1. Patterns -- 1 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 11b. Reference Models and Organizational Patterns Reference Models How to Build and Use them Organizational Patterns Social Design (Micro-) Patterns

2. Patterns -- 2 @2006 Manuel Kolp Dept of Information Engineering and Computer Science How do we Build Models? ➸ We would like to reuse existing models (or parts thereof) as much as possible. ➸ Two techniques used widely: Reference models –- define “exemplars” (good examples) for a certain class of models; modeler can adopt a reference model and change it to suit her purposes. Design patterns – these are generic descriptions of a class of models, guide a modeler in building her model. ➸ For example: exemplar of an Italian name: Paolo variants: Paola, Paulo, Taolo, Paoto, … pattern: (Cons (Vowl | Vowl Vowl))+ instances: No, Toa, Paolo, Tapa, … 2

3. Patterns -- 3 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 3 Reference Models  A reference model is a recommended model for a specific domain. As such, reference models are literally "points of reference" for the development of concrete models.  Reference models often come about by generalizing from concrete models.  Variant: A specific variation of a reference model.  Best Practice Model: A best practice model is a reference model adopted from the best concrete models. ©2006 Dimitris Karagiannis

4. Patterns -- 4 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 4 Metamodels  A metamodel is a model of another model. Instance-of Asso. Edge Entity Type Rel. Type Supplier Time Article Order Pos. ©2006 Dimitris Karagiannis

5. Patterns -- 5 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 5 Metamodels and Reference Models Syntactic Abstraction Semantic Abstraction Reference Model Model Reference Metamodel Meta- model Inductive RMM creation RM creation RM-based construction of model RM-based construction of MM is instance of Source: Schütte (1998), p. 73 ©2006 Dimitris Karagiannis

6. Patterns -- 6 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 6 Supplier Time Article Order Source Order Subject. Supplier Time Article Order Rel. Type Attr. Edge Asso. Edge Attribute Entity Type RM-based construction of model RM creation RM-based construction of MM Inductive RMM creation ©2006 Dimitris Karagiannis Asso. Edge Rel. Type Entity Type An Example

7. Patterns -- 7 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 7 Reference Model and Variants Reference Model Variant 1 Variant 2Variant 3 A model variant may not have all objects of the generic model (e.g. not all process paths) ©2006 Dimitris Karagiannis

8. Patterns -- 8 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 8 Objects contained in various model variants may have different attribute values (e.g. different time values or cost factors) Model Variants: Attribute/Content Level ©2006 Dimitris Karagiannis

9. Patterns -- 9 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 9 Reference Process Model Variant 1 Variant 2 Variant 3 Views Modeling Views with Reference Models ©2006 Dimitris Karagiannis

10. Patterns -- 10 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 10 Reference Process Model Variant 1 Variant 3 Variant 2 1. Working Copy 2. Consolidation Working Copies and Consolidation ©2006 Dimitris Karagiannis

11. Patterns -- 11 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 11 Reference Models: Pros and Cons Reference Models Specialized, Company-specific Models Process- - Selection - Elimination - Extension Process- - Selection - Elimination - Extension - Country-, Branch-, Company-, Business Unit-specific - Mainly used for process models, not for organizational models - Know-How acquisition (+) - Accelerated model creation / process design (+) - Possibility, that the reference models are supported by Standard-SW (+) - Insufficient questioning about (good / optimal) process structure (-) - Adaptation of company processes to reference processes (-) - Include unnecessary processes (-) - Country-, Branch-, Company-, Business Unit-specific - Mainly used for process models, not for organizational models - Know-How acquisition (+) - Accelerated model creation / process design (+) - Possibility, that the reference models are supported by Standard-SW (+) - Insufficient questioning about (good / optimal) process structure (-) - Adaptation of company processes to reference processes (-) - Include unnecessary processes (-) ©2006 Dimitris Karagiannis

12. Patterns -- 12 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 12 Patterns vs Reference Models  Patterns are generic composite structures that can be reused during design.  A pattern either matches or doesn’t match a structure.  For example, ‘X:CHAR & “A” & STRING(length=2)’ matches strings that begin with a character followed by an A, followed by a string of length 2.  The structures that match a pattern are its instances.  Patterns are used heavily in OO software design.  Patterns constitute an important cognitive concept: experts think in terms of patterns …  Reference architectures can be changed arbitrarily to create variants; patterns can not.

