Early Capacity Testing of an Enterprise Service Bus

An enterprise service-oriented architecture is typically done with a messaging infrastructure called an Enterprise Service Bus (ESB). An ESB is a bus which delivers messages from service requesters to service providers. Since it sits between the service requesters and providers, it is not appropriate to use any of the existing capacity planning methodologies for servers, such as modeling, to estimate the capacity of an ESB. There are programs that run on an ESB called mediation modules. Their functionalities vary and depend on how people use the ESB. This creates difficulties for capacity planning and performance evaluation. This article proposes a capacity planning methodology and performance evaluation techniques for ESBs, to be used in the early stages of the system development life cycle. The authors actually run the ESB on a real machine while providing a pseudo-environment around it. In order to simplify setting up the environment we provide ultra-light service requestors and service providers for the ESB under test. They show that the proposed mock environment can be set up with practical hardware resources available at the time of hardware resource assessment. Our experimental results showed that the testing results with our mock environment correspond well with the results in the real environment.

A Framework and Protocols for Service Contract Agreements Based on International Contract Law

Current protocols to agree to Web/Grid service usage do not have the capability to form negotiated agreements, nor do they take into account the legal requirements of the agreement process. This article presents a framework and a domain-independent negotiation protocol for creating legally binding contracts for service usage in a distributed, asynchronous service-oriented architecture. The negotiation protocol, which builds on a simple agreement protocol to form a multiround “symmetric” negotiation protocol, is based on an internationally recognized contract law convention. By basing our protocol on this convention and taking into account the limitations of an asynchronous messaging environment, we can form contracts between autonomous services across national and juridical boundaries, necessary in a loosely coupled, widely geographically distributed environment such as the Grid.

Issues on the Compatibility of Web Service Contracts

In the Service Oriented Architecture (SOA) model, a service is characterized by its exchange of asynchronous messages, and a service contract is a desirable composition of a variety of messages. Though this model is simple, implementing large-scale, cross-organizational distributed applications may be difficult to achieve in general, as there is no guarantee that service composition will be possible because of incompatibilities of Web service contracts. We categorize compatibility issues in Web service contracts into two broad categories: (a) between contracts of different services (which we define as a composability problem), and (b) a service contract and its implementation (which we define as a conformance problem). This chapter examines and addresses these problems, first by identifying and specifying contract compatibility conditions, and second, through the use of compatibility checking tools that enable application developers to perform checks at design time.

A Model-based Approach for Diagnosing Fault in Web Service Processes

Web services based on a service-oriented architecture framework provide a suitable technical foundation for business process management and integration. A business process can be composed of a set of Web services that belong to different companies and interact with each other by sending messages. Web service orchestration languages are defined by standard organizations to describe business processes composed of Web services. A business process can fail for many reasons, such as faulty Web services or mismatching messages. It is important to find out which Web services are responsible for a failed business process because we could penalize these Web services and exclude them from the business process in the future. In this paper, we propose a model-based approach to diagnose the faults in a Web service-composed business process. We convert a Web service orchestration language, more specifically BPEL4WS, into synchronized automata, so that we have a formal description of the topology and variable dependency of the business process. After an exception is thrown, the diagnoser can calculate the business process execution trajectory based on the formal model and the observed evolution of the business process. The faulty Web services are deduced from the variable dependency on the execution trajectory. We demonstrate our diagnosis technique with an example.

Complex Network Theory Based Web Services Composition Benchmark Toolkit

In recent years, while many research proposals have been made toward novel algorithmic solutions of a myriad of web services composition problems, their validation has been less than satisfactory. One of the reasons for this problem is the lack of real benchmark web services data with which researchers can test and verify their proposals. In this chapter, to remedy this challenge, we present a novel benchmark toolkit, WSBen, which is capable of generating synthetic web services data with diverse scenarios and configurations using complex network theory. Web services researchers therefore can evaluate their web services discovery and composition algorithms in a more systematic fashion. The development of WSBen is inspired by our preliminary study on real-world web services crawled from the Web. The proposed WSBen can: (1) generate a collection of synthetic web services files in the WSDL format conforming to diverse complex network characteristics; (2) generate queries and ground truth sets for testing discovery and composition algorithms; (3) prepare auxiliary files to help further statistical analysis; (4) convert WSDL test sets to the formats that conventional AI planners can read; and (5) provide a graphical interface to control all these functions. To illustrate the application of the WSBen, in addition, we present case studies selected from three domains: (1) web services composition; (2) AI planning; and (3) the laws of networks in Physics community. The WSBen toolkit is available at: http://pike.psu.edu/sw/wsben/. This chapter is an invited extension of authors’ previous publication (Oh & Lee, 2009).

