The link between APE and SLAs

Insightful analysis by consultants Steve Taylor and Jim Metzler, plus links to the latest WAN news headlines

In our last couple of newsletters we began to discuss a seldom-mentioned IT discipline - Application Performance Engineering (APE). In this newsletter we will discuss the linkage between APE and the internal service-level agreements (SLA) that IT organizations have begun to provide to the company's business unit managers.

SLAs have been around for decades. However, as common as it has been for an IT organization to get an SLA from their service providers, as recently as two years ago we rarely came across an IT organization that provided an SLA internally to the company's business unit managers. Starting roughly two years ago we began to notice a shift whereby IT organizations began to offer the company's business unit managers an internal SLA for a handful of applications. The IT executives that we have talked to all agree that successfully developing and managing SLAs is very difficult but that it is worth it because it improves the relationship that they have with the company's business unit managers.

One way to look at the movement on the part of IT organizations to provide an internal SLA for at least a handful of applications is that the ability of IT organizations to successfully manage these SLAs is highly reliant on their ability to successfully implement APE. For example, an IT organization that wanted to develop an SLA for a given application could avoid APE entirely and merely implement a good application performance management (APM) tool and observe the performance of the application over an extended period of time. Then, based on the observed performance, the IT organization could create a performance-based SLA that it felt comfortable it could meet. 

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In our last couple of newsletters we began to discuss a seldom-mentioned IT discipline - Application Performance Engineering (APE). In this newsletter we will discuss the linkage between APE and the internal service-level agreements (SLA) that IT organizations have begun to provide to the company's business unit managers.

SLAs have been around for decades. However, as common as it has been for an IT organization to get an SLA from their service providers, as recently as two years ago we rarely came across an IT organization that provided an SLA internally to the company's business unit managers. Starting roughly two years ago we began to notice a shift whereby IT organizations began to offer the company's business unit managers an internal SLA for a handful of applications. The IT executives that we have talked to all agree that successfully developing and managing SLAs is very difficult but that it is worth it because it improves the relationship that they have with the company's business unit managers.

One way to look at the movement on the part of IT organizations to provide an internal SLA for at least a handful of applications is that the ability of IT organizations to successfully manage these SLAs is highly reliant on their ability to successfully implement APE. For example, an IT organization that wanted to develop an SLA for a given application could avoid APE entirely and merely implement a good application performance management (APM) tool and observe the performance of the application over an extended period of time. Then, based on the observed performance, the IT organization could create a performance-based SLA that it felt comfortable it could meet. 

This approach will work under two conditions. One condition is that in the current environment the application almost always performs in an acceptable fashion. The other condition is that the environment never changes. The term environment refers to a wide range of factors including the functionality provided by the application, the number of users, the location of the users as well as the WAN, servers, storage and security functionality that are used to support the application. It is extremely difficult to believe that these two conditions apply to very many situations. For example, the application could perform acceptable within the continental U.S. where the round trip WAN delay between the application and the company's employees seldom exceeds 60 ms. However, the same application could perform in an unacceptable fashion if employees in the Pac Rim began to utilize the application because in this situation, the round trip WAN delay would be three or four hundred milliseconds.

Establishing SLAs for key applications

Since the approach described in the preceding paragraph will seldom work, a better approach for IT organizations that already have implemented, or soon will implement, internal SLAs that include application performance goals is to implement APE. By that we mean in part that the IT organization needs to design for application performance and then test, measure and tune performance throughout the application life cycle.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.