CSCI 578Software Architectures

Exam #1 Review

Materials you are responsible for

• Chapters 1-7 in the text book

• All lecture material through intro to Architectural Analysis (Week 7)

• Homework #1 and #2

Exam

• Closed book, closed note

• Format– Write in answers– No multiple choice

Material Review

• Canonical elements of software architecture– Component

• computation

– Connector• communication/coordination

– Configuration• topology and constraints

Material Review

• Architectural styles– Codify key constraints and architectural elements

(components, connectors, configurations) found effective used in a family of software systems over a given time period

• Architectural patterns– A set of architectural design decisions that are applicable to a

recurring design problem, and parameterized to account for different software development contexts in which that problem appears.

– Compared to styles, architectural patterns are at a coarser level of granularity (design decisions versus actual architectural elements) and are inherently more domain specific

Material Review• Examples of Architectural Styles

– Client/Server, P2P, Object Oriented, Layered, Data-Flow, Pipe and Filter, Blackboard, Rule Based

• Examples of Architectural Patterns– 3-tier (Stage-Logic-Display), MVC, Sense Compute Control

• Methods of evaluating design methods like styles and patterns– Vocabulary, structural patterns, computational model, invariants,

common examples, disadvantages, specializations

• Methods of design– Greenfield design (entirely fresh start, no baggage)

• Analogy searching, Brainstorming, Literature searching, Morphological Charts, Removing Mental Blocks, Insight from requirements/implementation

Material Review

• Software Connectors– Taxonomy

• 4 main roles– Communication, Conversion, Facilitation, Coordination

• 8 main types– Event, Stream, Procedure Call, Arbitrator, Data Access,

Distributor, Linkage, Adaptor

• Benefits of first-class connectors– Software evolution, separation of concerns,

modularity, pluggability

Material Review

• Architectural Modeling– An architectural model is an artifact that captures some

or all of the design decisions that comprise a system’s architecture

– Architectural modeling is the reification and documentation of those design decisions

• How to choose what to model?– Cost/Benefit Decision

• What do we model?– Structure (Architectural element), static/dynamic

behaviors, functional/non-functional aspects, Views/Viewpoints

Material Review

• Architectural Modeling– Important things to “get right”

• Consistency, Accuracy/Precision, Ambiguity

– How do we evaluate modeling techniques?• Scope/Purpose, Basic Elements, Style, Static/Dynamic

Aspects, Dynamic Modeling, Non-functional aspects, ambiguity, accuracy/precision, viewpoints, view consistency

– Modeling approaches• Generic, early ADLs, style-specific and domain-specific

languages, extensible ADLs

Material Review

• Architectural Modeling– Generic approaches

• Natural language, informal graphical tools (Powerpoint), semi-formal graphical tools with semantics (UML)

– Early ADLs• Darwin, Rapide, Wright

– Domain/Style-specific ADLs• Koala, Weaves, AADL

– Extensible Architecture Description Languages• xADL, ACME, ADML

Material Review

• Architectural Visualization– An architectural visualization defines how

architectural models are depicted, and how stakeholders interact with those depictions

– Two key aspects here:• Depiction is a picture or other visual

representation of design decisions• Interaction mechanisms allow stakeholders to

interact with design decisions in terms of the depiction

Material ReviewModelViz

One (canonical) visualization(common)

Model

Viz

Viz

Viz

Many visualizations for one model (common)

Model

Model Model

Viz

One visualization bringing together many models (uncommon)

Material Review

• Kinds of Architectural Visualizations– Textual (XML in a text editor, natural language, etc.)– Graphical (boxes, lines, etc.)– Hybrid (combine elements of textual and graphical)– Effect (depict the results or effects of design

decisions, not direct design decisions)• How do we evaluate architectural visualizations?

– Scope/Purpose, Basic Type, depiction, interaction, fidelity, consistency, comprehensibility, dynamism, view coordination, aesthetics, extensibility

Material Review

• Architectural Analysis– The activity of discovering important system

properties using the system’s architectural models.• Early, useful answers about relevant architectural aspects• Available prior to system’s construction

– Formal/Informal• Largely dependent on the underlying architectural model’s

expressivity

– Concerns• Goals, Scope, Primary architectural concern, level of

formality, Type, Level of automation, System stakeholders

Material Review• Architectural analysis

– Completeness• Does the architectural analysis take all the system elements

(components/connectors/etc.) into account? Does it take the other aspects (requirements, etc.) into account?

– Consistency• Do the results of analysis on one subset of a software system produce non

contradictory results with respect to the analysis of another (perhaps non-disjoint) subset?

– Name, Interface, Behavior, Interaction, Refinement

– Compatibility• Do the results of analysis conform to the expected properties/results of the

specific domain, style, or reference architecture?

– Correctness• Does the architectural analysis really represent properties of the full system

specification? Does the system implementation represent the predicted analysis?

Material Review

• Architectural analysis– Scope

• Component/Connector• System/Subsystem• Data• Refinement/Abstraction levels• Comparing architectures/analysis

– Techniques for analysis• Inspection-based, Model-based, Simulation-based