1. Web Services

6. Encapsulation message segment datagram frame source application transport network link destination application transport network link router switch H t H n H l M H t H n M H t M M H t H n H l M H t H n M H t M M network link link H t H n H l M H t H n M H t H n H l M H t H n M H t H n H l M H t H n H l M

13. But What Makes an Active Server Page Work ? Clients system Server Asp.dll Pre processing Translation to HTML Scripting Agents Execution Request HTML for display 1. Prestored instructions written by author

23. An Example of Nonpersistent HTTP Suppose user enters URL www.someSchool.edu/someDepartment/home.index This URL contains text and references to 10 jpeg images. Therefore there is 11 objects that must be sent to the user. An example of the steps that are taken are on the next 2 slides.

24. 1a . HTTP client initiates TCP connection to HTTP server (process) at www.someSchool.edu on port 80 2. HTTP client sends HTTP request message (containing URL) into TCP connection socket. Message indicates that client wants object someDepartment/home.index 3. HTTP server receives request message, forms response message containing requested object, and sends message into its socket time 1b. HTTP server at host www.someSchool.edu waiting for TCP connection at port 80. “accepts” connection, notifying client

25. Nonpersistent HTTP (cont.) 4 . HTTP client receives response message containing html file, displays html. Parsing html file, finds 10 referenced jpeg objects 6. Steps 1-5 repeated for each of 10 jpeg objects 5. HTTP server closes TCP connection. time

29. HTTP Request Request: GET/default.asp /HTTP://www.Wrox.com /HTTP1.1 Header: ACCEPT:*/* ACCEPT_LANGUAGE: en-us CONNECTION:Keep-Alive HOST:webdev.wrox.co.uk REFERER:http://webdev.wrox.co.uk/books/SampleList.asp?bookcode=3382 USER_AGENT:Mozilla/4.0 (compatible;MSIE 5.01;Windows NT 5.0) Body;(empty) Request line Header Body GET message Client form data

35. SOAP

39. Message Service Specification (MSS) The MSS contains two parts: Header container . This is the first MIME part, containing One SOAP message. The SOAP message is an XML document consisting of a SOAP Envelope element. The SOAP Envelope element consists of: SOAP-ENV:Header. This is a generic mechanism for adding features to SOAP message, including ebXML specific header elements. SOAP-ENV:Body. This is a container for message service handler control data and information related to the payload parts of the message. Payload containers. There can be zero or more additional MIME parts containing application specific payloads.