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This chapter explains how to configure connections from remote client applications to CORBA objects via the standard Internet Inter-ORB Protocol (IIOP). This chapter is specific to WLE servers.
This chapter discusses the following topics:
Note: In WLE V4.0, servers could only make invocations on other servers inside the WLE domain. In WLE V4.2, the servers can make invocations on any server, inside or outside a WLE domain.
Note: In WLE V4.0, a native client could not make invocations on objects outside the WLE domain.
Note: In WLE V4.0 and V4.1, a client could not act as a server.
Note: The server role of the native joint client/server is considerably less robust than that of an server. It has none of the WLE administrative and infrastructure components, such as tmadmin, FactoryFinder, and ISL/ISH (hence none of WLE's scalability and reliability attributes), it does not use the WLE TP Framework, and it requires more direct interaction between the client and the ORB.
Note: In WLE V4.0, a remote client could not act as a server.
Note: A joint client/server is different from a server that acts as a client as part of its server role. Once the server completes processing of an invocation, it returns to dormancy. A joint client/server is always in the active mode, executing code not related to a server role; the server role temporarily interrupts the active client role, but the client role is always resumed.
Note: The server role of the remote joint client/server is considerably less robust than that of a server. Neither the client nor the server has any of the WLE administrative and infrastructure components, such as tmadmin, FactoryFinder, and ISL/ISH (hence, none of WLE's scalability and reliability attributes).
Note: In WLE V4.0 and V4.1, callback objects existed but were not named as such; they could have implementations only in the WLE domain; that is, they could be located only in a server (as a CORBA object).
In this chapter, the term remote client means WLE client applications that you deployed on systems that do not have the full WLE server software installed. This means that no administration or application servers are running there and that no Bulletin Board is present. All communication between the client and the application takes place over the network. The types of clients are:
Note: A client process communicates with the native domain through the ISH.
Figure 12-1 shows an example of an application with remote clients connected. Any request by a remote client to access the CORBA server application is sent over the network to the ISH. This process sends the request to the appropriate server and sends the reply back to the remote client.
The client connects to the ISL process in the IIOP Listener/Handler using a known network address. This is initiated when the client calls the Bootstrap object constructor. The ISL process uses a function that is specific to the operating system to pass the connection directly to the selected ISH process. To the client application, there is only one connection. The client application does not know, or need to know, that it is now connected to the ISH process.
For CORBA C++ clients, environment variables can be used to pass information to the system, as follows:
Illustration of an Application with Remote Clients
Figure 12-1 Bank Application with Remote Clients
How the Remote Client Connects to an Application
Setting Environment Variables
Note:
The network address that is specified by programmers in the Bootstrap constructor or in TOBJADDR
must exactly match the network address in the server application's UBBCONFIG
file. The format of the address as well as the capitalization must match. If the addresses do not match, the call to the Bootstrap constructor will fail with a seemingly unrelated error message:
ERROR: Unofficial connection from client at
<tcp/ip address>/<port-number>:
For example, if the network address is specified as //TRIXIE:3500 in the ISL
command line option string (in the server application's UBBCONFIG
file), specifying either //192.12.4.6:3500 or //trixie:3500 in the Bootstrap constructor or in TOBJADDR will cause the connection attempt to fail.
On UNIX systems, use the uname -n command on the host system to determine the capitalization used. On Windows NT systems, see the host system's Network control panel to determine the capitalization used. Or use the environment variable COMPUTERNAME
. For example:
echo %COMPUTERNAME%
To join remote clients to an application, you must specify the MAXWSCLIENTS
parameter in the MACHINES
section of the UBBCONFIG
file.
MAXWSCLIENTS
tells the WLE system at boot time how many accesser slots to reserve exclusively for remote clients. For native clients, each accesser slot requires one semaphore. However, the ISH process (executing on the native platform on behalf of remote clients) multiplexes remote client accessers through a single accesser slot and, therefore, requires only one semaphore. This points out an additional benefit of the remote extension. By putting more clients out on remote systems and taking them off the native platform, an application reduces its IPC resource requirements.
MAXWSCLIENTS
takes its specified number of accesser slots from the total set in MAXACCESSERS
. This is important to remember when specifying MAXWSCLIENTS
; enough slots must remain to accommodate native clients as well as servers. Do not specify a value for MAXWSCLIENTS
greater than MAXACCESSERS
. The following table describes the MAXWSCLIENTS
parameter.
Setting the Maximum Number of Remote Clients
Remote clients access your application through the services of an ISL process and one or more ISH processes. The ISL is specified in one entry as a server supplied by the WLE system. The ISL can support multiple remote clients and acts as the single point of contact for all the remote clients connected to your application at the network address specified on the ISL command line. The listener schedules work for one or more remote handler processes. An ISH process acts as a surrogate within the administrative domain of your application for remote clients on remote systems. The ISH uses a multiplexing scheme to support multiple remote clients concurrently.
