J2EE Web Services Work

1
J2EE Web Services _at_ Work

• Tom Marrs
• Principal/Senior Software Architect
• Vertical Slice, Inc.
• thomasamarrs_at_comcast.net

2
Who Am I?

• Background
• Lead author of JBoss At Work A Practical Guide
  (OReilly, November 2005)
• Presented at
• XML One/Web Services One
• No Fluff Just Stuff Symposia
• User Groups
• Forming Denver JBUG
• Past President of DJUG
• Related Experience
• Used Web Services on Java/J2EE projects
• Spent a lot of time fixing problems

3
Learning Objectives

• As a result of this presentation you will learn
• When and when not to use Web Services
• How J2EE 1.4 and Web Services fit
• Expose an EJB as a J2EE 1.4 Web Service
• How to work around broken Open Source tools
• Advanced J2EE Web Services Issues (a.k.a Reality)

4
Prerequisites

• Java
• Core language
• Exposure to J2EE Basics JSPs, Servlets, EJBs
• XML
• Schema
• Web Services

5
Session Non-Agenda

• In this Session, we will not discuss
• In-depth Web Service Architecture
• Every last detail on SOAP, WSDL, and UDDI Yuck!
• In-depth details on JBoss or other J2EE
  application servers

6
Session Agenda

• In this Session we will discuss
• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service
• Consuming a Web Service
• Advanced J2EE Web Services Issues
• Summary

7
Session Roadmap

• Where are we?
• Business Reasons for Using Web Services
• JAW Motors B2B
• Reasons to Consider Web Services
• When Not to Use Web Services
• J2EE Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Summary

8
JAW Motors B2B

• JAW Motors A fictitious auto dealership
• Has a web site that shows its inventory
• Wants to move beyond a web site
• Can increase business by sharing inventory with
  VBAD (Virtual Big Auto Dealership)
• The problem interoperability
• JAW Motors uses Java/J2EE
• VBAD uses non-Java technology

9
Reasons to Consider Web Services

• Business
• You need to communicate with external clients
• Technical
• You need to communicate with non-Java clients
• Your clients are outside the firewall
• Political
• Management mandates the use of Web Services

10
When Not to Use Web Services

• All your clients are Java-based
• Communicating between J2EE architecture layers
• You control the object model
• Serialization/remoting are expensive
• Web Services/XML processing takes longer
• Dont Use XML to Communicate Unless You Really,
  Really Have To Floyd Marinescu, The Middleware
  Company
• Remember Web Services/XML are for integration

11
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• What are Web Services?
• Web Service Terminology
• Web Service Invocation
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Summary

12
What are Web Services?

• Network applications that
• Use
• SOAP (Simple Object Access Protocol)
• WSDL (Web Services Definition Language)
  Definition/Description
• Exchange information via XML documents
• Platform-independent
• Not tied to Java, CORBA, etc.
• There are 80 Web Service implementations

13
Web Service Terminology

• SOAP (Simple Object Access Protocol)
• An XML-based (text) wire protocol
• Enables remote communication
• Platform-neutral
• WSDL (Web Services Definition Language)
• Interface descriptor
• UDDI (Universal Description, Discovery, and
  Integration)
• Registry of Web Services
• Used for discovering Web Services

14
Web Service Invocation
15
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• JBoss 4.x and Web Services
• J2EE 1.4 and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Summary

16
JBoss 4.x and Web Services

• JBoss.Net
• Bundled with JBoss 3.x
• Non-standard
• Tightly Coupled to Apache Axis
• XDoclet tags and deployment worked well
• Now deprecated
• JBossWS
• Part of JBoss 4.x
• Follows J2EE 1.4 standard
• Moving away from Apache Axis
• Decent Deployment
• XDoclet needs help

17
J2EE 1.4 and Web Services

• Interoperability
• WS-I (Web Service Interoperability) compliance
• Platforms (J2EE, .Net)
• Operating Systems
• Programming Languages
• JSR-109
• Standard Deployment Runtime
• Descriptors
• Web Service Engine details hidden
• Still some bleed-through

18
J2EE 1.4 and Web Services continued

• Can expose the following as Web Services
• EJBs
• POJOs
• Were doing an EJB

19
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service Only 103
  Easy Steps ?
• Service Endpoint Interface
• Modify ejb-jar.xml
• webservice.xml
• JAX-RPC Mapping File
• WSDL File (Oh the Joy!)
• Fixing the WSDL URL
• Modifying the EJB
• Web Service Data Types Collections
• Packaging a Web Service
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Summary

