Introduction to Plug-Ins

In general usage, plug-in applications are programs that can easily be installed and used as part of your web browser. A plug-in application is recognized automatically by the browser and its function is integrated into the main HTML file that is being presented. Web browser plug-in applications generally play sound or motion video or perform some other functions.

In the N1 Grid Service Provisioning System environment, a plug-in differs only slightly in concept from the general usage. A plug-in for the N1 Grid Service Provisioning System product is a packaged solution that extends the provisioning capability of the product for a specific platform, application, or environment. For example, you might create a plug-in solution for a specific application, such as Oracle 8i, or for some feature of an operating system, such as Solaris Zones.

A plug–in includes all the relevant data needed to support a new custom application. The contents of the plug–in are described in the plug–in descriptor file. This file is located in a standard place within the plug–in packaging structure.

The plug-in descriptor contains meta-data about the plug-in including name, description, vendor, version number, previous version, and dependencies. In addition, the descriptor may contain a pointer to a readme.txt file. The descriptor also contains instructions for creating components, plans, folders, host types, host sets, host searches, resources, component types, and system services. The descriptor may optionally define a library of server-side plug-in code and a set of GUI extensions for the plug-in.

Objects defined in the plug-in are loaded in the order in which they are defined within the descriptor file. Objects defined in the plug-in may only reference objects defined earlier in the plug-in, or in a plug-in on which this plug-in directly depends. This dependency must be declared in the plug-in descriptor.

XML Schemas

In the N1 Grid Service Provisioning System environment, plans, components, and other parts of the solution are defined through XML. You can use several XML schemas to define your plug-in solution. The following schemas are provided in the docs/xml directory of the product media:

• plugin.xsd – Plug-in schema used to describe the parts of the plug-in through the plug-in descriptor file

• pluginUI.xsd – Plug-in user interface schema used to define an interface to the plug-in within the N1 Grid Service Provisioning System browser interface

• component.xsd – Component schema used to define components and component types

• plan.xsd – Plan schema used to define execution plans

• planCompShared.xsd – Schema that contains elements that are common to plans and components

This document includes examples that illustrate the XML schemas. For complete reference information about the elements and attributes used in the XML schemas, see N1 Grid Service Provisioning System 5.0 XML Schema Reference Guide.