Martin Garriga

RESTful service composition at a glance

In the last years, Web Service composition has undoubtedly become the most promising way to integrate business-to-business applications. However, the industry and the academia often disagree on materializing current solutions, which are based on either SOAP Web Services or semantic Web Services. Besides, any service composition mechanism entails multiple and complex factors such as adaptability, scalability and lightweightness. Recently, RESTful services have shown their potential to compose reliable and visible Web-scale applications based on the so-called mashups. In this paper, we survey a comprehensive set of RESTful composition approaches, i.e., the most promising in their area, totaling 29 approaches. Then, we propose two sets of features to analyze, characterize and compare such approaches: features inherent to SOAP services composition approaches and RESTful services composition features. Lastly, we discuss research challenges and open research problems in the area.

Web Services Composition Mechanisms: A Review

ABSTRACT Web Service composition is becoming the most promising way for business-to-business systems integration. However, current mechanisms for service composition entail a trade-off on multiple and complex factors. Thereby, existing solutions based on business Web Services, semantic Web Services, or the recent RESTful services, lack of a standardized adoption. This paper gives an overview of current approaches according to a set of features. Moreover, related core problems and future directions of service composition mechanisms are pointed out.

Service selection based on a practical interface assessment scheme

Service-oriented computing promotes building applications by consuming reusable services. However, facing the selection of adequate services for a specific application still is a major challenge. Even with a reduced set of candidate services, the effort of assessing candidates could be overwhelming. We have defined an approach to assist developers in the selection of services, which mainly comprises an assessment process for service interface compatibility. This assessment process is based on a comprehensive structural scheme for service interfaces matching. The scheme allows developers to gain knowledge on likely services’ interactions and their required adaptations to achieve a successful integration. We evaluated the performance of the interface compatibility analysis with a data set of 453 services and two different service discovery registries. The experiments show an improvement of up to 15% in precision and up to 8% in the DCG usefulness metric, with regard to the previous results obtained using on...

Testing-Based Process for Service-Oriented Applications

Service-Oriented Computing allows building applications by reusing web-accessible services. However, current approaches still involve a large effort both at discovery of services and their successful integration. This paper presents a novel approach to assist developers at discovery, selection and integration of services. In particular, the paper focuses on the selection method that involves two main evaluations on candidate services to achieve a concrete decision upon the most appropriate service. Initially, a syntactic Interface Compatibiliy assessment characterizes the list of candidate services according to a calculated syntactic distance to then proceed with a Behavior Compatibility evaluation that is based on a blackbox testing framework. The usefulness of the selection method is highlighted through a series of case studies.

A domain independent readability metric for web service descriptions

Web Services are influencing most IT-based industries as the basic building block of business infrastructures. A Web Service has an interface described in a machine-processable format (specifically WSDL). Service providers expose their services by publishing the corresponding WSDL documents. Service consumers can learn about service capability and how to interact with the services. Service descriptions (WSDL documents) should be ideally understood easily by service stakeholders so that the process of consuming services is simplified. In this work we present a practical metric to quantify readability in WSDL documents - attending to their semantics by using WordNet as the underlying concept hierarchy. In addition, we propose a set of best practices to be used during the development of WSDL documents to improve their readability. To validate our proposals, we performed both qualitative and quantitative experiments. A controlled survey with a group of (human) service consumers showed that software engineers required less time and effort to analyze WSDL documents with higher readability values. Other experiment compares readability values of a dataset of real-life WSDL documents from the industry before and after modifying them to adhere to the readability best practices proposed in this paper. We detected a significant readability improvement for WSDL documents written according to the best practices. In another experiment, we applied existing readability metrics for natural language texts detecting their unsuitability to the Web Service context. Lastly, we analyzed the readability best practices identifying their useful applicability to the industry. HighlightsA practical metric to quantify readability in Web Services descriptions (WSDL).A set of best practices to be used during the development of WSDL documents to improve their readability.A controlled survey has been done to show the effort reduction of software engineers to analyze WSDL documents with high readability values.Building documents following the best practices improve their readability values as we experienced with a dataset of real WSDL documents.

