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| e-docs > Tuxedo > Administering a Tuxedo Application at Run Time > CORBA Bootstrapping Programming Reference |
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Administering a Tuxedo Application at Run Time
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CORBA Bootstrapping Programming Reference
This topic includes the following sections:
Why Bootstrapping Is Needed
To communicate with BEA Tuxedo objects, a client application must obtain object references. Without an object reference, there can be no communication. To solve this problem, client applications use a bootstrapping mechanism to obtain object references to objects in a BEA Tuxedo domain.
Supported Bootstrapping Mechanisms
In the Tuxedo 8.0 release and later, two bootstrapping mechanisms are supported:
Use this mechanism if you using the BEA client ORB.
Use this mechanism if you using a client ORB from another vendor.
Note: The CORBA C++ and Java clients provided with BEA Tuxedo software may use the Interoperable Naming Service bootstrapping mechanism, however, for performance reasons, this is not recommended.
BEA Bootstrapping Mechanism
The BEA bootstrapping mechanism uses the Bootstrap object. Bootstrap objects are local programming objects, not remote CORBA objects, in both the client and the server. When Bootstrap objects are created, their constructor requires the network address of a BEA Tuxedo IIOP Listener/Handler. Given this information, the bootstrapping object can generate object references for the key remote objects in the BEA Tuxedo domain. These object references can then be used to access services available in the BEA Tuxedo domain.
How Bootstrap Objects Work
Bootstrap objects are created by a client or a server application that must access object references to the following BEA Tuxedo CORBA interfaces:
Bootstrap objects may represent the first connection to a specific BEA Tuxedo domain depending on the format of the IIOP Listener/Handler address. If the NULL scheme Universal Resource Locator (URL) format is used (the only address format supported in releases of BEA WebLogic Enterprise prior to version 5.1 and BEA Tuxedo release 8.0), the Bootstrap objects represent the first connection. However, if the URL format is used, the connection will not occur until after creation of the Bootstrap object. For more information on address formats and connection times, refer to Tobj_Bootstrap.
For a BEA Tuxedo CORBA remote client, Bootstrap objects are created with the host and the port for the BEA Tuxedo IIOP Listener/Handler. However, for BEA Tuxedo native client and server applications, there is no need to specify a host and port because they execute in a specific BEA Tuxedo domain. The IIOP Listener/Handler host and the port ID are included in the BEA Tuxedo domain configuration information.
After they are created, Bootstrap objects satisfy requests for object references for objects in a particular BEA Tuxedo domain. Different Bootstrap objects allow the application to use multiple domains.
Using the Bootstrap object, you can obtain references to the following objects:
The SecurityCurrent object is used to establish a security context within a BEA Tuxedo domain. The client can then obtain the PrincipalAuthenticator from the principal_authenticator attribute of the SecurityCurrent object.
The TransactionCurrent object is used to participate in a BEA Tuxedo transaction. The basic operations are as follows:
Begin a transaction. Future operations take place within the scope of this transaction.
End the transaction. All operations on this client application have completed successfully.
Abort the transaction. Tell all other participants to roll back.
Suspend participation in the current transaction. This operation returns an object that identifies the transaction and allows the client application to resume the transaction later.
Resume participation in the specified transaction.
The FactoryFinder object is used to obtain a factory. In the BEA Tuxedo system, factories are used to create application objects. The FactoryFinder provides the following different methods to find factories:
The Interface Repository contains the interface descriptions of the CORBA objects that are implemented within the BEA Tuxedo domain. Clients using the Dynamic Invocation Interface (DII) need a reference to the Interface Repository to be able to build CORBA request structures. The ActiveX Client is a special case of this. Internally, the implementation of the COM/IIOP Bridge uses DII, so it must get the reference to the Interface Repository, although this is transparent to the desktop client.
A NamingService object is used to obtain a reference to the root namespace. When you use this object, the ORB locates the root of the namespace.
The NotificationService object is used to obtain a reference to the event channel factory (CosNotifyChannelAdmin::EventChannelFactory) in the CosNotification Service. In the BEA Tuxedo system, the EventChannelFactory is used to locate the Notification Service channel.
The Tobj_SimpleEventsService object is used to obtain a reference to the event channel factory (Tobj_SimpleEvents::ChannelFactory) in the BEA Simple Events Service. In the BEA Tuxedo system, the ChannelFactory is used to locate the BEA Simple Events Service channel.
The FactoryFinder and Interface Repository objects are not implemented in the environmental objects library. However, they are specific to a BEA Tuxedo domain and are thus conceptually similar to the SecurityCurrent and TransactionCurrent objects in use.
