Sun Cluster 3.1 Data Services Developer's Guide

Using the Configure Screen

The Configure screen, shown in the following figure, appears after Agent Builder finishes creating the resource type and you select the Next button on the Create screen. You cannot access the Configure screen before the resource type has been created.

Dialog box that shows the Configure screen

The Configure screen contains the following fields:

Using the Agent Builder $hostnames Variable

For many applications, specifically network-aware applications, the hostname on which the application listens and services customer requests must be passed to the application on the command line. Therefore, in many cases, hostname is a parameter you must specify for start, stop, and probe commands for the target resource type (on the Configure screen). However, the hostname on which an application listens is cluster specific—it is determined when the resource is run on a cluster and cannot be determined when Agent Builder generates your resource type code.

To solve this problem, Agent Builder provides the $hostnames variable that you can specify on the command line for the start, stop, and probe commands. You specify the $hostnames variable exactly as you would an actual hostname, for example,

/opt/network_aware/echo_server -p port_no -l $hostnames

When a resource of the target resource type is run on a cluster, the LogicalHostname or SharedAddress hostname configured for that resource (in the Network_resources_used resource property of the resource) is substituted for the value of the $hostnames variable.

If you configure the Network_resources_used property with multiple hostnames, the $hostnames variable contains all of them separated by commas.

Creating Resource Types With Multiple Independent Process Trees

Agent Builder can create resource types for applications having more than one independent process tree. These process trees are independent in the sense that PMF monitors and starts them individually. PMF starts each process tree with its own tag.

In the case of a base application with multiple independent process trees, you cannot specify a single command line to start the application. Rather, you must create a text file, with each line specifying the full path to a command to start one of the application's process trees. This file must not contain any blank lines. You specify this text file in the Start Command text field in the Configure screen.

You must also make certain this text file does not have execute permissions. This enables Agent Builder to distinguish this file, whose purpose is to start multiple process trees, from a simple executable script containing multiple commands. If this text file is given execute permissions, the resources would come up fine on a cluster, but all the commands would be started under one PMF tag, precluding the possibility of monitoring and restarting the process trees individually by PMF.