20
The System So Far

• JAW Motors web site
• JSPs
• Controller Servlet
• Stateless Session Bean InventoryFacadeBean
• Hibernate DAOs
• We want to expose InventoryFacadeBean.findAllAvail
  ableCars() as a Web Service

21
Service Endpoint Interface

• Exposes business methods as Web Services
• Acts as a server-side stub
• Similar to EJB Remote Interface

22
Service Endpoint Interface continued

• package com.jbossatwork.ws
• /
• Service endpoint interface for
  InventoryFacade.
• /
• public interface InventoryEndpoint
• extends java.rmi.Remote
• public com.jbossatwork.ws.CarDTOArray
  findAvailableCars()
• throws java.rmi.RemoteException
• // InventoryEndpoint.java

23
Modifying ejb-jar.xml

• InventoryFacadeSB
• InventoryFacade
• com.jbossatwork.ws.InventoryEndpoint
• ejb-jar.xml

24
webservices.xml

• Defines and registers the InventoryService Web
  Service
• Ties Service Endpoint Interface class to the
  InventoryFacadeBean EJB
• Tells J2EE app server where to find WSDL and
  JAX-RPC Mapping files in EJB JAR file.

25
webservices.xml continued

• xmlns"http//java.sun.com/xml/ns/j2ee"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-insta
  nce"
• xsischemaLocation"http//java.sun.com/xml/ns/j2
  ee
• http//www.ibm.com/webservices/xsd/j2ee_web_servic
  es_1_1.xsd"
• version"1.1"
• InventoryServ
  ice
• META-INF/wsdl/InventoryService.
  wsdl
• META-INF/inventory-ma
  pping.xml
• Inventoryomponent-name
• InventoryEndpointPort-port
• com.jbossatwork.ws.InventoryEndpoi
  nt
• InventoryFacadelink

26
JAX-RPC Mapping File

• Helps JAX-RPC compiler map Java objects to WSDL
  objects
• Complex Java objects lead to complex JAX-RPC and
  WSDL files

27
JAX-RPC Mapping File continued

• ns/j2ee"
• xmlnsxsi"http//www.w3.org/2001/XMLSchema-instan
  ce"
• xsischemaLocation"http//java.sun.com/xml/ns/j2e
  e
• http//www.ibm.com/webservices/xsd/j2ee_jaxrpc_ma
  pping_1_1.xsd" version"1.1"
• com.jbossatwork.ws
• http//localhost8080/jbossatwor
  k-ws/types
• com.jbossatwork.ws
• http//localhost8080/jbossatwor
  k-ws
• com.jbossatwork.dto.CarDTOArrayva-type
• t8080/jbossatwork-ws/types"
• typeNSCarDTOArray
• complexType

28
JAX-RPC Mapping File continued

• com.jbossatwork.dto.CarDTOpe
• t8080/jbossatwork-ws/types"
• typeNSCarDTO
• complexType
• id
• id
• make
• make
• modele
• model

29
JAX-RPC Mapping File continued

• statusme
• status
• com.jbossatwork.ws.Inventor
  yService
• alhost8080/jbossatwork-ws"
• serviceNSInventoryService
• InventoryEndpointPort
  
• InventoryEndpointPortport-name

30
JAX-RPC Mapping File continued

• com.jbossatwork.ws.InventoryEndpoint
• host8080/jbossatwork-ws"
• portTypeNSInventoryEndpoint
• t8080/jbossatwork-ws"
• bindingNSInventoryEndpointBinding
• findAvailableCarsthod-name
• findAvailableCarsation
• com.jbossatwork.dto.C
  arDTOArray
• lhost8080/jbossatwork-ws"
• wsdlMsgNSInventoryEndpoint_findAvailabl
  eCarsResponse
• resultge-part-name

31
JAX-RPC Mapping File continued

• What were we trying to do?
• InventoryEndpoint Service Endpoint Interface has
  a findAvailableCars() method that takes no
  parameters and returns a CarDTOArray

32
WSDL File (Oh the Joy!)

• Describes a Web Service interface
• Describes its parameters
• Registers the web service with the server

33
WSDL File (Oh the Joy!) continued

• targetNamespace"http//localhost8080/jbossatwork
  -ws"
• xmlnstns"http//localhost8080/jbossatwork-ws"
• xmlns"http//schemas.xmlsoap.org/wsdl/"
• xmlnsxsd"http//www.w3.org/2001/XMLSchema"
• xmlnsns2"http//localhost8080/jbossatwork-ws/ty
  pes"
• xmlnssoap"http//schemas.xmlsoap.org/wsdl/soap/"
  
