Grokking XML - CSDAinc.com

Grokking XML Lab
David Andruchuk
Sr. Architect
Computer Systems Design Associates, Inc.
November 14, 2008
What can i do…..i can do XML
Grokking XML
Grok
To understand so thoroughly that the observer becomes a part of the observed—to merge,
blend, intermarry, lose identity in group experience. It means almost everything that we
mean by religion, philosophy, and science—and it means as little to us (because we are
from Earth) as color means to a blind man.
Grokking XML
Table of Contents
•
Introduction
Introduction to XML
•
Programmatic Approach
Using IBM RAD & XML
Using Excel & XML
Using SQL for XML compose
Using RPG for XML decompose
Grokking XML
• XML has become a standard for cross-platform
communications
• XML has or will impact your business if you
continue to be in business
• XML has gained acceptance as a preferred data
exchange technology in spite of the limitations
because of the flexibility and human readable
formatting
Grokking XML
Introduction to XML
Grokking XML
What you need to get started:
 XML Editing tool(s)

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WDSC, Rational Application Developer (RAD) (IBM)
XMLSpy (Altova)
Stylus Studio (Progress Software Corporation)
Microsoft Office 2003 or higher
 XML Reference(s)

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WDSC Step by Step (MC Press)
XML for eServer i5 and iSeries (MC Press)
Qshell for iSeries (MC Press)
XSLT 2nd Edition (WROX)
W3Schools Online Web Tutorials (www.w3schools.org)
Grokking XML
What is XML?
– XML is short for Extensible Markup Language
Pros of XML?
– XML is flexible
– XML is self documenting
– XML can replace or extend legacy systems
Cons of XML?
– XML is verbose
– XML can significantly increases the size of your data
– XML works best with hierarchal data in a relational
data base
Grokking XML
There are three main components of XML
• XML Document
– Document containing data
• XML Document Type Definition (DTD)
– Document that defines the document structure of the
XML Document
• XML Schema Definition (XSD)
– Document that defines the document structure of the
XML Document in an XML-based alternative to DTD
Grokking XML
Structure of XML documents
• An XML document has a tree-like structure that is
hierarchical
• The document must contain one and only one root
element
• An element is the parent of all the elements it contains
• The elements that are inside a parent element are called
its children
• Similarly, the elements that have the same parent
element are called siblings
Grokking XML
Grokking XML
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Structure of DTD documents
 Contains the list of tags which are allowed within the
XML document and their types and attributes
 Defines how elements relate to one another within the
document's tree structure and specifies which attributes
may be used with which elements
Grokking XML
Grokking XML
Structure of XSD documents
• Contains the legal building blocks of an XML document
similar to DTD
• Defines how elements relate to one another within the
document's tree structure and specifies which attributes
may be used with which elements
• Schema supports all data types used in most
programming languages such as string, decimal, integer,
Boolean, date and time
• Supports complexType elements that allows you to
define an element type that can consist of sub-elements
Grokking XML
Grokking XML
Programmatic Approach
Grokking XML
RAD & XML
This product provides a comprehensive visual Extensible Markup
Language (XML) development environment. Tools help you create,
import, edit, validate, and generate XML, XSL, DTDs, and XML
schemas (XSD) files. Mapping tools help you establish relationships
between XML files and between XML files and relational database
tables.
(C) Copyright IBM Corporation 1992, 2005. All Rights Reserved.
Grokking XML
Opening an XML document with RAD
XML document
Right click > open with > rationalsdp (eclipse on RAD 7.0)
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Create workspace
Enter C:\Grokking_XML\RAD_workspace and leave Use this as the default….unchecked!
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Open a Perspective
Window>Open Perspective>Other>Resource
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Create new project
In Navigator pane
Right Click>New>Project>Simple (General on RAD7.0)>Next
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Create new project (continued)
Enter Project Name Grokking_XML and click Finish
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Import employee XML document to project
Again in Navigator pane
Right click Grokking_XML project>Import>(General on RAD7.0) File
System>Next>Browse>Select XML file>Finish
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Create generic schema (XSD) to enable XML Development
Again in Navigator pane
Right click employee.XML document>New>Other>Show All Wizards.>XML>XML
Schema>Next> Check Always enable capabilities…>OK
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Create generic schema (XSD) (continued)
Enter or select the parent folder Grokking_XML>Leave file name NewXMLSchema.xsd>Finish
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Our new generic schema in project
The Navigator pane is redisplayed showing the new XSD
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Create employee schema (XSD)
With XML Development now enabled for our project, we can generate the Employee XSD from
our existing employee XML document.
In the Navigator pane
Right click the employee.xml document>Generate (NOT in RAD7.0) >XML Schema…
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Create employee schema (XSD) (continued)
Accept the File name as is and click Finish
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Create employee schema (XSD) (continued)
The XML Schema generated window is now displayed, click OK
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Delete generic schema (XSD)
The generic XML Schema generated to enable XML can now be deleted
In the Navigator pane
Right click the NewXMLSchema.xsd document>Delete>Click Yes…
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Create employee document type definition (DTD)
With the Employee XSD generated, we can generate the Employee DTD from our existing XSD
In the Navigator pane
Right click the employee.xsd document>Generate (NOT in RAD7.0) >DTD…
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Create employee document type definition (DTD) (continued)
Accept the File name as is and click Finish
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Create employee document type definition (DTD) (continued)
The DTD generated window is now displayed, click OK
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Exit RAD
Click File>Exit and if any resources need to be saved prior to exit, Click OK
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RAD & XML recap
What we accomplished:
 Created a project to Grok XML
 Imported our sample XML document
 Generated an XSD & DTD from the XML document
What we could still accomplish:
 Assign our XSD & DTD to our XML document for validation
 Edit our XML, XSD & DTD documents in RAD to verify that the XSD & DTD
generated are accurate in regards to
 Repeating elements are correctly defined
 Validations required for elements/attributes
 Required elements are defined

