OORPT — Architecture Recovery OORPT Object-Oriented Reengineering Patterns and Techniques 9. Architecture Recovery Prof. O. Nierstrasz © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 2
OORPT — Architecture Recovery References > > > > D. D'Souza, A. Wills, Objects, Components and Frameworks with UML, Addison-Wesley, 1999 F. Buschmann, et al. , Pattern-Oriented Software Architecture — A System of Patterns, John Wiley, 1996 M. Shaw, D. Garlan, Software Architecture: Perspectives on an Emerging Discipline, Prentice-Hall, 1996 C. Riva, View-based Software Architecture Reconstruction, Ph. D. thesis, Technical University of Vienna, 2004. H. Gall, Architecture Recovery and Reference Architecture, U Zürich, presentation, 2004 M. Pinzger, et al. , “Architecture Recovery for Product Families, ” PFE-5, LNCS 3014, Springer-Verlag, 2004. R. Kazman and S. J. Carriere, “Playing detective: Reconstructing software architecture from available evidence. , ” Automated Software Engineering, April 1999. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 3
OORPT — Architecture Recovery Roadmap > What is Architecture? — Viewpoints — Styles — ADLs > Architecture Extraction > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 4
OORPT — Architecture Recovery What is Software Architecture? The architecture of a system consists of: > the structure(s) of its parts — including design-time, test-time, and run-time hardware and software parts > the externally visible properties of those parts — modules with interfaces, hardware units, objects > the relationships and constraints between them in other words: — The set of design decisions about any system (or subsystem) that keeps its implementors and maintainers from exercising “needless creativity” — D’Souza, Wills © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 5
OORPT — Architecture Recovery Roadmap > What is Architecture? — Viewpoints — Styles — ADLs > Architecture Extraction > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 6
OORPT — Architecture Recovery IEEE 1471 -2000 > “A software architecture is the fundamental organization of a system embodied in its components, their relationships to each other, and to the environment, and the principles guiding its design and evolution. ” > “A system stakeholder is an individual, team, or organization with interests in, or concerns relative to, a system. ” > “A concern is an interest which pertains to the system’s development, its operation or any other aspects that are critical or otherwise important to one or more stakeholders. Concerns include system considerations as performance, reliability, security, distribution, and evolvability. ” > “A view is a representation of a whole system from the perspective of a related set of concerns. ” > “A viewpoint is a specification of the conventions for constructing and using a views. A pattern or a template from which to develop individual views by establishing the purposes and audience for a view and the techniques for its creation and analysis. ” © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 7
OORPT — Architecture Recovery © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 8
OORPT — Architecture Recovery Architectural Viewpoints Run-time How are responsibilities distributed amongst run-time entities? Process How many concurrent threads/processes exist; how do they communicate and synchronize? Dataflow How do data and tasks flow through the system? Deployment How are components physically distributed? Module How is the software partitioned into modules? Build What dependencies exist between modules? File How is the software physically distributed in the file system? © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 9
OORPT — Architecture Recovery Roadmap > What is Architecture? — Viewpoints — Styles — ADLs > Architecture Extraction > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 10
OORPT — Architecture Recovery Architectural Styles An architectural style defines a family of systems in terms of a pattern of structural organization. More specifically, an architectural style defines a vocabulary of components and connector types, and a set of constraints on how they can be combined. — Shaw and Garlan © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 11
OORPT — Architecture Recovery Some Classical Styles Layered Elements in a given layer can only see the layer below. Callbacks used to communicate upwards Client-Server Separate application logic from interaction logic. Clients may be “fat” or “thin” 4 -Tier Server is further divided into generic part, business logic and legacy adaptor. Dataflow Data or tasks strictly flow “downstream”. Blackboard Tools or applications coordinate through shared repository. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 12
OORPT — Architecture Recovery Product Line Architectures Reference family architecture Global style for all the products. Fixes the architecture requirements, rules, patterns, component types, infrastructure etc. Families with similar UI styles, features, standards, Family architecture hardware generations etc. Lead product architecture A reference product implementation, most typical of the family. Copy product Products “copied” and adapted from the lead product. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 13
