U

UDDI

See Universal Description, Discovery, and Integration

UDP

See User Datagram Protocol

Uniform Resource Identifier (URI)

A generic term for all names and addresses that reference objects on the Internet. A URL is a specific type of URI. See Uniform Resource Locator (URL).

Uniform Resource Locator (URL)

A text representation of a specific location on the Internet. URLs normally include the protocol (http:// for example), the target location (World Wide Web or www), the domain or server name (mycompany), and a domain type (com for

commercial). It can also include a hierarchical location within that Web site. The URL usually specifies a particular file on the Web server, although there are some situations when a Web server will use a default filename. For example, asking the browser to find http://www.mycompany.com, would probably display the DEFAULT.HTM or INDEX.HTM file at that location. The actual default filename depends on the Web server used. In some cases, the default filename is configurable and could be any of a number of files. For example, Internet Information Server (IIS) offers this feature, so the developer can use anything from an HTM to an ASP or an XML file as the default.

Universal Description, Discovery, and Integration (UDDI)

A standard method of advertising application and other software-related services online. The vendor offering the service registers at one or more centralized locations. Clients wishing to use the service add pointers to the service to their application.

URI

See Uniform Resource Identifier

URL

See Uniform Resource Locator

User Datagram Protocol (UDP)

Allows applications to exchange individual packets of information over an IP network. UDP uses a combination of protocol ports and IP addresses to get a message from one point of the network to another. More than one client can use the same protocol port as long as all clients using the port have a unique IP address. There are two types of protocol port: well known and dynamically bound. The well-known port assignments use the ports numbered between 1 and 255. When using dynamically bound port assignments, the requesting applications queries the service first to see which port it can use. Unlike TCP/IP, UDP/IP provides very few error recovery services, making it a fast way to deliver broadcast messages and perform other tasks where reliability isn’t a concern.