Architectural Models. Section Outline. What is an architectural design? Architecture Types. Example Logical Architecture. Example Deployment Diagram

Transcription

1 Section Outline Architectural Models Architecture Overview Logical Architectures UML Package and Subsystem Diagrams Computer Science Department Baylor University Architectural Models-1 Architectural Models-2 What is an architectural design? Architecture Types Concerned with identifying subsystems and their relationships Model shown is for a single system Italicized subsystems represent new systems; normal style represent existing components Dashed arrows represent dependencies; the precise nature of the dependency, including protocols, can be stated as annotations Relational DB Interface Presentation () Application Logic Communication Support Libraries Security Logical Architecture Organization of a system into logical units (eg, layers, subsystems) Logical units do not necessarily result in units of implementation (eg, Java packages, components) Implementation (Deployment) Architecture Organization of a system into physical units (eg, source files, Java packages, components) Architectural Models-3 Architectural Models-4 Example Logical Architecture Example Deployment Diagram Customer Services Customer Problem Tracking Order Processing System Order Tracking Invoicing i Shipping dependency Customers Od Orders dependent independent node :OrderProcessingServer :Order Tracking :Order :Order Invoicing :awindowspc :InvoicingClientFacade connection component :CustomerServer :CustomerCare :Cust :DatabaseServer :DataAccess Oracle Interface Relational DB Interface :Invoicing :OracleInterface :OracleDatabase Informix Interface Architectural Models-5 Architectural Models-6 1

2 Logical Architectures Layered System organized into layers of functionality Presentation/Application/ (Data) Each layer uses the services of a lower layer Supports separation of concerns Subsystems System decomposed into peer units Layers can be decomposed into layers Layered Architectures Separate presentation and application logic, and other areas of concern Subsystem Layer or Application Logic Layer Services Layer Logging Subsystem Architectural Models-7 Architectural Models-8 Layers (AKA Presentation, View) Layers (details) Application (AKA Workflow, Process, Mediation, App Controller) more Applicationspecific G windows reports speech interface HTML, XML, XSLT, JSP, Javascript, (AKA Presentation, View) (AKA Business, Application Logic, Model) Business Infrastructure (AKA Low-level Business Services) handles presentation layer requests workflow session state window/page transitions consolidation/transformation of disparate data for presentation Application (AKA Workflow, Process, Mediation, App Controller) more Applicationspecific Technical Services (AKA Technical Infrastructure, High-level Technical Services) Foundation (AKA Core Services, Base Services, Low-level Technical Services/Infrastructure) handles application layer requests implementation of domain rules domain services (POS, Inventory) - services may be used by just one application, but there is also the possibility of multi-application services (AKA Business, Application Logic, Model) width implies range of applicability width implies range of applicability Architectural Models-9 Architectural Models-10 Layers (details) continued Architecture Guidelines Worse mixes logical and deployment views Better a logical view (s) Technical Services (s) POS Technical Services Inventory a logical representation of the need for data or services related to these subdomains, abstracting implementation decisions such as a database Foundation Naming and Directory Services Web AppFramework MySQL Inventory «component» Novell LDAP Foundation UML notation: A UML component, or replaceable, modular part of the physical system UML notation: A physical database in the UML Architectural Models-11 Architectural Models-12 2

3 Architecture and SSDs Facades :System : Cashier enteritem(id, quantity) description, total endsale() Swing enteritem() endsale() Frame : Cashier enteritem() endsale() Register Swing Frame Sales Register Sale for applications with only a few system operations, perhaps only one object acts as the facade into the layer The Technical Services layer typically exposes many interfaces--at least one per subsystem enteritem() Technical Services the system operations handled by the system in an SSD represent the operation calls on the Application or layer from the layer DBFacade Log4J Jess SOAP Architectural Models-13 Architectural Models-14 Application Coordination Layer When you have many system operations consider an application coordination layer whose objects are use case controllers Summaries AppCoordination RentingVideo UCHandler Core Editors PayingFines UCHandler Evaluation Policies Major Functions Core Services AppCoordination Editors Evaluation Policies Logging Another Example: Session Facades Swing Application Sales SessionFacade Register JFrame ProcessRental SessionFacade Sale ProcessRental JFrame HandleReturns SessionFacade Rentals Rental Application session facade objects that maintain session state and control workflow related to some work--often by use case Architectural Models-15 Architectural Models-16 Packages Decomposition Criteria A package is a collection of model elements In logical architectures a package is a subsystem A package is rendered as a tabbed folder Functional cohesion Contents pertain to a single functional concept Example: Print subsystem Unit of reuse Contents can be reused together Should have minimal dependencies Unit of access control Limit access to contents Delivery unit Note: added on 2/11/2007 Architectural Models-17 Architectural Models-18 3

