Evolution of Software Architecture and Enterprise Application Integration

1. Enterprise Application Integration Walter Moerkerken Ilona Wilmont Integratie Software Systemen 8 mei 2006

2. Evolution of software architecture Middleware and EAI Message Brokers EAI with message brokers Publish/subscribe model of interaction History Workflow Management systems WfMs`s WfMs als programmeertaal Conclusions Today’s topics

3. Evolution of software architecture

4. Information system design • Presentation layer - communication with other entities • Application logic layer - actual operation • Resource management layer - data to work with

5. Architectural design • Information systems are composed of several layers, or tiers. • One-tier architectures • Two-tier architectures • Three-tier architectures • N-tier architectures

6. Middleware and EAI

7. Middleware • Interaction between applications across heterogeneous platforms • Solution to integrating set of servers and applications under a common service interface • Basic infrastucture behind distributed information system

8. Enterprise Application Integration • Extends middleware capabilities to cope with application integration • Uses application logic layers of different middleware systems as building blocks

9. The supply chain • Customer request - Querying company • Order processing - Analysis and verification purchase order - Scheduling manufacturing of goods • Order fulfillment - Delivery to customer - Financial issues

10. Difficulties • Different operating system • Support for different interfaces and functionality • Different data format • Different security requirements • Different infrastructure and interaction protocols

11. Message Brokers

12. Traditional MOM • Point-to-point links • No support for routing logic • No support for heterogeneity • Sender identifies receiver • Complexity increases as more applications are added to the system

13. Message Brokers • Enhanced MOM-systems • Distribution of messages • Provides flexibility in routing • Filtering of messages • Processing of messages • Adapters for uniform data format • Routing logic moved to middleware

14. Routing logic • Based on sender’s identity, message type or message content • Rule-based language • Message broker level • Queue level

15. MOM vs. Message Brokers

16. Message Broker Problems • No tools provided for debugging and maintenance • Performance decreases if application-specific rules are executed at each delivery • Inability to handle large messages

17. EAI with message brokers

18. EAI platform components • Adapters • map heterogeneous data formats into common format • Message broker • facilitates interaction among back-end systems

19. Advantages of message brokers • Lower development cost • Lower opportunity costs • Lower maintenance effort

20. Publish/subscribe interaction model

21. Publish/subscribe overview • Sender publishes message to middleware • Receivers subscribe with middleware to register their interest

22. Decoupling • Time • not actively participating in event at the same time • Space • no references to each other • Synchronisation • asynchronous publication and notification

23. Types of publish/subscribe • Topic-based • Content-based • Type-based

24. Topic-based publish/subscribe • Earliest scheme, based on topics • Identified by keywords • Represented as strings • Improvement: hierarchical addressing • SupplyChain.newPO • Static scheme with limited expressive power

25. Content-based publish/subscribe • Based on content of message • Attributes • Meta-data associated with message • Subscribe using subscription language • Specify filters for valid events • type = “newPO” AND quantity = “1200”

26. Type-based publish/subscribe • Only a suggestion • Filtering messages according to type • Message kind linked to message type • Closer integration of language and middleware

27. Workflow Management Systems

28. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

29. Geschiedenis • WfMs`s in chronologische volgorde • Administrative workflows • Production workflows • WfMs`s vs. EAI tools • Heterogeniteit • Logica definitie • Perfecte combinatie

30. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

31. Wat is een workflow? • Workflow proces: • Work Nodes • Routing Nodes • Start & Completion Nodes • Workflow instantie

32. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

33. Uitvoering van een Workflow Workflow Engine

34. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

35. Workflow als programmeertaal • Variabelen • Uitvoerder van de procedure • Resource regels • Afhandeling van fouten is anders • Forward Recovery • Backward Recovery • Exception-handling Languages • Deadlines

36. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

37. Workflow met andere middleware

38. Workflow Management Systems • Geschiedenis • Wat is een workflow? • Uitvoering van een workflow • Workflow als programmeertaal • Workflows met andere Middleware • Voordelen/Nadelen

39. Voordelen: Snel procesontwerp Foutenafhandeling Makkelijk te ondersteunen Nadelen: Een overvloed aan workflows Dure software licenties Complexe installatie en operatie Lange ontwikkelingsfase Voordelen/Nadelen

40. Conclusies Message broker & Workflow in EAI: • Message broker • Workflow modegevoelig • Lijmen van verschillende systemen • Bieden (nog) niet wat men verwachtte • Samenvoeging • Waarom zoekt men nog wel naar iets anders?