To join remote clients to an application, you must list the ISL processes in the SERVERS
section of the UBBCONFIG
file. The processes follow the same syntax for listing any server.
You use the following ISL
command-line options (CLOPT
) to pass information to the ISL process for remote clients. The format of the CLOPT
parameter is as follows:
ISL SRVGRP="identifier" For a detailed description of the CLOPT command line options, see the ISL command in the Reference. Listing 12-1 shows a sample UBBCONFIG
file to support remote clients, as follows:
Configuring a Listener for a Remote Client
Format of the CLOPT Parameter
SRVID="number"
CLOPT="[ -A ] [ servopts options ] -- -n netaddr
[ -C {detect|warn|none} ]
[ -d device ]
[ -K {client|handler|both|none} ]
[ -m minh ]
[ -M maxh ]
[ -T client-timeout]
[ -x mpx-factor ]
[ -H external-netaddr"Modifying the UBBCONFIG File to Support Remote Clients
Listing 12-1 Sample UBBCONFIG File Configuration
*MACHINES
SITE1
...
MAXWSCLIENTS=150
...
SITE2
...
MAXWSCLIENTS=0
...
*SERVERS
...
ISL SRVGRP="BANKB1" SRVID=500 RESTART=Y
CLOPT="-A -- -n //TRIXIE:2500 -d /dev/tcp
-m 5 -M 30 -x 5"
...
Support for outbound IIOP provides native clients and servers acting as native clients the ability to invoke on a remote object reference outside of the WLE domain. This means that calls can be invoked on remote clients that have registered for callbacks, and objects in remote servers can be accessed.
Administrators are the only users who interact directly with the outbound IIOP support components. Administrators are responsible for booting the ISLs with the correct startup parameters to enable outbound IIOP to objects not located in a connected client. Administrators may need to adjust the number of ISLs they boot and the various startup parameters to obtain the best configuration for their installation's specific workload characteristics. They have the option of booting the ISLs with the default parameters.
Note:
In this release, outbound IIOP is not supported for transactions or security.
Outbound IIOP support is required to support client callbacks. In the version4.0 and version 4.1 releases of the WLE software, the ISL/ISH was an inbound half-gateway. Outbound IIOP support adds the outbound half-gateway to the ISL/ISH. (See Figure 12-2).
There are three types of outbound IIOP connections available, depending on the version of GIOP supported by the native server and the remote joint client/server application:
Configuring Outbound IIOP for Remote Joint Client/Servers
Functional Description
Note: GIOP 1.2 is supported only by WLE V4.2 C++ clients, servers, and joint client/servers; GIOP 1.2 is not supported by WLE V4.0 or V4.1 clients and servers. Java clients, servers, and joint client/servers only support GIOP 1.0. WLE V4.0 and V4.1 C++ clients and servers support GIOP 1.0 and 1.1.
Bi-directional and dual-paired connection outbound IIOP provides outbound IIOP to object references located in joint client/servers connected to an ISH. Asymmetric outbound IIOP provides outbound IIOP to object references not located in a joint client/server connected to an ISH, and also allows WLE clients to invoke on any object reference, not only object references located in clients currently connected to an ISH.
Each type of outbound IIOP is described in more detail in the following sections.
With bidirectional outbound IIOP, the following operations are executed (see Figure 12-3):
Figure 12-2 Joint Client/Server IIOP Connections Supported
Bidirectional Outbound IIOP
With asymmetric outbound IIOP, the following operations are executed (see Figure 12-4):
With dual-paired connection outbound IIOP, the following operations are executed (see Figure 12-5):
The steps to finding an ISL are as follows:
Note: Normal BEA TUXEDO routing is used to find an ISL.
Note: Some invokes may be made to ISLs on nonlocal machines.
Outbound IIOP support is used when a native C++ or Java client, or a server acting as a native client, invokes on an object reference that is a remote object reference. The routing code recognizes that the object reference is from a non-WLE ORB or from a remote WLE joint client/server.
There are two kinds of remote object references:
Both are detected by the routing code and sent to the outbound IIOP support for handling.
The user interface to outbound IIOP support is the commandline interface for booting the ISL process(es). New command-line options to configure the outbound IIOP processing were added to the ISL command in this release of the WLE software. These options enable support for asymmetric IIOP to object references not located in clients connected to an ISH.
The ISL command syntax listed below shows the new options for outbound IIOP support:
ISL SRVGRP="identifier"
SRVID="number"
CLOPT="[ -A ] [ servopts options ] -- -n netaddr For a detailed description of the CLOPT
command-line options, see the ISL command in the Reference.
User Interface
[ -C {detect|warn|none} ]
[ -d device ]
[ -K {client|handler|both|none} ]
[ -m minh ]
[ -M maxh ]
[ -T Client-timeout]
[ -x mpx-factor ]
[-H external-netaddr]
#NEW options for outbound IIOP
[-O]
[-o outbound-max-connections]
[-s Server-timeout]
[-u out-mpx-users] "
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Copyright © 1999 BEA Systems, Inc. All rights reserved.
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