xml programming thomas lee e-mail: [email protected]

XML Programming

Thomas LeeE-Mail: [email protected]

XML Progamming - 2 © Thomas Lee, 2000-2001

Course Description

• This one-day workshop on XML programming will help you learn about the XML programming in B2B eCommerce and the implication of XML for web site development. XML (eXtensible Markup Language) defines a universal standard for electronically exchanging data for the B2B e-Commerce. It is supported by major IT vendors. Topics covered include: Background review of XML, Introduction to SAX, DOM and their usage. Simple Labs will be provided.


Course Outline

• XML Overview

• SAX

• DOM

• Lab 1

• Lab 2

• Lab 3


References• Books

– “Java and XML” Brett McLaughhlin, O’Reilly

• Online resources:

– http://www.xmlspy.com– http://www.w3.org/TR/xmsg/– http://www.w3.org/TR/xmlschema-1– http://www.w3org/TR/REC-xml-names– http://xml.apache.org

– http://www.alphaworks.ibm.com/tech/LotusXSL

– http://technet.oracle.com/tech/xml


Expected Background

. Basic Knowledge of HTML and XML.

• Basic Programming skill, such as visual• Basic, C++ or Java is a Plus !!!


Course Schedule

• 9:00 AM ~ 9:50 AM

Overview of XML and its usage in E-Commerce

• 10:00 AM~10:50 AM

Introduction to SAX Programming (Simple XML API)

• 11:00 AM ~ 11:50 AM Lab1

• 11:50 ~ 12:50 PM

Introduction to DOM Programming (Microsoft and Sun)

• 1:00 PM ~ 1:50 PM Lab2

• 2:00 PM ~ 2:50 PM

XML used in eCommerce Environment

• 3:00 PM ~ 4:00 PM Lab 3


Logistics

• Parking Permit

• Rest Room

• Café Tear


Course Instructor

• Thomas Lee

• Master in both Computer Science and Electronics

Engineer.

• Over 17 years industry experience.

• Has extensive experience in eCommerce

Application.

• Senior Consultant in Telecommunication Industry.


Attendee Introductions

• Your Name

• Background

• Why you take this course ?

• What you expect from this course ?


Quick Review of XML Background

• Background• In 1996, A new team of experts led by Jon

Bosak of Sun Microsystems and backed by W3 began to work on a new standard.

• Finalized in February in 1998 called XML.

• XML( eXtensible Markup Language) is derived from SGML ( Standard Generalized Markup Language).

• The percentage of IT shops in the US using XML in Web jumped from 1% to 16%.



• Background• A typical enterprise will use 35-40 percent of its

programming budget in developing data extraction and updating programs for the sole purpose of information transfer between different databases and applications, XML is the best candidate for those purpose.

• The eXtensible Markup Language(XML) has been developed by the World Wide Web Consortium(W3C) XML Working Group to bring SGML (Standard Generalized Markup Language) to the Web.



• Background• SGML is a language for the specification of

markup languages. SGML is parent of the well-known HyperText Markup Language(HTML).

• XML's design was conducted by looking at the strengths and weaknesses of SGML but without all the complex and rarely used features.

• The first working draft for XML was published in November 1996.



• Why XML• Simple,

• open,

• self-describing,

• provides a basis for author identification and versioning at the element level.

• Machine-readable context information

• Separates content from presentation

• Supports multilingual documents

• Facilitates the comparison and aggregation of data



• Why XML• Can embed multiple data types -- can contain

any possible data type

• form multimedia data (image, sound, video) to active components (Java applets)

• Can embed existing data

• ‘One server’ view for distributed data

• Wide-spread acceptance in the industry.


XML

DTD

HTML Resources XML

DataStore

Application

XSL

XPL

HTML/CSS

Display andReporting

XLL

XML DataTypes

Data Transfer

Definition and Structure

Link to otherresources

XML Schema

XML Technologies


Java and XML

• XML is an essential component in the Java 2 Platform, Enterprise Edition (J2EETM) and will be supported throughout the J2EE platform as a means for enabling business-to-business information interchange using XML.

