PWB519 Accessing Third-Party Enterprise JavaBeans Servers from PowerBuilder 9.0 Jim O’Neil Principal Technical Support Engineer Sybase, Inc. (Concord, MA) [email protected]
PWB519 Accessing Third-Party Enterprise JavaBeans Servers from PowerBuilder 9.0
Jim O’NeilPrincipal Technical Support EngineerSybase, Inc. (Concord, MA)[email protected]
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
Overview of the Enterprise JavaBeans Model
EJB is Sun’s J2EE transactional, vendor-neutral, enterprise component architecture providing
Modeling of business entities and synchronous and asynchronous processes Persistence via explicit code (bean-managed) or via services of the EJB server
(container-managed) Vendor neutrality and interoperability XML driven deployment and configuration
Core Concepts
Overview of the Enterprise JavaBeans Model
EJB types Session beans model processes
Stateless EJBs are reusable and ‘single-task’ oriented Stateful EJBs remain associated with a client and are disposed when
client is through Entity beans model objects that persist, often in the form of records in a
database Message-driven beans respond to asynchronous requests from the Java
Message Service (JMS)
Core Concepts
business method
createfindByPrimaryKey
Overview of the Enterprise JavaBeans Model
J2EE ServerClient Application
homeinterface stub
EJB Home
Implementation class
ancillary Java classes
remoteinterface stub
EJB Object
return value
lookupInitial
Context
Java Message Service
Message-driven bean
onMessage
JNDI Service
topic/queue
External messagingclient applications
messages
EnterpriseInformation
System
Representative Enterprise JavaBeans Server and Client Application
Overview of the Enterprise JavaBeans Model
Java Naming and Directory Interface (JNDI) Provides a standardized way of accessing resources in a distributed environment Protocol and naming service agnostic
DNS NDIS LDAP X.500
Implemented by the javax.naming package and three other packages below it javax.naming.InitialContext is the entry point to the EJB Server
bind – associates a name with an object lookup – finds an object given the name
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Home interface Provides remote client-view of methods affecting the EJB lifecycle Extends javax.ejb.EJBHome Can include business methods that are not specific to a given EJB instance Lacking for message-driven beans since they have no client-view
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Component interface Provides remote client-side view of bean’s business methods Extends javax.ejb.EJBObject thus providing methods to obtain access to
Home interface and Primary Key classes and to test for equality between EJB instances
Lacking for message-driven beans since they have no client-view
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Implementation class Implements one of the extensions of the javax.ejb.EnterpriseBean class
which provide lifecycle notification methods (e.g., ejbPassivate) javax.ejb.EntityBean javax.ejb.SessionBean javax.ejb.MessageDrivenBean
Class in which EJB developer codes the business methods defined in the bean’s component interface(s)
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Primary key class Applicable only to entity beans Uniquely differentiates one instance from the other instances sharing the same
EJBHome Class must be a legal value type in RMI-IIOP
Implements java.io.Serializable Does not implement java.rmi.remote
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Exceptions System exceptions are unchecked and propagate to the client as
java.rmi.RemoteException Application exceptions are checked and propagate to the client as a descendant of
java.lang.Exception EJB-specific exceptions include FinderException, CreateException,
RemoveException (all in javax.ejb package) Business method exceptions are at the discretion of the EJB developer
Interfaces and Classes
Overview of the Enterprise JavaBeans Model
Other interfaces and classes Local interfaces used for access within server context (e.g., intercomponent calls,
servlet invocation) javax.ejb.EJBLocalHome javax.ejb.EJBLocalObject
Interfaces for serializing EJB references HomeHandle - reference to EJBHome Handle - reference to EJBObject
EJBMetaData interface provides mechanism to gather information about the bean Reference to EJBHome object Home, component interface and primary key classes Functions to determine bean type
Interfaces and Classes
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
PowerBuilder EJB Client Implementation
Feature overview Uses Java Native Interface (JNI) for interoperability Supports 1.0, 1.1, and 2.0 EJBs Supports client-managed transactions Supports system and application exception handling Supplemented by EJB Proxy Generator
