Basics of SW Architecture

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Linette Robbins
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and Practice - Essential Software Architecture Basics of

1 Material and some slide content from: - Emerson Murphy-Hill - Software Architecture: Foundations, Theory, and Practice - Essential Software Architecture Basics of SW Architecture Reid Holmes Lecture 4 - Thursday, September

2 Proposal Presentations Finish the last two presentations. Select the most interesting idea. Select the most useful proposal.

3 Event Chimp for Facebook

4 Queue Up Your Event Salutes

5 GWT + Facebook U:liza:on of the Facebook API for birthdays, etc. Keeps you in touch with friends with very personal messages defined in advance Custom codes within message Hosted on Facebook when ready

6 Event Manager Calvin Hung Taufiq Husain Shuo Tan James Zhao

7 What is it?

8 What does it do? Automatic phone management oprevents phone ringing in class/meetings oavoid miss calls due to silent phone rings Stores daily activities and events onto a calendar application Synchronize with existing calendars ocentralized calendar with all events

9 The End! Any Questions?

10 Proposal Voting Huskies RendezVous Team Systems TriForce LTZ R4D Legendary Apps TimmyUs Event Chimp My Event Organizer Score board Return to location Pre-enrolment system Course planner Campus / building map Booking restaurant tables Advisor appointment system Who s treatin today? Don t miss that special message Coordinate phone with calendar

11 [TAILOR ET AL.] So what? What makes building systems so hard? Young field. High user expectations. Software cannot execute independently. Incidental difficulties [Brooks MMM]. Problems that can be overcome. (e.g.,...) Essential difficulties [Brooks MMM]. Those problems that cannot be easily overcome.

12 [TAILOR ET AL.] Essential Difficulties Abstraction alone cannot help. Complexity? Conformity System is dependent on its environment. Changeability? Intangibility Not constrained by physical laws.

13 [TAILOR ET AL.] Attacks on Complexity High-level languages. Development tools & environments. Component-based reuse. Development strategies. Incremental, evolutionary, spiral models. Emphasis on design. Design-centric approach taken from outset.

14 [TAILOR ET AL.] Architecture Analogies We live in them. We know (approximately) how they are built. Requirements. Blueprints (design). Construction (implementation). Use in practice.

15 [TAILOR ET AL.] The architect Distinctive role. Broadly trained. Requirements, design, implementation, & use. Has a keen sense of aesthetics. Strong understanding of the domain. What are these for buildings? What are these for software?

16 REID HOLMES - SE2: SOFTWARE DESIGN & ARCHITECTURE [TAILOR ET AL.] The architect How is building architecture different from software architecture? What common benefits can software gain from an architect that a building gets from its architect?

17 What is SW architecture? Definition: The set of principal design decisions about the system Blueprint for construction and evolution. Encompasses: Structure Behaviour Interaction Non-functional properties

18 Prescriptive vs descriptive Prescriptive architecture dictates how the system will be built a priori. (as-conceived) Descriptive architecture captures how the system was actually built after the fact. (as-implemented)

19 Architectural degradation Drift? Erosion? How can this happen?

20 Architectural recovery [ICSE 1999: Bowman, Holt, and Brewster] Conceptual architecture How developers think about the system. Focuses on meaningful relationships. Concrete architecture How the system was actually built. Necessary: the devil is in the details.

21 Components Elements that encapsulate processing and data at an architectural level. Definition: Architectural entity that: encapsulates a subset of functionality. restricts access via explicit interface. has explicit environmental dependencies.

22 Connectors Definition: An architectural entity tasked with effecting and regulating interactions between components. Connectors are often more challenging than components in large heterogenous systems. Often consists of method calls, but be much more. Examples? Often provide application-independent interaction mechanisms.

23 Topologies Bind components and connectors together in a specific way. Definition: An architectural configuration, or topology, is a set of specific associations between the components and the connectors of the system s architecture. Differentiates a bag of components and connectors from an implementable system.

24 Architectural styles Some design choices are better than others. Experience can guide us towards beneficial sets of choices (patterns) that have positive properties. Such as? An architectural style is a named collection of architectural design decisions that: Are applicable to a given context. Constrain design decisions. Elicit beneficial qualities in resulting systems.

Course Introduction and Overview of Software Engineering. Richard N. Taylor Informatics 211 Fall 2007

Course Introduction and Overview of Software Engineering Richard N. Taylor Informatics 211 Fall 2007 Software Engineering A discipline that deals with the building of software systems which are so large