• For robust, synchronous data messaging, Enterprise JavaBeansTM (EJBTM) architecture-based components (enterprise beans) can be used to create a business service object, and related XML content can be published on the web using JavaServer PagesTM technology. Currently, JavaServer Pages technology can be used to generate and consume XML between n-tier servers or between server and client.


Java and XML

• Java Messaging Service provides a means for asynchronous XML data messaging. In addition, EJB technology uses XML to describe its deployment properties, giving enterprise beans data portability in addition to their code portability.



• XML Components– Header

» Instruction e.g. <?xml version='1.0' encoding='UTF-8' ?>

» Document Type Declaration

e.g <!DOCTYPE Course SYSTEM "Demo1.dtd">

– Content» Root Element, Data Element

e.g <Course>………</Course>

» Element Attributes

e.g <Course Semester=‘Spring’>

» References

e.g. <Price>&onedayPrice</Price>

» Unparsed Data

e.g.<![CDATA[ sdfdsff <>s<<<>> ]]>



Well-Formed XML• Must start with an XML declaration

• Non-empty tags must match and nest properly

• Empty tags must end with />

• Must have exactly one root element

• Tag and attribute names are case-sensitive

• Attribute values must be quoted



Rules for Well-Formed XML(1)– Mandatory Closing Tags The set of Tags is unlimited but all container tags

must have end tags. <tag>…</tag> <TAG>…</TAG>

• Example of legal XML– <Person>

<Name>Adam Smith</Name>

<Title>General Manager</Title>

<Age>42</Age></Person>



Rules for Well-Formed XML(2)– Proper Element Nesting. All tags must be nested correctly. Like HTML, XML can

intermix tags and text, but tags may not overlap each other.

• Legal XML<Person>John Smith is an <role>advocate</role> for <technology>XML</technology></Person>

• Illegal XML<Person><Name>John </Name><KeyPoint><Hd>XML provides a data bus</Hd> </Person><More>…</More> </KeyPoint>



Rules for Well-Formed XML(3)– Double-quote value delimiters

All attribute values must be enclosed in single or double quotation marks.

• Legal: <tag attribute = "value"> or <tag attribute = 'value'>

• Illegal: <font size = 6>

XML tags are case sensitive.

<myTAG><Mytag> are different



Rules for Well-Formed XML(4)– Single tag elements. Singleton tags (called empty element or tags

without content) must be written in an abbreviated form using special XML syntax.

• Legal: <BR/>

<HR/>

• <TITLE></TITLE> is equivalent to <TITLE/>

• Illegal: <BR>

<HR>



XML Document: Validation Two kinds of ways to define rules for the

document. These rules can be used to validate an XML document or used by XML authoring tools to guide the creation of an XML document.– Document Type Definition (DTD): This is

used to define a grammar for the tags and attributes. This syntax is supported, but deprecated by MicrosoftMicrosoft. It uses a special non-XML-based grammar

– XML Schema (XML-Data): This is a much richer and more extensible way to describe the rules for the content of a document and uses XML itself as a grammar.



The attribute has a value that does not change throughout the document.

#FIXED

This value is specified in place of a keyword in the <!ATTLIST> tag. If a value is specified in the document, the default value is replaced. However, if the document leaves the attribute value blank, then the default value is assumed.

Default Value

The element must have a value for the attribute specified. If the value is not specified, the document will not be processed

#REQUIRED

The attribute may have a value declared, or it could be left empty.

