Lecture 5 - How do we structure the software (Architecture)?

The Architect

• distinctive role and character in a project

• broad training

• extensive experience

• deep understanding of the domain

• leads the team

• good communicator

• decision maker

• deals with a higher level of abstraction than those performing construction

• often serves as the interface to key business stakeholders/customers

Why architecture in software engineering?

• intellectual control

• conceptual integrity

• effective project communication

• reusability

• maintainability (management of a set of variant systems)

What is Software Architecture (1)?

the set of principal design decisions about the system

What is Software Architecture (2)?

the blueprint for a software system’s construction and evolution

World Wide Web (WWW)

• collection of resources, each with a unique name (URL)

• URL is used to determine the identity of a machine on the Internet (origin server), from which the resource is obtained

• clients (user agents / web browsers) make requests of servers for their resources

• clients manipulate representations of resources

• all communication between user agents and origin servers must be:

  • performed by a simple, generic protocol (HTTP)

  • fully self-contained

What Architecture Diagram is this?

Uber - ride apps

Software Architecture’s Elements

• components (

• connectors (interaction)

Components and Connectors are arranged into configurations

Prescriptive Architecture

as designed / as intended architecture

• planned — neater

Descriptive Architecture

as implemented / as real architecture

• sometimes messier

Linux Architecture: Prescriptive or Descriptive?

Prescriptive

Linux Architecture: Prescriptive or Descriptive

Descriptive

Architectural Erosion

• when a system evolves, ideally the prescriptive architecture is modified first

• in practice, the system (thus descriptive architecture) is often directly modified

Architectural Erosion Causes

• developer sloppiness

• short deadlines

• lack of (documented) prescriptive architecture

• code optimizations

• inadequate techniques or tool support