Oliver Hummel

Code Conjurer: Pulling Reusable Software out of Thin Air

For many years, the IT industry has sought to accelerate the software development process by assembling new applications from existing software assets. However, true component-based reuse of the form Douglas Mcllroy envisaged in the 1960s is still the exception rather than the rule, and most of the systematic software reuse practiced today uses heavyweight approaches such as product-line engineering or domain-specific frameworks. By component, we mean any cohesive and compact unit of software functionality with a well-defined interface - from simple programming language classes to more complex artifacts such as Web services and Enterprise JavaBeans.

A Practical Approach to Web Service Discovery and Retrieval

One of the fundamental pillars of the Web service vision is a brokerage system that enables services to be published to a searchable repository and later retrieved by potential users. This is the basic motivation for the UDDI standard, one of the three standards underpinning current Web service technology. However, this aspect of the technology has been the least successful, and the few Web sites that today attempt to provide a Web service brokerage facility do so using a simple cataloguing approach rather than UDDI. In this paper we analyze why the brokerage aspect of the Web service vision has proven so difficult to realize in practice and outline the technical difficulties involved in setting up and maintaining useful repositories of Web services. We then describe a pragmatic approach to web service brokerage based on automated indexing and discuss the required technological foundations. We also suggest some ideas for improving the existing standards to better support this approach and Web service searching in general.

Using cultural metadata for artist recommendations

Our approach to generate recommendations for similar artists follows a recent tradition of authors tackling the problem not with content-based audio analysis. Following this novel procedure we rely on the acquisition, filtering and condensing of unstructured text-based information that can be found in the Web. The beauty of this approach lies in the possibility to access so-called cultural metadata that is the agglomeration of several independent -originally subjective - perspectives about music.

Using the web as a reuse repository

Software reuse is widely recognized as an effective way of increasing the quality of software systems whilst lowering the effort and time involved in their development. Although most of the basic techniques for software retrieval have been around for a while, third party reuse is still largely a “hit and miss” affair and the promise of large case component marketplaces has so far failed to materialize. One of the key obstacles to systematic reuse has traditionally been the set up and maintenance of up-to-date software repositories. However, the rise of the World Wide Web as a general information repository holds the potential to solve this problem and give rise to a truly ubiquitous library of (open source) software components. This paper surveys reuse repositories on the Web and estimates the amount of software currently available in them. We also briefly discuss how this software can be harvested by means of general purpose web search engines and demonstrate the effectiveness of our implementation of this approach by applying it to reuse examples presented in earlier literature.

Strategies for the Run-Time Testing of Third Party Web Services

Because of the dynamic way in which service-oriented architectures are configured, the correct interaction of service users and service providers can only be fully tested at run-time. However, the run-time testing of web services is complicated by the fact that they may be arbitrarily shared and may have lifetimes which are independent of the applications that use them. In this paper we investigate this situation by first identifying the different types of tests that can be applied to services at run-time and the different types of web services that can be used in service-oriented systems. We then discuss how these can be combined - identifying the combinations of tests and web services that make sense and those that do not. The resulting analysis identifies six distinct forms of run-time testing strategy of practical value in service-oriented systems.

Automated creation and assessment of component adapters with test cases

The composition of new applications from pre-existing parts has been one of the central notions in software reuse and component-based development for many years. Recent advances with component retrieval technologies and dynamically reconfiguring systems have brought the automated integration of components into systems into the focus of research. Even when a component offers all functionality needed by the using environment there is often a host of “syntactic obstacles” and to date there is no general solution available that can automatically address syntactic mismatches between components and their clients. In this paper we present an approach that automatically creates all syntactically feasible adapters for a given component-client constellation and selects the semantically correct one with the help of “ordinary” unit test cases. After explaining how our approach works algorithmically, we demonstrate that our prototype implementation is already able to solve a large fraction of the adaptation challenges previously identified in the literature fully automatically.

Supporting agile reuse through extreme harvesting

Agile development and software reuse are both recognized as effective ways of improving time to market and quality in software engineering. However, they have traditionally been viewed as mutually exclusive technologies which are difficult if not impossible to use together. In this paper we show that, far from being incompatible, agile development and software reuse can be made to work together and, in fact, complement each other. The key is to tightly integrate reuse into the test-driven development cycles of agile methods and to use test cases - the agile measure of semantic acceptability - to influence the component search process. In this paper we discuss the issues involved in doing this in association with Extreme Programming, the most widely known agile development method, and Extreme Harvesting, a prototype technique for the test-driven harvesting of components from the Web. When combined in the appropriate way we believe they provide a good foundation for the fledgling concept of agile reuse.

Test-Driven Reuse: Key to Improving Precision of Search Engines for Software Reuse

The applicability of software reuse approaches in practice has long suffered from a lack of reusable material, but this situation has changed virtually over night: the rise of the open source movement has made millions of software artifacts available on the Internet. Suddenly, the existing (largely text-based) software search solutions did not suffer from a lack of reusable material anymore, but rather from a lack of precision as a query now might return thousands of potential results. In a reuse context, however, precisely matching results are the key for integrating reusable material into a given environment with as little effort as possible. Therefore a better way for formulating and executing queries is a core requirement for a broad application of software search and reuse. Inspired by the recent trend towards test-first software development approaches, we found test cases being a practical vehicle for reuse-driven software retrieval and developed a test-driven code search system utilizing simple unit tests as semantic descriptions of desired artifacts. In this chapter we describe our approach and present an evaluation that underlines its superior precision when it comes to retrieving reusable artifacts.

More archetypal usage scenarios for software search engines

The increasing availability of software in all kinds of repositories has renewed interest in software retrieval and software reuse. Not only has there been significant progress in developing various types of tools for searching for reusable artifacts, but also the integration of these tools into development environments has matured considerably. Yet, relatively little is known on why and how developers use these features and whether there are applications of the technology that go beyond classic reuse. Since we believe it is important for our fledgling community to understand how developers can benefit from software search systems, we present an initial collection of archetypal usage scenarios for them. These are derived from a survey of existing literature along with novel ideas from ongoing experiments with a state of the art software search engine.

Enhancing Music Recommendation Algorithms Using Cultural Metadata

In todays online commercial music marketplaces, a common requirement is to generate lists of artists that are “similar” to a given chosen artist. However, this is by no means a trivial task. A recent trend has been to tackle this challenge using sociocultural connotations rather than the traditional content-based audio or lyrics analysis. This article describes an enhancement to this approach that relies on the acquisition, filtering and condensing of unstructured, text-based information that can be found on the World Wide Web to recognize what the music community regards as “similar” artists. The beauty of this approach lies in its ability to access so-called “cultural metadata” (i.e., textual data about musical content) which is the aggregation of several independent – originally subjective – perspectives about a piece of music. The major focus of this work is the evaluation and enhancement of existing approaches in this area using filtering methods to increase their precision. A meaningful evaluation of the results is provided by a comparison with ground truth data.