PART 3: GLOSSARY

client pull - technology which allows a browser to periodically request an update of the page currently being viewed. The responsibility for the update lies with the client rather than the server, and since data flows from server to client, this is referred to as the client "pulling" data from the server.

HTML - Hyper-Text Mark-up Language, the basic language used for defining web pages. An SGML derivative.

HTTP - Hyper-Text Transport Protocol, a protocol used over TCP/IP to transfer WWW documents, often HTML.

ICMP - Internet Control Message Protocol, a protocol used over IP for link management - the basis of the "ping" program, for example

IETF - Internet Engineering Task Force, responsible for Internet standards and protocols.

IP - Internet Protocol, the basic underlying packet protocol of the Internet. This can be overlaid on various transmission media (such as Ethernet or PPP), and can contain various higher level protocols such as TCP, UDP, ICMP, etc.

MTU - Maximum Transfer Unit, the size (in bytes) of the largest packet that a particular connection (such as a SLIP or Ethernet connection) can handle. Typical MTUs range from 200 bytes for slow serial connections up to approximately 1.5k for Ethernet. Any larger packets must be broken into pieces to cross the particular link. (I believe) TCP handles this automatically, while UDP just drops oversized packets in the bit bucket.

NTP - Network Time Protocol, a standard mechanism allowing computers to check in with central servers for date and time information. Machines are defined as being at the n-th level depending on their distance from one of a few primary reference machines connected directly to atomic clock sources.

server push - technology which allows a server to continue updating the contents of the page currently being viewed even after the initial download is complete. The responsibility for the update lies with the server rather than the server, and since data flows from server to client, this is referred to as the server "pushing" data out to the client. FYI, this is one area in which Netscape's browser supports a capability not supported by Microsoft's.

SGML - Standard Generalized Mark-up Language, a general extensible language for marking up textual documents. Most modern document languages, including HTML, RTF, LaTeX, and XML, can be described as derivatives of SGML.

SNMP - Standard Network Management Protocol, a methodology developed (at CMU?) for remote management of IP network devices

TCP - Transmission Control Protocol, a protocol used for reliable, long term data connections such as telnet or HTTP. TCP/IP refers specifically to TCP used over IP.

UUCP - Unix-to-Unix Copy Program, a now mostly outdated protocol for transferring data between machines which only communicate infrequently. Probably inappropriate for our protocols.

UDP - User Datagram Protocol, (aka Unreliable Datagram Protocol), a protocol used for quick, connectionless transfers of information between machines. SNMP, NFS, talk, rwho, routed, and a variety of other protocols use UDP for many if not all of their communications.