Save our document(s) to a mapped IFS folder on our System i
Grokking XML
Excel & XML
New tools in Microsoft Office Excel 2003 make it easier to work with
Extensible Markup Language (XML). Learn how to use these tools to
create XML lists and XML maps. XML lists have the same look and feel
as regular Excel lists, but they take their data from XML files. XML maps
are sets of links between the cells in a worksheet and the elements in
an XML schema. You can import data into the map, modify the data,
and then save the changed data or export it for others to use.
Grokking XML
Create an Excel document
In our Grokking_XML\RAD_workspace\Grokking_XML folder
Right click>New>Microsoft Excel Worksheet
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Create an Excel document (continued)
Now name it employee.xls
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Create an Excel document (continued)
Now double click to open it
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Importing XML into Excel is easy
There are two ways we can import our XML data into our spreadsheet: with or without an
existing Schema (XSD).
In this example, we will simply import the XML data and let Excel generate a schema template
for us.
Click Data>Import External Data>Import Data
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Importing XML w/o a schema
Now select the source of our import, our employee.xml document and click Open
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Importing XML w/o a schema (continued)
Click OK when the Error in XML window is display to instruct Excel to create a schema for us
and apply to our worksheet
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Importing XML w/o a schema (continued)
Except the defaults on the Import Data window and click OK
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Importing XML w/o a schema (continued)
We have now successfully imported an XML document into an Excel worksheet
Grokking XML
Importing XML w/o a schema (continued)
Notice the bold column names. This indicates that the schema mappings apply to the columns
so that an XML document could be generated from this worksheet. Let’s display the
underlying XML of this worksheet.
Click Data>XML>XML Source
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Importing XML w/o a schema (continued)
In the XML Source window displayed to the right of our worksheet, the Excel generated
Employees_Map schema(XSD) is displayed
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Importing XML w/o a schema (continued)
If you click the Tips for mapping XML link, a help panel is displayed defining more about the
workings of Excel & XML
Grokking XML
Adding an XML Map using a schema (XSD)
In this example, we will use an existing schema (XSD) as the template.
Click Data>XML>XML Source…
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Adding an XML Map using a schema (XSD) (continued)
Click XML Maps>Add…>employee.xsd>Open
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Adding an XML Map using a schema (XSD) (continued)
Click Employees>OK in the Multiple Roots windows since Employees, not Employee is our root
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Adding an XML Map using a schema (XSD) (continued)
Click OK in the XML Maps windows
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Adding an XML Map using a schema (XSD) (continued)
In XML Source window, right click the Employees root>Map element…>Click OK in Map XML
Element window
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Our worksheet with the Employee Map
Notice the markings on the Employee_Map showing that each element is now mapped to a
worksheet column and that the columns are now in bold and the XML containment box
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Importing the Employee XML document
Click Data>XML>Import>employee.xml>Import
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Our worksheet with the Employee XML data
Notice the markings on the worksheet that surrounds the column data. The blue box
designates the containment of the XML Source template.
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Adding data to our worksheet
Right click a row>Insert>Row>key data to the row to populate each column as you would in any
worksheet
Grokking XML
Saving/Exporting our worksheet
To save the worksheet as XML data you can either:
Click File>Save As…>Save as type: XML Data(*.xml)>name file>Save
Click Data>XML>Export…>name file>Export
Grokking XML
Excel & XML recap
What we accomplished:
 Imported our employee XML document and generated an XML Map
 Applied an existing XSD schema as an XML Map to our worksheet
 Imported our employee XML data
 Added a row to our worksheet
 Saved/Exported our XML data
What we could still accomplish:
 Perform editing of column(s) in Excel to validate input
 Save our document(s) to a mapped IFS folder on our System i
Grokking XML
SQL & XML composition
Using the System i SQL engine we can create an SQL Procedure that
will generate the Employee XML document used in our lab so that we can
understand the simplicity of XML composition without any special coding
requirements or tools on our existing System i.
Grokking XML
Coding the SQL stored procedure
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Coding the SQL stored procedure (continued)
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Coding the SQL stored procedure (continued)
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Coding the SQL stored procedure (continued)
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Coding the SQL stored procedure (continued)
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Creating the SQL stored procedure
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Executing the SQL stored procedure
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Some considerations for SQL Composition