• /jbossatwork-ws/types"
• xmlnstnshttp//localhost8080/jbossa
  twork-ws/types
• xmlnssoap11-enc"http//schemas.xmlso
  ap.org/soap/encoding/"
• xmlnsxsi"http//www.w3.org/2001/XMLS
  chema-instance"
• xmlnswsdl"http//schemas.xmlsoap.org
  /wsdl/"
• xmlns"http//www.w3.org/2001/XMLSchem
  a"
• nillable"true" minOccurs"0"
• maxOccurs"unbounded"/ce

34
WSDL File (Oh the Joy!) continued

• nillable"true"/
• nillable"true"/
• nillable"true"/
• nillable"true"/
• rs"/
• rsResponse"
• message
• ailableCars"/
• vailableCarsResponse"/

35
WSDL File (Oh the Joy!) continued

• type"tnsInventoryEndpoint"
• p.org/soap/http" style"rpc"/
• namespace"http//localhost8080/jbossatwork-ws"/
  
• namespace"http//localhost8080/jbossatwork-ws"/
  
• binding"tnsInventoryEndpointBinding"
• URL"/

36
WSDL File (Oh the Joy!) continued

• What were we trying to do?
• Tie the InventoryService web service to the
  InventoryEndpoint interface
• Map CarDTO and CarDTOArray WSDL types to XSD data
  types
• But I thought we already did this (!)
• WSDL required for W3C
• JAX-RPC required for J2EE

37
Fixing the WSDL URL

• WSDL tells application server that it can choose
  its own URL
• 
  
• JBoss chooses
• http//localhost8080/jaw/ejb/Inventory?wsdl

38
Fixing the WSDL URL continued

• We want a meaningful URL
• 4.0//EN"
• "http//www.jboss.org/j2ee/
  dtd/jboss_4_0.dtd"
• InventoryFacade
• Inventorynent-name
• jbossatwork-ws/Invento
  ryService

39
Modifying the EJB

• /
• _at_ejb.bean
• name"InventoryFacade"
• view-type"all"
• _at_wsee.port-component
• name"Inventory"
• wsdl-port"InventoryEndpointPort"
• service-endpoint-interface"com.jbossatwork.ws
  .InventoryEndpoint"
• service-endpoint-bean"com.jbossatwork.ejb.Inv
  entoryFacadeBean"
• _at_ejb.interface
• service-endpoint-class"com.jbossatwork.ws.Inv
  entoryEndpoint"
• /
• public class InventoryFacadeBean implements
  SessionBean

40
Modifying the EJB continued

• /
• _at_ejb.interface-method
• view-type"all"
• /
• public CarDTOArray findAvailableCars() throws
  EJBException
• CarDTOArray carDTOArray new
  CarDTOArray()
• CarDTO cars (CarDTO)
  listAvailableCars().toArray(new CarDTO0)
• carDTOArray.setCars(cars)
• return carDTOArray
• /
• _at_ejb.interface-method
• view-type"both"
• /

41
Web Services Data Types

• Parameters and Return values must conform to
  JavaBean rules
• Default Constructor
• Each private/protected data member must have
  public getter/setter
• Must be Serializable

42
Web Services and Collections

• WSDL/XSD doesnt understand Java Collections
• package com.jbossatwork.dto
• import java.io.Serializable
• import com.jbossatwork.dto.CarDTO
• public class CarDTOArray implements Serializable
  
• private CarDTO cars
• public CarDTOArray()
• public CarDTO getCars()
• return cars
• public void setCars(CarDTO cars)
• this.cars cars

43
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service - Good Tools Gone Bad
• EJB JAR File Structure
• What Are We Automating?
• What About the Tools?
• Ant Build Script
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Summary

44
EJB JAR File Structure

• META-INF/
• ejb-jar.xml
• jboss.xml
• webservices.xml
• inventory-mapping.xml (JAX-RPC Mapping File)
• wsdl/
• InventoryService.wsdl
• com/jbossatwork/ws/
• InventoryEndpoint.class
• Everything else is the same

45
What Are We Automating?

• Generate 3 new descriptors
• webservices.xml
• JAX-RPC Mapping File
• WSDL
• Generate Service Endpoint Interface
• Modify ejb-jar.xml and jboss.xml

46
What About the Tools?

• XDoclet is broken (!)
• Can generate (with minor mistakes)
• Service Endpoint Interface
• webservice.xml
• Modify ejb-jar.xml
• Ant fixes XDoclets mistakes
• JWSDP (Java Web Services Developers Pack)
• Generate WSDL and JAX-RPC Mapping Files

47
Ant Build Script Generate Service Endpoint
Interface

• dp-1.5"/
• om/jbossatwork/ws/InventoryEndpoint.java"
• javax.ejb.EJBException,
• java.rmi.RemoteException
• java.rmi.RemoteException

