Anna Ruokonen

Pattern-based variability management in Web service development

Application frameworks are widely used in software engineering to support reuse by capturing the shared architecture among a family of applications. Their role in Web service construction has, however, been mostly ignored. Reuse in general has rather been considered in the context of Web service composition than as a means to use existing implementations to build new services with related functionality. In this paper we discuss reuse in Web service development, focusing on families of Web services that share a common architecture and a set of functionalities. Techniques supporting reuse rely on identifying and managing variation points. We propose a categorization of possible variation points in service endpoints, WSDI descriptions, and business logic. A pattern-based approach for managing variation and specifying a Web service framework to an actual service application is introduced. The approach is applied to specify a sample Web service framework.

Modeling a composite RESTful web service with UML

The process of web service composition involves different partner web services that are published over the internet. The Representational-State Transfer (REST) web services adopt different architectural style compared to Remote Procedure Call (RPC) web services. In this paper, we address these differences in the context of web service compositions and motivate the need for new designing techniques that lead to RESTful interfaces. We provide a UML based modeling approach for the composition of RESTful web services that models the composition for its static and behavioral features. These models provide RESTful compositions by construction, serve as a part of specification document, have mapping to several web implementation languages and can also be used to validate a RESTful composition. We illustrate the applicability of the approach with a sample Hotel and Flight booking RESTful composite web service.

Update Propagation Practices in Highly Reusable Open Source Components

In today’s business and software arena, more and more companies are adopting open source software. An example of this rising phenomenon is to base software products on highly reusable open source components. In this scenario, the evolution of the software product is coupled with the evolution of the open source component. A common assumption is that component updates are immediately and regularly propagated to the project. This paper investigates this assumption empirically by studying update propagation practices in two popular open source libraries, zlib and FFmpeg. For each library, we analyze various repository sources with information such as bug reports, revision history, and source code. The results of the case studies suggest that update propagation is subject to several technical and non-technical factors including the way the open source library is used, the extent to which updates are documented, and the degree of community involvement. Based on these findings, we propose a set of recommendations that would allow better follow-up of updates and smoother update propagation.

Modeling and Generating Mobile Business Processes

A mobile business process is a special case of a business process where most of the human interaction is done using mobile devices. In this paper, we propose UML-based support for developing such mobile business processes. Here, the business process is first modeled using UML. Then the process model is translated into a BPEL description, which can be run in mobile and/or network-based workflow engines. We propose rules to guide modeling of mobile business processes, to import existing WSDL decriptions into UML models, and to generate executable BPEL descriptions with appropriate WSDL definitions. In addition, we introduce our implementation of the approach. The practical applicability is demonstrated by designing a group messaging process. It provides a customizable mobile device based communication service offering a business case for mobile operators.

Variation Needs in Service-Based Systems

Even though service-orientation has been widely applied, there still is a lack of systematic and tool independent development methods. Partly due to that, little attention has been paid to accounting for variation. When developing a service-based system, it is important to identify which types of variation are relevant for the project and when is the right time to model them. If the variation needs are not recognized or they are ignored, it may hinder applicability and reuse and results in inflexible systems. If they are considered too late, it may require a lot of redecisions and rework. In this paper we explore variation needs in terms of the development process of service-based systems. This study results in a categorization of variation in service-based systems. We illustrate the categorization in a small example in telecommunication area.

Trust issues in open source software development

Open source software and the associated development model holds great promise, but the issue of trust is a major challenge. This applies to companies wishing to adopt the open source model but also within open source projects. We investigate this issue by data mining open source repositories to study two related phenomena: update propagation and distributed version control.

On Model-Driven Development of Mobile Business Processes

Web services are becoming an integral part of service and workflow systems even within mobile devices. A mobile business process is a special case of a business process where most of the human interaction is performed using mobile devices. Mobile business processes should be adaptable to different mobile devices and to support user interaction with different client applications. Requirements coming from mobility of devices addresses new challenges and interaction models to business process modeling and development. A proper tool support for process development is needed. Furthermore, while mobile business processes emphasize user interaction, a development process should support also creation of user interfaces based on process descriptions. In this paper, we identify characteristics of mobile business processes and propose a model-driven development (MDD) approach, which allows customization of user interfaces.

Scenario-Driven Approach for Business Process Modeling

The development of services-based systems starts from defining goals for business processes to be implemented, e.g., as a Web service orchestrations specified in WS-BPEL. In this paper, we propose a scenario-driven approach for modeling business processes. We aim for simplicity in the notation and leverage example-like modeling principles in order to improve process sketching. The first step in our approach is to identify the essential business requirements and model them using a simple scenario notation. The scenarios, given as UML sequence diagrams, are synthesized into a state machine, which is translated into a WS-BPEL flavored process skeleton given as UML activity diagram. The process skeleton can be further refined into executable process model.

Scenario-driven approach for business process development

The development of services-based systems starts from defining business requirements to be implemented as high-level business processes. In this paper, we describe a scenario-driven approach for developing business processes specified as WS-BPEL descriptions. We aim for simplicity in the business level notation and leverage example-like modelling principles in order to enable process sketching. The first step in our approach is to identify the essential functional requirements for business processes. The requirements are modelled as simple scenarios, each of them defining a sample run through the process, i.e., required behaviour that the underlying service-based system should allow. The scenarios, specifying sent and received messages among the services, are synthesised into a state machine. The state machine is transformed into an initial process model given in UML activity model notation. To enable mapping into WS-BPEL code, the transformation exploit domain-specific rules, i.e., our target model consi...

Service composition for end-users

RESTful services are becoming a popular technology for providing and consuming cloud services. The idea of cloud computing is based on on-demand services and their agile usage. This implies that also personal service compositions and workflows should be supported. Some approaches for RESTful service compositions have been proposed. In practice, such compositions typically present mashup applications, which are composed in an ad-hoc manner. In addition, such approaches and tools are mainly targeted for programmers rather than end-users. In this paper, a user-driven approach for reusable RESTful service compositions is presented. Such compositions can be executed once or they can be configured to be executed repeatedly, for example, to get newest updates from a service once a week.