AFP is an enhancement for ISAPI-compatible Web servers like IIS or Apache.  AFP3.DLL constitutes the required system library. It controls and directs the communication between the Web server and the AFP engine.

The actual course of action is straightforward: depending on its configuration for file extensions, the Web server passes all incoming requests for an AFP document to the ISAPI interface AFP3.DLL. The ISAPI extension will then attempt to establish a connection to a free AFP engine for a certain period of time. This connection is made through a Named Pipe named AFP3_QUEUE and/or AFP3_QUEUE_DEBUG with a debug option. First, availability of AFP3_QUEUE_DEBUG pipes is checked. If a pipe is available, it will be used instantly. If not, the search for an available AFP3_QUEUE pipe will be continued for a certain period of time. Once a connection is established, all data handed in by the Web server is packed and sent to the AFP engine through this pipe. The engine creates a response and returns it to the ISAPI interface. The ISAPI extension hands these files to the Web server. For compatibility reasons it does this through a synchronous data transfer.

There is an optional configuration file AFP3.INI with the single parameter BusyTimeout. It specifies the maximum waiting period in seconds that the AFP3.DLL lets elapse for the response of the AFP engine before an error message is returned to the Web server.  If this setting is absent, the standard period is 30 seconds.

You may re-name AFP3.DLL as you wish if you use a direct access without script mapping but want to cover up the fact that you are using the AFP for security reasons. If you re-name a DLL, the INI file has to be re-named accordingly.