13. Patterns -- 13 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Organizational Patterns ➸ Architectural Design ➸ 10 Architectural Styles ➸ Software Quality Attributes ➸ Correlation Catalogue ➸ Examples ➸ Agent Patterns

14. Patterns -- 14 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Architectural Styles ➸ Styles to guide high-level software system design. ➸ Pipe-filter, Main-Program & Subroutines, layered architecture,... ➸ Are there such styles for organizations? ➸ Software styles do not focus on organizational architectures.

15. Patterns -- 15 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Organizations ➸ Organizations coordinate the actions of many individuals for some purpose. Develop and manage structures such as business units, profitable enterprises, multi-national alliances,... Not constructed with a population of identical individuals doing the same thing; Diversify, delegate, negotiate, manage, cooperate, compete,... ➸ We need architectural styles defined in terms of such primitive concepts.

16. Patterns -- 16 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Flat Structure ➸ No fixed structure and no control of one actor over another is assumed. ➸ Main advantage: autonomy, distribution and continuous evolution of an actor architecture. ➸ Key drawback: an increased amount of reasoning and communication by each participating actor.

17. Patterns -- 17 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Structure-in-5 ➸ Many organizations structured this way. ➸ Typical strategic and logistic components found in organizations: Operational core : basic operations -- the input, processing, output associated with running the organization. Operational core : basic operations -- the input, processing, output associated with running the organization. Strategic apex : executive, strategic decisions. Strategic apex : executive, strategic decisions. Support : Assists the operation core for non-operational services outside the basic flow of operational procedures. Support : Assists the operation core for non-operational services outside the basic flow of operational procedures. Technostructure : standardizes the behavior of other components, helps the system adapt to its environment. Technostructure : standardizes the behavior of other components, helps the system adapt to its environment. Middle line : Actors who join the apex to the core. Middle line : Actors who join the apex to the core.

18. Patterns -- 18 @2006 Manuel Kolp Dept of Information Engineering and Computer Science

19. Patterns -- 19 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 19 Truck Manufacturing Volvo Trucks Corporation ©2006 Manuel Kolp

20. Patterns -- 20 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 20 LDV Bates Advertising Example from Advertising Industry ©2006 Manuel Kolp

21. Patterns -- 21 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 21 E-Commerce Architecture: ©2006 Manuel Kolp

22. Patterns -- 22 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Pyramid ➸ Actors at the lower levels depend on actors of the higher levels. ➸ Supervision from the apex. ➸ Managers and supervisors are only intermediate actors routing strategic decisions and authority They can coordinate behaviors or take decisions only at a local level.

23. Patterns -- 23 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Pyramid ➸ Applied when deploying simple systems. ➸ Encourages dynamicity: coordination and decision are direct, not complex and immediately identifiable. ➸ To manage and resolve crisis situations. A complex agent system faced with an intrusion from non trustable agents could dynamically migrate itself into a pyramid organization to resolve the security problem in a more efficient way. ➸ Evolvability and modifiability can be implemented at low costs. ➸ The computation can appropriately be defined via a hierarchy of procedure definitions: related to the classical main program and subroutines architectural style

24. Patterns -- 24 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Joint Venture ➸ Two or more organizations unite to pursue agreed upon goals. Organizations remain independent ➸ Partner organizations share the benefits and control over the performance of assigned tasks; contribute in key areas. ➸ Joint manager coordinates tasks and manages the sharing of resources between partners. ➸ Partners can manage and control themselves on a local dimension and interact directly with other partners ➸ The global strategic operation and coordination is ensured by the joint manager in which partners are entitled participation.

25. Patterns -- 25 @2006 Manuel Kolp Dept of Information Engineering and Computer Science

26. Patterns -- 26 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 26 Case Study: Steel Making at Carsid  CARSID  CARSID (Carolo-Sidérurgie) Duferco - Usinor (60/40)  Ex-Cockerill Sambre in Marcinelle-Marchienne  Steel, coke, sinter charge, cast iron, slabs.  Problems: DB applications (Re-)Engineering Process control Software project management System documentation migrationintegration  Project: migration, integration, new information system strategy  Context: Knowledge management, continuation, training  Demand for new modelling tools ©2006 Manuel Kolp

27. Patterns -- 27 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 27 Carsid Partners Cokerill-Sambre Duferco Usinor Carlam Duferco + Sogepa (Walloon Region) ©2006 Manuel Kolp

28. Patterns -- 28 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 28 Carsid Case Study ©2006 Manuel Kolp

29. Patterns -- 29 @2006 Manuel Kolp Dept of Information Engineering and Computer Science 29 Airbus Case Study ©2006 Manuel Kolp

30. Patterns -- 30 @2006 Manuel Kolp Dept of Information Engineering and Computer Science E-Business Architecture

31. Patterns -- 31 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Arm’s-Length No authority delegated/lost from a collaborator to another. For applications that involve a collection of independent computations whose execution proceed competitively. Can be considered a derivation of the classical communicating processes architectural style. Agreements between independent and competitive but partner actors. Partners keep their autonomy and independence but act and put their resources and knowledge together to accomplish common goals.

