Software Architecture Recovery: The 5 Questions You Always Asked Yourself About,

The 5 questions you always asked yourself about Software Architecture Recovery Mircea Lungu Faculty of Informatics, University of Lugano October 2008

5 Questions about SAR Software Architecture Recovery - Mircea Lungu, 2008

5 Questions about SAR • What is it? Software Architecture Recovery - Mircea Lungu, 2008

5 Questions about SAR • What is it? • Why is it important? Software Architecture Recovery - Mircea Lungu, 2008

5 Questions about SAR • What is it? • Why is it important? • How does it work? Software Architecture Recovery - Mircea Lungu, 2008

5 Questions about SAR • What is it? • Why is it important? • How does it work? • Who does it? Software Architecture Recovery - Mircea Lungu, 2008

5 Questions about SAR • What is it? • Why is it important? • How does it work? • Who does it? • Where is it headed? Software Architecture Recovery - Mircea Lungu, 2008

What? • Architecture Recovery • Architecture • Viewpoints

Architecture recovery ... Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... or Architecture Reconstruction, Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... or Architecture Reconstruction, or Reverse Architecting Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... or Architecture Reconstruction, or Reverse Architecting [...] an archaeological activity where the analysts must unveil all the historical design decisions by looking at the existing implementation and documentation of the system. [ Riva’00 ] Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... ... the ﬂavor of reverse engineering that concerns all activities for making existing of software architectures explicit. [Krikhaar’97] Software Architecture Recovery - Mircea Lungu, 2008

Architecture recovery ... ... the ﬂavor of reverse engineering that ... the techniques and concerns all activities for processes used to uncover making existing of software a system’s architecture architectures explicit. from available information. [Jazayeri’00] [Krikhaar’97] Software Architecture Recovery - Mircea Lungu, 2008

Architecture... Software Architecture Recovery - Mircea Lungu, 2008

Architecture... [...] the structure or structures of the system, which comprise software elements, the externally visible properties of those elements, and the relationships among them. [Bass et al.’03] Software Architecture Recovery - Mircea Lungu, 2008

Architecture... [...] the structure or structures of the system, which comprise software elements, the externally [...] the fundamental visible properties of those organization of a system, elements, and the embodied in its components, relationships among them. their relationships to each other and the environment, and the [Bass et al.’03] principles governing its design and evolution. [ANSI/IEEE Std. 1471-2000] Software Architecture Recovery - Mircea Lungu, 2008

Architecture... For many others visit www.sei.cmu.edu/architecture/ deﬁnitions.html [...] the structure or structures of the system, which comprise software elements, the externally [...] the fundamental visible properties of those organization of a system, elements, and the embodied in its components, relationships among them. their relationships to each other and the environment, and the [Bass et al.’03] principles governing its design and evolution. [ANSI/IEEE Std. 1471-2000] Software Architecture Recovery - Mircea Lungu, 2008

What is the difference between architecture and design? Software Architecture Recovery - Mircea Lungu, 2008

Architectural Styles • Recurring architectural solutions • Examples • Pipes and ﬁlters • Blackboard • Peer-to-peer • ... a Software Architecture Recovery - Mircea Lungu, 2008

Architectural Styles • Recurring architectural solutions • Examples • Pipes and ﬁlters • Blackboard SAR is not preoccupied with • Peer-to-peer recovering the architectural • ... style of the system. a Software Architecture Recovery - Mircea Lungu, 2008

Viewpoints • Viewpoints catalogues • Kruchten’95 • Hofmeister’99 • Ad-hoc viewpoints • Smolander’01 • Conway’s law Software Architecture Recovery - Mircea Lungu, 2008

Viewpoints • Viewpoints catalogues • Kruchten’95 • Hofmeister’99 • Ad-hoc viewpoints • Smolander’01 Most of the SAR processes focus on • Conway’s law recovering component-and- connector viewpoints. Software Architecture Recovery - Mircea Lungu, 2008

What is the relation between architecture recovery and reverse engineering? Software Architecture Recovery - Mircea Lungu, 2008

Why? • Reasons • Beneﬁts • Goals • Challenges

Architecture erosion [...] the documentation about the internal architecture becomes rapidly obsolete. To make changes, developers need a clear understanding of the underlying architecture of the products. C. Riva, Software Architecture Group, Nokia Research Software Architecture Recovery - Mircea Lungu, 2008

Architecture Evolution One frequently accompanying property of evolution is an increasing brittleness of the system -- that is, an increasing resistance to change, or at least to changing gracefully. [Perry & Wolf ’92] Software Architecture Recovery - Mircea Lungu, 2008

Architecture Evolution One frequently accompanying property of evolution is an • Architectural drift increasing brittleness of the system -- that is, an • Architectural erosion increasing resistance to change, or at least to • Architectural upgrade changing gracefully. [Perry & Wolf ’92] Software Architecture Recovery - Mircea Lungu, 2008

