next paragraph, but many of those that are listed here are well known and require no explanation after their introduction. The Transmission Control Protocol/Internet Protocol, better known as TCP/IP, is ultimately responsible for the creation of other TCP-backbone protocols: HTTP, DHCP, SOAP, Telnet, Rlogin, DNS, FTP, RSH, IMAP, NFS, SMTP, POP3, NNTP, SNMP, SSH, most chat protocols, and most X Window network communications. FTP, HTTP, and SMTP are three of many widely known standard proto- cols that are generally supported within an organization and that rely on TCP as a standard transport mechanism. FTP, HTTP, and SMTP are inter- active protocols that can trigger events by either programmatic contribution or  encountering  a  manual  user  transmission  of  meaningful  information. We will focus on these protocols in this section because they are the proto- cols with which most people are familiar. In  the  set  of  circumstances  surrounding  the  HTTP  protocol,  program- matic contributions offer a robust way to exchange information between a client and a server, and Component Services are committed to processing information in a very efficient manner. For example, the IIS Server does an excellent job handling HTTP user requests and responses as well as inter- preting and executing ASP requests. Because of the special relationship of IIS  with  MTS  and  COM+,  known  as  Component  Services,  server-side resources can be pooled, including connections to the database and COM+ transactions. In effect, the SOAP protocol overcomes the barriers discussed previously in  this  chapter  regarding  earlier  attempts  at  creating  custom  TCP-based solutions. Because the SOAP protocol uses XML and the TCP protocol to bypass firewalls, it masks itself as an HTTP response or request and is eas- ily passed through virtually all firewalls. Hence, without TCP/IP, the HTTP protocol could not exist. You might think of the SOAP protocol as a third-tier protocol and FTP and HTTP as second-tier  protocols,  depending  on  the  TCP  protocol  that  provides  for physical transmission. (See Figure 1.1.) The TCP/IP protocol negotiates handshaking and RPC (Remote Proce- dure Call) across an intranet and the public Internet. Handshaking is sim- ply   the   method   by   which   two   programs,   through   their   interfaces, determine the type of relationship that exists between them. (See Figure 1.2.) RPC is a way for the programs of one computer to actually execute code on another computer. 4 Chapter 1