Common use of SLA Specification‌ Clause in Contracts

SLA Specification‌. The SLA specification languages reviewed here are: (i) HQML, (ii) Web Service Level Agreement (WSLA), (iii) SLAng, (iv) Web Service Management Language (WSML), (v) Web Service Offering Language (WSOL), (vi) W3C WS-Policy (WSP), (vii) WS- Agreement, (viii) WSDM, and (ix) WS-Management The Hierarchical QoS Markup Language (HQML)24 developed at the University of Illinois in 2002, is an XML based language to enhance distributed multimedia applications on the web with QoS capabilities. The design of HQML was based on two observations: (1) the absence of a systematic QoS specification language, that can be used by distributed multimedia applications on the WWW to utilize the state-of-the-art QoS management technology; and (2) the power and popularity of XML to deliver richly structured contents on the web. HQML employs XML DTD as a schema model, which include tags such as <App>,<Configuration>,<Price>, and <PriceModel>. In order to use HQML, an associated visual QoS programming environment, called QoSTalk, has also been developed. The HQML schema is simple and it is more like a specification language for QoS management than a specification language for SLA. It is not closely tied to the use of web services. The proposed XML schema mixes the QoS metrics and price terms together. An example of using HQML for QoS specification is shown in Figure 14. < A p p n a m e = " L i v e M e d i a S t r e a m i n g " S e r v i c e P r o v i d e < C o n f i g u r a t i o n i d = " 1 0 0 " > < U s e r L e v e l Q o S > h i g h < / U s e r L e v e l Q o S > < / C o n f i g u r a t i o n > < C o n f i g u r a t i o n i d = " 1 0 1 " > < P r i c e u n i t = " $ " > 5 < / P r i c e > < U s e r L e v e l Q o S > A v e r a g e < / U e r L e v e l Q o S > < P r i c e u n i t = " $ " > 1 < / P r i c e > < P r i c e M o d e l > f l a t r a t e < / P r i c e M o d e l > < P r i c e M o d l e a lt > r fa t e < / P r i c e M o d e l > < / C o n f i g u r a t i o n > < C o n f i g u r a t i o n i d = " 2 0 0 " > < U s e r L e v e l Q o S > h i g h < / U s e r L e v e l Q o S > < P r i c e u n i t = " $ " > 2 < / P r i c e > < P r i c e M o d e l > p e r h o u r i n c r e a s e < P r i c e M o d e l > < / C o n f i g u r a t i o n > < / A p p > The Web Service Level Agreement (WSLA)25 is a specification language for service level agreements. It was proposed by IBM and version 1.0 was released in 2003. In WSLA, the structure of SLA can include: (i) Parties, (ii) Service definition, and (iii) Obligations.