32. Patterns -- 32 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Bidding ➸ Competitivity mechanisms and actors needed to run an auction. ➸ The auctioneer actor runs the show. ➸ The auction issuer issues the bidding. ➸ Implies fast response time and adjustability for the system.

33. Patterns -- 33 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Takeover ➸ Total delegation of authority and management from two or more partners to a single collective takeover actor. ➸ Similar to the joint venture style. ➸ Difference: In a joint venture identities and autonomies of the separate units are preserved, the takeover absorbs these critical units, no direct relationships tolerated except those involving the takeover.

34. Patterns -- 34 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Hierarchical Contracting ➸ Coordinating mechanisms that combine arm's-length features with aspects associated with pyramidal authority. ➸ Coordination mechanisms developed to manage arm's-length (independent) characteristics ➸ Involve a variety of negotiators, mediators and observers at different levels handling conditional clauses to monitor and manage possible contingencies, negotiate and resolve conflicts and finally deliberate and take decisions. ➸ Hierarchical relationships restrict autonomy and underlie a cooperative venture between the contracting parties.

35. Patterns -- 35 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Hierarchical Contracting ➸ Dual and admittedly complex contracting arrangements ➸ To manage conditions of complexity and uncertainty deployed in high-cost-high- gain (high-risk) applications. ➸ Suitable for applications that involve distinct classes of layered services that can be arranged hierarchically ➸ Can be considered a specialization of the classical layered architectural style.

36. Patterns -- 36 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Vertical Integration ➸ Merges system actors engaged in related tasks at different stages of a production process. ➸ A merger synchronizes and controls interactions between each of the participants that can be considered as workshops. ➸ Suitable for applications that require a defined series of independent computations to be performed on ordered data ➸ Can be viewed as a specialization of the classical pipe and filter architectural style.

37. Patterns -- 37 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Co-optation ➸ Involves the incorporation of representatives of external systems into the decision-making structure and behavior of an organization. ➸ Organizations trading confidentiality and authority for resource, knowledge assets and support. ➸ Each co-optated actor has to adjust his views with the policy of the system.

38. Patterns -- 38 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Quality Attributes ➸ Predictability Organizational actors have high degree of autonomy when they undertake action and communication in their domains. Difficult to predict individual characteristics as part of determining the behavior of a complex system. ➸ Security Protocols and strategies for verifying authenticity for these data sources by individual software entities are an important concern in the evaluation of overall system quality since, in addition to possibly misleading information acquired by system actors, there is the danger of hostile external actors spoofing the system to acquire information accorded to trusted domain actors.

39. Patterns -- 39 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Quality Attributes ➸ Adaptability Organizational actors may be required to adapt to modifications in their environment. Dynamic introduction of a new agents unknown or the manipulations of existing agents. ➸ Coordinability To coordinate with other actors. Two different antagonist ways: Cooperativity. Actors must be able to coordinate with other actors to achieve a common purpose. Competitivity. Actors must be able to coordinate with other actors except that the success of one agent implies the failure of others.

40. Patterns -- 40 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Quality Attributes ➸ Availability. Guard against the interruption of offered services. Must actually be considered a sub-attribute of security ➸ Robustness. Failure of one actor does not imply a failure of the whole system. To prevent failure: ensure similar or replicated capabilities and refer to more than one agent for a specific behavior. Induces redundancy in the system.

41. Patterns -- 41 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Software Quality Attributes ➸ Modularity increases efficiency of task execution, reduces communication overhead and usually enables high flexibility. Implies constraints on inter-module communication and dependence. ➸ Aggregability Actors surrender to the control of a composite actor. Efficient task execution and low communication overhead, Contradicts overall system flexibility, violates actor autonomy.

42. Patterns -- 42 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Correlation Catalogue HELP, MAKE, HURT, BREAK, respectively model partial-positive, sufficient-positive, partial-negative and sufficient-negative contributions.

