E210 Message Bridge for Java

1
E210 Message Bridge for Java

• Javier Cuerva
• Technical Architect
• eBusiness Division
• cuerva_at_sybase.com

2
Agenda

• Summarize Skills Prerequisites
• Identify Business and Technical Contexts
• Describe Message Bridge
• Overview and Architecture
• Features
• Description and Usage

3
Skills Prerequisites

• XML Concepts
• Syntax (elements, attributes, structure)
• Parsing SAX, DOM, validation
• Namespaces
• DTD vs. XML Schema
• Java
• Language concepts
• Object-oriented programming

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Definitions

• Document Schema
• Specifies structure and permissible values of
  documents
• Syntaxes supported by Message Bridge
• Document Type Definition
• XML Schema
• Root Element
• In DOM terminology, the document element
• Ancestor of all other elements in a document
  instance
• Message Definition
• Pairing of a root element and a schema

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Definitions, cont

• View
• Subset of a message definition
• Used to manipulate subset of overall document
• Binding
• XML document modelled via programming language
  (Java) constructs
• DataBean
• The Java binding produced by Message Bridge
• An object encapsulating a specific XML document

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Definitions, cont

• Validation
• Enforcement of document schema structure and
  constraints
• Valuable and useful in many situations but not
  required
• Serialization
• Conversion of DataBean object instances into XML
  documents
• Deserialization
• Parsing (and optionally, validation) of XML
  documents
• Reconstitution of DataBean object instances

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Business and Technical Contexts

• Message Bridge
• Does not process messages
• Not a broker, not a server
• Not a runtime environment
• Does not perform transformation or routing
• Binds messages to objects
• Focused on message content, not message
  processing
• Lightweight
• XML-focused solution
• Oriented towards programmers

8
Product Overview

• Purpose
• Help Sybase customers build XML-oriented
  applications
• Integrated Function
• Binds specific XML documents to Java objects at
  runtime
• Output incorporated into applications
• Compiles XML document schemas into Java classes

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Product Overview, cont

• Comprised of the following
• GUI for accessing design-time functionality
• Document schema importers
• Schema compilers to generate bindings
• Runtime library infrastructure
• Primary Audience
• B2B and B2C integration applications

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Architecture

• DataBean Framework
• Underlying functionality that supports the
  generated code
• Must also be included with deployed application
• Message Bridge GUI
• Design-time tool
• Document schemas are imported and displayed
• Code generation attributes optionally modified
• Generates Java code
• Generated Code
• Reflects concepts expressed in document schema
• Hides the details associated with XML parsing

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Architecture, cont
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Framework Feature Description

• Core Feature of Message Bridge
• Runtime Support Infrastructure
• All Required Components Are Bundled
• Xerces XML Parser, JDOM Library
• Message Definitions
• Provides access to entire document
• Views
• Provides access to subset of document
• Associated with a specific message definition

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Framework Usage

• API Documentation
• located in ltinstallgt/docs/javadoc directory
• Required Components
• located in ltinstallgt/lib directory
• DataBean.jar
• Contains the DataBean Framework
• jdom.jar
• JDOM Library (0.7p1)
• xerces.jar
• Xerces XML parser (version 1.4.3)
• Building Applications
• Include above-mentioned jar files in CLASSPATH

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Framework Usage, cont

• Methods Common To All DataBeans
• get() methods to access element data and
  attributes
• set() methods to modify element data and
  attributes
• Methods Provided By Root DataBean
• Constructors to create a new DataBean object
  graph
• get() and set() methods
• Retrieve the main document
• Access/modify root name
• Access location of source schema

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Framework Binding Example

• lt!ELEMENT Recipe (IndexCard IngredientList
  StepList) gt
• lt!ELEMENT IndexCard (Name, Description, Source)gt
• lt!ELEMENT Name (PCDATA)gt
• lt!ELEMENT Description (PCDATA)gt
• lt!ELEMENT Source (PCDATA)gt
• lt!ELEMENT IngredientList (Ingredient)gt
• lt!ATTLIST IngredientList serves CDATA REQUIREDgt
• lt!ELEMENT Ingredient (Food, Quantity)gt
• lt!ELEMENT Food (PCDATA)gt
• lt!ELEMENT Quantity (PCDATA)gt
• lt!ELEMENT StepList (Step)gt
• lt!ELEMENT Step (PCDATA)gt
• lt!ELEMENT Comments (PCDATA)gt

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Framework Binding Example, cont

• Simple XML Element Containing Text
• lt!ELEMENT Food (PCDATA)gt
• Corresponding Java
• Class Food
• Methods
• public String getData()
• public void setData( String data )

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Framework Binding Example, cont

• XML Element Containing Children
• lt!ELEMENT Ingredient (Food, Quantity)gt
• Corresponding Java
• Class Ingredient
• Methods
• public Food getFood()
• public Food setFood()
• public Quantity getQuantity()
• public Quantity setQuantity()

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Framework Binding Example, cont

