Overview 1 1 Find out why software engineering

Overview 1 1. Find out why software engineering is important ■ 2. see some software engineering failures Get acquainted with – ■ the Chair of Software Agile Engineering Development Accelerating ■ the research through Software Reuse ■ the people ■ the teaching Karlsruher Entwicklertag May 9 th, 2012 Colin Atkinson Software Engineering Prof. Dr. Colin Atkinson 1

Reconciling Agility and Reuse 2 ■ software reuse and agile development have the same underlying goal - ■ ■ but they are usually not applied at the same time ■ ■ to allow new applications to be built more rapidly and cost effectively agile processes almost exclusively focus on developing new software Challenge ■ make reuse a central part of agile development Test Analysis Code Reuse Software Engineering Prof. Dr. Colin Atkinson Design 2

Component Reuse 3 ■ ■ Software Reuse ■ “the process of creating software systems from existing software rather than building software systems from scratch. ” [Krueger 92] ■ software component markets famously proposed by Mc. Ilroy in 1968 [Mc. Ilroy 68] ■ the “holy grail” of software engineering, but has failed to take off to the extent expected or desired Software Component ■ any cohesive and compact unit of software functionality with a well defined interface ■ includes simple programming language classes as well as more complex artefacts such as web services and EJBs ■ not focussed on “snippets” Software Engineering Prof. Dr. Colin Atkinson 3

Why “Reuse” Did Dot Take Off 4 ■ Historically, there were there main barriers to systematic component reuse ■ Not enough good components to reuse ■ 200 was considered a lot of components in the golden years of reuse research (1980 s and 1990 s) ■ Crude retrieval technology ■ often returned a high proportion of unsuitable components or missed many relevant ones ■ Unfavourable risk/effort balance ■ chances of success through reuse too low to justify the effort involved Software Engineering Prof. Dr. Colin Atkinson 4

What’s Different Today ■ The situation has improved significantly since the turn of the millennium ■ Plenty of good components to reuse ■ high bandwidth internet available to all 5 ■ ■ vast repositories of open source code ■ web service revolution Advanced retrieval technology ■ Lucene indexing engine ■ ■ advanced retrieval algorithms Radically different risk/effort balance ■ unobtrusive component recommendation tools becoming available Software Engineering Prof. Dr. Colin Atkinson 5

Merobase 6 ■ One of the largest software component search engines ■ ■ more than 10 million components Public Features ■ multiple component types ■ source code, binary code, web services, Android apps ■ hybrid search algorithms ■ keyword, name, interface, . . ■ lookup (library, documentation, . . ) ■ service execution ■ metrics ■ …. Software Engineering Prof. Dr. Colin Atkinson 6

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Search Result Quality 9 ■ The new generation of code search engines provides dramatically enhanced search quality ■ Average precision: ■ ■ ■ Signature-based search string-based search = Name-based = Interface-based = = 16% 17% 54% However, this is not enough to significantly change the “build or buy” trade-off ■ Probability of finding component that are really “fit for purpose” is too low compared to the effort involved in exploring reuse opportunities Need higher precision ■ Semantic search Software Engineering Prof. Dr. Colin Atkinson 9 1%

Test-Driven Search 10 ■ most practical way of evaluating a component’s “fitness for purpose” is to test it ■ can deliver 100% precision b) define desired semantics as tests c) find matching components d) compile components e) establish acceptability through tests identify desired interface reuse public void test. Title. Retrieval () { Movie movie = new Movie("Star Wars", 0); assert. True(movie. get. Title (). equals("Star Wars")); } Software Engineering Prof. Dr. Colin Atkinson 10

Test Driven Search Example 11 ■ desired interface public class Mortgage { public Mortgage(double rate, int years, double loan) {} public double Monthly. Payment() {} public double Total. Payment() {} } ■ excerpt of JUnit test public void test. Mortgage() { private Mortgage m = new Mortgage(4. 5, 12, 250000); assert. Equals(2250. 02, m. Monthly. Payment(), 0. 01); private Mortgage m = new Mortgage(4. 5, 12, 250000); assert. Equals(324, 002. 94, m. Total. Payment(), 0. 01); …. } Software Engineering Prof. Dr. Colin Atkinson 11

Test Driven Search (Merobase) 12 Software Engineering Prof. Dr. Colin Atkinson 12

Code Conjurer Eclipse Plugin 13 ■ Seamlessly integrates Merobase driven search into the Eclipse development environment ■ Main Features ■ code-driven search ■ test-driven search JUnit test driven queries ■ unobtrusive (background) recommendation ■ component dependency resolution ■ interface recommendation ■ code metadata (metrics) ■ Interface adaptation ■ … Software Engineering Prof. Dr. Colin Atkinson 13

Test Driven (Code Conjurer) 14 Software Engineering Prof. Dr. Colin Atkinson 14

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Proactive Recommendation Example 16 Software Engineering Prof. Dr. Colin Atkinson 16

Conclusion 17 ■ Test-driven search fits naturally into agile, test driven development ■ ■ Is the key enabling technology for integrating reuse-oriented and agile development ■ ■ When used together with a test-driven development strategy like XP, test-driven search makes the effort involved in finding suitable components almost zero can accelerate the agile development process Get involved. . ■ Code Conjurer http: //www. code-conjurer. org/ ■ ■ use it, provide feedback, help enhance it (open source) make your own tools search-driven ■ ■ publically accessible Merobase API create your own code search engine ■ ■ merobase can crawl any content in CVS, SVN, . . repositories Further information: atkinson@informatik. uni-mannheim. de Software Engineering Prof. Dr. Colin Atkinson 17

For Further reading 18 ■ W. Janjic, M. Schumacher, Der Herr der Codes, Eclipse Magazin, 2. 12, S&S Media Gmb. H, Frankfurt am Main, 2012 ■ Software Engineering Prof. Dr. Colin Atkinson O Hummel, W Janjic, C Atkinson, Code conjurer: Pulling Reusable Software out of Thin Air, IEEE Software 25 (5), 2008 18