G. R. Gangadharan

Modeling the Mashup Ecosystem: Structure and Growth

Mashups combine data and services provided by third parties through open APIs (such as Google Maps and Flickr), as well as internal data sources owned by users. The creation of mashups is supported by a complex ecosystem of interconnected data providers, mashup platforms, and users. In this paper, we examine the structure of the mashup ecosystem and its growth over time. Several observations follow from our analysis. First, we can conclude that while the number of new APIs and mashups over time follows a linear growth pattern, the distribution of mashups over APIs is not uniform but follows a power law. This implies that a small number of APIs provides the basis for the majority of mashups, and the other APIs are only used in certain application niches. Second, our analysis suggests that mashup platforms were introduced in response to the increasing complexity of mashups, as mashups evolved from one-feature mashups (widgets). Third, we observe that complementary relationships between open APIs are formed based on the position of the APIs in the ecosystem. The propensity of two APIs to be used together in the same mashup depends on the existing number of mashups to which they both contribute. The growth of the mashup ecosystem follows a pattern where keystone data providers or ‘powerful hubs’ attract niche data providers as complementors, and the positions of keystones in the ecosystem are mutually reinforcing.

Service License Composition and Compatibility Analysis

Services enable the transformation of the World Wide Web as distributed interoperable systems interacting beyond organizational boundaries. Service licensing enables broader usage of services and a means for designing business strategies and relationships. A service license describes the terms and conditions for the use and access of the service in a machine interpretable way that services could be able to understand. Service-based applications are largely grounded on composition of independent services. In that scenario, license compatibility is a complex issue, requiring careful attention before attempting to merge licenses. The permissions and the prohibitions imposed by the licenses of services would deeply impact the composition. Thus, service licensing requires a comprehensive analysis on composition of these rights and requirements conforming to the nature of operations performed and compensation of services used in composition. In this paper, we analyze the compatibility of service license by describing a matchmaking algorithm. Further, we illustrate the composability of service licenses by creating a composite service license, that is compatible with the licenses being composed.

Computational Intelligence Based QoS-Aware Web Service Composition: A Systematic Literature Review

Web service composition concerns the building of new value added services by integrating the sets of existing web services. Due to the seamless proliferation of web services, it becomes difficult to find a suitable web service that satisfies the requirements of users during web service composition. This paper systematically reviews existing research on QoS-aware web service composition using computational intelligence techniques (published between 2005 and 2015). This paper develops a classification of research approaches on computational intelligence based QoS-aware web service composition and describes future research directions in this area. In particular, the results of this study confirms that new meta-heuristic algorithms have not yet been applied for solving QoS-aware web services composition.

Data contracts for cloud-based data marketplaces

Currently, rich and diverse data types have been increasingly provided using the data-as-a-service (DaaS) model, a form of cloud computing services and the core element of data marketplaces. This facilitates the on-the-fly data composition and utilisation for several dataintensive applications in e-science and business domains. However, data offered by DaaS are constrained by several data concerns that, if not automatically being reasoned properly, will lead to a wrong way of using them. In this paper, we support the view that data concerns should be explicitly modelled and specified in data contracts to support concern-aware data selection and utilisation. We perform a detailed analysis of current techniques for data contracts in the cloud. Instead of relying on a specific representation of data contracts, we introduce an abstract model for data contracts that can be used to build different types of data contracts for specific types of data. Based on the abstract model, we propose several techniques for evaluating data contracts that can be integrated into data service selection and composition frameworks. We also illustrate our approach with some real-world scenarios and show how data contracts can be integrated into data agreement exchange services in the cloud.

On Analyzing and Developing Data Contracts in Cloud-Based Data Marketplaces

Currently, rich and diverse data types have been increasingly provided using the Data-as-a-Service (DaaS) model, a form of cloud computing services. However, data offered by DaaS are constrained by several data concerns that, if not automatically being reasoned properly, will lead to a wrong way of using them. In this paper, we support the assumption that data concerns should be explicitly modeled and specified in data contracts to support concern-aware data selection and utilization. Instead of relying on a specific definition of data contracts, we analyze contemporary data contracts and we present an abstract model for data contracts. Based on the abstract model, we propose several techniques for evaluating data contracts that can be integrated into data service selection and composition frameworks. We also illustrate our approach with some real world scenarios.

Managing license compliance in free and open source software development

License compliance in Free and Open Source Software development is a significant issue today and organizations using free and open source software are predominately focusing on this issue. The non-compliance to licenses in free and open source software development leads to the loss of reputation and the high costs of litigation for organizations. Towards an automated compliance management, we use the Open Digital Rights Language to implement the clauses of open source software licenses in a machine interpretable way and propose a novel algorithm that analyzes compatibility between free and open source software licenses. Also, we describe a framework that inductively manages compliance of license clauses in a free and open source software development. We simulate and evaluate the formalized license compliance management by analyzing a real-time open source software project GRASS.

Licensing services: formal analysis and implementation

The distribution of services spanning across organizational boundaries raises problems related to intellectual value that are less explored in service oriented research. Being a way to manage the rights between service consumers and service providers, licenses are critical to be considered in services. As the nature of services differs significantly from traditional software and components, services prevent the direct adoption of software and component licenses. We propose a formalisation of licensing clauses specific to services for unambiguous definition of a license. We extend Open Digital Rights Language to implement the clauses of service licensing, making a service license compatible with all the existing service standards.

Service licensing: conceptualization, formalization, and expression

Service licensing enables a broader usage of services and a means for designing business strategies and relationships. A service license describes the terms and conditions that permit the use of and access to a service, in a machine interpretable way, which services can understand. The distribution of services spanning across organizational boundaries raises problems related to intellectual value that are less explored in service-oriented research. Being a way to manage the rights between service consumers and service providers, licenses become significant in services. As the nature of services differs significantly from traditional software and components, services prevent the direct adoption of software and component licenses. The concept of preserving certain rights of owner and presenting certain rights to consumer, addressed by service licensing, is incipient in the field of service-oriented computing. We propose a formalization of licensing clauses for an unambiguous definition of a service license. We extend the Open Digital Rights Language to implement the clauses of service licensing, in a machine interpretable way. We illustrate the concepts of service licensing based on a case study of service license compliance verification in a real world scenario.

Fostering Green IT [Guest editors' introduction]

IT professionals are being called upon not only to make IT systems and work practices greener but also to harness the power of IT to address growing the environmental and social problems we face. IT professionals can make a difference by advancing green IT and embracing it in several areas of enterprise and personal activities, as highlighted in this special issue.

Free/Open Services

A novel concept of free/open services adopts the principles of the free/ open source software approach and adapts them for service-oriented computing to enhance the widespread use of services.