Software Engineering Lecture 3 Designing and Visualizing Software

Software Engineering Lecture 3 – Designing and Visualizing Software Architecture Slides inspired by Richard Taylor, University of California

Last time • The context of Architecture – How it fits into the Software Development Lifecycle 2

• How do you communicate code/design? 3

Objectives • Concepts – What is visualization? – Differences between modeling and visualization – What kinds of visualizations do we use? – Visualizations and views – How can we characterize and evaluate visualizations? • Constructing visualizations – Guidelines for constructing new visualizations – Pitfalls to avoid when constructing new visualizations – Coordinating visualizations 4

Objectives • Concepts – What is visualization? – Differences between modeling and visualization – What kinds of visualizations do we use? – Visualizations and views – How can we characterize and evaluate visualizations? • Constructing visualizations – Guidelines for constructing new visualizations – Pitfalls to avoid when constructing new visualizations – Coordinating visualizations 5

Models vs. Visualizations • Models and visualizations are very closely related • A model is just abstract information – a set of design decisions • Visualizations give those design decisions form: – they let us depict those design decisions and interact with them in different ways – Because of the interaction aspect, visualizations are often active – they are both pictures AND tools 7

Models vs. Visualizations <? xml version=“ 1. 0”> <model> <decision num=“ 1”…/> <decision num=“ 2”…/> </model> XML-based visualization DD DD C 1 Model DD Our first decision is that the system will have two components, C 1 and C 2. . . DD DD C 2 Box-and-arrow visualization Natural language visualization 8

Visualizations • Some notations are textual – Natural language, XML-based ADLs • …or graphical – Power. Point-style • …or a little of both – UML 9

Different Relationships Viz Model One visualization (common) Viz Model Viz Many visualizations for one model (common) Model One visualization bringing together many models (uncommon) 10

Kinds of Visualizations: Textual Visualizations – Generally conform to some syntactic format, like programs conform to a language – Decorative options • Fonts, colors, bold/italics • Tables, bulleted lists/outlines 11

Textual Visualizations <instance: x. Arch xsi: type=”instance: XArch”> <types: arch. Structure xsi: type=”types: Arch. Structure” types: id=”Client. Arch”> <types: description xsi: type=”instance: Description”> Client Architecture </types: description> <types: component xsi: type=”types: Component” types: id=”Web. Browser”> <types: description xsi: type=”instance: Description”> Web Browser </types: description> <types: interface xsi: type=”types: Interface” types: id=”Web. Browser. Interface”> <types: description xsi: type=”instance: Description”> Web Browser Interface </types: description> <types: direction xsi: type=”instance: Direction”> inout </types: direction> </types: interface> </types: component> </types: arch. Structure> </instance: x. Arch> XML visualization 12 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Textual Visualizations (cont’d) <instance: x. Arch xsi: type=”instance: XArch”> XML visualization <types: arch. Structure xsi: type=”types: Arch. Structure” types: id=”Client. Arch”> <types: description xsi: type=”instance: Description”> Client Architecture </types: description> <types: component xsi: type=”types: Component” types: id=”Web. Browser”> <types: description xsi: type=”instance: Description”> Web Browser x. Arch{ </types: description> arch. Structure{ <types: interface xsi: type=”types: Interface” id = “Client. Arch” types: id=”Web. Browser. Interface”> description = “Client Architecture” <types: description xsi: type=”instance: Description”> component{ Web Browser Interface id = “Web. Browser” </types: description> description = “Web Browser” <types: direction xsi: type=”instance: Direction”> interface{ inout id = “Web. Browser. Interface” </types: direction> description = “Web Browser Interface” </types: interface> direction = “inout” </types: component> } </types: arch. Structure> } </instance: x. Arch> } } Compact visualization 13 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Textual Visualizations: Interaction • Generally through an ordinary text editor or word processor • Some advanced mechanisms available – – Syntax highlighting Static checking Autocomplete Structural folding 14

Textual Visualizations • Advantages – – Depict entire architecture in a single file Good for linear or hierarchical structures Hundreds of available editors Substantial tool support if syntax is rigorous • Disadvantages – – Can be overwhelming Bad for graphlike organizations of information Difficult to reorganize information meaningfully Learning curve for syntax/semantics 15

Kinds of Visualizations: Graphical Visualizations • Depict architectures (primarily) as graphical symbols – – – Boxes, shapes, pictures, clip-art Lines, arrows, other connectors Photographic images Regions, shading 2 D or 3 D • Generally conform to a symbolic syntax – But may also be ‘free-form’ and stylistic 16