PowerBuilder IDE EJB2PB90 command line utility
Architecture Overview
PowerBuilder EJB Client Implementation
Implementation overview Built using the PowerBuilder Native Interface (PBNI) which allows developers to
Extend core features of PowerBuilder via custom C++ classes, and Access PowerBuilder objects from other languages like C++, VisualBasic, and
Delphi Three PBNI classes are exposed in the PBEJBCLIENT90.PBD
JavaVM EJBConnection EJBTransaction
EJBLocator Java class, which wraps javax.naming.InitialContext, is contained in PBEJBCLIENT90.JAR
PowerBuilder proxy objects represent all other Java classes and interfaces required for a given EJB
JDK required for development, JRE for runtime – PowerBuilder installs Sun JDK 1.4 by default to ease configuration issues
Architecture Overview
PowerBuilder EJB Client Implementation
JavaVM object Loads and initializes Java VM inside of the PowerBuilder process Supported by configurable PowerBuilder ‘JVM Service’ which handles all JDK/JRE
needs in PowerBuilder environment JDBC Connectivity EJB Client Functionality JSP Deployment XSL-FO
Be aware… Once Java VM is loaded, for whatever reason, by PowerBuilder, you cannot
modify its environment, classpath, etc.; use return value of CreateJavaVM to determine if Java VM was actually loaded or already resident
Debug option for CreateJavaVM method is not available for JDK 1.4 Methods exist for determining the actual class for a returned interface,
downcasting classes, determining interfaces implemented by classes, etc.
Architecture Overview
PowerBuilder EJB Client Implementation
PowerBuilder JVM Service configuration JDK and JRE Location can be specified in System Options dialog
JVM properties and CLASSPATH entries are in the registry Design-time: \\HKLM\Sybase\PowerBuilder\9.0\Java\PBIDEConfig
• PBJVMConfig• PBJVMProps• PBSysClasspath
Run-time: \\HKLM\Sybase\PowerBuilder\9.0\Java\PBRTConfig• PBJVMConfig• PBJVMProps
Architecture Overview
PowerBuilder EJB Client ImplementationArchitecture Overview
EJBConnection object Analog of the PowerBuilder Connection object Serves as a PowerBuilder façade to the InitialContext class within the
PBEJBCLIENT90.JAR file
ConnectToServer - sets initialContext
DisconnectServer - closes initialContext Lookup - returns EJBHome reference given JNDI name
GetEJBTransaction - returns reference enabling client-managed transactions
CreateJavaInstance – create a Java class within client Java VM
Be aware…
Properties array argument to ConnectToServer is the only ‘vendor-specific’ requirement; PowerBuilder doesn’t ‘know’ what EJB server you are using
CreateJavaInstance is used to create a Java class on the client – you don’t need an EJB server at all to do this!
PowerBuilder EJB Client ImplementationArchitecture Overview
EJBTransaction object Populated by GetEJBTransaction method of the EJBConnection object Wraps javax.transaction.UserTransaction and so provides methods for
initiating, coordinating, and completing a transaction from a client application Begin GetStatus Commit SetRollbackOnly Rollback SetTransactionTimeout
Be aware… Not all EJB servers support client-managed transactions Best practices have a session bean on the server controlling the transaction
PowerBuilder EJB Client ImplementationArchitecture Overview
EJBLocator Java class Single Java class residing in PBEJBCLIENT90.JAR:
com.sybase.powerbuilder.ejb.EJBLocator Four methods, all wrapped by the EJBConnection PBNI object Required for deployed applications
JAR is included in CLASSPATH managed by JVM Service with the assumption that it is located relative to the PBJVM90.DLL
PowerBuilder EJB Client ImplementationArchitecture Overview
PowerBuilder proxy objects Used to delegate requests to and from the underlying Java classes Inherited from Nonvisualobject or Exception class like other PowerBuilder proxies Generated using javap command in JDK
EJB Client Proxy wizard / project in PowerBuilder development environment EJB2PB90 stand-alone utility
Includes Public methods defined on its associated Java class Public class variables in PowerBuilder 9.0.1 and later
To avoid conflicts with PowerBuilder reserved words, names may be decorated Proxy name prefix “java_”, for example, java_integer Method name postfix ”_j”, for example, and_j
Java methods that return arrays will return any in PowerBuilder Proxies are also supported by a PowerBuilder mapping structure that correlates the
PowerBuilder proxy name to the underlying Java class name
PowerBuilder EJB Client ImplementationArchitecture Overview
Sample source for a PowerBuilder proxy object
$PBExportHeader$ejbobject.srx
$PBExportComments$Proxy imported from EJB via EJB Proxy generator.
