Andres Flores

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 Evaluating Component Replaceability

Replacing pieces of component-based systems carries a serious risk on the expected stability. Substitutability of components must then be carefully identified. With this intent, this paper presents a process to evaluate replacement components by complementing the conventional compatibility analysis with component testing criteria. Functions of data transformation encapsulated by components (i.e. their behaviour) are analysed according to the Observability testing metric. For a component under substitution, a Component Behaviour Test Suite is built to be later applied on candidate replacement components. This approach is also known as Back-to-Back testing. The whole process is currently supported through the tool testooj, which is focused on testing Java components.

Semantic-structural assessment scheme for integrability in service-oriented applications

This work improves a novel Service Selection Method for the development of Service-Oriented Applications in the context of the Service-Oriented Computing (SOC) paradigm. We have defined a Semantic-Structural Scheme to assess Web Services on Interface Compatibility exploring the available information from WSDL documents. The structural information involves data types from return, parameters and exceptions. The semantic information concerns identifiers from parameters and operation names. The lexical database WordNet is used as a semantic basis. Two appraisal values were defined: compatibility gap and adaptability gap. The former is centered on functional aspects. The latter explains the adaptation effort to a successful integration. We validated those appraisals values through different experiments with a data-set of 465 real-life Web Services and measured the results using three metrics from the Information Retrieval field.

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.

Testing-Based Selection Method for Integrability on 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 help developers to easily deal with discovery, selection and integration of services, and it is based on two recent approaches addressing software maintainability. The first one, called EasySOC, provides specific semi-automated methods for both discovery and integration of services. The second one, initially developed for substitutability of component-based systems, supplies a method for selection of an appropriate third-party candidate component or service, by applying black-box testing techniques. In this paper we present the usefulness of the selection method within the whole approach.

.Net approach to run-time component integration

This work is related to the area of component-based software development. We intend to automate a component integration process as a support for run-time adjustments of applications, when the environment involves highly dynamic changes of requirements. This implies to evaluate components against a given set of requirements. We propose a framework for such process and consider related concepts like assessment and adaptation. Assessment is based on meta-data added to components, involving assertions, and usage protocols. Meta-data is evaluated with a technique based on abstract syntax trees. We also report on a prototype developed on the .Net technology to implement the proposed assessment and adaptation procedures which allowed us to gain understanding about the complexity and effectiveness of our model.

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.