• XML Element Containing Repeating Child And
  Attribute
• lt!ELEMENT IngredientList (Ingredient)gt
• Corresponding Java
• Class IngredientList
• Methods
• public Object get( int index )
• public Ingredient getIngredient( int index)
• public List getIngredients()
• public Ingredient setIngredient( int index)
• public void setIngredient( Ingredient instance,
  int index )

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GUI Feature Description

• Standalone Design-time Tool
• DTD and XML Schema Import
• View Creation
• Code Generation
• Online Help

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GUI Usage

• Step 1, Import DTD
• Select a schema group (such as Default Group)
• Select File New Message Definition from the
  menu
• Brings up Add Message Schema dialog
• Select DTD or XML Schema from drop-down list
• Navigate to the directory containing DTD or XML
  Schema to be imported
• User is prompted to select a root element
• Message definition is added to project
• Window opens to display diagram

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GUI Usage, cont

• Step 2 (Optional) Create View
• Right-click on element in diagram window
• Select New View from menu
• Brings up View Name dialog
• Type in a name for the view and click OK
• Window opens to display diagram for view

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GUI Usage, cont

• Step 3 Generate Code
• Select the newly-imported message definition
• Select Tools Generate from the menu
• Prompts for permission to save project
• Brings up Generate dialog
• Specify code generation parameters
• Package name
• Output Directory
• Jar file name
• Can optionally request documentation generation,
  too

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Generated Code

• Feature Description
• Usage
• Constructing Instances from an XML document
• Getting elements
• Populating a new DataBean
• Creating an XML document
• Identifying the DTD in an XML document

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Generated Code Feature Description

• Binding
• Concepts expressed in specific document schema
  represented by Java classes and methods
• Serialization / Deserialization
• Parse XML documents and populate object hierarchy
• Store data encapsulated by object hierarchy in
  XML format

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Generated Code Usage

• Constructing Instances From An XML Document
• FileInputStream input
• new FileInputStream( xml_filename )
• // false in next method call means no validation
• Recipe rcp new Recipe( input, false )
• Or
• FileInputStream input
• new FileInputStream( xml_filename )
• // again, false means no validation
• Recipe rcp new Recipe()
• Rcp.deserializeXML( input, false )

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Generated Code Usage, cont

• Getting Elements
• // rcp is Recipe instance from previous slide
• IngredientList ing_list rcp.getIngredientList()
  
• // Get the first (0-based index) ingredient
  element
• Ingredient ing ing_list.getIngredient( 0 )
• // Determine whether there actually were any
• // ingredients
• if (!ing.hasValidElement())
• // no ingredients to process
• return

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Generated Code Usage, cont

• Populating A New DataBean
• Recipe rcp new Recipe()
• Ingredient ing
• rcp.setIngredientList( 0 ).setIngredient( 0 )
• ing.setFood().setData( Onions )
• ing.setQuantity().setData( 2 )
• // more code to populate recipe . . .

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Generated Code Usage, cont

• Creating An XML Document
• FileOutputStream output
• new FileOutputStream( xml_filename )
• // rcp is Recipe object from previous slide
• rcp.serializeXML( output )

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Generated Code Usage, cont

• Identifying DTD In An XML Document
• FileInputStream input
• FileInputStream( xml_filename )
• DataBeanOpaque dbean
• new DataBeanOpaque( input, false )
• String dtd_name dbean.getDocTypeSystemID()
• if (dtd_name.equals( recipe.dtd ))
• Recipe rcp_v1 new Recipe( dbean, true )
• // do something with version 1 recipe
• else if (dtd_name.equals( recipe_v2.dtd ))
• Recipe2 rcp_v2 new Recipe2( dbean, true )
• // do something with version 2 recipe

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Generated Code Enabling Validation

• How To Enable Validation For DTDs
• Pass true as the value of the validate parameter
  to the DataBean constructor
• Call the validate() method
• XML document must include a DOCTYPE statement

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Generated Code Validation, cont

• Runtime Location of DTDs
• SYSTEM or PUBLIC keyword value
• absolute path framework uses the path as is
• relative path Xerces parsers default location
  (current working directory of the JVM) is
  prepended
• otherwise, set Java system propertycom.sybase.Dat
  aBean.EntityResolver.dtdswith one or more
  directories to search in
• entries separated by semicolons
• safety net if document specifies incorrect path

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Where to go for help

• Technical Library Product Manuals Web site
• http//www.sybase.com/support/manuals
• W3C Web site
• http//www.w3.org/XML/
• Learning XML
• Erik T. Ray, O'Reilly Associates (ISBN
  0596000464)
• Professional XML
• Martin, Birbeck, Kay, et al., Wrox Press (ISBN
  1861003110)

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Summary

• Binds Java classes and XML documents
• Supports DTD and XML Schema syntaxes
• Composed of three pieces
• DataBean Framework
• Runtime infrastructure library
• GUI
• Design-time tool
• Generated Code
• Document schema-specific runtime classes
• No external dependencies
• New product with minimal installed base
• mainly early adopters

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Questions ?