Integration with Internet Information Services 6.0


When Windows Server 2003 is installed, IIS is not installed by default. So before you can install Exchange 2003, you’ll need to install IIS 6.0. The SMTP and other protocols that Exchange uses run inside the inetinfo.exe process and allow the abstraction of these protocols to dedicated servers, called front-end servers.

These protocols are basically transport stacks for the operating system, Windows Server 2003 no longer relies on RPCs. For instance, it is possible to have Active Directory information replicated over SMTP rather than RPCs.

Note

An RPC allows an application to execute code that resides on a remote machine. RPC-based applications use the network to transport the request. The client computer issues a call to “stub code” that takes the place of a local procedure. The stub code uses both communication and data conversion utilities to execute the request within the memory of the remote computer. Because RPC uses the network for its transport, TCP handshakes must be established for each new RPC between two machines, which results in high overhead on the network. RPC also requires permanent, high- bandwidth connectivity to ensure that the TCP connection can stay active. Compare this to SMTP, under which commands can be passed between servers in the form of messages. SMTP is thus more tolerant of lower-bandwidth environments and as a result is a better protocol over which to conduct server overhead functions, such as directory replication.

Given the ability to exploit Active Directory information via traditional Internet protocols, such as HTTP (and the improved version, WebDAV) and SMTP, as well as via Outlook Web Access (OWA), Web-based applications will become more popular, especially in environments where the work force is distributed but the information is centralized.

In addition, because IIS is now installed as part of the operating system and can run the transport protocols independently, the ability to host the protocols on different servers allows you to design an Exchange 2000 topology that will scale into the millions of users. Using a bank of front-end and back-end servers, Exchange 2000 can work with any size of installed base. For example, you can design your Exchange Server 2003 topology with a bank of front-end servers that allow non-MAPI clients, such as HTTP clients, to connect to virtual IP- addressable front-end servers while storing messages and collaboration data on separate back-end servers.

The protocols shipped with Exchange Server 2003, such as SMTP and NNTP, lead to services such as OWA, instant messaging, and data conferencing. These protocols and services are discussed in the sections that follow.

Simple Mail Transport Protocol

Exchange Server 2003 relies entirely on the Windows Server 2003 operating system to provide SMTP services. During the installation of Exchange Server 2003, the IIS SMTP protocol is extended to include additional command verbs that enable link state routing and other advanced features. In addition, an advanced queuing engine and an enhanced message categorization agent are installed. For more information on the SMTP protocol, see Chapter 20.




Microsoft Exchange Server 2003 Administrator's Companion
Microsoft Exchange Server 2003 Administrators Companion (Pro-Administrators Companion)
ISBN: 0735619794
EAN: 2147483647
Year: 2005
Pages: 254

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