System-Wide Load Balancing and Failure Processing
To locate Info*Engine components, the Naming Service starts its search at the LDAP search base specified in its LDAP entry. It locates all component entries under the search base that have the specified name. When there is more than one component with the same name in the search base, Info*Engine randomly chooses the one that receives a request.
If you install an Info*Engine component in only one location and that component fails, an error message is generated and returned to the user or calling application. If you install and configure multiple instances of a component and one of the components fails, the Naming Service sends the request to another instance of the same component.
After you have installed an Info*Engine task processor, adapter, or gateway multiple times, you can set up load balancing and failure processing by configuring the components so that they have a common service name. This configuration is done using the Info*Engine Property Administration utility. After you have established a common service name, task and JSP authors must specify this name in the INSTANCE parameter of the adapter webjects or in the task tag attribute that identifies the task processor to use.
You can configure components so that they have a common service name using the following processes:
• Create one LDAP entry for all redundant components. In this entry, all information for the components is the same except that you specify multiple host and port attributes, where each host and port pair match the host and port required for one of the components. If you want to run multiple instances on a single host you can specify a port range in place of a single port number, separating the lower port number from the higher port number with a dash (for example, 1001-1005).
• Create an LDAP entry for each component using a unique service name for each component. Edit each LDAP entry and add a common service name as an additional service name. Tell task and JSP authors to use this common service name when accessing the component.
• Create an LDAP entry for each component on a unique branch in your directory and use the same service name, but a unique runtime service name, for each component.
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If you configure multiple adapter components with the same name and one of the adapters runs in-process, the Naming Service always selects the in-process adapter. Load balancing does not occur in this case. However, if accessing the classes of the in-process adapter produces an error, a connection to an out-of-process adapter is attempted.
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The following sections provide examples of setting up these methods of load balancing and failure processing.
