I’m writing a series of posts about Generalizing Apdex. This is #15. To minimize confusion, section numbers in the current spec are accompanied by the section symbol, like this: §1. The corresponding section numbers in the generalized spec, Apdex-G, are enclosed in square brackets, like this: .
I have been working systematically through the process of generalizing the current Apdex spec. Along the way, I have been skipping over parts of the current spec to work on the paragraphs that presented challenges. I am now ready to go back and fill in those less contentious paragraphs. Over the next week, I plan to post updated drafts of each section of the Apdex-G spec, beginning today with Section  Introduction.
Because this material includes some drafts posted previously, some of which I have edited, everything in this series of posts is considered the second draft of Apdex-G. After the second draft is posted, I will begin work on Apdex-R, the addendum addressing measurements of response times. Apdex-R will cover all the domain-specific content of the current spec that has been excised from Apdex-G.
In this section of Apdex-G, I have reorganized the material in Apdex section §1 as follows:
- The introduction contains a brief generic description of Apdex, originally discussed in Generalizing the Apdex Language.
- Section [1.1] is largely new in Apdex-G. It introduces the separation of Apdex specifications into generic and domain-specific documents. This was originally discussed in Which Apdex Features Can Be Generalized?
- Section [1.2] corresponds to Apdex section §1.1, apart from material that has been moved to [1.3]
- Section [1.3] summarizes Alliance goals and points to the Alliance website for more details. It replaces material currently found in Apdex sections §1.1 and §1.2.
Parts of the current spec, shown on the left below, have been rearranged to show correspondences with the Apdex-G proposal:
Apdex, current spec:
Apdex-G, second draft:
The Apdex Alliance is a group of companies collaborating to promote an application performance metric called Application Performance Index (Apdex). Apdex is a numerical measure of user satisfaction with the performance of enterprise applications, intended to reflect the effectiveness of IT investments in contributing to business objectives. The Apdex metric may be used by any organization seeking insight into their IT investments. This specification defines Apdex, which is a method for calculating and reporting a metric of transactional application response time in the form of an index with a value of 0 to 1.
Apdex (Application Performance Index) is a metric that reflects the degree to which a set of performance measurements achieves designated targets.
Originally designed as an index of user satisfaction with the responsiveness of enterprise applications, Apdex can also be used to report on many other quality measures, such as the degree to which a product conforms to technical standards, or the degree to which a service achieves business objectives.
This document, Apdex-G, specifies rules for calculating and reporting the Apdex index.
The suffix ‘G’ denotes generic, indicating that this document specifies domain-independent rules. A supplemental document, termed an addendum, may contain rules that apply only to applications of Apdex within a specific measurement domain. An addendum is named Apdex-X, where the suffix ‘X’ is the Addendum Type, and denotes a specific measurement domain. For example, the addendum Apdex-R contains supplemental rules for applying Apdex to response times.
This specification document is the cornerstone of the Apdex Alliance. It was developed and ratified by the current Alliance member companies through a consensus process. The voting members of the Apdex Alliance at the time that this document was formally adopted are:
[… list of names … ]
Advisory Board Members
[… list of names … ]
This appears at the end of section §1.1 of the current spec:
This specification may be updated over time based upon feedback from practical experience with Apdex, or to reflect new insights into application performance and its impact on business.
This document was developed by the Apdex Alliance, a group of companies and individuals collaborating to promote Apdex. It was ratified by …
[ Ratification history/status of Apdex-G will be inserted here ].
Apdex specifications may be updated from time to time to reflect feedback based on practical experience with Apdex. Current versions of all Apdex specifications are available from the Alliance web site, www.apdex.org.
The Apdex Alliance plans to develop and maintain additional documents and educational material to help enterprises understand the Apdex metric and put it to productive use within their organizations. The Apdex Technical Guide will provide detailed information on defining Apdex parameters within an enterprise. Most recent information about the Alliance and Apdex documents will be made available at the Alliance web site at www.apdex.org.
This appears in section §1.1 of the current spec:
Members of the Alliance have made a commitment to implement tools or services that adhere to this specification. The Alliance is also committed to supporting an ongoing process of inquiry into the relationship between application responsiveness and user satisfaction.
The Apdex Alliance has adopted the following statements of intent:
Tools: Members of the Alliance will implement tools and/or services that adhere to this specification.
Research: Members of the Alliance support an ongoing process of inquiry into the relationship between application or process performance and customer satisfaction.
Education: Members of the Alliance will develop and maintain additional documents and educational material to help enterprises understand the Apdex metric and put it to productive use within their organizations.
Documentation: Members of the Alliance will contribute to an Apdex Technical Guide, which will provide detailed information about implementing Apdex.
These statements reflect goals that fall outside the scope of this specification. Currrent information about Apdex Alliance goals and activities can be found at the Alliance web site, www.apdex.org
As usual, all these proposals are open for public discussion. Please use the comment form below to contribute any comments, suggestions, or questions.