XML, XSL, and SOAP Building Object Systems from Documents CSC/ECE 591o Summer 2000

XML, XSL, and SOAP

Building Object Systems from Documents

CSC/ECE 591oSummer 2000

Copyright © 2000, Sandeep Singhal

New Web Technologies Technologies under development by the

World Wide Web Consortium (W3C) See http://www.w3.org

Standards for Web-based documents XML: Extensible Markup Language XSL: Extensible Stylesheet Language SOAP: Simple Object Access Protocol Other technologies: XML Pointer, XML

Fragments, XML Schema, Resource Description Framework (RDF)…


XML, the Extensible Markup Language Structured meta-data language

Derived from SGML (Simple Generalized Markup Language)

Same heritage as HTML, so looks similar

Used to describe any type of information in a machine-readable way


Components of XML DTD (Document Type Definition)

Description of valid XML document syntax (elements and structure)

Element XML document component Example: <NAME> … </NAME> Example: <YES/>

CDATA: Text inside an element Comments:  Tags: <TAG>, </TAG>, <TAG/> Processing instructions: <!pi>


Example XML Document

<?xml version="1.0"?>

<!DOCTYPE greeting SYSTEM "hello.dtd">

<greeting>Hello, world!</greeting>


Example DTD

<!ELEMENT greeting (#PCDATA)>


A More Complex DTD

<!ELEMENT doc (title, chapter*)>

<!ELEMENT chapter (title, (para|note)*, section*)>

<!ELEMENT section (title, (para|note)*)>

<!ELEMENT title (#PCDATA|emph)*>

<!ELEMENT para (#PCDATA|emph)*>

<!ELEMENT note (#PCDATA|emph)*>

<!ELEMENT emph (#PCDATA|emph)*>


XSL – Extensible Stylesheet Language XSL is a language for expressing

stylesheets (XSL:T) A language for transforming XML

documents An XML vocabulary for specifying formatting

semantics (under development) An XSL stylesheet specifies the

presentation of a class of XML documents by describing how an instance of the class is transformed into an XML document that uses the formatting vocabulary


Thinking of XSL Model the XML document as a “tree” XSL document is a list of node

“patterns” and “actions” Search XML tree for matching

patterns and apply corresponding actions

Result is target document


A Simple XSL Example<xsl:stylesheet version="1.0“

xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

xmlns="http://www.w3.org/TR/xhtml1/strict">

<xsl:template match="doc/title">

<h1>

<xsl:apply-templates/>

</h1>

</xsl:template>

</xsl:stylesheet>


Applying the Example<!DOCTYPE doc SYSTEM "doc.dtd">

<doc>

<title>Document Title</title>

<chapter>

<title>Chapter Title</title>

</chapter>

</doc> <?xml version="1.0" encoding="iso-8859-1"?><html xmlns="http://www.w3.org/TR/xhtml1/strict"><h1>Document Title</h1><doc> <chapter> <title>Chapter Title</title> </chapter></doc>


Defining an “area” of the Tree Types of relationships

Child Sibling Parent Descendant Ancestor Root


Examples of Template Matching para (element match) * (any element) chapter|appendix (either/or) olist/item (parent/child) appendix//para (ancestor/child) / (root) id(“W11”) (any node with ID W11) para[1] (para element that is first child) para[last()=1] (only para child) para[position()>1] (not first para child) para[position() mod 2=1] (odd numbered child

para)


Content Generation Among the things you can do:

Generate numbered lists Create XML processing instructions Apply variables and dynamic values Create comments Sort


Uses of XSL Convert XML data

Into HTML, WML, VoiceXML, etc. One XSL document per target format Single input document

Bridge disparate systems EDI Legacy integration


SOAP: Simple Object Access Protocol Developed by IBM, Microsoft, Lotus,

DevelopMentor, and UserLand Software Lightweight protocol for exchanging

information in a decentralized distributed environment

XML description of an RPC call Implementation could be RMI or ActiveX or

something else Represents an alternative to IIOP Uses HTTP to transport request/response


Document Structure <Envelope> (mandatory)

[Describes SOAP message type] <Header> (optional): Includes

processing instructions for the request <Body> (mandatory): Describes the

parameters

Fault: Includes error codes


SOAP Example RequestHOST /StockQuote HTTP/1.1Host: www.stockquoteserver.comContent-Type: text/xml; charset=“utf-8”Content-Length: nnnnSOAPAction: “Some-URI”

<SOAP-ENV:Envelope xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/ SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/> <SOAP-ENV:Body> <m:GetLastTradePrice xmlns:m=“Some-URI”> <symbol>DIS</symbol> </m:GetLastTradePrice> </SOAP-ENV:Body></SOAP-ENV:Envelope>


SOAP Example ResponseHTTP/1.1 200 OK

Content-Type: text/xml; charset=“utf-8”

Content-Length: nnnn

<SOAP-ENV:Envelope

xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/

SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/>

<SOAP-ENV:Body>

<m:GetLastTradePriceResponse xmlns:m=“Some-URI”>

<price>34.5</price>

</m:GetLastTradePriceResponse>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>


Another SOAP Example…<SOAP-ENV:Envelope xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/ SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/> <SOAP-ENV:Header> <t:Transaction xmlns:t=“some-URI” SOAP-ENV:mustUnderstand=“1”> 5 </t:Transaction> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:GetLastTradePrice xmlns:m=“Some-URI”> <ticker>IBM</ticker> <showVolume>Yes</showVolume> </m:GetLastTradePrice> </SOAP-ENV:Body></SOAP-ENV:Envelope>


Some Other Capabilities Encoding

Can define structures, arrays, enumerations, and other basic data types

Transmission Use standard HTTP 1.1 Use HTTP Extension Framework