#IMPLIED

ImplicationKeyword



Sample of DTD ( Embedded)<?xml version='1.0' encoding='UTF-8' ?>

<!DOCTYPE Course [

<!ELEMENT Title (#PCDATA)>

<!ELEMENT Price (#PCDATA)>

<!ELEMENT Instructor (#PCDATA)>

<!ELEMENT Date (#PCDATA)>

<!ELEMENT Course (Title, Price, Instructor, Date) >

]>

<Course>

<Title>XML Programming</Title>

<Price>$275</Price>

<Instructor>AIT</Instructor>

<Date>March 17,2001</Date>

</Course>



Sample of DTD (Reference)

Demo1.dtd

<?xml version='1.0' encoding='UTF-8' ?>

<!DOCTYPE Course [

<!ELEMENT Title (#PCDATA)>

<!ELEMENT Price (#PCDATA)>

<!ELEMENT Instructor (#PCDATA)>

<!ELEMENT Date (#PCDATA)>

<!ELEMENT Course (Title, Price, Instructor, Date) >

]>



Sample of DTD (Reference)

<?xml version='1.0' encoding='UTF-8' ?>

<!DOCTYPE Course [<?SYSTEM “\DTD\Demo1.dtd”? >] >

<Course>

<Title>XML Programming</Title>

<Price>$275</Price>

<Instructor>AIT</Instructor>

<Date>March 17,2001</Date>

</Course>



XML Schema • XML Schema is designed to replace and amplify

DTDs ( because DTD is a strange animal in XML

community)

• It offers an XML-centric means to constrain XML documents.

• Reference: http://www.w3.org/TR/xmlschema-1



• Well-Formed XML: – A well-formed XML document does not

necessarily include a DTD or a schema.

• Valid XML: – XML that conforms to the vocabulary

specified in a DTD or schema.



Namespaces• A mapping between an element prefix and a URI

• Is used for handling namespace collisions and defining data structures that allow parsers to handle collisions.

• Examples

<Airplane:Engine>

<Car:Seat>

• http://www.w3org/TR/REC-xml-names



XSL and XSLT• XSL ( Extensible Stylesheet Language)

– Transforms and translates XML data from one XML format to another format.

• XSLT ( Extensible Stylesheet Language

Transformation)– A Complete Text-based transformation process.

• Reference:– Apache Xalan: http://xml.apache.org

– Lotus XSL Processor: http://www.alphaworks.ibm.com/tech/LotusXSL

– Oracle XSL Processor:http://technet.oracle.com/tech/xml



XSL and XML Samplegreeting.xml<?xml version="1.0" standalone="yes"?><?xml-stylesheet href="greeting.xsl" type="text/xsl" ?>

<greeting>Hello World!</greeting>greeting.xsl<xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl"> <xsl:template match="/"> <H1> <xsl:value-of /> </H1> </xsl:template></xsl:stylesheet>



Xpath• The XPath Recommendation defines a path

language and expression syntax used by XSLT, XPointer, and XLink, it defines how a specific item within an XML document can be located.

• An XML document is considered a tree of nodes ( any piece of XML data, including elements, attributes, and textual data), where each node can be accessed by specifying the location in the tree at which it is located.

• Reference: http://www.w3.org/TR/xpath



SAX• It is Simple API for XML

• It provides the means to parse a document.

• It provides an event-based framework for parser to parse XML data.

• Available parsers:– Sun’s Project x

– Oracle’s XML parser

– Apache’s Xerces

– IBM’s XML4J

• Reference:

http://www.w3.org/DOM



DOM• It is an API for the Document Object Model

• It provides a means of manipulating the XML data.

• It provides a representation of an XML document as a tree.

• Reference:

http://www.w3.org/DOM



SAX/DOMPros Cons

SAX Event-

driven,sequentialprocessing,

Fast Less memory

requirement can handle large

streams of XML thatmay come fromdatabase.

Web Application(Servlet)

Network-orientedprogramms

Does not retain stateknowledge

Programmer shouldhandle it.

Hard to visualize No way to re-navigate,

change it.

DOM Works on

top of SAX Build tree

structure

Can use XPath toperform the movementacross nodes.