Graphical Visualizations Abstract, stylized visualization 17 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Graphical Visualizations Abstract, stylized visualization More rigorous deployment visualization 18 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Graphical Visualizations: Interaction • Generally graphical editors with point-and-click interfaces – Employ metaphors like scrolling, zooming, ‘drill-down’ • Editors come with various support for notations • More exotic editors and interaction mechanisms exist in research – 3 D editors – “Sketching-based” editors 19

Graphical Visualizations • Advantages – Symbols, colors, and visual decorations more easily parsed by humans than structured text – Handle non-hierarchical relationships well – Diverse spatial interaction metaphors (scrolling, zooming) allow intuitive navigation • Disadvantages – Cost of building and maintaining tool support • Difficult to incorporate new semantics into existing tools – Do not scale as well as text to very large models 20

Hybrid Visualizations • Few graphical notations are purely symbolic – Text labels, at a minimum – Annotations are generally textual as well 21

Hybrid Visualizations (cont’d) Primarily graphical UML class diagram 22 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Evaluating Visualizations • Scope and Purpose – What is the visualization for? What can it visualize? • Basic Type • Depiction • Interaction 24

Evaluating Visualizations (cont’d) • Fidelity – How well/completely does the visualization reflect the information in the underlying model? – Consistency should be a minimum requirement, but details are often left out • Consistency – How well does the visualization use similar representations for similar concepts? • Comprehensibility – How easy is it for stakeholders to understand use a visualization • Note: this is a function of both the visualization and the stakeholders 25

Evaluating Visualizations (cont’d) • Dynamism – How well does the visualization support models that change over time (dynamic models)? • View Coordination – How well the visualization is connected to and kept consistent with other visualizations • Aesthetics – How pleasing is the visualization (look and feel) to its users? • A very subjective judgment • Extensibility – How easy is it to add new capabilities to a visualization? 26

Automatically generated? • Code Sonar • Google Codepro Analyti. X - Webpage 29

Objectives • Concepts – What is visualization? – Differences between modeling and visualization – What kinds of visualizations do we use? – Visualizations and views – How can we characterize and evaluate visualizations? • Constructing visualizations – Guidelines for constructing new visualizations – Pitfalls to avoid when constructing new visualizations – Coordinating visualizations 30

Constructing New Visualizations • Must answer many questions in advance – Can I achieve my goals by extending an existing visualization? – Can I translate into another notation and use a visualization already available there? – How will my visualization augment the existing set of visualizations for this notation? – How will my visualization coordinate with other visualizations? 31

New Visualizations: Guidelines • Borrow elements from similar visualizations – Leverages existing stakeholder knowledge – Improves comprehensibility • Be consistent among visualizations – Don’t conflict with existing visualizations without a good reason (e. g. , developing a domain-specific visualization where the concepts and metaphors are completely different) • Give meaning to each visual aspect of elements 32

New Visualizations: Guidelines (cont’d) • Document the meaning of visualizations – Visualizations are rarely self-explanatory – Focus on mapping between model and visualization • Balance traditional and innovative interfaces – Stakeholders bring a lot of interaction experience to the table – But just because a mechanism is popular doesn’t mean it’s ideal 33

Common symbols 34

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New Visualizations: Anti. Guidelines • Same Symbol, Different Meaning 37 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; (C) 2008 John Wiley & Sons, Inc. Reprinted with permission.

New Visualizations: Anti. Guidelines (cont’d) • Differences without meaning 38 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; (C) 2008 John Wiley & Sons, Inc. Reprinted with permission.

New Visualizations: Anti. Guidelines (cont’d) • Decorations without meaning 39 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; (C) 2008 John Wiley & Sons, Inc. Reprinted with permission.

New Visualizations: Anti. Guidelines (cont’d) • Borrowed symbol, different meaning 40 Software Architecture: Foundations, Theory, and Practice ; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; (C) 2008 John Wiley & Sons, Inc. Reprinted with permission.

Coordinating Multiple Visualizations • How do we keep multiple simultaneous visualizations of the same (part of the) architectural model consistent with each other and the model? 41

DESIGN RECONSTRUCTION 42

Architecture Reconstruction Process • Raw view extraction – Source code, execution traces, build scripts, etc. • Database construction • View fusion and manipulation – Observe data relationships etc. from database – Create a fused view to illustrate how data fit together • Architecture analysis – Conformance 43

Architecture Reconstruction Process 44

Discussion • How do you analyze design? • What do you look for to – Understand structure? – Understand what is going on? – Understand where to add code? 45

How to identify design IMHO • Two alternatives – Top down (Overall Modules Classes Code) – Follow the execution path • What launches the application • What happens next? • Pick a specific operation (use-case) and follow the execution path for that operation (e. g. logging in or load a document) 46

Summary • Choose the right tool for visualizing design – – Shareability Contributability Flexibility Expressability 51