43. Patterns -- 43 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Selecting System Architecture

44. Patterns -- 44 @2006 Manuel Kolp Dept of Information Engineering and Computer Science A Joint Venture System Architecture

45. Patterns -- 45 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Architectural Design ➸ Global architecture in terms of interconnected subsystems. ➸ 3 Steps Organizational 1 Macrolevel : Organizational Styles (Organization Theory) Vertical Integration, Pyramid, Joint Venture, Structure in 5, Bidding, Hierarchical Contracting, Co- optation, Takeover 2 Micro level : Patterns (Agent Community) Broker, Matchmaker, Contract-Net, Mediator, Monitor, Embassy, Wrapper, Master-Slave,... 3 Assigning Actors to Agents, Positions, Roles

46. Patterns -- 46 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Patterns for Agents: Monitor ➸ One monitor, a number of subscribers and at least one subject of interest. ➸ Accepts subscriptions, request notifications from subjects of interest, receive such notifications of events and alerts subscribers to relevant events. ➸ The subject provides notifications of state changes as requested. ➸ The subscriber registers for notification of state changes to distributed subjects, receive notifications with current state information, and update its local state information. ➸ Used in the horizontal contracting, vertical integration, arm’s- length and bidding styles implying observation requirements.

47. Patterns -- 47 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Monitor and Broker

48. Patterns -- 48 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Broker ➸ One broker, a number of service consumers and providers. ➸ The broker is an arbiter and intermediary accessing services of one actor to satisfy the request of another. ➸ Consumers may also be in turn service providers, and inversely providers can also be consumers. ➸ Roles of each actors are established in the context of a particular dialogue. ➸ Used in the horizontal integration and joint venture styles.

49. Patterns -- 49 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Matchmaker ➸ Locates a provider corresponding to a consumer request for service, and then hands the consumer a handle to the chosen provider directly. ➸ The broker directly handles all interactions between the consumer and the provider ➸ Here the negotiation for service and actual service provision are separated into two distinct phases. ➸ Used in the horizontal integration and joint venture styles.

50. Patterns -- 50 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Matchmaker and Mediator

51. Patterns -- 51 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Mediator ➸ A mediator, and any number of colleague actors who play either the role of initiator or performer. ➸ A colleague (initiator) addresses the mediator in place of asking directly another colleague (performer). ➸ He has acquaintance models of colleagues and coordinates the cooperation between them. ➸ Each colleague has an acquaintance model of the mediator. ➸ A broker simply matches providers with consumers, ➸ A mediator encapsulates interactions and maintains models of initiators and performers behaviors over time. ➸ Used in pyramids, takeovers, vertical integrations and horizontal contracting: underlies direct cooperation and encapsulation features reinforcing authority mechanisms.

52. Patterns -- 52 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Embassy ➸ Involves a foreign actor, a single embassy actor and any number of local actors. ➸ The foreign actor request access to a local actor from its embassy actor. ➸ Depending on the level of certificate provided, access may be granted or denied. ➸ When the access is granted, the foreign actor can submit messages to the embassy for translation. ➸ The content is translated in accordance with a standard ontology. ➸ Translated messages are forwarded to target local actors. ➸ The results of the query are passed back out to the foreign actors, translated in reverse.

53. Patterns -- 53 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Embassy ➸ For structure-in-5, arm’s-length, bidding and co-optation ➸ Take in charge security aspects between component related to the competitivity mechanisms inherent to these styles.

54. Patterns -- 54 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Wrapper ➸ A wrapper, a number of clients and only one legacy system since the wrapper is domain-specific. ➸ Allows a legacy application to be coupled with a MAS. ➸ Interfaces the clients to the legacy by acting as a translator. ➸ Ensures that communication protocols are respected and the legacy system remains decoupled from the clients. ➸ Used in the co-optation style when one of the co-optated actor is a representative for a legacy system.

55. Patterns -- 55 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Wrapper and Contract-Net

56. Patterns -- 56 @2006 Manuel Kolp Dept of Information Engineering and Computer Science Contract-Net ➸ Involves a manager and any number of participants. ➸ The manager issues a request for proposal for a particular service to all participants and then accepts "proposals" to meet the service request at a particular "cost". ➸ The manager selects among these proposals and indicates acceptance to exactly one participant. ➸ The selected participant performs the contracted work and informs the manager upon completion. ➸ The contract-net pattern is used in the bidding and arm’s- length style since they are based on competitive features. ➸ This pattern is especially used in the arm’s-length and bidding and co-optation styles due to their inherent competitive features.