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ISBN: 978-972-8939-25-0 © 2010 IADIS“encryption” specific provided encryption standards are given as a value set (discrete). TypeOfValue (tov)gives the data type of the values like String, Integer or Boolean. Additional information or extensions can bedefined in info. For assembling the decision matrix a parameter priority and value preference are introducedaccording to [Chun03]. The priority prio(p i ) of the parameter p i defines the weighting of p i in relation to theother parameters p 1 ,...,p n . The preference pref(v pi ) defines the degree of importance for v pi compared to theother possible values for p i. Figure 2 illustrates the representation of parameter constraints. The ConstraintListcontains a list of all parameters (constraints) with its appropriate priority, the meta-information tuple and thevalue set with the preferences.Figure 2. Overview of the representation model for user preferencesThis representation (Figure 2) of the user preferences is defined as an XML schema and can extend or beembedded into different SLA languages. WS-Agreement e.g. defines in wsag:Template awsag:CreationConstraints section with the free form element wsag:Constraint. This can be used to embed theprovider preferences. In the drafted extension of WSAG, WS-Agreement Negotiation [wsag-neg], a wsagneg:NegotiationConstraintssection with the same type as wsag:CreationConstraint will be defined and givesthe consumer a possibility to provide their constraints to the negotiation partner.shows an example, where two parameters ‘Response_Time’ and ‘Support_Language’ are defined in aWSAG-Template....Support_LanguageISO639-1Response_TimePROVIDERsecDISCRETEPROVIDERSTRINGCONTINUOUSINTEGER´ ende10fr1The parameter ‘Support_Language’ gives three alternatives, whereas “en” (English) is the most preferred.Listing 1. Excerpt of a WS-Agreement Template with embedded user preferences284