A Web filter must be installed locally on each Forefront TMG computer where it will be invoked. The installation process must include copying the dynamic-link library (DLL) of the Web filter to the Forefront TMG computer and registering the Web filter as an extension of the Forefront TMG Web proxy in the stored Forefront TMG configuration. The installation process can include defining events, alerts, and other elements in the Forefront TMG configuration. Each time that the Forefront TMG Web proxy is launched on a Forefront TMG computer, the DLLs of all the installed Web filters are loaded into memory and stay in memory until it shuts down.
When an enterprise with central array management is deployed, Web filters can be registered in the stored Forefront TMG con figuration on the enterprise level and on the array level.
Note Enterprise-level configuration settings are not not available in Forefront TMG Medium Business Edition. Forefront TMG Medium Business Edition is always installed as a standalone server in a configuration containing one array that is associated with a single Forefront TMG computer.
The process of installing and registering a Web filter includes the following steps:
In addition, Forefront TMG Management can be extended for a Web filter by adding property pages for configuring the Web filter. Registering a Forefront TMG Management extension for the Web filter is optional. A Forefront TMG Management extension is required only if configuration settings are defined for the Web filter in one or more vendor parameters sets. The Forefront TMG Management extension for a Web filter should be installed in a separate process that includes copying its DLL to the Forefront TMG computer and registering it as an extension. For information about creating an extension to Forefront TMG Management for a Web filter and registering the extension, see Extending Forefront TMG Management.
The process of registering or unregistering the Web filter in the array of the Forefront TMG computer on which it is run uses properties and methods of the Forefront TMG administration COM objects. This process can be implemented in your DLL using the DllRegisterServer or DllInstall function, which must be exported by your DLL, or in a script or application. This code also automatically registers or unregisters the Web filter as an installed extension of the Web proxy on the Forefront TMG computer.
The process of registering and unregistering a Web filter in the local array of a Forefront TMG computer consists of the following steps:
After you register a new Web filter in the array, you can change the order of the filters in the collection using the MoveDown and MoveUp methods. Each FPCWebFilter object is specified by the GUID used to add it to the FPCWebFilters collection.
The registration of the Web filter is accomplished autmatically for the server on which the FPCWebFilters.Add method is run. The Web filter's GUID which was provided in the Name parameter of the FPCWebFilter.Add method was used to create a reference to the new FPCWebFilter object in the FPCRefs collection held in the InstalledWebFilters property of the local Forefront TMG computer.
You can write code into a Web filter so that it can be registered or unregistered from the command line, and added to Forefront TMG Management. For information about how to build a Web filter that supports self-registration of the filter with Forefront TMG, see Self-Registering Web Filters. For code examples that demonstrate how a Web filter can be registered from the command line, see Forefront TMG Web Filter Sample Administration Steps.
For information about registering Web Filters in ISA Server Enterprise Edition, see Registering Web Filters in Enterprise Edition.
Build date: 11/30/2009
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