Software MEIC. (Lesson 20)

Transcription

1 Software MEIC (Lesson 20)

2 Last class C&C styles Multi-tier style Dynamic reconfiguration style Peer-to-Peer style

3 Today C&C styles Publish-subscribe style Service-oriented architecture style Pipe-and-Filter style

4 Publish-subscribe style

5 Interaction pattern: communication by events

6 Subscribe and/or Publish C1 C2 C3 C4 C5 Publish/Subscribe

7 Components May subscribe events (consumers) May publish events (producers)

8 Connector Works as an event bus Allows several components Manages subscriptions Manages notification of events

9 C1 C2 C6 C3 C4 C5 C7 Publish/Subscribe

10 Implicit invocation vs Explicit invocation

11 Advantages?

12 Decouples producers from consumers (Modifiability, extensibility)

13 Properties

14 Who subscribes/announces what? Dynamic change of subscriptions Dynamic creation of event types Temporal or causal ordering Reliability of event delivery When is an announcer blocked?

15 Examples

16 GUI applications MVC-based applications Social networks (friend notifications)

17

18 Service-Oriented Architecture (SOA) style

19 Interaction pattern: distributed components provide and/or consume services

20 Consumer Provider Call-return connector

21 What s the difference for Client-Server?

22 Consumer/ Provider Consumer/ Provider Provider

23 What s the difference for Peer-to-peer?

24 Components are standalone services (deployed independently, belonging to systems/organizations)

25 Typically use implementation languages/platforms

26 Adventure Builder Web browser Consumer Web site jdbc Adventure Catalog DB Key Client-side application Java EE application External Web service provider User s client OpcPurchase OrderService OPC OpcOrder TrackingService jdbc Adventure OPC DB Web services endpoint Data repository TBD CreditCard Service Web Service Broker service registry HTTP/HTTPS Bank ActivityPO Service SOAP call AirlinePO Service Airline Provider Lodging Provider LodgingPO Service Activity Provider Data access SMTP Scope of the application (not a component)

27 Keyword: interoperability

28 Typical SOAs use specialized components

29 Specialized SOA components Enterprise Service Bus (ESB) Service Registry Orchestration server

30 ESB: hub-and-spoke vs point-to-point topology

31 Consumer/ Provider Consumer/ Provider Provider

32 Consumer/ Provider Consumer/ Provider Enterprise Service Bus (ESB) Provider

33

34 ESB Routes messages Converts messages (e.g. HTTP to JMS) Transforms data Security checks Manages transactions

35 Improves interoperability, security, modifiability

36 Service registry improves transparency of location of service providers

37 Service Registry Consumer Provider

38 Increases modifiability

39 Orchestration server orchestrates interaction among consumers/providers

40 Consumer/ Provider Consumer/ Provider Enterprise Service Bus (ESB) Consumer Provider Orchestration Server

41 Orchestration server executes scripts upon the occurrence of an event (Typically defined in BPEL)

42 Improves interoperability, modifiability, reliability

43 SOA connectors Call-return - SOAP (XML messages over HTTP) - REST (HTTP commands on resources) Asynchronous messaging - Point-to-point - Publish-Subscribe

44 Adventure Builder Web browser Consumer Web site jdbc Adventure Catalog DB Key Client-side application Java EE application External Web service provider User s client OpcPurchase OrderService OPC OpcOrder TrackingService jdbc Adventure OPC DB Web services endpoint Data repository TBD CreditCard Service Web Service Broker service registry HTTP/HTTPS Bank ActivityPO Service SOAP call AirlinePO Service Airline Provider Lodging Provider LodgingPO Service Activity Provider Data access SMTP Scope of the application (not a component)

45 SOA often used to integrate legacy and external systems

46 End User Application Portal Internal System External Consumer Service Consumers SOA Infrastructure Internet Security Discovery Data Transformation Infrastructure Service A Service B Service C Service D Service Interfaces Internal Users Enterprise Information System Legacy or New Service Code External System Service Implementation

47 Pipe-and-filter style

48 Interaction pattern: transformation of data streams

49 Filters Comp1 Comp2 Pipe

50 Filter Transforms data Has input ports Has output ports

51 Pipe Transports data between filters Does not change data Typically buffered (asynchronism)

52 C1 C2 C3 C4 C5

53 Advantages?

54 Filters work independently, concurrently, asynchronously

55 We may replace a filter by another

56 We can add a new filter without changing the others

57 Modifiable Compositional Reusable (It packs a few tactics...)

58 Pipe-and-filter is used when we have data transformation

59 A common example Lex Syn Sem Opt Code (Compiler...)