Case-based Reasoning for Web Service Discovery and Selection

Web Service discovery and selection deal with the retrieval of the most suitable Web Service, given a required functionality. Addressing an effective solution remains difficult when only functional descriptions of services are available. In this paper, we propose a solution by applying Case-based Reasoning, in which the resemblance between a pair of cases is quantified through a similarity function. We show the feasibility of applying Case-based Reasoning for Web Service discovery and selection, by introducing a novel case representation, learning heuristics and three different similarity functions. We also experimentally validate our proposal with a dataset of 62 real-life Web Services, achieving competitive values in terms of well-known Information Retrieval metrics.

A structural-semantic web service selection approach to improve retrievability of web services

Service-Oriented Computing promotes building applications by consuming and reusing Web Services. However, the selection of adequate Web Services given a client application is still a major challenge. The effort of assessing and adapting candidate services could be overwhelming due to the “impedance” of Web Service interfaces expected by clients versus the actual interfaces of retrieved Web Services. In this work, we present a novel structural-semantic approach to help developers in the retrieval and selection of services from a service registry. The approach is based on a comprehensive structural scheme for service Interface Compatibility analysis, and WordNet as the semantic support to assess identifiers of operations and parameters. We also empirically analyze, compare and contrast the performance of three service selection methods: a pure structural approach, a pure semantic approach, and the structural-semantic (hybrid) approach proposed in this work. The experimental analysis was performed with two data-sets of real-world Web Services and a service discovery support already published in the literature. Results show that our hybrid service selection approach improved effectiveness in terms of retrievability of Web Services compared to the other approaches.

Assessing Web Services Interfaces with Lightweight Semantic Basis

In the last years, Web Services have become the technological choice to materialize the Service-Oriented Computing paradigm. However, a broad use of Web Services requires efficient approaches to allow service consumption from within applications. Currently, developers are compelled to search for suitable services mainly by manually exploring Web catalogs, which usually show poorly relevant information, than to provide the adequate “glue-code” for their assembly. This implies a large effort into discovering, selecting and adapting services. To overcome these challenges, this paper presents a novel Web Service Selection Method. We have defined an Interface Compatibility procedure to assess structural-semantic aspects 1002 M. Garriga, A. De Renzis, A. Flores, A. Cechich, A. Zunino from functional specifications – in the form of WSDL documents – of candidate Web Services. Two different semantic basis have been used to define and implement the approach: WordNet, a widely known lexical dictionary of the English language; and DISCO, a database which indexes co-occurrences of terms in very large text collections. We performed a set of experiments to evaluate the approach regarding the underlying semantic basis and against third-party approaches with a data-set of real-life Web Services. Promising results have been obtained in terms of well-known metrics of the Information Retrieval field.

Testing-supported Case-Based Reasoning for Web Service Selection

Web Service discovery and selection deals with the retrieval of the most suitable Web Service, given a required functionality. Addressing an effective solution remains difficult when only functional descriptions of services are available. The Artificial Intelligence (AI) field have contributed significantly to support the Web Services lifecycle. In this paper, we propose an extension of a previous approach that applied Case-Based Reasoning (CBR) for Web Service Selection, in which Web Services are behaviorally tested for conformance of a given required functionality.

RESTful mobile architecture for social security services: A case study

Nowadays, Web Services is the technological weapon-of-choice to implement Service-oriented Architectures (SOA). Companies like Google, Amazon, Twitter and Facebook offer Web Services to provide easy access to some of their resources, allowing third parties to combine, reuse and add value to their applications. In particular, mobile services promote the use of mobile devices as service consumers, with a remarkable growth in recent years. However, it is still challenging to identify the most appropriate architecture to integrate applications at organizational level in this new ecosystem of services and heterogeneous devices. Architectural decisions should be based on technical arguments, being crucial in the design of distributed system. This requires an unbiased analysis of the specific capabilities offered by services, mobile platforms and back-end options. Moreover, mobile services face different difficulties to spread in the market, which constrain their success. In particular, mobile devices have distinctive features (screen, battery, keyboard, etc.), which must be carefully considered in the development of mobile applications. For all these reasons, this work defines a mobile service-oriented software architecture based upon RESTful services. We analyzed architectural aspects and decisions to maximize desired quality attributes, particularly for the social security domain. These design decisions were then applied in a case study: a service-oriented architecture and mobile application for the social security provider SOSUNC, from the National University of Comahue.