Conceptual vs. As-is architecture Software systems must evolve or become obsolete [...] [Lehmann’80] Software Architecture Recovery - Mircea Lungu, 2008

Conceptual vs. As-is architecture Software systems must Change In Environment evolve or become obsolete [...] Change In Code Environment Code [Lehmann’80] Change In Code Architecture Change In Architecture As-Is Architecture Software Architecture Recovery - Mircea Lungu, 2008

Conceptual vs. As-is architecture Software systems must Change In Environment evolve or become obsolete [...] Change In Code Environment Code [Lehmann’80] Change In Code Change In Architecture Architecture There is a need for As-Is Architecture enforcing the architecture of a system Software Architecture Recovery - Mircea Lungu, 2008

Conceptual vs. As-is architecture Software systems must evolve or become Architectural Change In Firewall Environment obsolete [...] Change In Code Environment Code [Lehmann’80] Change In Code Change In Architecture Architecture There is a need for enforcing the architecture of a system Software Architecture Recovery - Mircea Lungu, 2008

Consultant’s POV [...] Frequently we are asked to analyze • Missing architectural a systemʼs software speciﬁcations architecture and are • Support the given only its code • Re-documentation and the (limited) time • Reengineering of a designer. [Kazman et al.’99] Software Architecture Recovery - Mircea Lungu, 2008

Beneﬁts • Stepping stone towards reengineering • Supports detecting components for reuse Software Architecture Recovery - Mircea Lungu, 2008

Challenges • What process can support uncovering the software architecture within a system? • How much can you automate in this process? • What are the limits of architecture recovery? (e.g., Recovering all design decisions). Software Architecture Recovery - Mircea Lungu, 2008

How? • Generic approach • Processes • Bottom-up • Top-down • Integrated

Phases of Reconstruction Knowledge Information Data Extraction Organization Exploration [Tilley et al.’96] Software Architecture Recovery - Mircea Lungu, 2008

The Meta- Phases of Reconstruction Architecture of Architecture Recovery Tools Knowledge Information Data Extraction Organization Exploration [Tilley et al.’96] Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) • Historical Information Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) • Historical Information • Human Expertise Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) • Historical Information • Human Expertise • Runtime Behavior (dynamic analysis) Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) • Historical Information • Human Expertise • Runtime Behavior (dynamic analysis) • Physical Organization Software Architecture Recovery - Mircea Lungu, 2008

Data Extraction • Source Code (static analysis) • Historical Information • Human Expertise • Runtime Behavior (dynamic analysis) • Physical Organization • Social Organization Software Architecture Recovery - Mircea Lungu, 2008

[Pollet et al.’07] Software Architecture Recovery - Mircea Lungu, 2008

Facts extracted from code [Guo et al.’99] Software Architecture Recovery - Mircea Lungu, 2008

Knowledge Abstraction • Get rid of useless information • Aggregation • Directory • Packages • Clustering • Filtering [Lungu et al.’05] Software Architecture Recovery - Mircea Lungu, 2008

p n -u w om do d ri p- tt yb Bo To H Processes Software Architecture Recovery - Mircea Lungu, 2008

p n -u w om do d ri p- tt yb Bo To H Processes [Pollet et al.’07] Software Architecture Recovery - Mircea Lungu, 2008

• Start with low-level fact 1. Bottom-up extraction Approaches • Aggregate the information to higher abstraction levels either manually or automatically Software Architecture Recovery - Mircea Lungu, 2008

Tools 4 bottom-up • Arch • ArchView • ArcVis • ARMIN • BUNCH • DALI • Gupro • Intensive • Rigi • Softwarenaut Software Architecture Recovery - Mircea Lungu, 2008

Arch • Developed at Siemens Research • Mavericks - individual procedures in the wrong modules • Heuristic modularization advice [Schwanke’91] Software Architecture Recovery - Mircea Lungu, 2008

Archview [Pinzger’05] Software Architecture Recovery - Mircea Lungu, 2008

Dali Rigi, IAPR (Interactive Architecture Pattern Recognition) [12], RMTool [14], and Perl for analysis and manipulation. Lightweight Source Model Extraction PostgreSQL (based (LSME), Imagix, make, and Perl on POSTGRES) for for extraction of source model model storage, information for C and C++, Software Architecture Recovery - Mircea Lungu, 2008

Advertising break! Software Architecture Recovery - Mircea Lungu, 2008

Advertising break! • Aggregation: based on directory structure, clustering, package structure Software Architecture Recovery - Mircea Lungu, 2008

Advertising break! • Aggregation: based on directory structure, clustering, package structure • Filtering: based on evolutionary information, metrics Software Architecture Recovery - Mircea Lungu, 2008

Advertising break! • Aggregation: based on directory structure, clustering, package structure • Filtering: based on evolutionary information, metrics • Visualization: polymetric Software Architecture Recovery - Mircea Lungu, 2008

