Component-Based Software Engineering

Transcription

1 Component-Based Software Engineering CSM-15 Paul Krause Contents Lecture 1 (Part 2) - Software Architecture Why is this interesting? What is Software Architecture? Why is Software Architecture Important? Architectural Views and Frameworks Architecture-Based Development Summing Up 1

2 Why Study Architecture? The choice of Architecture determines many of the qualities of a software system Architecture is the blueprint for component integration Defines the context in which a class of components may be used Software Architecture is? Software architecture is about structural properties: Components Interrelationships Principles Guidelines It is one of the earliest stages in software system design 2

3 Mac OS X Component Architecture AQUA CLASSIC CARBON COCOA JAVA QUARTZ OPENGL QUICKTIME DARWIN Mac OS X Component Architecture AQUA IMAGING LAYER CLASSIC CARBON COCOA JAVA QUARTZ OPENGL QUICKTIME BSD SUBSYSTEM MACH KERNEL 3

4 Mac OS X Component Architecture API LAYER AQUA CLASSIC CARBON COCOA JAVA QUARTZ OPENGL QUICKTIME BSD SUBSYSTEM MACH KERNEL Mac OS X Component Architecture USER INTERFACE LAYER AQUA CLASSIC CARBON COCOA JAVA QUARTZ OPENGL QUICKTIME BSD SUBSYSTEM MACH KERNEL 4

5 Structural Issues? Gross organisation and global control structure Protocols for communication, synchronisation and data access Assignment of functionality to design elements Physical distribution Composition of design elements Scaling and performance Why is it important? If a project has not achieved a system architecture, including its rationale, the project should not proceed to full-scale system development. Specifying the architecture as a deliverable enables its use throughout the development and maintenance process. Barry Boehm, Invited talk, First International Workshop on Architecture for Software Systems 5

6 Three Basic Reasons: Mutual communication A common high-level abstraction that can be used by all the system s stakeholders Early design decisions Ones that will be important throughout the lifecycle (development, service and maintenance) Transferable abstraction of the system Relatively small, intellectually graspable model of the system Transferable Model Reuse at the architectural level for systems with similar requirements Entire product lines can share a common architecture Facilitates use of externally-developed components Architecture constrains how components interact with their environment How they receive and relinquish control The data they work with and produce The protocols they use for communication and resource sharing 6

7 The Need for Multiple Views As well as functionality, we need to reason about physical distribution, process communication and synchronisation May need different views to reflect the concerns of different stakeholders The structure represented in a view May or may not exist at runtime May describe the product, the process of building the product, or the process of using the product Some Representative Views Conceptual (Logical) View Abstract representation of the functional requirements: block diagrams, class diagrams Module (Development) View Organisation of modules, components, subsystems (e.g. layered architecture) Process (Coordination) View Runtime behaviour: concurrency, synchronisation The Physical View Mapping of software onto hardware 7

8 Summary of Views End Users - functionality Programmers - software management Conceptual Module Process Physical System Integrators - performance - scalability - throughput System engineers - system topology - delivery - installation - telecommunication Summing Up Component-based software engineering is a highly structured way of working Software architecture concerns the structural properties of a system Getting the software architecture right is a critical success factor in component-based software engineering 8

9 Lecture 1 Part 3 - Object-Orientation & UML Contents Overview Classifiers Static Modelling Dynamic Behaviour Summing Up Unified Modelling Language Visual modelling language Specify Visualise Construct Document UML can be used to capture information about: Static structure Dynamic behaviour Environmental aspects Organisational aspects 9

10 Overview Static View Person height: Real age: Real Male_Person Female_Person Overview Behavioural View: Single Object timed out Available lock Locked buy Sold unlock 10

11 Overview Dynamic behaviour: communication patterns customer vendor credit service request item show availability select item demand payment insert card charge card Overview Deployment View CreditCardCharges ItemSeller 1 ManagerInterface ItemDB SalesServer 1 Client * SalesTerminal * CustomerInterface ServiceInterface 11