Web Server Master Agent


This page is related to Classic Agent only. If you're using the AppMon Agent, see the page for the specific technology you use:

The Web Server Agent monitors Apache Webserver, Internet Information Server (IIS), and NGINX server. It has two components. One is a module that gets loaded as a Web Server Module, and the other component is a separate process that acts as the Web Server Agent which services all Web Servers on that machine.

It is common to have multiple Web Server instances running on a single Web Server Host. To optimize communication with the Collector, the communication proxies through that process. The Web Server Module on Linux machines and the Web Server Agent on Windows machines launch this process. This is true for all supported Web Servers (Apache, IIS, and NGINX).

See Web Server Agent configuration to learn how to configure the Agent.


The Agent for Web Servers consists of two parts:

  • The Web Server Module (slave) is the module that is loaded by the web server. It gathers the information that is used for analysis on the AppMon Server.
  • The Web Server Agent (master) is a separate process that collects data of all slaves worker processes. It handles communication with the Collector, retrieves configuration data, and provides other functions.

The Web Server Modules communicate with the Master Agent through these channels:

  • A shared memory segment propagates configuration data, received from the Collector by the Master Agent, to the worker processes and to hold other information that must be shared across all worker processes. The shared memory segment is backed by a file in <DT_HOME>/agent/conf on all platforms where the worker processes and the Agent process must have read/write access.
  • The Web Server Modules (slaves) send collected data to the Master Agent using a stateless UDP connection. The Agent collects the data, transforms it, and forwards it to the Collector (standalone or Server-embedded).


Sensor Classic Agent AppMon Agent
WebServer Sensor Yes Yes
Apache modules No Yes
Nginx modules No Yes