OORPT — Architecture Recovery Roadmap > What is Architecture? — Viewpoints — Styles — ADLs > Architecture Extraction > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 14
OORPT — Architecture Recovery Architectural Description Languages > ADLs — Formal languages for representing and reasoning about software architecture. — Provide a conceptual framework and a concrete syntax for characterizing architectures. — Some are executable, or implemented in a general-purpose programming language. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 15
OORPT — Architecture Recovery Common ADL Concepts System connector component role port © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 16
OORPT — Architecture Recovery Common ADL Concepts > Component: unit of computation or data store. Typically contains interface (ports) and formal behavioral description. > Connector: architectural building block used to model interactions among components. Typically contains interface (roles) and formal behavioral description. > Configuration: connected graphs of components and connectors that describe architectural structure. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 17
OORPT — Architecture Recovery Some ADLs > Darwin: focuses on supporting distributed applications. Components are single-threaded active objects. > Wright: underlying model is CSP, focuses on connectivity of concurrent components. > C 2: component- and message-based architectural style with concurrent components linked together by connectors in accordance with a set of style rules. > Rapide: focuses on developing a new technology for building large-scale, distributed multi-language systems. http: //en. wikipedia. org/wiki/Architecture_Description_Language © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 18
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction — Extract-abstract-present — Rigi, Dali, PBS, … — Reflexion models — Querying and Soul > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 19
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction — Extract-abstract-present — Rigi, Dali, PBS, … — Reflexion models — Querying and Soul > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 20
OORPT — Architecture Recovery Extract-abstract-present Tilley et al. , 1996; Krikhaar 1999 © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 21
OORPT — Architecture Recovery Architecture Reconstruction Analyze & record rationales Rationales for design decisions 5. Re-document © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz © Harald Gall, Uni. ZH 22
OORPT — Architecture Recovery Extracting Architecture > Various techniques — Human experts — Recognizing known patterns — Static and dynamic analysis — Clustering and data mining — Comparing products within a family © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 23
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction — Extract-abstract-present — Rigi, Dali, PBS, … — Reflexion models — Querying and Soul > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 24
OORPT — Architecture Recovery Rigi Programmable reverse engineering environment — C parser; relational data import — Visualization of hierarchical typed graphs — Graph manipulation, filtering, layout — Tcl-programmable — www. rigi. csc. uvic. ca/ © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 25
OORPT — Architecture Recovery Dali Workbench > > Workbench built on Rigi, Postgre. SQL, perl scripts … Three techniques used: — Architectural extraction from source artifacts — User-defined patterns — Visualization © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 26
OORPT — Architecture Recovery Software Bookshelf > A web-based paradigm for presentation and navigation of large software systems — PBS (Portable Bookshelf) is one implementation > Extract-abstract-present — C fact extractor generates Rigi Standard Format (RSF) files — Reconstructors define tree-structure by assigning files to subsystems — GROK relational calculator determines high-level relations and visualizes as graphs > Applications to Linux, Apache and Mozilla — swag. uwaterloo. ca/pbs/ © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 27
OORPT — Architecture Recovery SWAGkit > Toolkit to extract, abstract and present Software Architectures — Pipeline architecture based on PBS and GROK — Mainly used to reconstruct module views — swag. uwaterloo. ca/swagkit/ © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 28
OORPT — Architecture Recovery SWAGkit tools Three categories of tools: > Fact extractors — cppx - C++ fact extractor based on GNU g++ compiler. – One output file (TA) generated for each source file. > Fact manipulators — Several grok scripts and C++ programs used to manipulate the facts into a form that can be meaningfully analyzed – linking, abstracting, layout, containment > Fact analyzers — lsedit - visualize system as navigable “box and arrow” diagrams. — Sgrep - query facts via a command line interface © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 29
