Modeling Information Systems Architectures. Paul Grefen (DB MA-IS-CS) CTIT-UT

Transcription

1 Modeling Information Systems Architectures Paul Grefen (DB MA-IS-CS) CTIT-UT

2 Purpose of this lecture The purpose of this lecture is not to present pre-cooked solutions to architectural problems, but rather to clarify architectural issues and discuss a number of important topics in this context.

3 Table of contents What are IS architectures? Aspects of IS architectures Types of IS Architectures Reference Architectures Designing IS architectures Architectural platforms Conclusions

4 What are IS architectures?

5 General architecture architectuur' (architektuur), v., 1. bouwkunst, de kunst en de leer van het ontwerpen en uitvoeren van bouwwerken; - toepassing daarvan: onder architectuur gebouwd, naar de plannen van een bekend architect; - 2. bouwstijl: Griekse architectuur; - 3. (fig.) bouw, constructie: de architectuur van de kaak (Vestdijk); - 4. (meton.) bouwsel(s), bouwwerk(en): voorbeelden van moderne architectuur; Van Dale

6 Software architecture The architecture of a software system defines that system in terms of computational components and interactions among those components. Software Architecture; Shaw & Garlan; Prentice Hall, 1996

7 Example architecture

8 Information system architecture The architecture of an information system defines that system in terms of components and interactions among those components, from the viewpoint of specific aspects of that system, and based on specific structuring principles.

9 Interpreting IS architectures Syntax: structure of the architecture Semantics: meaning of components and interactions Pragmatics: reasons behind structure & meaning

10 Aspects of IS Architectures

11 Aspects architecture communication organization system configuration Truyens et al.; 1990

12 Data aspect architecture Architecture of managed by systems, e.g. using (E)ER diagrams. communication organisation system configuration

13 System aspect architecture Architecture of application software, e.g. using flow diagrams or module diagrams. Req. 1 book trip organisation system 2 proc. ackn. 4 proc. inv. a trip b fin. Pay. configuration communication 3 proc. docs. 5 proc. paym.

14 Configuration aspect architecture Architecture of hardware and low-level software (e.g. OS, DBMS), e.g. using configuration diagrams. communication organisation configuration system Oracle UNIX SPARC FlowMark

15 Communication aspect architecture (I) Architecture of communication infrastructure (networks, communication software), using e.g. topology diagrams. system OLD 3174 LOS Mb/s 19,2 Kb/s ES/9000 (HBS) 3745 Token Ring ES/9000 (APL) Commun. Controller PDP 11/74 organisation Haemodialyse Systeem 3174 PMK configuration communication Cluster Controller Specialisten Systemen PC PC PC

16 Communication aspect architecture (II) OLD 3174 LOS Mb/s 19,2 Kb/s ES/9000 (HBS) 3745 Token Ring ES/9000 (APL) Commun. Controller PDP 11/74 Haemodialyse Systeem 3174 communication organisation configuration system Cluster Controller PMK Specialisten Systemen PC PC PC

17 Organization aspect architecture Architecture of organization structure and processes related to administration and maintenance of systems, using e.g. organigrams and procedure handbooks communication organisation system configuration

18 A design path with aspects start arch.: major apects combined global arch.: major apects combined

19 Types of IS Architectures

20 Type of IS architectures Based on structuring principles: Monolithic / Layered / Columned / OO Single-Level versus Multi-Level Based on purpose: Conceptual versus Technical Application versus General System Reference versus Concrete

21 Structuring principles (I) Monolithic Layered Columned Object-Oriented and combinations

22 Structuring principles (II) Multi-level architectures: allow for multiple aggregation levels of functionality

23 Structuring principles (III) Columned Pipe Syntax: several system modules in the same layer. Semantics: multiple subsystems at the same abstraction level using each others functionality. Pragmatics: separation of concerns (system arch.) or distribution (conf. arch.).

