Implementation Case with Java tools and experiences

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Implementation - Case with Java (tools and
experiences)

• Heikki Pakkala, THL
• WP1.8 TG3.1 EuroFIR Web Services
• 3rd Meeting, Florence 2009

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Implementation - Case with Java

• What the Web Services are supposed to do?
• Our Solution stack
• Our Starting points
• From WSDLs to Web Services
• Web Service FCDB
• From FCDB into Java Persistence API (JPA)
• Working with the XML files
• The work flow from request to response
• Some thoughts of test driven development
• How to design for change?

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The big picture
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Implementation with Java solution stack

• (Windows) Tomcat MySQL Java (J2EE)
• Why Java why not?
• Java EE Web Services Technologies (Metro stack)
• Java API for XML-Based Web Services (JAX-WS)
• Java Architecture for XML Binding (JAXB)
• Java Persistence API (JPA), implementation with
  Hibernate
• Tools
• Eclipse (Myeclipse)
• SoapUI

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Implementation with Java starting points

• Experience with Java still many new things
  (like e.g. Web services)
• Things can be done with very different ways
• This is not how-to-make-it manual
• Our principles
• Do not reinvent the wheel use frameworks
• Design for change isolate potential change
• Test driven development

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Basic tool Eclipse (Myeclipse)
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Starting with the WSDLs

• WSDLs ? creation of Web Services stubs with
  MyEclipse tools
• A large set of generated classes
• Creating a common service dispatcher
• Delegation
• authentication
• errors

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FCDB for the Web services 1/3

• FCDB designed specially for Web services
• FCD will be loaded from the production FCDB (new
  releases)
• Only those entities and fields needed
• FCD translated against TA and FDTP (naming, data
  types)
• Search intensive structure heavy indexed
• Structures supporting our needs (like e.g.
  LanguaL search)
• Nothing very special but this structure would
  not fit to our FCD storing needs
• Some surrogates added to make our life easier
  with the Hibernate

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FCDB for the Web services 2/3
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FCDB for the Web services 3/3

• Think ahead the things that you will need!
• Tree traversing is not for SQL
• LanguaL NT (linked with food)
• LanguaL BT search uses tree
• LanguaL tree is created when loading the FCD
• All branches are multiplied for all foods
• This set is SQL compatible

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Java Persistence API (JPA) for FDQL Hibernate
implementation
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JPA Hibernate in action

• OR mapping
• Reverse engineer from Web Service FCDB
• A large set of generated classes
• Database Communication always via Hibernate
• Let Hibernate do all database operations (get the
  food and Hibernate will find the rest connected
  with it lazy or eager)
• HQL or SQL available

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JAXB working with XML files 1/2
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JAXB working with XML files 2/2

• We need the XML schema first
• Bind the XML schema with a JAXB compiler
• A large set of generated classes
• Generate your XML object tree
• Fill it with data
• Marshall it to XML document
• Or
• Generate your XML object tree
• Link it with a document
• Validate document
• Unmarshal data from document to your XML object
  tree

• Available XML schemata for FDQL, FDTP, MDTP
• also usable for parameters, term lists etc (do
  your own XML schemata)

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Main actions from request to response

• SOAP request receiving
• authentication
• FDQL parsing to XML object (create unmarshall)
• Delegation to the right Web Service and creating
  it
• Web Service
• FDQL interpretation (possible or not, search
  plan)
• FDQL translation (mapping with Hibernate objects)
• Query execution to FDQL with Hibernate objects
  (HQL, SQL)
• Getting the results with Hibernate objects
• Creating the FDTP/MDTP object tree
• Fill the tree from Hibernate objects
• Marshall it to XML document (FDTP or MDTP)
• Put the FDTP or MDTP into SOAP envelope
• Send SOAP response

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Test driven development

• Iteration
• Test cases
• Unit testing
• Writing the test cases sometimes challenging
• Rerun test patterns after changes

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Testing the whole Web Service - soapUI

• Write your own request and see what comes out
• Write test requests
• Mock-up response for development of eSearch

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Design for change ?

• Isolate changing elements interfaces
• Production FCDB and Web Service FCDB
• JPA Hibernate
• WSDLs
• FDQL
• XML schemata
• Actions inside Web Services
• FDTP and MDTP
• SOAP
• Separate generated code (large amount of
  generated classes from WSDL, Hibernate and XML
  schemata) from written code

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Summary

• What the Web Services are supposed to do?
• Our Solution stack
• Our Starting points
• From WSDLs to Web Services
• Web Service FCDB
• From FCDB into Java Persistence API (JPA)
• Working with the XML files
• The work flow from request to response
• Some thoughts of test driven development
• How to design for change?
• Thank you for your patience!