Guidelines1. Loading XML as a

DOM object if less than50000 or so records

Requires huge memory



XML Application:– Presentation ( XML + XSL)

– Communication (HTTP/XML, XML-PRC)

– Configuration» EJB ( deployment descriptor)

» Servlet API version 2.2.



XML IDE & Editors

Examples:– Microsoft XML Notepad ( editor)– XML Spy 3.5(Editor & IDE)

» XML editing & validation» Schema/DTD editing & validation» XSL editing & transformation» Reference: http://www.xmlspy.com


SAX Programming

In Java


SAX Programming

• Guidelines– (1) Finding a Parser

» e.g. Apache Xerces parser

» http://xml.apache.org

– (2) Make sure which SAX Version: 1.0/2.0» We will use SAX 1.0 in our Lab

– (3) Make sure the following classes( packages) in your jar files ( we use utils.jar in our lab)

org.xml.sax, org.xml.sax.helper,

javax.xml.parser, com.sun.xml.parser

com.sun.xml.tree


SAX Programming

• Guidelines– (4)Prepare a XML document

– (5)Write Programs to parse XML document.


SAX Programming

• Run your first program– Run Script: SAXDemo1\Bulid.bat

– Java Program: SAXDemo1\SAXDemo1.java

– XML Document: SAXDemo1\ Demo0.xml

SAXDemo1\ Demo1.xml

SAXDemo1\ Demo2.xml

SAXDemo1\ Demo1.dtd

– Test Case 1: No DTD Validation

– Test Case 2: DTD Validation


SAX Programming

• SAX Related package

• org.xml.sax

• org.xml.sax.helpers


SAX Programming-SAXDemo1.javaImport necessary libraries• java.io.*

• org.xml.sax.*

• java.util.*;

• javax.xml.parsers.SAXParserFactory

• javax.xml.parsers.ParserConfigurationException

• javax.xml.parsers.SAXParser

Parser

API Interface


SAX Programming-SAXDemo1.java• org.xml.sax : -Defines the SAX interfaces

• org.xml.sax.helpers– It defines the ParserFactory class, which lets you acquire

an instance of a parser either by specifying a name string or by using the value defined by the org.xml.sax.parser system property.

• javax.xml.parsers– Defines the SAXParserFactory class which returns the

SAXParser

• com.sun.xml.parser– Contains the Java XML parser

(com.sun.xml.parser.Parser),

– validating parser (com.sun.xml.parser.ValidatingParser), and entity resolver


SAX Programming-SAXDemo1.javaContents in org.xml.sax package

Interfaces AttributeList Attributes ContentHandler DocumentHandler DTDHandler EntityResolver ErrorHandler Locator Parser XMLFilter XMLReader

Classes HandlerBase InputSource

Exceptions SAXException SAXNotRecognizedException SAXNotSupportedException SAXParseException

For SAX 1.0

Bold: for SAX 2.0


SAX Programming-SAXDemo1.javaContents in org.xml.sax.helpers package

Bold for SAX 2.0

Classes AttributeListImpl AttributesImpl DefaultHandler LocatorImpl NamespaceSupport ParserAdapter ParserFactory XMLFilterImpl XMLReaderAdapter XMLReaderFactory


SAX Programming-SAXDemo1.javaCreating /Setting Parser Object/Features

try{SAXParserFactory mfactory =

SAXParserFactory.newInstance();

mfactory.setValidating(bValidate); if (mfactory!=null){ SAXParser saxParser =

mfactory.newSAXParser();

saxParser.parse( new File(fileName), this); }} catch (SAXParseException spe) {…}catch(……){…}

Set DTDValidatingFeature

Create SAXParser

Read from FileUseful if we setvalidating to true


SAX Programming-SAXDemo1.java

Implements ContentHandler Functions(0)• SAX parser generates the following linear

events:– setDocumentLocator– start document– start element– characters– end element– end document