4 Core Concepts Construct Description Syntax Package Import Access A grouping of model elements A dependency indicating that the public contents of the target package are added to the namespace of the source package A dependency indicating that the public contents of the target package are available in the namespace of the source package Name Packages as a Namespace A package defines a namespace A model element belongs to at most one package Model elements can be referenced outside of the packages they are defined in package1::class1 package3::class1 A package can contain other packages package1::package2::class2 Architectural Models-19 Architectural Models-20 Package Examples Sales Customer Order Warehouse Location Item Packages A package owns its model elements destruction of the package results in destruction of the model elements relationship between a model element and its package is a composition Stock Item Order Item Architectural Models-21 Architectural Models-22 Package Containment Package Dependencies Packages are shown in static diagrams Two equivalent ways to show containment: It is useful to show the coupling with UML dependency lines A CASE tool can reverse engineer these diagrams Major Functions Core Services AppCoordination Editors Evaluation Policies Logging Architectural Models-23 Architectural Models-24 4

5 Accessing Package Elements To control access to elements in packages they are accessed or imported Import/Access: A package that imports/accesses another has access to the public elements of the imported/accessed package public elements are said to be exported Import versus Access Package1 contains public Class1; Package2 contains public Class2 Package1 access Package2 elements in Package1 must reference Class2 as follows: Package2::Class2 Package1 import Package2 elements in Package1 can reference Class2 as just Class2 Architectural Models-25 Architectural Models-26 Import vs Access Subsystem Design X Y Z B Y::C +C +Z::F +F -D Y::F A +E -Z::G +G Y::E X Y Z B +C +F -D Y::Z::F A +E +Z::F +G -H -H Subsystem design is concerned with describing how subsystems accomplish their tasks (as defined by their interfaces) Class diagrams describe design elements and their relationships Interaction diagrams describe how objects in a subsystem interact to accomplish tasks Architectural Models-27 Architectural Models-28 Subsystem Interfaces Operations and Interfaces Trunk Traffic Control Subscription IX1 operation1( ) operation2( ) «realize» operation4( ) X operation1( ): Type 1 operation2( ): Type 2 operation3( ) : Type 3 operation4( ) : Type 4 operation5( ) : Type 5 IX2 operation2( ) «realize» operation3( ) operation5( ) Trunk Traffic Control Subscription IX1 operation1( ) operation2( ) operation4( ) IX1 X operation1( ): Type 1 operation2( ): Type 2 operation3( ) : Type 3 operation4( ) : Type 4 operation5( ) : Type 5 IX2 IX2 operation2( ) operation3( ) operation5( ) Architectural Models-29 Architectural Models-30 5

6 Requirements Models to Architectural Design Models: An Example Simple Library Example Library consists of reference and general copies: Only general copies can be checked out, Reference copies cannot be checked out A borrower cannot check out a copy if they have outstanding fines A borrower is charged $1 for each week after its due date that it is not returned A simple Library System Example (cont) Required Services CheckOutCopy ReturnCopy AddCopy DeleteCopy AddBorrower DeleteBorrower FindCopy Architectural Models-31 Architectural Models-32 A simple Library System Example (cont) Requirements Class Model UseCase: CheckOutCopy Clerk enters borrower and copy identifiers If borrower is registered, does not have fines, and copy is a general copy then system indicates that checkout is successful; else system indicates that checkout is not successful Architectural Models-33 Architectural Models-34 Architectural Static Model Architectural Sequence Model - Exercise Show an architectural sequence model describing how subsystems accomplish CheckOutCopy task using subsystem interfaces given in an architectural static model Architectural Models-35 Architectural Models-36 6

7 Acknowledgements: This lecture material is prepared based on slides by Craig Larman and Dr R France (CSU) Architectural Models-37 7