OORPT — Architecture Recovery GUPRO > Integrated workbench of program understanding tools — Based on extract-abstract-present — Graph-based source model – Graph querying, manipulation and browsing — www. uni-koblenz. de/~ist/gupro. en. html © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 30
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction — Extract-abstract-present — Rigi, Dali, PBS, … — Reflexion models — Querying and Soul > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 31
OORPT — Architecture Recovery Reflexion models > Semi-automated approach > Repeat — Define/Update high-level model of interest — Extract a source model — Define/Update declarative mapping between high-level model and source model — System computes a software reflexion model — Interpret the software reflexion model. Until “happy” © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 32
OORPT — Architecture Recovery Reflexion Approach Reflexion Model Mapping High-Level Model Reflexion Model Tools Extraction Specification Source Code Extraction Tool © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz Source Model 33
OORPT — Architecture Recovery High-Level Model > Describes boxes and arrows model of system. Memory Hardware. Trans Virt. Address. Maint User VMPolicy © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz Kernel. Fault. Handler Pager File. System 34
OORPT — Architecture Recovery Mapping > Relates source model entities to high-level model entities. > Example: [ file=. *pager. * [ file= vm_map. * [ file=vm_fault. c [ dir=[un]fs [ dir=sparc/mem. *] [ file=pmap. * [ file=vm_pageout. c map. To=Pager ] map. To=Virt. Address. Maint ] map. To=Kernel. Fault. Handler ] map. To=File. System ] map. To=Memory ] map. To=Hardware. Trans ] map. To=VMPolicy ] © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 35
OORPT — Architecture Recovery Source Model > Particular information extracted from source code > Calculated with Lightweight Source extraction: — Specifications easy to write — Flexible: few constraints on source — Tolerant: source code can be incomplete, not compilable, … > Lexical Approach > Intrinsically Approximate > For every Source Model, a new scanner is generated © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 36
OORPT — Architecture Recovery Source Model Specification Example > Writing out C calls [ <type> ] <function. Name> ( [ { <formal. Arg> }+ ] ) [ { <type> <arg. Decl> ; }+ ] { <called. Function> @ write ( function. Name, “ calls “, called. Function ) @ ( [ { <parm> }+ ] ) ( ) | ; ) © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 37
OORPT — Architecture Recovery Software Reflexion Model > Indicates where the source model and high-level model differ: — Convergences — Divergences — Absences > Has to be interpreted by developer. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 38
OORPT — Architecture Recovery Software Reflexion Model Example convergence Memory divergence absence Hardware. Trans Virt. Address. Maint User VMPolicy © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz Kernel. Fault. Handler Pager File. System 39
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction — Extract-abstract-present — Rigi, Dali, PBS, … — Reflexion models — Querying and Soul > Formal Concept Analysis © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 40
OORPT — Architecture Recovery Soul > Express source-code views and relations as logic programming queries > A source-code view — Is a set of source-code entities that address a same concern — One view can contain many entities — Views may crosscut dominant implementation decomposition > A source-code entity — Can be any tangible language construct: method, class, variable, … — One source-code entity can reside in multiple source-code views © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 41
OORPT — Architecture Recovery Defining Source-code views > Structure — Name — Comments — Definition(s) — Default definition > Definition can be defined — Extensionally = by explicit enumeration of their elements — Intentionally = by declaratively describing their elements > All definitions — Should yield the same extension — This can be checked automatically © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 42
OORPT — Architecture Recovery Source-code view example view(soul. Predicates, <by. Category, by. Hierarchy>). view. Comment(soul. Predicates, ['This intentional view contains ALL classes that implement SOUL predicates (i. e. , Prolog-like predicates that may use Smalltalk code due to language symbiosis). ']). default(soul. Predicates, by. Category). intention(soul. Predicates, by. Category, ? class) if category(? category), name(? category, ? name), starts. With(? name, ['Soul-Logic']), class. In. Category(? class, ? category). include(soul. Predicates, by. Category, [Soul. Test. Classifications]). intention(soul. Predicates, by. Hierarchy, ? class) if … © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 43
OORPT — Architecture Recovery Software Tomography > Repository-based toolset — Detects and checks architectural layers — Uses metrics and graph-based queries to detect “bad smells” and architectural violations — www. software-tomography. com © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 44
