There are several ways of interacting with the HTCondor system. Depending on your application and resources, the interfaces to HTCondor listed below may be useful for your installation. Generally speaking, to submit jobs from a program or web service, or to monitor HTCondor, the python bindings are the easiest approach. Chirp provides a convenient way for a running job to update information about itself to its job ad, or to remotely read or write files from the executing job on the worker node to/from the submitting machine.
Older programs which have SOAP bindings may find the HTCondor SOAP interfaces useful.
If you have developed an interface to HTCondor, please consider sharing it with the HTCondor community.