SAX Programming-SAXDemo1.javaImplementing ContentHandler Functions(1)

public void startElement (String name, AttributeList attrs)

throws SAXException

{

mFindName = name;

}

public void characters (char buf [], int offset, int len)

throws SAXException

{ String s = new String(buf, offset, len);

mTable.put(mFindName,s );

}


SAX Programming-SAXDemo1.javaImplementing ContentHandler Functions(2)public void endElement (String name)

throws SAXException

{ }

public void startDocument ()

throws SAXException

{ }

public void endDocument ()

throws SAXException

{ }


SAX Programming-SAXDemo1.javaImplementing ContentHandler Functions(3)public void setDocumentLocator (Locator l)

{

// Save this to resolve relative URIs or to give

// diagnostics.

System.out.println ("LOCATOR");

System.out.println ("\n SYS ID: " + l.getSystemId() );

}

output example:SYS ID: file:E:/XMLClass/SAXDemo1/Demo0.xml


SAX Programming-SAXDemo1.javaImplementing ErrorHandler Functions• Report the violation of a validity constraint. The default

behavior is to take no action

public void error (SAXParseException e)

throws SAXParseException

{ ………. }

• Default behaviour is to take no action.

public void warning (SAXParseException err)


{ ….. }


SAX Programming-SAXDemo1.javaImplementing ErrorHandler Functions

Report the violation of a well-formedness constraint.

public void fatalError (SAXParseException ferr)


{ throw ferr; }


SAX Programming-SAXDemo1.javaImplementing Test Procedurepublic static void main(String[] args) {

SAXDemo1 oDemo = new SAXDemo1();

Hashtable oTable;

try{

if( args[1].equals("v")||args[1].equals("V"))

oDemo.ProcessFromFile(args[0],true);

else

oDemo.ProcessFromFile(args[0],false);

oTable=oDemo.getResultTable();

System.out.println("Title: " + (String)oTable.get("Title"));

System.out.println("Price: " + (String)oTable.get("Price"));

System.out.println("Instructor: " +

(String)oTable.get("Instructor"));

System.out.println("Date: " + (String)oTable.get("Date"));

}catch(SAXParseException e){….} }

}


SAX Programming-SAXDemo1.javabulid.batset CLASSPATH=.;E:\XMLClass\xmlclasslib.jar;%CLASSPAH%

javac %1.java

java %1 %2 %3

Run the Script - case1 ( ignore validation)E:\XMLClass\SAXDemo1 >bulid SAXDemo1 Demo1.xml gLOCATOR

SYS ID: file:E:/XMLClass/SAXDemo1/Demo0.xml

Title: Introduction to XML Programming

Price: $275

Instructor: AIT

Date: null


SAX Programming-SAXDemo1.javaRun the Script - case2 (enforce validation)E:\XMLClass\SAXDemo1 >bulid SAXDemo1 Demo1.xml v

LOCATOR

SYS ID: file:E:/XMLClass/SAXDemo1/Demo0.xml

** Parsing error, line 7, uri file:E:/XMLClass/SAXDemo1/Demo0.xml

Element "Course" requires additional elements.

Sorry! this parsing cannot go through!


SAX Programming-SAXDemo1.java• SAX parser generates the following linear events:

– setDocument: SYS ID: file:E:/XMLClass/SAXDemo1/Demo0.xml– start document– start element: Course– start element: Title– characters: Introduction to XML Programming – end element : Title – start element: Price– characters: $275– end element : Price – ……………...– end element :Course– end document


SAX Programming-SAXDemo1.java• Try to modify Demo1.dtd and SAXDemo1.java and rerun

bulid SAXDemo Demo1.xml v

and

bulid SAXDemo Demo1.xml g


DOM Programming

In Java


DOM Programming

• Demo files under XMLClass\DomDemo1• DomDemo2.java:Print out everything from a XML String

– Bulid DomDemo2

• DomDemo3.java: This sample show you how to parse a XML string and display name-value pair information

