CSC3530 Software Technology

1. CSC3530 Software Technology Tutorial 10 Assignment Two (III) Demo Update to Assignment One java.net package nanoxml XSLT,XPath

2. Assignment Two Part III • Demo link • http://sparc68.cse.cuhk.edu.hk:8080/examples/servlet/CompareXML • http://sparc68.cse.cuhk.edu.hk:8080/examples/servlet/CompareXML1 • Flow of part III • 1.Post a query to servlet – CompareXML (with check flag on) • 2.For each product found in product table, find those corresponding supplier in supplying table • 3.Check if the price quote from supplier exceeds a certain value • 3.1 If yes, post a query to that supplier • 3.2 The URL is obtain in a field URL of supplier table (URL of CompareXML1) • 3.3 Parse the XML return from query • 4.Update the price quote • 5.Presents the user with details of products • Price lower than the current site should not be display

3. DB1 DB2 Flow diagram of Part III 1 User post a query 5 XML data internet CompareXML1 XML data 3.1 CompareXML 3.3 XML data 2,3 check if need to update CompareXML2 4 update price quote DB

4. Product - CompareXML Product – CompareXML1 supplying 1 4 2 Get the URL and whenthe quote is updated 5 supplier 3

5. Update to assignment one database schema • Reuse of table • Originally, you have • Supplying(supplier_code,product_code,price) • Supplier(code,name,address,e-mail,tel) • Product(code,name,category,on_hand,low_limit) • Update • alter table supplying add (quote date,on_hand int) • Indicate when the price quote is updated • How many product the supplier has • alter table supplier add url varchar2(100) • Store the price quote servlet URL of supplier • alter table product add price number(10,2) • Store the price quote of current company

6. Suggested SQL • select SU.url, S.code from supplying SU, supplier S where SU.supplier_code=S.code and SU.product_code=‘xxx’ and (SYSDATE-SU.quote)*24*60 > 30; • Find those supplier’s price quote URL which supply product xxx to us and the price quote is not update for 30 minutes • update supplying set price=100, quote=SYSDATE where supplier_code=‘xxx’ and product_code=‘yyy’; • Update the price quote of product yyy supplied by supplier xxx and set the time to current time • You should not show supplier whose price quote is lower that your company • SYSDATE is the current date/time • Date arithmetic is in number of days

7. java.net package • How to post query to a CGI in java program? • Use java.net.URL, java.net.URLConnection • Java will open an http connection for your program • No need to do socket programming • To use • import java.net.*; • Import java.io.*; (for reader and writer) • Key objects • URL – an object to model the url (http://……) • URLConnection – an object to model connection between server and client • PrintWriter – an object for you to post request to a CGI URL • BufferedReader – and object for you to read the CGI output (html page)

8. Code fragment • Example • http://www.cse.cuhk.edu.hk/~kcsia/csc3530/Query.java • Please run in unix machine, and make sure sparc68 is up URL url=new URL(“http://sparc68.cse.cuhk.edu.hk:8080/examples/servlet/CompareXML”); URLConnection urlconnection=url.openConnection(); urlconnection.setDoOutput(true); PrintWriter out=new PrintWriter(urlconnection.getOutputStream()); out.print(“field=id&query=111”); out.close(); BufferedReader in=new BufferedReader(new InputStreamReader(urlconnection.getInputStream()); String temp; do { temp=in.readLine(); if (temp!=null) System.out.println(temp); else break; } in.close();

9. Explanation • Construct an URL object, using the URL of price quote CGI • openConnection() - to obtain an URLConnection object • setDoOutput(true) - to enable sending data to CGI • new PrintWriter – obtain an writer object for sending request to CGI • out.println() - send query data to CGI • out.close() – close the writer • … getInputStream() - get the stream for reading CGI output (xml data) • in.close() – close the reader • Parse the XML … (use nanoXML)

10. XML for exchanging data Tag Name <products> <product> <id>ABCD</id> <description>rogue spear</description> <category>computer games</category> <company> <name>Amazon</name> <price>200.2</price> <onhand>50</onhand> </company> </product> <product> <id>EFGH</id> <description>black thorn</description> <category>computer games</category> <company> <name>Amazon</name> <price>150.3</price> <onhand>200</onhand> </company> </product> </products> Content

