Axis 207MW Manuale Utente

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AXIS 207W/AXIS 207MW - Glossary of Terms
are created and used with a set of programming requests or 
"function calls" sometimes called the sockets application 
programming interface (API). 
SSL/TSL (Secure Socket Layer/Transport Layer Security)
These two protocols (SSL is succeeded by TSL) are 
cryptographic protocols that provide secure communication 
on a network. SSL is commonly used over HTTP to form 
HTTPS, as used e.g. on the Internet for electronic financial 
transactions. SSL uses public key certificates to verify the 
identity of the server. 
Subnet/subnet mask - A subnet is an identifiably separate 
part of an organization's network. Typically, a subnet may 
represent all the machines at one geographic location, in 
one building, or on the same local area network (LAN). 
Having an organization's network divided into subnets 
allows it to be connected to the Internet with a single shared 
network address.
The subnet mask is the part of the IP address that tells a 
network router how to find the subnet that the data packet 
should be delivered to. Using a subnet mask saves the router 
having to handle the entire 32-bit IP address; it simply 
looks at the bits selected by the mask.
Switch - A switch is a network device that connects 
network segments together, and which selects a path for 
sending a unit of data to its next destination. In general, a 
switch is a simpler and faster mechanism than a router, 
which requires knowledge about the network and how to 
determine the route. Some switches include the router 
function. See also Router.
TCP (Transmission Control Protocol) - TCP  is used along 
with the Internet Protocol (IP) to transmit data as packets 
between computers over the network. While IP takes care of 
the actual packet delivery, TCP keeps track of the individual 
packets that the communication (e.g. requested a web page 
file) is divided into, and, when all packets have arrived at 
their destination, it reassembles them to re-form the 
complete file.
TCP is a connection-oriented protocol, which means that a 
connection is established between the two end-points and is 
maintained until the data has been successfully exchanged 
between the communicating applications. 
Telnet - Telnet is a simple method with which to access 
another network device, e.g. a computer. The HTTP protocol 
and the FTP protocols allow you to request specific files 
from remote computers, but do not allow you logon as a 
user of that computer. With Telnet, you log on as a regular 
user with whatever privileges you may have been granted 
for specific applications and data residing on that computer.
TVL (TV Lines) - A method of defining resolutions in 
analog video.
UDP (User Datagram Protocol) - UDP is a communications 
protocol that offers limited service for exchanging data in a 
network that uses the Internet Protocol (IP). UDP is an 
alternative to the Transmission Control Protocol (TCP). The 
advantage of UDP is that it is not required to deliver all data 
and may drop network packets when there is e.g. network 
congestion. This is suitable for live video, as there is no 
point in re-transmitting old information that will not be 
displayed anyway.
Unicast - Communication between a single sender and a 
single receiver over a network. A new connection is 
established for each new user. 
URL (Uniform Resource Locator) - An "address" on the 
network.
USB - (Universal Serial Bus) A plug-and-play interface 
between a computer and peripheral devices, e.g. scanners, 
printers, etc.
Varifocal lens - A varifocal lens provides a wide range of 
focal lengths, as opposed to a lens with a fixed focal length, 
which only provides one. 
VPN (Virtual Private Network) - This creates a secure 
"tunnel" between the points within the VPN. Only devices 
with the correct "key" will be able to work within the VPN. 
The VPN network can be within a company LAN (Local Area 
Network), but different sites can also be connected over the 
Internet in a secure way. One common use for VPN is for 
connecting a remote computer to the corporate network, via 
e.g. a direct phone line or via the Internet.
VOP (Video Object Plane) - A VOP is an image frame in an 
MPEG-4 video stream. There are several types of VOP:
- An I-VOP is complete image frame.
- A P-VOP codes the differences between images, as long as 
it is more efficient to do so. Otherwise it codes the whole 
image, which may also be a completely new image. 
WAN (Wide-Area-Network) - Similar to a LAN, but on a 
larger geographical scale. 
W-LAN (Wireless LAN) - A wireless LAN is a wireless local 
area network that uses radio waves as its carrier: where the 
network connections for end-users are wireless. The main 
network structure usually uses cables.
Web server  - A Web server is a program, which allows 
Web browsers to retrieve files from computers connected to 
the Internet. The Web server listens for requests from Web 
browsers and upon receiving a request for a file sends it 
back to the browser.
The primary function of a Web server is to serve pages to 
other remote computers; consequently, it needs to be 
installed on a computer that is permanently connected to 
the Internet. It also controls access to the server whilst 
monitoring and logging server access statistics.
WEP (Wireless Equivalent Privacy) - A wireless security 
protocol, specified in the IEEE 802.11 standard, which is 
designed to provide a wireless local area network (WLAN) 
with a level of security and privacy comparable to that 
usually expected of a wired LAN. Security is at two different