Glossary

cache

A copy of original data stored locally so that it doesn't have to be retrieved again from a remote server when requested.

cache build

The creation of the Netscape cache hierarchy.

cache directory hierarchy

Netscape Proxy's directory structure for storing cache files.

cache refresh

Replacing a cached document with a fresh copy.

cache repair

A process to repair a cache damaged by a software failure, system crash, disk breakdown, or full filesystem.

cache root

A directory on the proxy server that contains all cached files. The proxy controls which documents are copied to the cache root, and the garbage collector daemon purges this directory structure to control the amount of data stored.

cache up-to-date check

This checks that the copy in the cache is still valid, and if not, refreshes it.

CERN

The European Laboratory for Particle Physics (CERN) invented the World Wide Web to share information among research groups. This is where the CERN proxy prototype was produced.

common log file format

The common log file format is the format used by the server for entering information into the access logs. The format is the same among all of the major servers, Netscape Commerce and Communications servers, CERN httpd, and NCSA httpd.

DNS

Domain Name System. The system used by systems on a network to associate standard IP addresses (such as 198.93.93.10) with hostnames (such as www.netscape.com). Systems normally get this translated information from a DNS server, or look it up in tables maintained on their systems.

DNS alias

A DNS alias is a hostname that the DNS server knows points to a different host—specifically a DNS CNAME record. Systems always have one real name, but they can have one or more aliases. For example, www.[yourdomain].[domain] might be an alias that points to a real system called realthing.[yourdomain].[domain] where the server currently exists.

EMACS

A text editor that can also be used to read e-mail and news.

expires header

The expiration time of the returned document, specified by the remote server.

extended log file format

Similar to the common log file format, but it contains more information.

file extension

The last section of a filename that typically defines the type of file (for example, GIF and HTML). For example, in the filename index.html the file extension is html.

file type

The format of a given file. For example, a graphics file doesn't have the same file type as a text file. File types are usually identified by the file extension (for esample, .GIF or .HTML).

garbage collector

A process to periodically clean up the cache—for example it removes old files to make room for new ones.

garbage collector daemon

A process that monitors the cache size and spawns the garbage collector when necessary.

GIF

A cross-platform image format originally created by CompuServe. The acronym stands for Graphics Interchange Format. GIF files are usually much smaller in size than other graphic file types (BMP, TIFF). GIF is one of the most common interchange formats. GIF images are readily viewable on UNIX, Microsoft Windows, and Apple Macintosh systems.

hard restart

Terminating the process, and starting it up again.

hostname

A name for a host of the form host.domain.dom, which is translated into an IP address. For example, www.netscape.com is the system www in the subdomain netscape and com domain.

HTML

Hypertext Markup Language is a formatting language used for documents on the World Wide Web. HTML files are plain text files with formatting codes that tell browsers such as the Netscape Navigator how to display text, position graphics and form items, and display links to other pages.

HTTP

Hypertext Transfer Protocol is the method for exchanging information between HTTP servers and clients.

HTTPD

An abbreviation for the HTTP daemon, a program that serves information using the HTTP protocol. The Netscape Communications Server is often called an httpd.

HTTPS

A secure version of HTTP, implemented using the secure sockets layer, SSL.

IP address

Internet Protocol address—a set of numbers, separated by dots, that specifies the actual location of a host on the Internet.

last-modified header

The last modification time of the document file, returned in the HTTP response from the server.

MD5

A message digest algorithm by RSA Data Security, Inc., which can be used to produce a short digest of data of any size, which is unique with high probability, and for which it is mathematically extremely hard to produce a piece of data that will produce the same message digest.

MD5 signature

A message digest produced by the MD5 algorithm.

MIME

Multi-Purpose Internet Mail Extensions. This is an emerging standard for multimedia e-mail and messaging.

NIS

Network Information Service—a system of programs and data files that IRIX systems use to collect, collate, and share specific information about systems, users, filesystems, and network parameters throughout a network of computers.

NCSA

The National Center for Supercomputing Applications is a research organization at the University of Illinois at Urbana-Champaign.

Password file

A file on UNIX systems that stores UNIX user login names, passwords, and user ID numbers. It is also known as /etc/passwd, because of where it is kept. The proxy also has its own password files for user authentication; these are not connected with UNIX users.

proxy server

A proxy server stands between the originating and receiving hosts, performing specified monitoring and control operations for an application protocol.

RAM

Random Access Memory. The physical semiconductor-based memory in a computer.

rc.local

A file that describes programs that are run when the system starts. It is also called /etc/rc.local because of its location.

realm

A term used in HTTP and proxy access authorization that helps the user identify what part of the system is asking for an HTTP or proxy user name and password. For example, the realm in the Netscape Proxy Server Manager is “Netscape Proxy Administration.”

redirection

A system by which clients accessing a particular URL are sent to a different location, either on the same server or on a different server. This is useful if a resource has moved and you want the clients to use the new location transparently. It's also used to maintain the integrity of relative links when directories are accessed without a trailing slash.

resource

Any document (URL), directory, or program that the server can access and send to a client that asks for it.

root

The most privileged user available on IRIX systems. The root user has complete access privileges to all files on the system.

server daemon

The server daemon is a process that, once running, listens for and accepts requests from clients.

server root

A directory on the server system dedicated to holding the server program, configuration, maintenance, and information files.

SOCKS

Firewall software that establishes a connection from inside a firewall to the outside when direct connection would otherwise be prevented by the firewall software or hardware (for example, the router configuration).

soft restart

Causes the server to internally restart, that is, reread its configuration files, by sending the process the HUP signal (signal number one). The process itself does not die, as it does in hard restart.

SSL

Secure Sockets Layer. A software library establishing a secure connection between two parties (client and server) used to implement HTTPS, the secure version of HTTP.

superuser

The most privileged user available on UNIX systems (also called root). The superuser has complete access privileges to all files on the system.

telnet

A protocol where two systems on the network are connected to each other and support terminal emulation for remote login.

timeout

A specified time after which the server should give up trying to finish a service routine that appears hung.

top

A program that shows the current state of system resource usage. See also gr_top(1).

top-level domain authority

The highest category of hostname classification, usually signifying either the type of organization the domain is (.com is a company, .edu is an educational institution) or the country of its origin (.us is the United States, .jp is Japan, .au is Australia, .fi is Finland).

UID

A unique number associated with each UNIX user on a system.

URL

Uniform Resource Locator—the addressing system used by the server and the client to request documents. It is often called a location. The format of a URL is [protocol]://[system:port]/[document]. A sample URL is http://www.netscape.com/index.html.

URL database

A database in the Netscape cache that contains all the URLs found in the cache and links them to the cache files. This database can be browsed using the Cache Manager.

URL database repair

A process that repairs and updates a URL database that has been damaged by a software failure, a system crash, a disk breakdown, or a full filesystem.