Specifications

Niagara Release 2.3
Niagara Networking & Connectivity Guide
Glossary
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H
host A device on an IP network. This could be a PC, a router, a printer, or any other device
that is configured with at least one IP address.
HOSTS file The HOSTS file is a text file residing on each local machine. Each line of the text file
typically contains an IP address of a host and a name for it. HOSTS files were the
original mechanism used to resolve an IP address to a name, but now other
technologies, such as WINS, DNS, and DDNS are more common.
HTTP Hypertext transfer protocol. The protocol used by the World Wide Web. HTTP
defines how Web servers and browsers transmit and format messages, including
actions commands. HTTP is called a stateless protocol because each command is
executed independently, without knowledge of the commands that came before it.
Newer technologies such as Java overcome this limitation to make Web pages react
intelligently. The other main standard that controls how the World Wide Web works
is HTML, which determines how Web pages are formatted and displayed.
I
interstation links Links between two Niagara stations for the purposes of passing real-time data. Also
known as an external link, because the link is external to the station database. To
create an interstation link, each station must have the other station in its address book,
and the address book entries must have valid user names and passwords.
IP Internet protocol. See TCP/IP and protocol.
IP address In IP version 4, an IP address is a 32-bit number which uniquely identifies a host on
the Internet. It is typically written in dotted decimal form nnn.nnn.nnn.nnn (for
example, 192.168.1.1 or 27.34.100.3). Like a telephone number that is used to direct
a call to a company, an IP address is used to direct data to a computer (for example,
displaying a web page with a browser).
IP address class An IP address is made up of two parts, the network portion and the host portion. The
class determines which portion of the address belongs to the network and which part
belongs to the host. There are five classes, A-E, but hosts are only assigned IP
addresses from classes A-C.
J
JACE or JACE controller Java Application Control Engine (rhymes with “pace”). The Tridium-manufactured
controller that runs the core runtime Niagara software in a Java Virtual Machine
(JVM), providing a station with direct support for field device integration plus