SQL Stored Procedures contain two parts: a catalog entry and a program
object. These two items can exist separate of each other but only work
when both parts are there at run time and are not as easy to implement as
using a SAVOBJ & RSTOBJ.
Work around for this limitation:
- Run the SQL Create Procedure statement on each box they are to be
used on
to create the catalog entry and program object
Grokking XML
SQL & XML recap
What we accomplished:
 Created a source member that contained our SQL source
 Created the SQL procedure using RUNSQLSTM
 Executed the SQL procedure to generate the employee XML data
What we could still accomplish:
 Add variables to the SQL source for our procedure for flexibility
 Add maintenance coding to DROP the procedure before create and the
Outfile table once complete
Grokking XML
RPG & XML decomposition
The ILE RPG Compiler as of the V5R4 release of i5/OS has new native
operations codes and built in functions that facilitate decomposition of an
XML document into data structures defined in the program using a
non-validating parser. For more information on the XML parser used by
ILE RPG, please refer to Chapter 11 in the WebSphere Development
Studio ILE RPG Programmer’s Guide, SC09-2507.
The advantage of using the new operation codes and built-in functions
added to RPG is that once the hierarchy of the XML document is
replicated using data structures in our RPG program code, the
decomposition of the XML data and population of data structure fields is
done automatically and efficiently without the developer having to
manipulate storage to get the XML data in to workable form. The
complexity has been removed from the XML decomposition process
and the developer now can just concentrate on business logic required
to implement the XML data. No pointers, API interfaces, buffer
manipulation, just straight forward RPG coding.
Grokking XML
Coding a CMD interface
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Coding a PNLGRP for the CMD interface
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Coding a PNLGRP for the CMD interface (continued)
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Coding a PNLGRP for the CMD interface (continued)
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Coding a CLLE validation module
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Coding a CLLE validation module (continued)
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Coding a CLLE validation module (continued)
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Coding a CLLE validation module (continued)
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Coding the SQLRPGLE module for decomposition
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Coding the SQLRPGLE module (continued)
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Executing the XML decomposition
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Some considerations for RPG Decomposition

Use of the Java Virtual Machine (JVM) on a System i requires some simple
tuning to optimize performance. Since we use the JVM to run our Transform
class it is important to note the memory pool that your JVM executes in be
set appropriately to improve performance.

XML-INTO operation cannot handle empty elements or attributes that
contain zero length numeric, date, time or timestamp fields during
decomposition.
Work around for this limitation:
- Use a stylesheet (XSL) as we did to remove the empty limitations
noted above
Grokking XML
Some considerations for RPG Decomposition (continued)

The RPG compiler limits character variables to 65535 characters in length. Data
Structures, being considered character fields, are subject to this length limitation
as well. You must be aware when replicating the XML tree using data
structures, especially data structures that are dimensional, that the total size of
the data structure tree does not exceed this limit as well.
Work around for this limitation:
- break apart the data structures without nesting them in side each other and
use multiple XML-INTO operations to decompose specifying the specific
path of the XML document that matches the data structure names.
Grokking XML
Questions?