From the AD perspective, this isn't important. However, the message queue
may still be needed to achieve certain scalability goals of the apps or
serve other purposes. However, if you are pretty sure you don't need the
queue, you can definitely write directly to AD. The nice thing about the
queue is that you have more explicit control over how many threads and
connections you might open to AD. Especially if you have multiple sources
dumping into the queue and you really don't know how many might be talking
to AD at once, you might be able to achieve more reliablity this way.
However, you'd probably have to have pretty high usage for that to become an
Ultimately, this is more of an architectural thing that you have to decide
based on the other factors involved.
Joe Kaplan-MS MVP Directory Services Programming
Co-author of "The .NET Developer's Guide to Directory Services Programming"