iiThis section describes the ILS software architecture, including the Windows NT services, DLLs, and other server components. The software components are defined in relation to the hardware that these components run on. The section covers product design goals, service component descriptions, and available programming options.
ILS supports three protocols: HTTP, LDAP, and ULP. HTTP provides the interface for Web browser clients through IIS. LDAP provides the interface for LDAP clients through IIS. ULP provides the interface for NetMeeting clients.
The following table describes the components that make up the ILS services.
|
Component |
Description |
|
Internet Information Server |
Internet Information Server provides the Web server and the Internet Server Application Programming Interface (ISAPI) platform. The ASP processor is an ISAPI. |
|
Active Server Pages script processor |
The ASP processor executes ASP scripts on the server to produce HTML for the client browser. |
|
ILS ActiveX server component |
The ILS ActiveX server component is used by ASP scripts to interact with ILS: it is the Web author’s interface for the ILS database DLL. |
|
The ILS directory layer manages the ILS directory. It provides a common interface for the ILS server component, LDAP service, and ULP protocol. | |
|
ILS database DLL |
Manages the interaction between the ILS directory DLL and each RAM database. |
|
Authentication |
Provides user authentication and access control for ILS database operations. |
|
ILS RAM database |
Represents the memory-based database for storage of dynamic entries. |
|
HTTP interface |
Provides dynamic directory services to HTTP-based client applications such as Web browsers. This interface is supported only if the administrator is using the ILS ActiveX server component. |
|
LDAP interface |
Provides directory services to LDAP client applications. It accesses the dynamic database through the ILS database DLL. |
|
ULP interface |
Enables dynamic directory access to ULP-based client applications. It is included with ILS for compatibility with existing applications. As client applications move to LDAP for access to dynamic directories, the ULP interface will be phased out. |
The following diagram illustrates the relationships between the key components of ILS.
Overall, the components of ILS provide a flexible system that offers a dynamic directory service to a variety of different client applications.
Dynamic directory information is handled by ILS. A user’s IP address, which can be different every time the user logs on to the Internet, is an example of dynamic directory information that other users may want to retrieve.
When users connect to the Internet, they can register their names and IP addresses with the ILS server. While they are online, client applications send periodic refreshes to the server to keep user ILS entries valid. If a client application crashes, the ILS server deletes user entries after the refresh period has elapsed, thereby protecting against stale dynamic directory information.
Because of the frequency of client refreshes, ILS stores its information in a RAM database. This provides better performance than if the information were stored in a disk-based database. Clients can access the directory through the ILS LDAP interface, through the ULP (User Location Protocol) interface, or through a Web page that includes the Active Server Pages scripting.
ILS can service standard Web browsers through ActiveX technology. Web authors can use the ILS ActiveX server component on an ASP page to enable users to perform Web-based queries and database information management. Results can be displayed in standard HTML format.
ILS provides sample scripts that enable the service provider to create customized Web pages for ILS. Using the ActiveX server component provided for ILS, developers can make use of ILS services in their Web pages. For example, a developer might include a "Who is online?" directory search form in a Web page.
iiiFor more information about custom programming options, see the Active Server Pages Roadmap online documentation and the Internet Locator Server Web Page Author’s Guide.