1. Introduction   Web Services Agreement          Jan 2004
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Current specification of WS-Agreement defines only a generic
term with usage and negotiability attributes that are used
by the negotiation protocol. The generic WS-Agreement term
type can be extended for specific use of agreement terms.
Hence, it is left as an exercise for defining guarantee terms,
which are rather fundamental in an agreement specification.
The current document provides mechanisms for defining guarantee
terms.


The primary motivation for creating a service agreement
between a provider and an agreement initiator is to provide
assurance to the agreement initiator on the service quality
and/or resource availability by the provider. For example,
it may provide assurance on the bounds on service response
time and availability. Alternatively, it may provide assurance
on the availability of minimum resources such as memory,
CPU MIPS, storage, etc. These bounds are referred to as
service level objectives. An expression of assurance also
includes qualifying conditions on external factors such as
time of the day as well as the conditions that a service
client must meet. For example, bound on response time is
assured only if client request rate is below a specified
threshold during weekdays.


An assurance also includes strength
of this commitment by the provider, referred
to as a business value. This may include the importance
of this assurance to the agreement initiator and/or
provider’s confidence in meeting this assurance. In
business SLAs, this importance to agreement initiator,
and a measure of provider’s confidence, is indirectly
expressed by specifying the consequences of not meeting
this guarantee. Here, each violation of a guarantee
term will incur a certain penalty.


Expression of guarantee terms, i.e., business value in meeting
certain assurances and flexible specification of client
requirements also free a provider from fixed allocation
of resources. A provider dynamically allocates resources
based on actual measured or estimated client requirements,
and evaluation of business value. For example, a new
arrival of a high priority job may result in reduction
of allocated resources or suspension of an existing
low priority job.


1.1 Goals and Requirements

1.1.1 Requirements The goal of WS-Agreement guarantee
term specification is to provide the mechanisms
needed to enable Web Services applications to
specify agreement terms expressing guarantee
semantics irrespective of resource or service
definition language. Specifically, this specification
extends the definition of agreement term to specify
three essential parts in expressing a guarantee:


Conditions under which a specific guarantee is to be
observed,

Service level objective expressed as
conditions over the attributes of the service,

Business value or importance associated with meeting this guarantee


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