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.hk8080/examples/servl
  et/CompareXML
• http//sparc68.cse.cuhk.edu.hk8080/examples/servl
  et/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

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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
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Product - CompareXML
Product CompareXML1
code Category On_hand Price
111 Printer 20 800
abc Scanner 20 150
defg Scanner 50 600
code Category On_hand Price
111 Printer 10 600
abc Scanner 20 200
def printer 10 800
supplying
1
4
Product code Supplier code price On_hand Quote
111 t1 500 30 12/11
def t2 300 50 12/10
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Get the URL and whenthe quote is updated
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supplier
3
code name URL
t1 company1 http//sparc68.cse.cuhk.edu.hk8080/example/servlet/CompareXML1
t2 company2 http//sparc68.cse.cuhk.edu.hk8080/example/servlet/CompareXML2
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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

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Suggested SQL

• select SU.url, S.code from supplying SU, supplier
  S where SU.supplier_codeS.code and
  SU.product_codexxx and (SYSDATE-SU.quote)2460
  gt 30
• Find those suppliers price quote URL which
  supply product xxx to us and the price quote is
  not update for 30 minutes
• update supplying set price100, quoteSYSDATE
  where supplier_codexxx and product_codeyyy
• 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

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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)

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Code fragment

• Example
• http//www.cse.cuhk.edu.hk/kcsia/csc3530/Query.ja
  va
• Please run in unix machine, and make sure sparc68
  is up
• URL urlnew URL(http//sparc68.cse.cuhk.edu.hk80
  80/examples/servlet/CompareXML)
• URLConnection urlconnectionurl.openConnection()
• urlconnection.setDoOutput(true)
• PrintWriter outnew PrintWriter(urlconnection.getO
  utputStream())
• out.print(fieldidquery111)
• out.close()
• BufferedReader innew BufferedReader(new
  InputStreamReader(urlconnection.getInputStream())
  
• String temp
• do
• tempin.readLine()
• if (temp!null)
• System.out.println(temp)
• else
• break

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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)

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XML for exchanging data
Tag Name

• ltproductsgt
• ltproductgt
• ltidgtABCDlt/idgt
• ltdescriptiongtrogue spearlt/descriptiongt
• ltcategorygtcomputer gameslt/categorygt
• ltcompanygt
• ltnamegtAmazonlt/namegt
• ltpricegt200.2lt/pricegt
• ltonhandgt50lt/onhandgt
• lt/companygt
• lt/productgt
• ltproductgt
• ltidgtEFGHlt/idgt
• ltdescriptiongtblack thornlt/descriptiongt
• ltcategorygtcomputer gameslt/categorygt
• ltcompanygt
• ltnamegtAmazonlt/namegt
• ltpricegt150.3lt/pricegt
• ltonhandgt200lt/onhandgt

Content
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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()

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DOM Tree and XMLElement
All nodes are XMLElement object
getTagName() returns the nodes name
getChildren() returns the childnodes contained
in a Vectorobject
getContents(), e.g. when call on price
XMLElementit will return 150.3
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How to use XML

• Sample http//www.cse.cuhk.edu.hk/kcsia/csc3530/
  QueryXML.java
• String xmlltproductsgtltproductgtltcompanygtltpricegt200
  lt/pricegtlt/companygtlt/productgtlt/productsgt
• XMLElement rootnew XMLElement()
• root.parseString(xml)
• XMLElement productfindTag(root,"product")
• if (product!null)
• XMLElement companyfindTag(product,"company")
• if (company!null)
• XMLElement pricefindTag(company,"price")
• if (price!null)
• System.out.println("The price
  is price.getContents())
• // findTag is a function that you have written

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How to use XML

• private static XMLElement findTag(XMLElement
  src,String str)
• Vector v src.getChildren()
• for (int i 0 i lt 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)

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XSLT, XPath

• How to present the XML in a browser?
• Specify a XSL file in the XML
• lt?xmlstylesheet type"text/xsl"
  href"http//www.cse.cuhk.edu.hk/kcsia/display.xs
  l"?gt
• XSL - eXtensible Stylesheet Language
• To transform XML document to HTML (mainly)
• XSL has two standard versions
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0"gt
• 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
• ltxslstylesheet xmlnsxsl"http//www.w3.org/TR/WD
  -xsl"gt
• Working draft (supported by IE 5.5)

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Sample XSL file

• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0"gt
• ltxsltemplate match"/"gt
• ltHTMLgt
• ltHEADgt
• ltTITLEgtQuery Resultlt/TITLEgt
• lt/HEADgt
• ltBODYgt
• ltH1gtQuery Resultlt/H1gt
• ltxslfor-each select"/products/product"gt
• Product ID ltxslvalue-of select"id"/gtltBR/gt
• Product Code ltxslvalue-of select"description"/
  gtltBR/gt
• Product Category ltxslvalue-of
  select"category"/gtltBR/gt
• ltTABLE BORDER"1"gt
• ltTRgt
• ltTHgtcompany namelt/THgt
• ltTHgtpricelt/THgt
• ltTHgton handlt/THgt
• lt/TRgt

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Sample XSL file

• ltxslfor-each select"company"gt
• ltxslsort select"price" data-type"number"
  order"ascending" /gt
• ltTRgt
• ltTDgtltxslvalue-of select"name"/gtlt/TDgt
• ltTDgtltxslvalue-of select"price"/gtlt/TDgt
• ltTDgtltxslvalue-of select"onhand"/gtlt/TDgt
• lt/TRgt
• lt/xslfor-eachgt
• lt/TABLEgtltBR/gt
• lt/xslfor-eachgt
• lt/BODYgt
• lt/HTMLgt
• lt/xsltemplategt
• lt/xslstylesheetgt

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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
• ltxsltemplate match"/"gt
• Xsl will process the whole xml file, / means the
  root
• ltxslfor-each select"/products/product"gt
• 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
• ltxslsort select"id" data-type"text"
  order"ascending" /gt
• Sort the selected nodes according to the content
  in child node id
• Sort function is supported in XSLT version 1.0
• ltxslvalue-of select"name"/gt
• Display the value (content) in node named name

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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/authornationalityRussian/name
authors/author/_at_periodclassical
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IE Setting
Prompt or Enable
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Reference

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