global type EJBObject from Remote
end type
type variables
protected:
string EJBObject_javaname= "javax.ejb.EJBObject"
end variables
forward prototypes
public:
function EJBHome getEJBHome() throws RemoteException alias for
"getEJBHome,()Ljavax/ejb/EJBHome;"
function any getPrimaryKey() throws RemoteException alias for
"getPrimaryKey,()Ljava/lang/Object;"
subroutine remove() throws RemoteException, RemoveException alias for "remove,()V"
function Handle getHandle() throws RemoteException alias for "getHandle,()Ljavax/ejb/Handle;”
function boolean isIdentical( EJBObject EJBObject_1) throws RemoteException alias for
"isIdentical,(Ljavax/ejb/EJBObject;)Z"
end prototypes
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
Coding a PowerBuilder EJB Client Application
Setting up your environment Adding the EJB client implementation to your target Generating proxies
Basic client coding steps Advanced topics
Coding a PowerBuilder EJB Client Application
Adding the EJB Client implementation to your target Include PBEJBCLIENT90.PBD in your target’s library list
Setting Up Your Environment
Coding a PowerBuilder EJB Client Application
Generating proxies Use EJB Client Proxy Wizard
Setting Up Your Environment
EJB home interface name must be same as remote interface name followed by ‘Home’
Coding a PowerBuilder EJB Client Application
Generating proxies Use EJB2PB90.EXE, a completely stand-alone utility, and import resulting files
into PowerBuilder target
Syntax: ejb2pb90 [-classpath pathlist] EJBName [prefix]
Output includes Various .srx files – the proxy objects ejbproxies.txt – listing the .srx files produced ejbproxies.err – containing the diagnostic message in the event an error
occurs while the proxies are generated $EJBName$_ejb_pb_mapping.srs – the mapping structure
Setting Up Your Environment
Coding a PowerBuilder EJB Client Application
Basic client coding steps Initialize the Java VM Connect to the EJB Server Lookup an EJB Invoke methods on the EJB Disconnect from the EJB Server
Coding a PowerBuilder EJB Client Application
Initialize the Java VM
TRY
g_JavaVM = CREATE JavaVM
CHOOSE CASE g_JavaVM.CreateJavaVM(is_ClassPath, false)
CASE 0
// JVM just loaded
CASE 1
// JVM was already loaded, is_ClassPath ignored
CASE -1
// failure, likely due to not finding JVM.DLL
CASE -2
// failure, do to not finding EJBLocator class
END CHOOSE
CATCH (PBXRuntimeError prte)
// catch any exception raised in PBNI extension
END TRY
Basic Client Coding Steps
Coding a PowerBuilder EJB Client Application
Connect to the EJB Server
TRY
g_EJBConn = CREATE EJBConnection
// set initial context properties
ls_props[1] = "javax.naming.Context.INITIAL_CONTEXT_FACTORY=" + &
"com.sybase.ejb.InitialContextFactory"
ls_props[2] = "javax.naming.Context.PROVIDER_URL=iiop://localhost:9000"
ls_props[3] = "javax.naming.Context.SECURITY_PRINCIPAL=jagadmin"
ls_props[4] = "javax.naming.Context.SECURITY_CREDENTIALS="
// connect to EJB server
g_EJBConn.connectToServer(ls_props)
CATCH (NamingException ne)
// naming exception may occur when initial context class not found
CATCH (PBXRuntimeError prte)
// catch any exception raised in PBNI extension
END TRY
Basic Client Coding Steps
Coding a PowerBuilder EJB Client Application
Lookup an EJB
TRY
g_HelloHome = g_EJBConn.lookup("HelloHome", "PB9/Hello", "pb9.HelloHome")
g_hello = g_helloHome.create()
CATCH (NamingException ne)
// raised if EJB not located
CATCH (CreateException ce)
// raised if problem in instantiating EJB
CATCH (RemoteException re)