11. nanoxml • How to interpret the XML return from other URL • Use XML parser • http://nanoxml.sourceforge.net/index.htmlversion 1.6.8 • http://www.cse.cuhk.edu.hk/~kcsia/csc3530/nanoxml.jar • To use • Place nanoxml.jar in the same directory with your code orset CLASSPATH to include nanoxml.jar • import nanoxml.*; • XMLElement (a class in nanoxml) • It models a node in the DOM tree • Methods to use • parseString() • getChildren() • getTagName() • getContents()

12. products product id category company description price name DOM Tree and XMLElement All nodes are XMLElement object getTagName() returns the node’s name getChildren() returns the childnodes contained in a Vectorobject getContents(), e.g. when call on price XMLElementit will return 150.3

13. How to use XML Sample: http://www.cse.cuhk.edu.hk/~kcsia/csc3530/QueryXML.java … String xml=“<products><product><company><price>200</price></company></product></products>”; XMLElement root=new XMLElement(); root.parseString(xml); XMLElement product=findTag(root,"product"); if (product!=null) { XMLElement company=findTag(product,"company"); if (company!=null) { XMLElement price=findTag(company,"price"); if (price!=null) { System.out.println("The price is:“+ price.getContents()); } } } } // findTag is a function that you have written

14. How to use XML private static XMLElement findTag(XMLElement src,String str) { Vector v = src.getChildren(); for (int i = 0; i < v.size(); i++) { XMLElement e = (XMLElement)(v.elementAt(i)); if (e.getTagName().compareTo(str) == 0) { return e; } } return null; } • To use Vector, you should import java.util.*; • getChildren() is a method of XMLElement • If you call product.getChildren, it will return a vector containing XMLElement: id, description, category and company. • getTagName() and getContents() (refer to page 9)

15. XSLT, XPath • How to present the XML in a browser? • Specify a XSL file in the XML • <?xml:stylesheet type="text/xsl" href="http://www.cse.cuhk.edu.hk/~kcsia/display.xsl"?> • XSL - eXtensible Stylesheet Language • To transform XML document to HTML (mainly) • XSL has two standard versions • <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> • version 1.0 (supported by IE 6, need to install msxml 3.0 in replace mode) • http://www.cse.cuhk.edu.hk/~kcsia/csc3530/XmlInst.exe • <xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl"> • Working draft (supported by IE 5.5)

16. Sample XSL file <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> <xsl:template match="/"> <HTML> <HEAD> <TITLE>Query Result</TITLE> </HEAD> <BODY> <H1>Query Result</H1> <xsl:for-each select="/products/product"> Product ID: <xsl:value-of select="id"/><BR/> Product Code: <xsl:value-of select="description"/><BR/> Product Category: <xsl:value-of select="category"/><BR/> <TABLE BORDER="1"> <TR> <TH>company name</TH> <TH>price</TH> <TH>on hand</TH> </TR>

17. Sample XSL file <xsl:for-each select="company"> <xsl:sort select="price" data-type="number" order="ascending" /> <TR> <TD><xsl:value-of select="name"/></TD> <TD><xsl:value-of select="price"/></TD> <TD><xsl:value-of select="onhand"/></TD> </TR> </xsl:for-each> </TABLE><BR/> </xsl:for-each> </BODY> </HTML> </xsl:template> </xsl:stylesheet>

18. XPath • XPath is to enable the addressing of, or navigation to, chosen part of XML document • XSL use XPath for testing whether or not an node matches a pattern • <xsl:template match="/"> • Xsl will process the whole xml file, / means the root • <xsl:for-each select="/products/product"> • XPath: /products/product • Find the nodes named product, with parent node named products • For-each loop will take out these node and do an iteration • <xsl:sort select="id" data-type="text" order="ascending" /> • Sort the selected nodes according to the content in child node id • Sort function is supported in XSLT version 1.0 • <xsl:value-of select="name"/> • Display the value (content) in node named “name”

19. authors author (period) name nationality XPath • Describe a path through the XML hierarchy with a slash-separated list of child element names • Identify all the elements that match the path • Simple query mechanism authors/*/name authors/author/* authors/author[nationality=‘Russian’]/name authors/author/[@period=“classical”]

20. IE Setting Prompt or Enable

21. Reference • TopXML • http://www.topxml.com/default.asp • Servlet 2.1 Documentation • http://java.sun.com/products/servlet/2.1/api/packages.html • JDK1.3 Documentation • http://java.sun.com/j2se/1.3/docs/api/index.html • Java Tutorial • http://java.sun.com/docs/books/tutorial/