Future Internet_**2012**, \(4\), 92-109; doi:10.3390/fi4010092  
_future internet_  
**ISSN 1999-5903**  
www.mdpi.com/journal/futureinternet  
_Article_  
**Web Service Assurance: The Notion and the Issues**  
**[PERSON] \({}^{1}\), [PERSON] \({}^{1}\), [PERSON] \({}^{1}\), [PERSON] \({}^{1,\star}\), [PERSON] \({}^{2}\) and [PERSON] \({}^{2}\)**  
\({}^{1}\) Dipartimento di Tecnologie dell'Informazione, Universita degli Studi di Milano, via Bramante 65-26013 Crema (CR), Italy; E-Mails: [PERSON]] (M.A. ); [PERSON] (C.A.A. ); [EMAIL_ADDRESS] (E.D.) \({}^{2}\) Department of Computer Science, University of Victoria, STN CSC, Victoria, BC V8W 3P6, Canada; E-Mails: [EMAIL_ADDRESS] (H.A.M. ); [EMAIL_ADDRESS] (A.P.) \({}^{\star}\) Author to whom correspondence should be addressed; E-Mail: [EMAIL_ADDRESS]; Tel. : +39-0373-898064; Fax: +39-0373-898010. _Received: 21 December 2011; in revised form: 16 January 2012 / Accepted: 3 February 2012 / Published: 14 February 2012_  
**Abstract:** Web service technology provides basic infrastructure for deploying collaborative business processes. Web Service security standards and protocols aim to provide secure communication and conversation between service providers and consumers. Still, for a client calling a Web service it is difficult to ascertain that a particular service instance satisfies--at execution time--specific non-functional properties. In this paper we introduce the notion of certified Web service assurance, characterizing how service consumers can specify the set of security properties that a service should satisfy. Also, we illustrate a mechanism to re-check non-functional properties when the execution context changes. To this end, we introduce the concept of _context-aware certificate_, and describe a dynamic, context-aware service discovery environment. **Keywords:** assurance; context-aware service certification; service discovery; service security; web service certification Introduction  
The goal of software assurance is to provide to software purchasers and users the justifiable confidence that the software will consistently exhibit some desired non-functional properties, including security-related ones. The expanding portfolio of Web services available over the global network has the welcome effect of enabling on-the-fly service selection, but at the cost of increased security and reliability risks with respect to ordinary components--off-the-shelf or developed in-house. For this reason, a number of assurance tools have been proposed, aimed at monitoring the delivery of Web Services and remotely diagnosing and resolving Web Service issues. Generally speaking, assurance tools consolidate and correlate the measurements of some aspects of the Quality of Experience (QoE) perceived by a Web service user. Such measurements are then stored into a database for further processing, including data analysis and visualization. Today, most commercial Web service engines, a.k.a. _containers_, such as WSO2 ([[http://wso2.com](http://wso2.com)]([http://wso2.com](http://wso2.com))), IBM WebSphere ([[http://www.ibm.com/software/websphere](http://www.ibm.com/software/websphere)]([http://www.ibm.com/software/websphere](http://www.ibm.com/software/websphere))), OpenESB ([[http://java.net/projects/openesb](http://java.net/projects/openesb)]([http://java.net/projects/openesb](http://java.net/projects/openesb))), Apache AXIS2 ([[http://axis.apache.org/axis2](http://axis.apache.org/axis2)]([http://axis.apache.org/axis2](http://axis.apache.org/axis2))), Glassfish Metro ([[http://metro.java.net](http://metro.java.net)]([http://metro.java.net](http://metro.java.net))) support Web service assurance in some way. Security assurance, that is, assurance aimed at monitoring security and dependability properties, is a less established subject. Well-known Web security standards, such as the WS-* stack [1], implement secure transactions, conversation, and access control systems.