The Bootstrap object implies an association or "session" between the client application and the BEA Tuxedo domain. Within the context of this association, the Bootstrap object imposes a containment relationship with the other Current objects (or contained objects); that is, the SecurityCurrent and TransactionCurrent. Current objects are valid only for this domain and only while the Bootstrap object exists.
Note: Resolving the SecurityCurrent when using the new URL address format (corbaloc://hostname:port_number) is a local operation; that is, no connection is made by the client to the IIOP Listener/Handler.
In addition, a client can have only one instance of each of the Current objects at any time. If a Current object already exists, an attempt to create another Current object does not fail. Instead, another reference to the already existing object is handed out; that is, a client application may have more than one reference to the single instance of the Current object.
To create a new instance of a Current object, the application must first invoke the destroy_current() method on the Bootstrap object. This invalidates all of the Current objects, but does not destroy the session with the BEA Tuxedo domain. After invoking destroy_current(), new instances of the Current objects can be created within the BEA Tuxedo domain using the existing Bootstrap object.
To obtain Current objects for another domain, a different Bootstrap object must be constructed. Although it is possible to have multiple Bootstrap objects at one time, only one Bootstrap object may be "active;" that is, have Current objects associated with it. Thus, an application must first invoke destroy_current() on the "active" Bootstrap object before obtaining new Current objects on another Bootstrap object, which then becomes the active Bootstrap object.
Note: If you want to access objects in multiple domains, either import the object to the local domain or administratively configure your application access multiple domains. For more information on multi-domain configurations configurations, see "Configuring Multiple CORBA Domains" in Using the BEA Tuxedo Domains Component
.Servers and native clients are inside of the BEA Tuxedo domain; therefore, no "session" is established. However, the same containment relationships are enforced. Servers and native clients access the domain they are currently in by specifying an empty string, rather than //host:port.
Note: When using the Bootstrap object, client and server applications must use the Tobj_Bootstrap::resolve_initial_references()method, not the ORB::resolve_initial_references() method.
Types of BEA Remote Clients Supported
Table 4-1 shows the types of remote clients that can use the Bootstrap object to access the other environmental objects, such as FactoryFinder, SecurityCurrent, TransactionCurrent, and InterfaceRepository. These clients are provided with the BEA Tuxedo CORBA software. Third-party client ORBs should use the CORBA Interoperable Naming Service.
Capabilities and Limitations Bootstrap objects have the following capabilities and limitations:
Bootstrap Object API
The Bootstrap object application programming interface (API) is described first in terms of the OMG Interface Definition Language (IDL) (for portability), and then in C++, Java, and ActiveX. The C++ and Java descriptions add the necessary constructor to build a Bootstrap object for a particular BEA Tuxedo domain.
Tobj Module
Table 4-2 shows the object reference that is returned for each type ID.
Table 4-3 describes the Tobj module exceptions.
C++ Mapping Listing 4-1 shows the C++ declarations in the Tobj_bootstrap.h file. Listing 4-1 Tobj_boostrap.h Declarations class Tobj_Bootstrap { Java Mapping Listing 4-2 shows the Tobj_Bootstrap.java mapping. Listing 4-2 Tobj_Bootstrap.java Mapping public void register_callback_port(orb.omg.CORBA.Object objref) Microsoft Desktop Client Mapping The Bootstrap object is provided in the BEA ActiveX Client software for use by clients that are implemented on Microsoft desktops. There are two possible interfaces that desktop clients may use:
#include <CORBA.h>
public:
Tobj_Bootstrap(CORBA::ORB_ptr orb, const char* address);
CORBA::Object_ptr resolve_initial_references(
const char* id);
void register_callback_port(CORBA::Object_ptr objref);
void destroy_current( );
};package com.beasys;
public class Tobj_Bootstrap {
public Tobj_Bootstrap(org.omg.CORBA.ORB orb,
String address)
throws org.omg.CORBA.SystemException;
public class Tobj_Bootstrap {
public Tobj_Bootstrap(org.omg.CORBA.ORB orb, String address,
java.applet.Applet applet)
throws org.omg.CORBA.SystemException;
throws org.omg.CORBA.SystemException;public org.omg.CORBA.Object
resolve_initial_references(String id)
throws Tobj.InvalidName,
org.omg.CORBA.SystemException;
public void destroy_current()
throws org.omg.CORBA.SystemException;
}
Automation Mapping
Listing 4-3 shows Automation Bootstrap interface mapping.
Listing 4-3 Automation (Dual) Bootstrap Interface Mapping
interface DITobj_Bootstrap : IDispatch
{
HRESULT Initialize(
[in] BSTR address);
HRESULT CreateObject(
[in] BSTR progid,
[out, retval] IDispatch** rtrn);
HRESULT destroy_current();
};
C++ Member Functions
This section describes the C++ member functions supported by the BEA bootstrapping mechanism.
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