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Systems Management: Software License Use Management (XSLM)
Copyright © 1999 The Open Group

Function Sets and Functional Towers

XSLM functionality is described in terms of a set of Base Function and one or more optional Function Towers. Function Towers provide for the optional extensions in licensing system functionality while retaining consistency across all licensing systems that implement the same function towers.

The Base Function set is a prerequisite for all function towers. That is, the Base Function set must be present before any optional function tower may be implemented. Each Function Tower offers a complete set of functions; that is, if one function of the Tower is implemented, then all functions defined as being part of that same Tower must also be implemented.

Currently Defined Functional Towers

The relationship between the Base Function set and the Functional Towers is depicted in Base Function Set and Functional Towers. The current level of the XSLM specification defines four Functional Towers:

Figure: Base Function Set and Functional Towers

Base Function Set

The Base Function set consists of two elements:

The common License Certificate (data) Architecture provides the capability to fully encode application license terms and conditions in the form of an architected (standardized) license certificate that may be installed into any XSLM-compliant licensing system that supports the embedded certificate data elements. These certificates may be subsequently managed and/or interpreted by any compliant management application. The XLCA is also used to define license certificate meta data (for example, usage measures) and optionally, licensing system specific certificate data elements.

The XMAPI defines the set of programming interfaces necessary to build licensing system management tools capable of managing (installing, removing, etc.) standardized license certificates and/or providing comprehensive application license usage reports.

The XAAPI defines the set of programming interfaces (API functions) necessary to enable for license management those applications that run in trusted environments. A trusted environment is, in this context, one which is by design physically secured, or through hardware and/or software services protects programs and data from unauthorized alteration. (The Base Function set does not include the XAAPI).

Advanced Function Towers

The Advanced Application API Function Tower adds a set of services intended to provide more comprehensive protection (with respect to licensing) and flexibility for application publishers, particularly for those applications that run in untrusted operating environments.

Function-Related Management API Functions

Management applications must have the ability to determine the set of XLCA defined data elements, as well as the APIs, supported by the license servers that comprise a customer's licensing system. The xslm_query_server_info() function is defined to satisfy this requirement.

This function facilitates processing of licensing data provided by Legacy Functional Level license servers; servers which may, at the discretion of the implementor, elect to limit support to a proper subset of XLCA-defined certificate data (and meta data) elements and logged data.

Legacy Functional Level (Level 0)

This functional level is intended to provide a transition path to the standard compliance level (or higher) for existing licensing systems; specifically, the ability to respond to a subset of XMAPI functions (the ones querying certificate and logged data), returning a semantically correct subset of XLCA-defined (the Basic XLCA set) certificate data elements and a semantically correct subset of logged data.

To support Legacy Functional Level a licensing system must implement the following XMAPI functions (the Basic XMAPI set):

xslm_get_certificate() xslm_query_cert_ids() xslm_query_next_level_cert_names() xslm_query_servers() xslm_get_license_instances() xslm_get_logged_data()

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