Reusing pre-existing components in the development of new applications has proven beneficial in mainstream software engineering for many years, and in the last decade a number of dedicated code search engines have sprung up to help developers find components that fulfil their needs. However, these all focus on general purpose software components rather than mobile applications or Android source code. A search engine specialising in the discovery of Android components would significantly boost the productivity of the Android development community and allow developers to exploit existing Android components [1] such as Activities, Services, Content Providers or Broadcast Receivers. In this talk we present Merodroid – a search engine for Android software components. Powered by Merobase [2], the leading code search engine from the University of Mannheim, Merodroid supports a wide range of search capabilities over a large index of pre-existing Android components harvested from open source projects on the Internet. In addition to simple text-based searches, retrieving components that have a given name or contain a given string, Merodroid offers also the ability to search for Android specific artifacts or information based on Android manifests [3]. The search capabilities of the Merobase also provides other interesting search possibilities for Android components such as signature or interface based searches that receive components matching a particular profile. In the near future we are planning to make Merodroid the basis of a vibrant Android component market between developers that complements the current Android Application market between developers and consumers. [1] Application Fundamentals, Android Developers, http://developer.android.com/guide/topics/fundamentals.html [2] Merobase Software Component Finder, http://www.merobase.com/ [3] AndroidManifest.xml, Android Developers, http://developer.android.com/guide/topics/manifest/manifest-intro.html

1. Overview
1. Find out why software engineering is important
Merodroid
1
■ see some software engineering failures
2. Get acquainted with –
■ the Chair of Software Engineering
■ the research A Search Engine for
■
Android Software Components
the people
■ the teaching
Colin Atkinson, Marcus Kessel, Marcus Schumacher
droidcon. 2012, Berlin
Software Engineering
Prof. Dr. Colin Atkinson 1

2. Outline
■ About Us
2
■ Motivation
■ Search Android Components with Merodroid
■ What is Merodroid?
■ Core Features
■ How does it work?
■ Indexing of Android Software Artifacts
■ Analysis and Recognition
■ Demo
■ Conclusion
■ Appendix
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Prof. Dr. Colin Atkinson 2

3. About Us
■ Chair of Software Engineering, Prof.
3 Colin Atkinson, at the University of
Mannheim [1]
Prof. Dr. Colin Atkinson
■ Research Areas
■ Software Reuse
■ Model-Driven Development
■ Component/Service Oriented
Development
M.Sc. Wirtschaftsinformatik
Marcus Kessel
■ Search Driven Development – current
research project
■ Merobase – Software Component
Finder
Dipl. Informatik
Marcus Schumacher
Software Engineering
Prof. Dr. Colin Atkinson 3

4. Motivation
■ Fast-growing market of mobile devices, mainly smartphones and internet
4 tablets
■ Lots of mobile applications already exist (~375.000 in Android Market,
February 2012 [2])
■ High demand for new mobile applications (e.g. provide all kind of
functionality as “apps”)
■ Developer perspective
■ Redundant work ..
■ Tired of reinventing the wheel for every new app
■ Organizational perspective
■ Reduce the effort and save money at application development
■ Component Reuse
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Prof. Dr. Colin Atkinson 4

5. Our Approach: Search-Driven Development
■ Search-Driven Development
5
■ Semantic component retrieval
■ Special query language and constraints to retrieve
potential reuse candidates
■ Merobase
■ General search engine for software components
■ Merodroid
■ Component search engine based on Merobase
adjusted to the needs of Android application
developers
■ Specifics of Android application development
■ Project layout, resources,
AndroidManifest.xml
■ Special component types
■ …
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Prof. Dr. Colin Atkinson 5

6. Core Features (1)
■ App queries
6
■ Browse all components of an “app”
■ Includes additional information sources (AndroidManifest.xml, Android
Market information, …)
■ Component queries
■ Query for specific Android application
components
■ activity, fragment, service, content
provider, broadcast receiver
■ Interface/method signature search
■ Keyword search
■ Constraints (restrict result set)
■ Combined queries: app + component + constraints
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Prof. Dr. Colin Atkinson 6

7. Core Features (2)
■ Create queries by
7
■ Using a graphical wizard
■ Hand
■ Component details
■ Source and component type
■ Tree-like view of methods and fields
■ Metrics
■ Documentation (JavaDoc)
■ Intent filter and capabilities defined in AndroidManifest.xml
■ Android Market information (if available)
■ Unrelated Android components
■ Usual Java classes
■ Publish your own components
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Prof. Dr. Colin Atkinson 7

8. Indexing Android Software Artifacts (1)
8
Crawling Process
Recognition Index
Parsing &
Crawling of artifact
Linking
type
Analysis: Recognition & Data Mining Process
Recognition
Iterate over of Linking Index
index components
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Prof. Dr. Colin Atkinson 8

9. Indexing Android Software Artifacts (2)
■ Supported Android software artifacts
9
■ Application projects (incl. resources)
■ APK, Dalvik Executable
■ Single classes (source & binary)
■ Java classes are analyzed and indexed
■ Fields, methods, inheritance hierarchy, dependencies …
■ AndroidManifest.xml
■ Additional information source
■ Capabilities of components (intent filter)
■ Recognition of components
■ Android (application) components (e.g. activity) are tagged
■ Tagged components are linked with additional information from
AndroidManifest.xml
■ E.g. Intent filter declarations
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10. Android Component Recognition
■ Analysis of inheritance hierarchy of classes represented by the data model
10 (tree traversal)
■ Interfaces/classes of key components are known from the Android API
■ Interfaces/classes can be easily configured for later extensibility (e.g.
Android API changes)
■ For instance, any Activity implementation has to inherit from the class
android.app.Activity
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Prof. Dr. Colin Atkinson 10

11. Demo
11
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Prof. Dr. Colin Atkinson 11

12. Conclusion
■ Merodroid – Android Component Finder
12
■ Software component search engine adjusted to the needs of Android
Application developers
■ Powerful query language
■ Links several information sources (components, AndroidManifest.xml,
Android Market ..)
■ Public web service available at merodroid.com
■ Search for Android application projects & components crawled from
open source repositories
■ Future work
■ Eclipse plugin (http://code-conjurer.org)
■ Test-driven development support (query components by using JUnit
tests/TestSheets)
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Prof. Dr. Colin Atkinson 12

13. Questions
13
Thank you for listening!
Software Engineering
Prof. Dr. Colin Atkinson 13

14. Literature
■ [1] Chair of Software Engineering, University of Mannheim,
14 http://swt.informatik.uni-mannheim.de/
■ [2] AppBrain, Android Statistics, http://www.appbrain.com/stats/number-of-
android-apps (02/20/2012)
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15. Appendix: Query Samples
Description Query Result
15 Find app by id packageId:com.example. All related components
app¹
Find Android application android:activity or All Activities
component android:service or All Services
android:fragment or All Fragments
android:provider or All ContentProviders
android:receiver or All BroadcastReceivers
Find all Activities of app .. packageId:com.example. All Activities of app ..
app¹ android:activity
Find all Activities android:activity List of all Activities supporting
supporting mime-type: mimetype:image/jpeg specified mime-type (known from
image/jpeg manifest)
Find all Activities packageId:com.example. List of all Activities supporting
supporting mime-type: app¹ android:activity specified mime type in app ..
image/jpeg in app .. mimetype:image/jpeg
Find Activity by name android:activity Sudoku List of all Activities containing
„Sudoku“ as name
¹ Unique package id known from AndroidManifest.xml (also widely used in several app markets as identifier)
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