Lecture Building reliable component-based systems - Chapter 17: Architectural support for reuse

Lecture Building reliable component-based systems - Chapter 17: Architectural support for reuse. In this chapter, the following content will be discussed: Industrial automation systems, the motivation for a platform, the architecture, developing a domain specific application.

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Building Reliable Componentbased Systems

Chapter 17 Architectural Support for Reuse

Overview

Industrial Automation Systems

The Motivation for a Platform

The Architecture

Developing a Domain Specific Application

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Industrial Automation Systems

Highly specialized, independent, and incompatible

hardware and software system solutions

A flexible combination of basic hardware and software components, communications infrastructure, and

application components

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The 6-layer Model of a Technical Process

Group Control Level

Production Management Level

Process Level Field Level

Enterprise Level

Process Control Level

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The Motivation for a Platform

Envisioned seamless link between front-end business processes and plant control processes:

Motivations for a large global company to invest into the development of a “single” platform

Avoidance of parallel developments in different business segments

Harmonization of the diversity of ‘legacy’ automation platforms acquired through company mergers or

resulting from previous parallel developments

Adoption of product line business strategies (i.e

pursuing a system family concept both within and across vertical market segments).

Implicit expectation of a reuse payoff.

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Some Aspect-specific software is needed.

(binary) Software component; Microsoft COM component following specific rules

The basic set of ASOs distributed with the AIP contains functionality for alarming, event handling etc.

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AspectObjects

The most central type of entity in the model

AspectObjects model physical objects

E.g a specific valve in a dairy (“FIC 201 Valve”)

Does not contain any data

Related data is carried by its Aspects

AspectObject Aspect

Aspect

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<<Aspect>>

Maintenance Instructions

<<Aspect>>

Operator Graphics

<<is modeled by>>

<<Aspect>>

Operation Report

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Aspect Types

Defines how the data in an Aspect is used

In a “Mechanical Drawing” Aspect, the data is opened with AutoCad

In a “Maintenance Instructions” Aspect, the data is opened with Acrobat Reader

Reuse!

+Name : string(idl) = "Mechanical Drawing"

+Action : string(idl) = "Open With AutoCad"

Aspect Type

+Data : <unspecified> = 10110100010110010110

Aspect

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Aspect Types, cont.

+Name : string(idl) = "Mechanical Drawing"

+Action : string(idl) = "Open With AutoCad"

Aspect Type

+Data : <unspecified> = 10110100010110010110

Aspect

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Object Types

Models the type of an AspectObject

The type of “FIC 201” is “Valve”

Defines what Aspect Types an AspectObject can have

A “Valve” can have a “Mechanical drawing” etc.

Reuse!

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Object Types, cont.

+Name : string(idl) = "Valve"

+Aspects : Aspect Type = "Mechanical Drawing",

Object Type

+Name : string(idl) = "FIC 201"

+Aspects : Aspect

AspectObject

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Structures

Models a structure

Location structure Functional structure Batch structure

Typically, each AspectObject is part of several

structures

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Structures, cont.

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Physical view

Client-server system

Freedom to choose number of servers

Scalability Reliability

Freedom to choose number of services

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Physical view, cont.

WP host

SH C WP

Server host ASM

SP A

SP B

SP C

Server host ASM

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Developing a Domain Specific Application

Jacobson et al have introduced the distinction between

an application system and a component system:

Reusing a single component is usually insufficient

Requires the reuse of a set of components.

A set of components must be reused to obtain the alarm handling functionality

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4-Layer Representation

Application system layer:

Offers a coherent set of use cases to some end users

The business-specific:

Layer several component systems used by the application engineer.

The middleware layer:

Independent of particular types of business GUI builders, database management systems, etc

The system software layer:

Operating systems

Indistinct boundaries between itself and middleware.

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AIP Reuse Hierarchy

W2k AIP base infrastructure AIP base ASOs project specific ASOsAIP base Services project specific Services

AIP built-in admin

Aspect Types

project specific Aspect Types

AIP built-in general- purpose Aspect Types

domain specific Aspect Types

domain specific Object Types

domain specific templates and patterns project specific templates and

patterns

enablers

engineering guidelines and tools AIP library concept AIP export/import

OT inheritance

AIP export/import

AT inheritance

COM VC++

configuration

3 rd party applications

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Some Words of Caution

Possible risks:

Only relying on a platform, not having a reuse-driven process or product line practice with a top-down and planned approach to reuse will not succeed.

Requirements management:

Requirements elicitation, prioritisation and trade-offs across products, domains, and organizational units are extremely complex

Bugs in a released version

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