24 Purpose of architecture (I) Conceptual architecture: describes structure of conceptual design of system Technical architecture: describes structure of implementation of system conceptual technical

25 Purpose of architecture (II) Application: describes architecture for specific application and context General system: describes architecture for general application and context Concrete: describes architecture of a specific system to be directly applied Reference: describes blue-print of abstract system to be concretized before application

26 Reference Architectures

27 Reference architecture A reference architecture is a general, abstract architecture that can be instantiated for specific situations. Instantiated = filled in, detailed parameterized, adapted extended, selected

28 ISO-OSI reference architecture application presentation session transport network link physical Structure: layered Aspects: system configuration communication Pragmatics: standard interface levels for horizontal communication

29 ANSI/SPARC reference architecture external model conceptual model internal model Structure: layered Aspects: system organization Pragmatics: separation between base levels for different purposes

30 ANSI/SPARC in DDBS Glob.Ext. Schema Loc.Map. Schema Loc.Conc. Schema Glob.Ext. Schema Glob.Conc. Schema Fragm. Schema Alloc. Schema Loc.Map. Schema Loc.Conc. Schema Glob.Ext. Schema Loc.Map. Schema Loc.Conc. Schema Structure: idem Aspects: idem + communicat. Pragmatics: idem + distribution Loc.Int. Schema Loc.Int. Schema Loc.Int. Schema DB DB DB Connolly, Begg & Strachnan, 1995

31 WfMC reference architecture (I) Process Definition Tools IF1 Workflow API & Interchange Formats Adminstration & Mngmnt Tools IF5 Workflow Engine(s) Workflow Enactment Service IF4 Workflow Engine(s) Other WF Enactment Service(s) IF2 Workflow Client Applications IF3 Invoked Applications

32 WfMC reference architecture (II) Process Definition Workflow Clients Administr. & Mngmnt Workflow Engine Applications Structure: first layered, then columned

33 Designing IS Architectures

34 Example architecture design Mercurius initiative (1995) Purpose: specification of reference WFMS Focus: detailed system architecture Participants: 2 universities, polytechnic consultancy firm, financial institution

35 Mercurius architecture design principles Flexibility (detail, aspect) Top-down architecture design strategy WF design versus WF enactment Kernel versus additional functionality Positioning in context Explicit interfaces to environment

36 Mercurius overall WFMS architecture organization UIS UIS stores WF Design WF Clients AS/OS/ DBMS communication system WF Server CS WF Server DBMS AS/OS stores configuration

37 Mercurius design module architecture Extension Module software bus UIS Interface WF Design Engine AS Interface DBMS Interface organ. def. proc. appl.

38 Mercurius design engine architecture Organisat. Design Product Design organ. proc. appl. Global Design Detail Design Tuning def.

39 Mercurius enactment module architecture AS WFC Interface AS Interface Extension Module software bus WFS Engine CS Interface DBMS Interface OS Interface organ. def. proc. man. appl.

40 Mercurius enactment engine architecture WFC Interface Clock Module Event Receptor CS Interface proc. Event Analyzer AS Interface def. Action Synthesizer software bus appl. Action Executor OS Interface

41 Architectural Platforms

42 Distributed Object Architectures object model architecture vs. system model architecture application object access vs. server system access fine grain computation vs. coarse grain computation transparent distribution vs. no/explicit distribution

43 Example architecture traditional Workflow Client Transaction Manager Workflow Engine trans case

44 Example architecture a la DOA client client transact. case case transact. scheduler

45 OMG-OMA Application Objects Common Facilities Object Request Broker Object Services

46 Example architecture: WIDE WFMS Global Trans. Man. GT Workflow Engine LTM LT BAL Local Trans. Interface DBMS

47 Conclusions

48 Conclusions Modeling of architectures of paramount importance CIS design Modeling of CIS architectures has many aspects Modeling of CIS architectures is a discipline that is in its infancy