– Bulid DomDemo3

• DomDemo4.java: This sample show you how to parse a XML file and display Name-value pair information

– Bulid DomDemo4 Demo1.xml• DomDemo5.java:This sample show you how to parse a

XML file and provides collection of Element Name/value information

– Bulid DomDemo5 Demo1.xml


DOM Programming-DomDemo3.java

Processing Instruction Text Comment

EntityReference CDATASection Element

Document Type

comment

Processing Instruction Document

(Root) Element

Attributes

Attributes

EntitiesNotations

childNodes

DOM Model



Guidelines

– (1) Finding a Parser » e.g. Apache Xerces parser

» http://xml.apache.org

– (2) Make sure the following classes( packages) in your jar files ( we use utils.jar in our lab)

org.xml.sax, org.xml.sax.helper,

javax.xml.parser, com.sun.xml.parser

com.sun.xml.tree



Node:– Represents the basic class for all

document objects.

– Allow direct manipulation of the underlying document.

NodeList– Ordered in a manner consistent with a

preorder traversal of the parser treeRoot

Leftmost Right branch



NamedNodeMap– Collection of Node Objects.

– Used by Node object to return set of attributes.

– Access by Name.

CharacterData– Represents Text and Comment objects



Text– Characters between “StartTag” and

“Closing Tag” .

– Used by Node object to return set of attributes.

Element– Manages its attributes directly instead of as

children.



Attribute– Associated with the Elements that they are

declared with.

ProcessingInstruction

CDATASection– Unparsed text that is identified between

<![CDATA and ]]>



EntityReference– A holder for aliased parsed text.



• Import Librariesimport java.io.*;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import org.w3c.dom.Document;

import org.w3c.dom.DOMException;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.FactoryConfigurationError;

import javax.xml.parsers.ParserConfigurationException;

import javax.xml.parsers.DocumentBuilder;

import org.xml.sax.SAXException;

import org.xml.sax.SAXParseException;



Static Document document;try { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

DocumentBuilder parser = factory.newDocumentBuilder(); factory.setValidating(true); factory.setNamespaceAware(true); document = parser.parse(new File(argv[0]));}catch(…){}

Create Parser



private String traversing(Node node) { String rValue=""; String name; NodeList child; switch(node.getNodeType()) { case Node.DOCUMENT_NODE: name= node.getNodeName(); child = node.getChildNodes(); if( child!=null)

{ for ( int i=0; i< child.getLength(); i++)

{ rValue= traversing(child.item(i));

if(!rValue.equals("")) return rValue; } } break;

Implement traversing



case Node.ELEMENT_NODE:name= node.getNodeName();

if( name.equals(sElName)) bFind=true; else bFind=false; child = node.getChildNodes(); if( child!=null)

{ for ( int i=0; i< child.getLength(); i++) { rValue = traversing(child.item(i)); if(!rValue.equals("")) return rValue; } }

break;




case Node.TEXT_NODE: if(bFind) { rValue= node.getNodeValue(); return rValue; } break;case Node.CDATA_SECTION_NODE: //System.out.println(node.getNodeValue()); break; case Node.PROCESSING_INSTRUCTION_NODE: //System.out.println(node.getNodeValue()); break;case Node.ENTITY_REFERENCE_NODE: break;case Node.DOCUMENT_TYPE_NODE: break; } return "";}




//Get Elment Value public String getElValue(String el) { sElName = el; return traversing(document); }

Provides a getElValue methodThis method provides the content inside a given Element name



DomDemo3 oDemo = new DomDemo3(); try { //create DOM Parser and parse the // given XML file or XML string and get back // XMLdocument objectSystem.out.println("Title:" + oDemo.getElValue("Title")); System.out.println("Instructor:" + ……. }

Catch(….){}

Use this getElValue


DOM Programming

In VB


DOM Programming in VB

• Make sure you have msxml.dll under your system/system32 directory

• Open VB Project

• Go to Project/References and select

Microsoft XML, version 2 library

• Use DOMDocument to process your XMLstring



• Methods Samples– loadXML

» Load XML input String into DomDocument Object

– Load» Load XML File into DomDocument Object.

