Architectural Patterns

Transcription

1 Architectural Patterns CS 718 lecture series Prof. Rushikesh Joshi IIT Bombay

2 wrapper provide a single layer of abstraction on top of many related functions

3 wrapper an example the semop system call in unix-- it wraps around many functions related to semaphores int semop(int semid, struct sembuf *sops, unsigned nsops);

4 Layering A large system is decomposed into layers of abstractions

5 Layers: examples operating systems system calls, inner kernel, hardware abstractions, hardware networking layers APIs-platform independent Implementation- Platform dependent implementation 3-tiered architecture UI, BL, Data

6 Pipelines data in data out processing steps in a pipeline are sometimes referred to as filters, and the connectors as pipes stream of data passes through pipes and filters

7 pipelines-- examples language processing lexical analysis, syntax analysis, semantic analysis, code generation, optimization unix pipes and filters instruction pipelines

8 The difference between layers and pipes

9 client- call/service invocation client return results client does not provide an interface, the only communication from the to client is through return results or exception/error values

10 client- examples Lan services on a unix machine/windows machine ldap, portmapper, nslookup, directories RMI, RPC, Web-s and web clients

11 Blackboard monitors blackboard blackboard controller activates knowledge sources and task solvers operate on/use/share collaborative problem solving through knowledge sharing

12 blackboard-examples Linda tuple space shared memory based parallel/distributed problem solvers

13 Master-Slave master task distribution slave slave slave

14 master-slave example used in parallel computing on clusters master process splits a big task into subtasks, distributes and coordinates slave processes, collects and collates results

15 Broker client proxy broker stub/ skeleton coordinating communication (requests, replies, exceptions) in a distributed remote service invocation scenario

16 broker--examples direct communication broker- connect and then let client communicate directly trader broker (select one of many s) middleware brokers (e.g orb in corba) locating s, supporting interoperability

17 Example: Activation Broker -1 machine messaging broker client machine client process service repository

18 Example: Activation Broker -2 machine messaging broker client machine specific req client process service repository

19 Example: Activation Broker -3 machine activation messaging broker client machine client process service repository

20 Example: Activation Broker -4 machine activation messaging broker client machine USE client process service repository

21 Example: Activation Broker -5 machine activation reqister messaging broker client machine USE client process service repository

22 Example: Activation Broker -6 machine activation reqister messaging broker client machine USE specific req client process service repository

23 Example: Activation Broker -7 machine activation reqister messaging broker client machine forward specific req USE specific req client process service repository

24 Example: Activation Broker -8 machine activation reqister messaging broker client machine LOAD forward specific req USE specific req client process service repository

25 Example: Activation Broker -9 machine activation start event messaging broker client machine LOAD USE specific req client process service repository

26 Example: Activation Broker -10 machine activation messaging broker client machine specific req specific req client process service repository

27 Activation Policies Per client's request Per client Per service request Per

28 Who does the registration into repository A separate application that creates implementations Server implementations are registered in implementation repositories Server interfaces can be registered with interface repositories

29 Model - View Controller -1 Main title Main title Row 1 Row 2 Row 3 Row 4 view controller Row 1 Row 2 Row 3 Row 4 Model pradeep vinay namita yogita

30 Model - View Controller Main title user/control inputs Main title Row 1 Row 2 Row 3 Row 4 view controller Row 1 Row 2 Row 3 Row 4 Model pradeep vinay namita yogita

31 Model - View Controller Main title user/control inputs Main title Row 1 Row 2 Row 3 Row 4 view controller Row 1 Row 2 Row 3 Row 4 Model update model pradeep vinay namita yogita

32 Model - View Controller Main title user/control inputs Main title view controller Row 1 Row 2 Row 3 Row 4 Row 1 Row 2 Row 3 Row 4 change intimation update model Model pradeep vinay namita yogita

33 Model - View Controller Main title user/control inputs Main title view controller Row 1 Row 2 Row 3 Row 4 Row 1 Row 2 Row 3 Row 4 pull updates change intimation Model update model pradeep vinay namita yogita

34 Model - View Controller -6 control view model view pull updates user inputs view messages change intimation Model controller update model input events sent to controller model contains the state information model is displayed in view

35 Properties of MVC controller not aware how the state is displayed model not aware of how the state is displayed controller does not directly inform the view about updates model sends update intimations to view the view can pull in the updates

36 mvc -- examples smalltalk MVC different look and feel standards Java pet-store example ob based systems

37 Pull Type Architecture

38 Push type Architecture

39 Combining them.. Pull Push Architecture

40 Combining them.. Push Pull Architecture

41 Combining them.. Push Push Architecture

42 Combining them.. Pull Pull Architecture

43 Design issues Buffer spaces at source at intermediate channel Connectivity dynamic disconnections Service orientation, payment model Failure Handling Performance

44 Design of interfaces interface pushconsumer { interface pullpublisher { } notifyevent(event e); disconnectingpushpublisher(); } boolean subscribe (pullconsumer c); unsubscribe (pullconsumer c); Event pullevent (); interface pushpublisher { interface pullconsumer { subscribe (pushconsumer c) unsubscribe (pushconsumer c) } disconnectingpullpublisher(); }