Architecture Design
PV167 Project in Object-oriented
Design of Information Systems
B. Bühnová 1
System Modularization
Architecture Design/Part 1
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Modularization of Software
 Motivation
 Separation of concerns
 Break-down of system complexity
 Reuse
 Architecture design
 UMLPackage diagram (Analysis)
 UMLComponent diagram (Design/Implementation)
 UMLDeployment diagram (Realisation)
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Implementation-oriented Modularization
 Motivation
 Reuse
 Architectural tactics
 Separation of concerns
 Implementation
 Service-oriented approach
 Data passing, i.e. we can no longer rely on shared knowledge
 Challenges
 Shared knowledge that is hard to pass along
 Crosscutting concerns
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Components and Interfaces
 Provided interfaces
 Required interfaces
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Architectural Patterns and Tactics
Architecture Design/Part 2
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Architectural Patterns
 The Model-View-Controller (MVC) pattern
 Separates presentationand interaction from the system data.
 The Layered architecture pattern
 System organised into layers with interfaces to other layers.
 The Repository architecture pattern
 Interaction through a central repository.
 The Client-server architecture pattern
 Distributionof data and processing across stand-alone serviceproviding
servers and clients calling the services.
 The Pipe and filter architecture pattern
 Functional transformations process their inputs to outputs.
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Architectural Tactics for Dependability
 Redundancy
 Keep more than 1 version of a critical component available so
that if one fails then a backup is available.
 E.g. switch to backup servers automatically if failure occurs.
 Diversity
 Provide the same functionality in different ways so that they will
not fail in the same way.
 E.g. different servers may be implemented using different
operating systems (e.g. Windows and Linux).
 However, adding diversity and redundancy adds
complexity and this can increase the chances of error.
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N-version programming pattern
 Multiple versions of a software system carry out
computations at the same time.
 The results are compared using a voting system and the
majority result is taken to be the correct result.
Which of the tactics
are involved here?
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Architectural Tactics for Security
 Use redundancy and diversity to reduce risk
 Keep multiple copies of data and use diverse infrastructure so
that an infrastructure vulnerability cannot be the single point of
failure.
 Compartmentalize your assets
 Organize the system so that assets are in separate areas and
users only have access to the information that they need rather
than all system information.
 Design for recoverability
 Design the system to simplify recoverability after a successful
attack.
Chapter 14 Security Engineering 10
Architectural Tactics for Performance
 Introduce concurrency
 If requests can be processed in parallel, the blocked time can be
reduced.
 Maintain multiple copies of either data or computations
 The purpose of replicas is to reduce the contention that would
occur if all computations took place on a central server.
 Increase available resources
 Faster processors, additional processors, additional memory,
and faster networks all have the potential for reducing latency.
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Architectural Quality and its Prediction
Architecture Design/Part 3
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Quality prediction
 Palladio Component Model
 Quality prediction and design simulation framework
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