48
Ant Build Script Fix the URL

• "
• Invento
  ryFacade
• InventoryFacade/ejb-name
• Inv
  entory
• jbos
  satwork-ws/InventoryService

49
Ant Build Script Generate webservices.xml

• let"
• classname"xdoclet.modules.wsee.W
  seeDocletTask"
• classpathref"xdoclet.lib.path"/
  
• oryService.wsdl"
• jaxrpcMappingFile"META-INF/in
  ventory-mapping.xml"
• wseeSpec"1.1"
• destdir"gen.source.dir"
• excludedtags"_at_version,_at_author
  "
• addedtags"_at_xdoclet-generated
  at TODAY"
• verbose"true"
• name"InventoryService"/

50
Ant Build Script Fix webservices.xml

• es.xml"
• WEB-
  INF/
• /replacevalue
• es.xml"
• -fileWEB-INF/
• -file
• es.xml"
• acetoken
• ue
• es.xml"
• lacetoken
• ue

51
Ant Build Script Generate JAX-RPC Mapping and
WSDL files

• depends"compile"
• and WSDL files."/
• includes"tools.jar"/
• fork"true"
• server"true"
• features"rpcliteral"
• mapping"gen.source.dir/inve
  ntory-mapping.xml"
• config"wscompile-config.xml"
• nonClassDir"gen.source.dir"
  

52
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service
• Developing a Web Service Client
• Generate Web Service Proxy Code
• Client Code
• Advanced J2EE Web Services Issues
• Summary

53
Generate Web Service Proxy Code

• description"Generates WS proxy code from WSDL"
• url"InventoryService.wsdl"
• verbose"true"
• 080/jbossatwork-ws"
• package"com.jbossatwork.clie
  nt"/
• 080/jbossatwork-ws/types"

54
Client Code

• package com.jbossatwork.client
• public class MyAxisClient
• public static void main(String args)
• try
• System.out.println("Finding
  InventoryService ...\n")
• InventoryService service new
  InventoryServiceLocator()
• System.out.println("Getting InventoryEndpoint
  ...\n")
• InventoryEndpoint endpoint
  service.getInventoryEndpointPort()
• System.out.println("Getting Cars ...")

55
Client Code continued

• // If you're using J2SE 1.4, the next
  2 lines of code will work.
• CarDTOArray carDTOArray endpoint.findAvailab
  leCars()
• CarDTO cars carDTOArray.getCars()
• // If you're using Java 5 (J2SE 1.5), delete
  the previous 2 lines of
• // code and uncomment the next line of code.
  Axis 1.2.1 optimized away
• // the CarDTOArray.
• // CarDTO cars endpoint.findAvaila
  bleCars()
• for (int i 0 i
• System.out.println(
• "Year " carsi.getModelYea
  r() ", Make "
• carsi.getMake()
• ", Model " carsi.getModel()
  ", status "
• carsi.getStatus() "")
• catch(Exception e)
• e.printStackTrace()

56
Session Roadmap

• Business Reasons for Using Web Services
• Web Service Architecture
• J2EE/JBoss and Web Services
• Implementing/Deploying a Web Service
• Packaging a Web Service - Good Tools Gone Bad
• Developing a Web Service Client
• Advanced J2EE Web Services Issues
• Tool/Product Limitations
• RPC vs. Document
• Summary

57
Tool/Product Limitations

• Apache Axis 1.2.x
• Problems consuming Web Services with XSD types
• Enumerations
• Unbounded array of Choices
• Need to fix generated code yuck!
• Not yet WS-I compliant
• JBoss 4.x
• WS Engine still uses Axis
• Serializer/De-Serializer problems with
  deep/complex object types
• Use proprietary XML descriptor to fix the
  problem
• Moving away from Axis
• Still production-worthy
• Commercial WS tools work better

58
RPC vs. Document

• Havent we done this before?
• RPC
• Can lead to tightly coupled interface
• Can be brittle
• Tools dont always work
• Simple procedure call
• Document
• Loosely coupled interface
• Absorbs change better
• No serializer/de-serializer issues
• Requires extra design effort
• Interpret client messages and perform actions
• Use Castor

59
Summary

• Use Web Services for interoperability
• J2EE Web Service deployment is tedious
• Tools make things easier be careful
• Automate J2EE Web Service deployment
• Work around broken tools
• Encapsulate everything with Ant or Maven
• Understand design tradeoffs
• Know the limitations of your application server
  tools
• Automate get on with your life you have
  better things to do

60
Questions?

• Tom Marrs
• Senior Software Architect
• thomasamarrs_at_comcast.net