// raised whenever there is a unchecked exception on server
CATCH (PBXRuntimeError prte)
// raised whenever there is an exception in the PBNI extension
END TRY
Basic Client Coding Steps
Coding a PowerBuilder EJB Client Application
Invoke methods on the EJB
TRY
MessageBox("Hello", g_hello.sayHello()
CATCH (YourCustomException yce)
// handle user-defined exception raised by EJB, for example, an exception
// indicating that an account lacks sufficient funds for withdrawal
CATCH (RemoteException re)
// raised whenever there is a unchecked exception on server
CATCH (PBXRuntimeError prte)
// raised whenever there is an exception in the PBNI extension
END TRY
Basic Client Coding Steps
Coding a PowerBuilder EJB Client Application
Disconnect from the EJB server
TRY
g_EJBConn.disconnectServer()
CATCH (NamingException ne)
// naming exception is unlikely here, but could be thrown by underlying
// Java InitialContext object
CATCH (PBXRuntimeError prte)
// raised whenever there is an exception in the PBNI extension
END TRY
Basic Client Coding Steps
As in many distributed processing scenarios, disconnecting a client does NOTautomatically free server resources, such as stateful EJBs that the client was using.
Coding a PowerBuilder EJB Client Application
Advanced topics java.lang.Object references Using interfaces and casting Client-managed transactions Creating proxies for stand-alone Java classes
Coding a PowerBuilder EJB Client Application
java.lang.Object references• Many EJB methods will return java.lang.Object references or expect them as
parameters• PowerBuilder will treat a java.lang.Object reference as a PowerBuilder any
variable within the method prototype• The mapping structure created when generating proxies is consulted at run-time to
map the underlying Java class to an appropriate proxy
Advanced Topics
global type Hello_ejb_pb_mapping from structure
string item1 = "java.rmi.Remote:Remote"
string item2 = "java.io.Serializable:Serializable"
string item3 = "java.io.IOException:IOException"
string item4 = "java.io.OutputStream:OutputStream"
string item5 = "java.io.FilterOutputStream:FilterOutputStream"
string item6 = "java.io.UnsupportedEncodingException:UnsupportedEncodingException"
string item7 = "java.io.PrintStream:PrintStream"
…
Coding a PowerBuilder EJB Client Application
Using interfaces and casting• Additional JavaVM object methods extend your capabilities
GetActualClass – determines the actual Java class name when provided a PowerBuilder proxy object that represents a Java interface
GetSuperClass – determines the Java class that is the ancestor of the Java class or interface represented by the PowerBuilder proxy object
GetInterfaces – returns list of Java interfaces implemented by the Java class represented by the given PowerBuilder proxy object
DynamicCast – casts a PowerBuilder proxy object to another object – typically used to downcast a Java reference, use cautiously since invalid casts can cause instability
Advanced Topics
Coding a PowerBuilder EJB Client Application
Using interfaces and casting – an example
Collection px_Collection
Vector px_Vector
Stack px_Stack
TRY
px_ListMgr = px_ListMgrHome.create()
px_Collection = px_ListMgr.getList(as_listType)
CHOOSE CASE g_JavaVM.GetActualClass(px_Collection)
CASE "java.util.Stack"
px_Stack = g_JavaVM.DynamicCast(px_Collection, "Stack")
DO WHILE TRUE
this.processItem(px_Stack.pop())
LOOP
CASE "java.util.Vector“
px_Vector = g_JavaVM.DynamicCast(px_Collection, “Vector”)
FOR i TO px_Vector.size()
this.processItem(px_Vector.elementAt(i))
NEXT
...