Softwarenaut Software Architecture Recovery - Mircea Lungu, 2008

• Start with previous high- 2. Top-down level knowledge about the application domain approaches • Formulate hypotheses and verify them against the source code Software Architecture Recovery - Mircea Lungu, 2008

Tools 4 top-down • RMTool • Pulse • W4 Software Architecture Recovery - Mircea Lungu, 2008

Reﬂexion Models Marco... Software Architecture Recovery - Mircea Lungu, 2008

Pulse • Fraunhofer Institute for ESE • Architecture- and Domain-Oriented Re-engineering • Product Line Software Engineering Software Architecture Recovery - Mircea Lungu, 2008

Pulse Software Architecture Recovery - Mircea Lungu, 2008

W4 By distilling pearls of wisdom stored deep inside source control systems, we can assist developers to understand the state of their project and plan conﬁdently for its future [Hassan & Holt’04] Software Architecture Recovery - Mircea Lungu, 2008

W4 By distilling pearls of wisdom stored deep inside source control systems, we can assist developers to understand the state of their project and plan • Which,Who,Why,When conﬁdently for its future [Hassan & Holt’04] Software Architecture Recovery - Mircea Lungu, 2008

• Combine top-down with 3. Hybrid bottom-up Approaches • Abstract low-level information • Reﬁne high-level information Software Architecture Recovery - Mircea Lungu, 2008

Tools 4 hybrid • Albortz • ARM • Bauhaus • Cacophony • DiscoTect • ManSART • PBS/SBS • Symphony / Nimeta Software Architecture Recovery - Mircea Lungu, 2008

ManSART • Mitre Corporation • Used to provide architecture level consulting in multiple military systems Software Architecture Recovery - Mircea Lungu, 2008

ManSART [Harris et al.’ 95] Software Architecture Recovery - Mircea Lungu, 2008

Discotect • Examine runtime behavior • Big problem: abstraction gap • State machines to map between implementation- level events and architectural operations [Yan et al.’04] Software Architecture Recovery - Mircea Lungu, 2008

Who? • SEI at Carnegie Mellon • Hasso-Plattner Institute • Nokia Research Center

Case Study #1 • Author: CMU Software Engineering Institute • Subject: VANISH, 50KLOC • Tools: Dali, ARMIN • Goals • generate several architectural views • determine if strict layering is in place • Assumptions: little documentation, no developers available Software Architecture Recovery - Mircea Lungu, 2008

#1: Results Software Architecture Recovery - Mircea Lungu, 2008

Case Study #2 • Author: Hasso-Plattner Institute • Subject: Apache, 100KLOC C code • Participants: 60 4th semester students • 32 topics assigned • Sources • documentation (well written, little info about the conceptual architecture) • “Writing Apache modules with Perl” • Results: overview analysis, detailed state diagrams, memory management • Time:: half a semester for getting accustomed with the domain and half for analyzing the implementation Software Architecture Recovery - Mircea Lungu, 2008

#2: Results www.fmc-modeling.org/category/projects/apache/amp/Apache_Modeling_ Project.html - Software Architecture Recovery - Mircea Lungu, 2008

Case Study #3 • Author: Nokia Research • System: Embedded Software Written in C • Existing Reference Architecture • Scripts that extract information about messages Software Architecture Recovery - Mircea Lungu, 2008

#3: Results Software Architecture Recovery - Mircea Lungu, 2008

Others • “Linux as a Case Study, it’s Extracted Architecture”, Bowman et al. • “Static evaluation of Software Architectures”, Knodel et al. Software Architecture Recovery - Mircea Lungu, 2008

Where? • Future of SAR • Further Reading

The Future of SAR Software Architecture Recovery - Mircea Lungu, 2008

The Future of SAR • Integrating with forward engineering (continuous supervision, architectural ﬁrewalls, etc.) Software Architecture Recovery - Mircea Lungu, 2008

The Future of SAR • Integrating with forward engineering (continuous supervision, architectural ﬁrewalls, etc.) • Collaborative architecture recovery Software Architecture Recovery - Mircea Lungu, 2008

The Future of SAR • Integrating with forward engineering (continuous supervision, architectural ﬁrewalls, etc.) • Collaborative architecture recovery • Product family architecture Software Architecture Recovery - Mircea Lungu, 2008

The Future of SAR • Integrating with forward engineering (continuous supervision, architectural ﬁrewalls, etc.) • Collaborative architecture recovery • Product family architecture • Ecosystem architecture Software Architecture Recovery - Mircea Lungu, 2008

Further Reading • Annotated Bibliography www.inf.unisi.ch/phd/lungu/recovery • Essays on Architecture http://www.sei.cmu.edu/architecture/essays.html • PhD Theses: Pinzger’05, Krikhaar’99 • Survey Articles: Pollet’07 Software Architecture Recovery - Mircea Lungu, 2008

THE END Software Architecture Recovery - Mircea Lungu, 2008

Software Architecture Recovery: The 5 Questions You Always Asked Yourself About,

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