UNIVERSITAS SCIENTIARUM SZEGEDIENSISUNIVERSITY OF SZEGEDDepartment of Software Engineering

Source code analysis with Columbus

Quality assessment Architecture reconstruction

Árpád BeszédesDepartment of Software Engineering, University of Szeged, Hungary

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Who we are

One of the leading SE research groups in Hungary■ http://www.inf.u-szeged.hu/sed/

Competences■ Software quality■ Software testing■ Embedded systems■ Networks■ Open Source■ .NET■ Java

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Monitor

Source code quality

Test management

Architecture

IT operation performance

Processes(e.g. issue m)

Place of source code analysis

Software maintenance / evolution of large systems

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References Telecom, financial, other Analyzed systems (1-30 MLOC)

■ Graphisoft ArchiCAD■ Nuance-Scansoft Recognita■ evoSoft■ Erste Bank■ Nokia S60 platform■ Mozilla Firefox & Thunderbird■ SUN, OpenOffice.org■ Eclipse■ NASA WorldWind■ Etc.

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Source code-based QA methodology architecture

Continuous measurement and monitoring is needed!

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Quality decrease of sw systems

from: Roger Pressman - Software Engineering Software Engineering: A Practitioner's Approach, McGraw-Hill

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Columbus technology

Analysis of large sw systemsIn the scope of regular maintenance

■ C/C++/C#/Java/SQL■ Quality measurements, auditing■ Reverse Engineering, architecture

reconstruction■ One-shot assessment■ Continuous monitoring

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Some history

1998-2001: Nokia Research CenterFrontEndART Software Ltd.Further development

■ Industrial projects■ Grants

50-100 man-years

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Main components Robust source code parsers Analysis methodologies Representation metamodels designed for maintenance

tasks (language schemas) Programming interfaces (API) Extensions: CFG, call graph, DU, support for dynamic

analysis (testing), etc. Back ends

■ Code measurement■ Reverse engineering

Standalone or SDK integration, command-line, API■ SourceAudit, SourceDoc (previously Columbus/CAN)

Monitoring subsystem: SourceInventory (was Monitor)

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Reverse Engineering SourceDoc tool Creation of UML logical views of the analyzed system

■ Class diagrams■ In standard XMI format

– can be loaded e.g. into Rational Rose Automatic generation of HTML documentation

■ Class-level■ Hyperlinked

Design pattern usage detection Detecting architecture-level dependencies

■ “Superlinking”■ Among physical components (e.g. exe, dll)■ E.g. function calls, includes

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“Bad smell” detection

SourceAudit toolFinds code fragments that

■ might be problematic■ and error-prone,■ so it needs refactoring■ e.g.: Feature Envy: a function which does not

use its own class, but relies on others

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Clone detection

Finds duplicated code fragments (copy/paste, clones)

Clones can cause many hard-to-find bugsThe detection can be scaled

■ from exact match■ to similar code fragments

Uses efficient flat-tree based recognitionLanguage independent

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Code checking Checking conformance to coding rules

■ Some of them indicate bugs The rules

■ check the coding style■ extend the warning capabilities of the compiler■ check typical implementation errors■ new rules can be added easily (C++ API)

General good practice rules Company specific rules Integration of other checkers’ results Integration with MS Visual Studio and Eclipse Command-line operation

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Code measurement – metrics

All popular metrics for procedural, OO, SQL languages■ CK, size, complexity, coupling, cohesion, OO-ness,

etc.

Interpretation of metrics?■ E.g. different types of cyclomatic complexity

The metrics-based fault predictor model selects C++ classes that are liable to errors1

■ successfully tested on Mozilla

[1] Gyimóthy T, Ferenc R and Siket I. Empirical Validation of Object-Oriented Metrics on Open Source Software for Fault Prediction. IEEE TSE vol.31, no.10, October 2005

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Connectivity to other tools ART (RSF) {CPP|J|CS}ML (XML) FAMIX XMI GXL Maisa (Prolog) RSF UML XMI VCG Machine readable CSV Human readable txt

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Technical details

Own and commercial front endsAnalysis of complex systems:

■ Compiler wrapping technology

Standard schemas■ OO-style■ C++ API

High-level language independent modelCross-module dependencies:

superlinking

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Scalability?

Limited low-level analyses■ Lightweight?■ Problems of other kind

Common high-level modelRelatively easy system integration

Anything else you wanted to know?

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Monitoring subsystem SourceInventory The source code of the

system is■ downloaded automatically

by the framework from a configuration management system (e.g. CVS)

■ analyzed, and the results are stored in a database

■ queries can be run and diagrams can be drawn from a web-based interface, which communicates with the database

Monitor

Source code analysisand measurement

SQL database

Source code configurationversioning repository

Web clientWeb client

...

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Monitoring subsystem (cont.)

Automatic alerts can be issued when indicators overrun critical thresholds■ metric baselines

Internally: quality assessmentCustomer: continuous measurementPublic databases: Mozilla, maemo,

(OpenOffice, Eclipse)

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Screenshots (1)

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Screenshots (2)

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Screenshots (3)

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Screenshots (4)

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Screenshots (5)

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Screenshots (6)

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Screenshots (7)

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Screenshots (8)

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Screenshots (9)

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Nokia R&D projects

History■ 1998 – TED projects: C++ to UML■ 2005 – ART projects: Symbian platform

Architecture reconstruction of Symbian platform■ Identification of “architectural erosion”

Quality measurement of Symbian platform■ Metrics■ Official Symbian coding guidelines (SourceAudit)

Quality measurement of maemo platform

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Technology extensions – 1 SourceAudit coding rules (114)

■ general 'good practice' C++ coding rules ■ Symbian OS-specific rules ■ Nokia recommended rules

viability – the code will not work reliability – the code may not work maintainability – the code may be difficult to modify readability – the code may be difficult to understand reusability – the code may be less usable in

conjunction with other code convention – the code will be unconventional

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Technology extensions – 2 Architecture cross-component dependencies

■ call: inter-component function calls■ include: the same header file is included by two components ■ resource: the consumer’s serviceClass attribute equals to the

provider’s interface_uid, the consumer’s contentType attribute equals to provider's default data item, and consumer's serviceCmd attribute equals to provider's opaque_data

■ publish & subscribe: if a component sets a property (category and key), and an other subscribes for this property then there is a P&S dependency between the two components

Dependency metrics, e.g. xCallIn, xCallOut, xInclude Visualization

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Technology extensions – 3

Build process (Symbian SDK) wrapping■ Hides the original compiler with wrapper programs

(e.g. gcc.exe)

After activating the SDKWrapper the project can be built as usual■ creating abld.bat by ‘bldmake bldfiles’ and■ building the project by ‘abld build …’

Build scripts provided for linking and inter-component dependency computation

Difficulties: compiling resource files, excluding test components