iAgree Studio: A Platform to Edit and Validate WS-Agreement Documents

The widespread use of SLA-regulated Cloud services, in which the violation of SLA terms may imply a penalty for the parties, have increased the importance and complexity of systems supporting the SLA lifecycle. Although these systems can be very different from each other, ranging from service monitoring platforms to auto-scaling solutions according to SLAs, they all share the need of having machine-processable and semantically valid SLAs. In this paper we present iAgree studio, the first application, up to our knowledge, that is able to edit and semantically validate agreement documents that are compliant with the WS–Agreement specification by checking properties such as its consistency, and the compliance between templates and agreement offers. In addition, it reports explanations when documents are not valid. Moreover, it allows users to combine the validation and explanation operations by means of a scenarios developer. 1 Overview and Motivation SLAs are widely used nowadays as a means to regulate the terms and conditions under which a service is provided. As the use of SLAs in Cloud services and applications in which the violation of SLA terms may imply a penalty for the parties increases, the complexity and demand of systems supporting the SLA lifecycle also increases. These systems include service monitoring platforms that use SLAs to decide which service metrics should be monitored, auto-scaling solutions that automates the provisioning or deprovisioning of resources according to the SLA, and billing components that calculate the penalties incurred during the use of a service, amongst others. Although very different from each other, all of these systems require having semantically valid SLAs (i.e., without semantic errors) and defined in a machine processable manner. WS–Agreement [1] is arguably the most widespread recommendation for defining machine processable SLAs. It specifies a template-based agreement creation protocol and an XML Schema that defines the basic structure of an SLA and the other documents used in the agreement creation protocol like agreement templates and agreement offers. However, WS–Agreement leaves open how the different elements of a WS–Agreement document such as a Service Level Objective (SLO) must be specified. ? This work was partially supported by the European Commission (FEDER), the Spanish and the Andalusian R&D&I programmes (grants TIN2009–07366 (SETI), TIN2012–32273 (TAPAS), TIC–5906 (THEOS)).