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xDSL. It is yet to be extended to application and content services like web-hosting etc.
But, this scheme is quite generic and is not precise. It can only serve as a guideline to
serve a particular need or a particular situation wherein the entire mapping mechanism
would need to be reworked.
B. QoS Specification Languages
Most research in the QoS specification deal only with QoS specification at the
application level and had little to do with the SLA to QoS mapping. People have
come up with langauges with QML, HQML, CQML etc which specifies QoS at the
application level and then the applications above interact to ensure that the QoS is met or
not. The following example tries to make this clear.
Say, a client which has its QoS requirements specified in QML requests for a
particular service from a server which may or may not be capable of providing it the
required service. Thus, they interact say in the CORBA environment and fulfil the request.
These have little to do with the co-relation with the network performance metrics.
[LSE03] comes with a language SLAng, a language for SLA (service level
agreements) which describes the proper syntax for SLA. These people say that SLA can be
of 2 kinds : vertical and horizontal. Horizontal SLAs are the ones at one of the following
levels: 1. Application level. 2. Container level. 3. Network level. And then there are
vertical SLAs which maps the SLAs vertically which clearly is also our objective. But, he
just came with the way to represent SLAs starting from SLS (Service level
specification) of the Tequila engineering work.
C. Aquila Mapping Scheme
The application level services which are specified by the user through a browser
specifying a application level profile in XML created by Aquila group. This partial
information is then mapped to servicecomponent profile (again in XML) which are
detailed requirements of the resources that we need to reservce from the network.
The mapping is static meaning the classfication of network services as is done
above in above 5 categories is sufficient to meet almost all application level
requirements. And for any given application requirement, we map it to one of these
services that most closely meet its requirement.
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