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Chapter 17 Architectural Support for Reuse Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 1 Overview  Industrial Automation Systems  The Motivation for a Platform  The Architecture  Developing a Domain Specific Application Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 2 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. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 3 The 6-layer Model of a Technical Process Enterprise Level Production Management Level Process Control Level Group Control Level Field Level Process Level Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 4 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. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 5 The Architecture  AspectObject, Object Type, Aspect and Aspect Type.  Aspect System  A collection of Aspect Types for a certain context or purpose.  Domain-related reuse.  AspectSystemObject  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. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 6 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 Aspect Aspect AspectObject Aspect Aspect Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 7 Aspect  Encapsulates a subset of the data related to an AspectObject  Different types of electronic information (e.g. documents) <> Valve <> <> Valve 1 1 1 1 <> <> <> <> Control Operator Graphics Operation Report Mechanical Drawing Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse 1 <> Maintenance Instructions Page 8 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! Aspect Type +Name : string(idl) = "Mechanical Drawing" +Action : string(idl) = "Open With AutoCad" Aspect +Data : = 10110100010110010110... Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 9 Aspect Types, cont. Aspect Type +Name : string(idl) = "Mechanical Drawing" +Action : string(idl) = "Open With AutoCad" Aspect +Data : = 10110100010110010110... Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 10 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! Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 11 Object Types, cont. Object Type +Name : string(idl) = "Valve" +Aspects : Aspect Type = "Mechanical Drawing", ... AspectObject +Name : string(idl) = "FIC 201" +Aspects : Aspect Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 12 Structures  Models a structure  Location structure  Functional structure  Batch structure  ...  Typically, each AspectObject is part of several structures Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 13 Structures, cont. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 14 Structures, cont.  Location structure  Enables browsing through the physical layout  See what valves are physically connected to a pipe  Functional structure  Enables browsing through the functional layout  See what control units are connected to a valve Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 15 Physical view  Client-server system  Freedom to choose number of servers  Scalability  Reliability  Freedom to choose number of services Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 16 Physical view, cont. WP host WP SH A SH C SH A SH B Service group A WP host WP Service group B SH C Service group C1 Service group C2 SH B station network Server/WP host WP ASM SH A Server host SP C SH B ASM SP A SP B Server host ASM SP C SH C SP A Server host ASM SP C SP A SP B SP C Controller network SP: service provider SH: service handler ASM: Afw Service Manager Controller Controller Controller Controller WP: workplace Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 17 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. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 18 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. Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 19 AIP Reuse Hierarchy enablers project specific templates and patterns domain specific templates and patterns AIP built-in admin Object Types AIP built-in admin Aspect Types AIP built-in generalpurpose Object Types domain specific Object Types AIP built-in generalpurpose Aspect Types domain specific Aspect Types project specific Object Types AIP export/import project specific Aspect Types project specific ASOs AIP base ASOs AT inheritance 3rd party applications AIP base infrastructure W2k Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse OT inheritance AIP export/import project specific Services AIP base Services engineering guidelines and tools AIP library concept COM VC++ configuration Page 20 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 Building Reliable Component-based Systems Chapter 17 - Architectural Support for Reuse Page 21