1. client presentation layer resource management layer application logic layer information system Copyright Springer Verlag Berlin Heidelberg 2004

2. presentation layer resource management layer application logic layer client information system 1. define access channels and client platforms 2. define presentation formats and protocols for the selected clients and protocols 3. define the functionality necessary to deliver the contents and formats needed at the presentation layer 4. define the data sources and data organization needed to implement the application logic top-down design Copyright Springer Verlag Berlin Heidelberg 2004

3. top-down design PL-APL-B PL-C AL-A AL-B AL-D AL-C RM-1RM-2 top-down architecture RM-1RM-2 AL-A AL-D AL-C AL-B PL-A PL-B PL-C Copyright Springer Verlag Berlin Heidelberg 2004

4. presentation layer resource management layer application logic layer client information system 1. define access channels and client platforms 2. examine existing resources and the functionality they offer 3. wrap existing resources and integrate their functionality into a consistent interface 4. adapt the output of the application logic so that it can be used with the required access channels and client protocols bottom-up design Copyright Springer Verlag Berlin Heidelberg 2004

5. bottom-up design PL-APL-B PL-C AL-A AL-B AL-D AL-C bottom-up architecture AL-A AL-D AL-C AL-B PL-A PL-B PL-C wrapper legacy application legacy application legacy system legacy system legacy system Copyright Springer Verlag Berlin Heidelberg 2004

6. client presentation layer resource management layer application logic layer information system 1-tier architecture Copyright Springer Verlag Berlin Heidelberg 2004

7. client presentation layer resource management layer application logic layer information system server 2-tier architecture Copyright Springer Verlag Berlin Heidelberg 2004

8. resource management layer server service interface service interface service interface service interface server’s API service Copyright Springer Verlag Berlin Heidelberg 2004

9. client presentation layer 1 resource management layer application logic layer server 1 resource management layer application logic layer server 2 presentation layer 2 application logic Copyright Springer Verlag Berlin Heidelberg 2004

10. client presentation layer resource management layer application logic layer information system 3-tier architecture middleware Copyright Springer Verlag Berlin Heidelberg 2004

11. resource management layer client presentation layer application logic layer middleware integration logic 2-tier 1-tier wrapper client wrapper 3-tier Copyright Springer Verlag Berlin Heidelberg 2004

12. client resource management layer application logic layer information system N-tier architecture middleware presentation layer Web server Web browser HTML filter Copyright Springer Verlag Berlin Heidelberg 2004

13. ... remote clients INTERNET FIREWALL LAN Web server cluster LAN, gateways LAN internal clients LAN middleware application logic resource management layer database server LAN middleware application logic additional resource management layers LAN Wrappers and gateways file server application Copyright Springer Verlag Berlin Heidelberg 2004

14. request response invoking execution thread invoked execution thread blocking period Copyright Springer Verlag Berlin Heidelberg 2004

15. put invoking execution thread invoked execution thread queue fetch queue thread remains active Copyright Springer Verlag Berlin Heidelberg 2004