When you start up an application, Nucleus reads the configuration path, which is a list of directories to use to find configuration files. Within one of those directories is a file called Nucleus.properties that contains the name of the first component to create. In the standard Oracle Commerce Platform configuration, the start of the Nucleus.properties file looks like this:
$class=atg.nucleus.Nucleus
initialServiceName=/InitialThe initialServiceName property instructs Nucleus to configure and start up its initial service using Initial.properties, which in the standard configuration looks like this:
$class=atg.nucleus.InitialService initialServices=\ /atg/Initial,\ VMSystem,\ /atg/dynamo/StartServers
If you want to add another service to the list of initial services, you can edit the /Initial component in the Components window:
Select the
Initialcomponent and click Open Component.
A Component Editor opens, displaying the properties of theInitialcomponent.Select the first property,
initialServices. This property displays for its values the services listed in theInitial.propertiesfile.Click ... to view the complete list of the values for the
initialServicesproperty.From that list of values, select the last value,
/atg/dynamo/StartServers, and click Insert After. A new blank value field appears, with an @ button.Click the @ button. A dialog appears, displaying the available components.
Select the
test/services/Personcomponent and click OK. The new component appears in the list of values for theinitialServicesproperty.
The next time you start your application, the test/services/Person component is run as an initial service.
Most components do not need to be started from the Initial service when an application starts up; they can be instantiated by Nucleus when they are needed, typically in response to a page request from a user. A component started through the initialServices property must be globally scoped.
To show that Nucleus really is doing something, change the Person class to print some output:
public class Person {
String name;
int age;
public Person () {
System.out.println ("constructing Person");
}
public String getName () { return name; }
public void setName (String name) {
System.out.println ("setting name to " + name);
this.name = name;
}
public int getAge () { return age; }
public void setAge (int age) {
System.out.println ("setting age to " + age);
this.age = age;
}
}Compile this class, reassemble your application, and restart it. On the console you should be able to watch the class get constructed and initialized.
Note: The forward slash / in /test/services/Person is always used when naming Nucleus components. It is independent of the file separator character that varies among operating systems.
