISSN : 1796-217X
Volume : 1    Issue : 1    Date : July 2006

Semantics and Extensions of WS-Agreement
Ganna Frankova, Daniela Malfatti, and Marco Aiello
Page(s): 23-31
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When having repeated interactions with a service provider, a service consumer might desire
guarantees on the delivery of the service. These guarantees involve both functional and
non-functional properties of the offered service over a number of invocations. When the guarantee
terms are explicitly defined in a document, we talk about a service level agreement.WS-Agreement
is an industry driven emerging protocol for the specification of agreements in the context of Web
Services. If, on the one hand, WS-Agreement defines the XML syntax for the language and protocol,
on the other hand, it gives only a vague textual overview of the intended meaning. We fill this gap by
providing a formal definition of an agreement and analyzing the possible evolutions of agreements
and their terms over an execution. As a result we identify a number of extensions which involve the
initial negotiation, the monitoring of running agreements, and the possibility of renegotiating
agreements in executions. We evaluate the proposed approach through experimentation.

Index Terms
Service-Oriented Computing, Service Level Agreement, Quality of Service, Web Services.