Writing in-house 'C' routines does create additional complexity with the maintenance of your ESL application. You will need to purchase additional tools to compile the routines, and may need specialist staff available to write and update the routines. Routines written in 'C' are not generally portable between Operating System versions. It is recommended that 'C' routines are not used as a replacement for a lack of knowledge of the ESL language. Consider contacting the Esl Help Desk to discover if something can be written in Esl before resorting to 'C'.

There 2 problems that commonly effect the stability of a DLL written for use with ESL;

•Passing on strings, as an argument or a return value

•Memory Leaks

These 2 issues can result in the ESL application appearing unstable. Unfortunately, these problem are not always apparent immediately and may only be uncovered when your application goes into production, and occasionally, when a new version of ESL is installed.