= Viewlet Framework: Creating a JSP-only Viewlet =

To add a JSP-only [wiki:Viewlet] to an !InfoGrid application, the following steps need to be performed:
 * Decide on a fully-qualified name for the new [wiki:Viewlet], using the reverse domain name convention as it is common for Java classes. For example, `com.example.viewlet.CustomerViewlet`.
 * Decide on the exact criteria which types of MeshObject can be rendered by this [wiki:Viewlet]. For example, it may apply to any MeshObject of type `com.example.models.CustomerModel/Customer`, or only to a MeshObject of type `com.example.models.CustomerModel/Customer` whose `com.example.models.CustomerModel/Customer_Balance` is less than $10 while it is also related to at least one MeshObject of type `com.example.models.CustomerModel/Order`.
 * Determine which other [wiki:Viewlet Viewlets] this [wiki:Viewlet] may compete with, and decide which of them should be the default.
 * In your application's ViewletFactory, encode your rule, e.g.:
{{{
    if( subject.isBlessedBy( CustomerModelSubjectArea.CUSTOMER )) {
        ret.add( DefaultJspViewlet.choice( "com.example.viewlet.CustomerViewlet", ViewletFactoryChoice.GOOD_MATCH_QUALITY ));
    }
}}}
 * Create the JSP file with name `/v/com/example/viewlet/CustomerViewlet.jsp` that contains the JSP code to run when the [wiki:Viewlet] is run.

Within the JSP file, the following variables are pre-defined:
|| Variable || Description ||
|| `lid-appcontext`         || The application context, e.g. whether this is the main window or a popup. May be null.                                            ||
|| `Subject`                || The MeshObject whose URL was accessed. Always provided.                                                                           ||
|| `Viewlet`                || Instance of the subtype of `Viewlet` that backs this JSP file. Here, this is an instance of `DefaultJspViewlet`. Always provided. ||
|| `ViewletState`           || The desired `JeeViewletState`. May be null.                                                                                         ||
|| `ViewletStateTransition` || The desired `JeeViewletStateTransition`. May be null.                                                                               ||

See also:
 * [wiki:Docs/ViewletFramework/CreatingCustomViewlet Creating a custom Viewlet]
 * Source code to MeshWorld
 * [wiki:Docs/ViewletFramework ViewletFramework].