Shock Absorption for Legacy Systems

When it comes to performance testing, some people (not used to working with legacy systems) can have a hard time understanding that limiting the number of concurrent requests that hit the back end application can actually improve performance.

A very talented colleague of mine quite often refers to "the knee of the curve" i.e. the point at which response times dramatically increase because the target system is having a hard time of it.

In pre-sales calls we quite often describe our Legacy Integration products as the shock absorption layer for the back end application. We have a handy little feature that enables us to limit the number of concurrent requests active on a connector (a connector being the implementation of a specific protocol for a specific resource.e.g. TN5250, TN3270, JDBC and anything else you care to shake a stick at).

I spent this week tuning an implementation of our Legacay Integration product for a rather large client. The target was a test database on an underpowered iSeries. Past a certain point we saw dropped connections and all manner of strangness. I played around with our throttle control and the size of the connection pool. It didn't take long to find the sweet spot and the average response times dropped back to where they should be.

This is a good example of less is more :-)

To many of you reading this I am sure that the above seems like common sense. Any system, legacy or contemporary has a finite set of resources, so of course performance will degrade as the load exceeds the systems capabilites. My point is that shock absorption must be considered when planning and implenting an integration solution for Legacy systems.

For example, most iSeries shops run at or near capacity. When the iSeries Admins express concerns about the additional load that an integration solution may bring, the handy throttle control can save the day.

So, if your current legacy integration product does not cater for shock absoption or transaction throttling, feel free to drop me a line :-D

James
Atlanta
August 2008