* Inside the Apdex standard
A group of vendors have joined forces to define a measure of user satisfaction with application performance.
Dubbed the Apdex Alliance, the group includes application acceleration and WAN optimization vendors such as Expand Networks and FineGround, as well as content delivery providers such as Akamai and Web site measurement vendor Keynote – the two most recent additions to the group.
Apdex, short for application performance index, is a standard method for benchmarking and tracking application performance. It is a numerical measure of user satisfaction of enterprise applications and uses a system to convert many application performance measurements from multiple users into one number. All values fall between 0 and 1, with 0 representing no users satisfied and 1 representing all users satisfied.
The index is based on three zones of application responsiveness. To quote from the Apdex Web site, the three zones are:
* Satisfied. The user is fully productive. This represents the time value (T seconds) below which users are not impeded by application response time.
* Tolerating. The user notices performance lagging within responses greater than T, but continues the process.
* Frustrated. Performance with a response time greater than F seconds (where F=4T) is unacceptable, and users may abandon the process.
Using these performance measurement metrics, Apdex-compliant software and monitoring tools would be able to calculate customer satisfaction with a simple formula, the organization claims.
The Apdex formula is the number of “satisfied” samples plus half of the “tolerating” samples plus none of the “frustrated” samples, divided by all the samples. The Apdex Web site gives an example: If there are 100 samples with a target time of 3 seconds, where 60 are below 3 seconds, 30 are between 3 and 12 seconds, and the remaining 10 are above 12 seconds, the Apdex is 0.75, with a subscript of 3 as the target time.
With recent new editions of Netli and Symphoniq, the organization now boasts 15 members: Adlex, Akamai, Coradiant, Expand Networks, FineGround, Keynote, NetForecast, NetQoS, Network Physics, Packeteer, Peribit, Swan Labs and WildPackets. Founded in 2004 by NetForecast President Peter Sevcik, Apdex is headquartered in Charlottesville, Va.
Correction: In the March 24 Network Optimization newsletter, a product name was incorrect. Pricing for Swan Labs’ NetCelera appliances starts at $4,000.
