Web Service Discoverability

Discoverability anti-patterns: frequent ways of making
undiscoverable Web Service descriptions
Juan Manuel Rodriguez, Marco Crasso, Alejandro Zunino and Marcelo Campo
ISISTAN Research Institute. UNICEN University. Campus Universitario, Tandil (B7001BBO),
Buenos Aires, Argentina. Tel.: +54 (2293) 439682. Fax.: +54 (2293) 439681

Abstract. The ever increasing number of publicly available WebServices makes
standard-compliant service registries one of the most essential tools for serviceoriented application developers. Previous works have showed that the retrieval
effectiveness of this kind of registries strongly depends on the descriptiveness
of published service descriptions. This paper presents a catalog of frequent bad
practices in the creation of Web Service descriptions thatattempt against their
chances of being discovered, along with novel practical solutions to them. Additionally, the paper presents empirical evaluations that corroborated the benefits
of the proposed solutions. These anti-patterns will help service publishers avoid
common discoverability problems and improve existing service descriptions.

Web Services; Web Service discoverability anti-patterns.1 Introduction
An evolutionary process currently taking place in the software industry is the shift from
developing specific functionality from scratch, to discovering and combining functionalities offered by third-parties. Service-oriented computing (SOC) is a new paradigm
for building software systems, in which developers search software pieces with publicly available interfaces, calledservices, within specialized registries to form their applications [1,2]. Providers can use registries to advertise their services, while consumers
can use registries to discover services that match their needs. The SOC paradigm promotes standard methods for remotely consuming services regardless of the technology. Accordingly, SOC enables succeeding at software development in heterogeneousdistributed environments [2] and, at the same time, promises reduction of coupling
between components, agility to respond to changes in requirements, transparent distributed computing and lower ongoing investments [3].
Currently, the SOC paradigm is mostly implemented by using Web Services technologies [2]. A Web Service is a software system that can be discovered and invoked
through standard Webprotocols. The growth of the Internet has popularized large repositories of Web Services [1,4]. Unfortunately, finding proper services is very challenging,
mainly because, unlike traditional software libraries, Web Service repositories rely on
little meta-data to support service discovery [5] and the ever increasing number of published Web Services [4]. In the end, these challenges hinder theadoption of the SOC
paradigm [6].

38º JAIIO - Simposio Argentino de Ingeniería de Software (ASSE 2009), pp. 1-15, 2009

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J. M. Rodríguez et al.

A starting point to understand the challenges associated with current discovery
methods is Universal Description, Discovery and Integration (UDDI)1 , a specification
of standardized formats for programmatic business and service discovery, so thatsearch
engines could be built on top of it. With UDDI, publishing services consists of supplying a registry with the information associated with providers and technical descriptions
of the functionalities of their services in Web Service Description Language (WSDL)2 .
WSDL is an XML-based language for describing a service intended functionality by
means of an interface with methods andarguments, in object-oriented terminology, and
documentation in the form of textual comments. On the other hand, discoverers may
look up third-party services by performing keyword-based searches.
Mostly because of the inconsistency between keywords in interfaces of publicly
available services and queries [7,8], efficiently finding proper services through implementations of UDDI is similar to finding a...