– createAttribute, getElementsByTagName, abort, appendChild, cloneNode, createNode,save

• Member Samples– validateOnParse,……...



• Xml related data type– IXMLDOMNode

– IXMLDOMAttribute

– IXMLDOMElement

– IXMLDOMEntity

– IXMLDOMNamedNodeMap

– IXMLDOMText

– …………….

You can use the same approach in Java to do your DOM relatedwork in VB, Please see CXMLParser.cls filefor detail information



HTTP/XML



• HTTP/XML is a very popular data exchange approach in B2B environment.

• You can use ASP, JSP or Servlet in Server side to read/write XML format data from/to any kind of Client.

• The client can be an application sit at another Server and a generic GUI application.



• How to send XML data via Http/Post/Get method

• VB– Using OpenURL method provides by Inet COM

object to mimic Http/Post/Get method

• Java– Using URL to mimic Http/Post /Get to send request

in XML format as well as receive response in XML format.



• VB – Open Project\Components

– Select Microsoft Internet Transfer Control 6.0

COM Object.

– Drag this COM Icon from ToolBox onto your form

– Implement the following codes

URLString = szBaseURL + "?FUNCTION=GETSPECIALITYLIST"

getResult URLString, xmlObj

Private Sub getResult(ByVal sURL As String, obj As CXMLParser)

szReturnedXML = Inet1.OpenURL(sURL)

xmlObj.XMLString = szReturnedXML

End Sub

Dom Object



• Java– Make sure

import java.net.*;

– Put the following codes in your send methodString mResponse;

String request;

request= “…….”; //request string in XML format

mResponse ="";

DataInputStream dis = null;

Properties pro = new Properties();

pro.put(”RequestXML", request) ;

HttpURLConnection connection=null;



try {

msUrl = “http://hostIpAddress:port/……/Test.asp?”;

mTheServer = new URL(msUrl);

connection = (HttpURLConnection) mTheServer.openConnection();

connection.setDoOutput(true);

connection.setUseCaches(false);

// Set Post Method and send Post Message

connection.setRequestMethod("POST");

connection.setRequestProperty("Content-Type",

"application/x-www-form-urlencoded");

Set request method and content-type



DataOutputStream out =

new DataOutputStream(connection.getOutputStream());

String argString = toEncodedString(pro);

out.writeBytes(argString);

out.flush();

out.close();

// Get Response

mResponse = readData(connection);

}

} Encode request string and send it toserver.

Read Response back(XML format)and use SAX or DOM to parse it



toEncodedString Methodprivate String toEncodedString(Properties args) {

StringBuffer buf = new StringBuffer(1);

Enumeration names = args.propertyNames();

while(names.hasMoreElements()) {

String name = (String)names.nextElement();

String value = args.getProperty(name);

buf.append(URLEncoder.encode(name)+"=" +

URLEncoder.encode(value));

if(names.hasMoreElements())

buf.append("&");

}

return buf.toString();

}



readData Methodprivate String readData(URLConnection connection)

{ Object content;

BufferedReader buffReader = null;

// Read upto 1024 characters or EOF from the return reponse

char[] cInputData;

String sReponse = "";

try {

content = connection.getContent(); if (content instanceof InputStream)

{

buffReader =

new BufferedReader(new InputStreamReader( (InputStream)content) );

} // When Input stream not null



readData MethodDataInputStream dis = new

DataInputStream(connection.getInputStream());

String theLine;

if (dis != null) {

while ((theLine = dis.readLine()) != null)

{

sReponse = sReponse + theLine;

}}

}

catch (IOException e) {……. }

return sReponse;

xml programming thomas lee e-mail: [email protected]

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