Information Technology Reference
In-Depth Information
When an individual uses remote file access to edit a file, the
user's changes may be communicated as they are made (write
through), when the user has finished editing (writeonclose), or in
batches (writedelayed). When several people wish to make changes
in the same file, different copies of the file may contain different ver
sions of the material, and care is needed to determine which copy is
correct. Solutions to this concurrentupdate problem may follow an
ostrich approach or a filelocking mechanism.
When several people use different operating systems to share
common files, complications can arise if the computers follow dif
ferent file formats. When a file following one convention is viewed
by a system using another convention, the file may seem garbled or
unintelligible.
Underlying file sharing, computer networks often use Transmission
Control Protocol/Internet Protocol (TCP/IP) to organize information
into packets and send those pieces of information through the network.
As part of the transmission process, each message contains a port num
ber so the receiving computer can identify what application to give the
information to. Common applications have port numbers specified by
the Internet Corporation for Assigned Names and Numbers (ICANN).
■
Terminology from This Chapter
Anonymous FTP
Cache coherence
Client
Clientinitiated
update
Concurrent update
problem
File server
File Transfer
Protocol (FTP)
Frame
Location
independence
Location
transparency
Lock
Port address
Packet
Remote file access
Server
Serverinitiated
update
Transmission
Control Protocol/
Internet Protocol
(TCP/IP)
■
Discussion Questions
1.
Suppose caching is used for remote file access.
a.
Why would it be important for a client computer to have
either a large main memory or a disk?