Advanced Topics
Coding a PowerBuilder EJB Client Application
Client-managed transactions• The EJBTransaction object in the PBNI implementation has a direct
correspondence to javax.transaction.UserTransaction Begin - starts a transaction Commit - commits the current transaction SetRollbackOnly - marks the current transaction as doomed SetTransactionTimeout - sets the amount of time a transaction can be in
progress before it is rolled back. GetStatus - returns the status of the current transaction
Not all EJB servers support this and even if they do, best practices discourage its use
Advanced Topics
Coding a PowerBuilder EJB Client Application
Client-managed transactions – an example
EJBConnection connEJBTransaction trans
conn = create EJBConnectionTRY
conn.connectToServer(is_props)trans = conn.getEJBTransaction() trans.Begin()
// Create a component and call methods to be// executed within the transaction
trans.Commit()
CATCH (Exception e)
trans.Rollback()
END TRY
Advanced Topics
Coding a PowerBuilder EJB Client Application
Creating proxies for stand-alone Java classes• You can use the EJB client implementation to call Java classes on the client as
well!• Create ‘dummy’ home and remote interface Java classes and reference the
desired Java class as a method argument or return value• Generate proxies for this ‘pseudo’ EJB and the proxies for the referenced classes
will be automatically generated• Now use the CreateJavaInstance method of the EJBConnection object to
create instances of your Java class on the client (you can do this without issuing a ConnectToServer)
Advanced Topics
public interface DummyHome {}
Dummy Home interface Java code Dummy Home interface Java code
public interface Dummy{ public abstract void foo(com.your.JavaClass x);}
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
Deploying PowerBuilder NVOs to EJB Servers
Sunlly Group’s PBridge (http://www.sunlly.com) Since PowerBuilder 7, you can use PowerBuilder NVOs natively in EAServer and
have them interoperate with EJB components and Java clients Sunlly PBridge’s offering will allow you to deploy your PowerBuilder components
into other application servers such as WebLogic and WebSphere Built on PBNI architecture offered by PowerBuilder 9 Currently in beta and supporting
BEA WebLogic IBM WebSphere Sun J2EE reference implementation
Visit them at TechWave!
Deploying PowerBuilder NVOs to EJB ServersSunlly PBridge – Client Deployment Interface
Accessing Third-Party EJB Servers
Agenda Overview of the Enterprise JavaBeans (EJB) Model PowerBuilder EJB client implementation Coding a PowerBuilder EJB client application Deploying PowerBuilder NVOs to EJB servers Additional resources
Accessing Third-Party EJB Servers
InitialContext classes and default URLs for major EJB servers
Additional Resources
Server INITIAL_CONTEXT_FACTORY Class PROVIDER_URL (default)
Sybase EAServer com.sybase.ejb.InitialContextFactory iiop://server:9000
BEA WebLogic Server
weblogic.jndi.WLInitialContextFactory t3://server:7001
IBM WebSphere Application Server
com.ibm.websphere.naming.WsnInitialContextFactory
iiop://server:900 (v. 4)
Iiop://server:2809 (v. 5)
Sun ONE com.sun.jndi.cosnaming.CNCtxFactory iiop://server:9010
Oracle9iAS com.evermind.server.ApplicationClientInitialContextFactory
ormi://server:23791/application
Jboss org.jnp.interfaces.NamingContextFactory jnp://server:1099
Accessing Third-Party EJB Servers
Learning more about the EJB client feature PowerBuilder Extension Reference in product documentation set EJB specification (http://java.sun.com/products/ejb/docs.html)
3rd party J2EE server web sites BEA Systems WebLogic Server (http://www.bea.com/framework.jsp?
CNT=index.htm&FP=/content/products/platform/) Jboss (http://www.jboss.org) IBM WebSphere Application Server (http://www.ibm.com/websphere) Oracle9iAS (http://http://www.oracle.com/ip/deploy/ias/)
SAMS Publishing PowerBuilder: Internet and Distributed Application Development (http://www.pb9book.com)
Sybase Developer Network (http://sdn.sybase.com) Technical document: “Accessing 3rd Party EJB Servers from PowerBuilder 9”
(http://www.sybase.com/detail?id=1024977) CodeXchange…
Additional Resources
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PBNI OLEObject utilities) Contribute your own code or start your own collaborative project with input
from other PowerBuilder experts
Any SDN member can participate Log in using your MySybase account via SDN
Join the collaboration already underway http://powerbuilder.codexchange.sybase.com or via SDN at
www.sybase.com/developer
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Accessing Third-Party EJB Servers
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