Cache ISAPI Application Option Causes ASP to Return Error

• Microsoft Internet Information Server, version 4.0

SYMPTOMS

It is possible to configure the way that Microsoft Internet Information Server (IIS) 4.0 caches Internet Server Application Programming Interface (ISAPI) applications. Changing the default selection from caching ISAPI application to not caching ISAPI application causes IIS 4.0 to return the following error to the browser when an Active Server Page (ASP) is executed on the server:

   The requested resource is in use

CAUSE

This setting can be changed from the Web Site properties by selecting Configuration on the Home Directory tab. In Application Mappings there is a checkbox for the Cache ISAPI Applications option. Changing this selection modifies the default behavior of IIS 4.0. This option is for non-production testing only.

If the Cache ISAPI Applications option is deselected, IIS 4.0 does not cache ISAPI applications. All ISAPI applications are loaded and unloaded from IIS 4.0 memory immediately after the ISAPI application is executed on the server, including ASP. ASP sets up application and session state object and variable that must be gracefully unloaded from memory. ASP returns the error when it is being unloaded from memory and an ASP page is attempting to execute. When ASP is loaded and unloaded from memory, an event is logged in the Windows NT Application event log. Event ID of Event 3 "Service started" and Event 4 "Service stopped" will be logged every time ASP is loaded or unloaded from memory.

MORE INFORMATION

This behavior is by design. Microsoft welcomes suggestions or comments about changes in functionality and product design. You are invited to submit suggestions by filling out the form at the following Microsoft Web site:

   http://www.microsoft.com/regwiz/regwiz.asp