Privacy-Preserving Trust Establishment with Web Service Enhancements

Web services are increasingly utilized in people’s daily lives to achieve various functionalities. Trustworthiness has become a critical factor for service provision and governance. The lack of effective trust establishment mechanisms impedes the deployment of diverse trust models for web services. One important issue is that collaborating organizations need mechanisms to bridge extant relationships among cooperating parties. Meanwhile, a trust establishment mechanism for web services must ensure privacy and owner control at all times due to the subjectivity of trust relationships. As an alternative and complementary approach to direct trust establishment, we describe an indirect trust establishment mechanism to bridge and build new trust relationships from extant trust relationships with privacy protection. Another issue is the lack of mechanisms that can directly establish trust relationships with privacy-preserving capabilities for web services. Current web service technologies encourage a service requester to reveal all its private attributes in a pre-packaged digital credential to the service provider to fulfill the requirements for verification. This may lead to privacy leakage. We propose a mechanism whereby the service requester discovers the service provider’s requirements from a web service policy document, then formulates a trust primitive by associating a set of attributes in a pre-packaged credential with a semantic name, signed with the requester’s digital signature, to negotiate a trust relationship. Thus the service requester’s privacy is preserved because only those attributes required to build a trust relationship are revealed.

Security for Web Services

This article discusses the main security requirements for Web services and it describes how such security requirements are addressed by standards for Web services security recently developed or under development by various standardizations bodies. Standards are reviewed according to a conceptual framework that groups them by the main functionalities they provide. Covered standards include most of the standards encompassed by the original Web Service Security roadmap proposed by Microsoft and IBM in 2002 (Microsoft and IBM 2002). They range from the ones geared toward message and conversation security and reliability to those developed for providing interoperable Single Sign On and Identity Management functions in federated organizations. The latter include Security Assertion Markup Language (SAML), WS-Policy, XACML, that is related to access control and has been recently extended with a profile for Web services access control; XKMS and WS-Trust; WS-Federation, LibertyAlliance and Shibboleth, that address the important problem of identity management in federated organizations. The article also discusses the issues related to the use of the standards and open research issues in the area of access control for Web services and innovative digital identity management techniques are outlined.

XML Data Binding for C++ Using Metadata

Mapping XML document schemas and Web Service interfaces to programming languages has an important role in effective creation of quality Web Service implementations. The authors present a novel way to map XML data to the C++ programming language. The proposed solution offers more flexibility and more compact code that makes it ideal for embedded environments. The article describes the concept and the architecture of the solution and compares it with existing solutions. This article is an extended version of the paper from ICWS 2006. The authors include a broader comparison with existing tools on Symbian and Linux platforms and evaluate the code size and performance.

Autonomous Web Services Migration in Mobile and Wireless Environments

With the emergence of powerful mobile Internet devices such as smartphones, mobile devices are expected to play the role of service providers or even brokers, as well as clients. However, the frequent mobility of devices and the intermittent disconnection of mobile and wireless network may degrade the availability and reliability of services. To resolve these problems, this paper proposes an efficient method for migrating and replicating Web services among mobile devices. Specifically, the proposed method splits the source code of a Web service into subcodes depending on users’ preferences for its constituent operations. For the seamless provisioning of services, a subcode with a higher preference is migrated earlier than others. To evaluate the performance of the proposed method, the effect of the code splitting on migration was analyzed.

An Efficient Service Discovery Method and its Application

To discover services efficiently has been regarded as one of important issues in the area of Service Oriented Computing (SOC). This article carries out a survey on the issue and points out the problems for the current semantic-based service discovery approaches. After that, an information model for registered services is proposed. Based on the model, it brings forward a two-phase semantic-based service discovery method which supports both the operation matchmaking and operation-composition matchmaking. Th authors import the bipartite graph matching to improve the efficiency of matchmaking. An implementation of the proposed method is presented. A series of experiments show that the method gains better performance on both discovery recall rate and precision than a traditional matchmaker and it also scales well with the number of services being accessed.