OORPT — Architecture Recovery Software Tomography © Software Tomography Gmb. H, 2003, 2004 © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 45
OORPT — Architecture Recovery Feature-oriented analysis > Select a feature and a use case > Step through scenarios and collect traces > Combine the traces with the high-level static view to generate the feature view > Abstract the feature view by detecting interaction patterns © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 46
OORPT — Architecture Recovery The Dynamic Analysis Process Extract/Filter Abstract Present Static Model Execute a scenario Instrumented system Traces Original MSC A B Visualisation C AB C abstractions Vertical abstraction Horizontal abstraction A C B AB C Horizontal and Veritcal M 1 M 2 M 1 -M 4 M 3 M 7 M 5 M 6 M 7 M 8 M 9 M 1 -M 4 M 5 M 6 M 7 M 10 M 11 M 8 M 10 M 11 M 7 M 9 -M 12 © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz © Harald Gall, Uni. ZH 47
OORPT — Architecture Recovery An Example of Feature View © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz © Harald Gall, Uni. ZH 48
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction > Formal Concept Analysis — Detecting implicit patterns © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 49
OORPT — Architecture Recovery Identifying Design Patterns Template Method Look for protected and abstract methods being overridden in subclasses (hook methods). The caller is often a template method. Proxy, Decorator Look for interfaces implemented by classes in different hierarchies. Look for delegation to instance variables of the same type. Composite Look for instance variables whose type is the superclass. Observer Look for methods “update” and “notify”. Visitor Look for an “accept*” method. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 50
OORPT — Architecture Recovery Con. An: Detecting hidden contracts > Concept analysis — Identify groups of entities (software artifacts) with common properties (contracts) > X-Ray Views — Understanding the internals of a class > Inheritance Patterns — Analysing behavioral dependencies in a class hierarchy > Collaboration Patterns — Detecting structural relationships in an object oriented systems Gabriela Arévalo, “High Level Views in Object-Oriented Systems using Formal Concept Analysis, ” Ph. D. thesis, University of Berne, 2005. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 51
OORPT — Architecture Recovery Concept Analysis: Definitions Rock Jazz Houari True Yann-Gael Pierre Rap Top True Blues {Houari, Petko, Pierre}, {Jazz} True Petko Pop True Mohamed True Gaby True {Houari, Petko}, {Rock, Jazz} § Specification of Elements and Properties § Concept: Maximal groups of elements based on their common properties Bottom {Pierre}, {Jazz, Pop, Rap} § Lattice: partial order over the concepts © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 52
OORPT — Architecture Recovery Con. An: Tool Architecture X-Ray Views Software Patterns Inheritance Patterns Abstraction of the lattice Identify groups Concept Analysis CA Pre-Filters CA Mapping Code Representation Keep one access to an attribute in a method Element: <add: > Property: access: #first. Index Class: Ordered Collection attribute defines first. Index add: Source Code © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 53
OORPT — Architecture Recovery Roadmap > What is Architecture? > Architecture Extraction > Formal Concept Analysis — Detecting implicit patterns © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 54
OORPT — Architecture Recovery Collaboration Patterns Abstract X P Y Abstract A Z T B C D Collaboration Patterns: Common structural aspects between classes © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 55
OORPT — Architecture Recovery Using CA to detect Patterns Elements: tuples of classes Properties: relationships over the tuples. (i, j)relation and (i)feature (3, 2)Sub (C, A, P) True (C, A, B) True (Z, X, Y) (Z, X, P) Tuples of classes (1, 2)Sub (1, 2)Acc (3, 2)Acc True A (2)Abs True True 2 C P 1 3 True A B C P X Y Z: all classes in a system © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 56
OORPT — Architecture Recovery Found Collaboration Patterns Subclass Star A Attribute Star A A Order = 3 Order = 4 A Order = 3 Bridge Composite A Order = 3 A Order = 4 © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz Order = 4 A Order = 3 A Order = 4 57
OORPT — Architecture Recovery License > http: //creativecommons. org/licenses/by-sa/2. 5/ Attribution-Share. Alike 2. 5 You are free: • to copy, distribute, display, and perform the work • to make derivative works • to make commercial use of the work Under the following conditions: Attribution. You must attribute the work in the manner specified by the author or licensor. Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one. • For any reuse or distribution, you must make clear to others the license terms of this work. • Any of these conditions can be waived if you get permission from the copyright holder. Your fair use and other rights are in no way affected by the above. © Stéphane Ducasse, Serge Demeyer, Oscar Nierstrasz 58
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