Computer resource made available from one host to other hosts on a computer network
In
computing
, a
shared resource
, or
network share
, is a
computer resource
made available from one
host
to other hosts on a
computer network
.
[1]
[2]
It is a device or piece of information on a computer that can be remotely accessed from another computer transparently as if it were a resource in the local machine. Network sharing is made possible by
inter-process communication
over the network.
[2]
[3]
Some examples of shareable resources are
computer programs
,
data
,
storage devices
, and
printers
. E.g.
shared file access
(also known as
disk sharing
and
folder sharing
), shared printer access, shared scanner access, etc. The shared resource is called a
shared disk
,
shared folder
or
shared document
The term
file sharing
traditionally means shared file access, especially in the context of operating systems and
LAN
and
Intranet
services, for example in Microsoft Windows documentation.
[4]
Though, as
BitTorrent
and similar applications became available in the early 2000s, the term
file sharing
increasingly has become associated with
peer-to-peer file sharing
over the Internet.
Common file systems and protocols
[
edit
]
Shared file and printer access require an
operating system
on the client that supports access to resources on a server, an operating system on the server that supports access to its resources from a client, and an
application layer
(in the four or five layer
TCP/IP reference model
) file sharing
protocol
and
transport layer
protocol to provide that shared access. Modern operating systems for
personal computers
include
distributed file systems
that support file sharing, while hand-held computing devices sometimes require additional software for shared file access.
The most common such file systems and protocols are:
The "primary operating system" is the operating system on which the file sharing protocol in question is most commonly used.
On
Microsoft Windows
, a network share is provided by the Windows network component "File and Printer Sharing for Microsoft Networks", using Microsoft's SMB (
Server Message Block
) protocol. Other operating systems might also implement that protocol; for example,
Samba
is an SMB server running on
Unix-like
operating systems and some other non-MS-DOS/non-Windows operating systems such as
OpenVMS
. Samba can be used to create network shares which can be accessed, using SMB, from computers running
Microsoft Windows
. An alternative approach is a
shared disk file system
, where each computer has access to the "native" filesystem on a shared disk drive.
Shared resource access can also be implemented with
Web-based Distributed Authoring and Versioning
(WebDAV).
Naming convention and mapping
[
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]
The share can be accessed by client computers through some naming convention, such as
UNC
(Universal Naming Convention) used on
DOS
and
Windows
PC computers. This implies that a network share can be addressed according to the following:
- \\
ServerComputerName
\
ShareName
where
ServerComputerName
is the
WINS
name,
DNS
name or
IP address
of the server computer, and
ShareName
may be a folder or file name, or its
path
. The shared folder can also be given a ShareName that is different from the folder local name at the server side. For example,
\\
ServerComputerName
\c$
usually denotes a drive with drive letter
C:
on a Windows machine.
A shared drive or folder is often
mapped
at the client PC computer, meaning that it is assigned a
drive letter
on the local PC computer. For example, the drive letter
H:
is typically used for the user home directory on a central file server.
Security issues
[
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]
A network share can become a security liability when access to the shared files is gained (often by devious means) by those who should not have access to them. Many
computer worms
have spread through network shares. Network shares would consume extensive communication capacity in non-broadband network access. Because of that, shared printer and file access is normally prohibited in
firewalls
from computers outside the
local area network
or enterprise
Intranet
. However, by means of
virtual private networks
(VPN), shared resources can securely be made available for certified users outside the local network.
A network share is typically made accessible to other users by marking any
folder
or file as shared, or by changing the
file system permissions
or access rights in the properties of the folder. For example, a file or folder may be accessible only to one user (the owner), to system administrators, to a certain group of users to public, i.e. to all logged in users. The exact procedure varies by platform.
In operating system editions for homes and small offices, there may be a special
pre-shared folder
that is accessible to all users with a user account and password on the local computer. Network access to the pre-shared folder can be turned on. In the English version of the
Windows XP Home Edition
operating system, the preshared folder is named
Shared documents
, typically with the
path
C:\Documents and Settings\All users\Shared documents
. In
Windows Vista
and
Windows 7
, the pre-shared folder is named
Public documents
, typically with the path
C:\Users\Public\Public documents
.
[6]
Workgroup topology or centralized server
[
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]
In home and small office networks, a
decentralized
approach is often used, where every user may make their local folders and printers available to others. This approach is sometimes denoted a
Workgroup
or
peer-to-peer
network topology, since the same computer may be used as client as well as server.
In large enterprise networks, a centralized
file server
or
print server
, sometimes denoted
client?server paradigm
, is typically used. A client process on the local user computer takes the initiative to start the communication, while a server process on the
file server
or
print server
remote computer passively waits for requests to start a communication session
In very large networks, a
Storage Area Network
(SAN) approach may be used.
Online storage
on a server outside the local network is currently an option, especially for homes and small office networks.
Comparison to file transfer
[
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]
Shared file access should not be confused with file transfer using the
file transfer protocol
(FTP), or the
Bluetooth
IRDA
OBject EXchange
(OBEX) protocol. Shared access involves automatic synchronization of folder information whenever a folder is changed on the server, and may provide server side file searching, while file transfer is a more rudimentary service.
[7]
Shared file access is normally considered as a local area network (LAN) service, while FTP is an Internet service.
Shared file access is transparent to the user, as if it was a resource in the local file system, and supports a multi-user environment. This includes
concurrency control
or
locking
of a remote file while a user is editing it, and
file system permissions
.
Comparison to file synchronization
[
edit
]
Shared file access involves but should not be confused with
file synchronization
and other information synchronization. Internet-based information synchronization may, for example, use the
SyncML
language. Shared file access is based on server-side pushing of folder information, and is normally used over an "always on"
Internet socket
. File synchronization allows the user to be offline from time to time and is normally based on an agent software that polls synchronized machines at reconnect, and sometimes repeatedly with a certain time interval, to discover differences. Modern operating systems often include a local
cache
of remote files, allowing
offline access
and synchronization when reconnected.
History
[
edit
]
The first international heterogenous network for resource sharing was the 1973 interconnection of the
ARPANET
with early
British academic networks
through the computer science department at
University College London
(UCL).
[8]
[9]
[10]
See also
[
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]
References
[
edit
]
- ^
Padlipsky, Michael A.
(September 1982).
A Perspective on the ARPANET Reference Model
.
IETF
.
doi
:
10.17487/RFC0871
.
RFC
871
. Retrieved
15 December
2013
.
- ^
a
b
Walden, David C. (July 1970).
A Note on Interprocess in a Resource Sharing Computer Network
.
IETF
.
doi
:
10.17487/RFC0061
.
RFC
61
. Retrieved
15 December
2013
.
- ^
Walden, David C. (August 1970).
A System for Interprocess Communication in a Resource Sharing Computer Network
.
IETF
.
doi
:
10.17487/RFC0062
.
RFC
62
. Retrieved
15 December
2013
.
- ^
Microsoft Technet,
File and Printer Sharing in Windows Vista
, May 14, 2007
- ^
"Apple shifts from AFP file sharing to SMB2 in OS X 10.9 Mavericks"
.
AppleInsider
. Quiller Media, Inc. 11 June 2013.
- ^
Katy Ivens,
Networking for dummies
, 4th edition, 2007, page 121. Suggest the term "pre-shared folder".
- ^
Share Files across Cloud Storage
.
- ^
M. Ziewitz & I. Brown (2013).
Research Handbook on Governance of the Internet
.
Edward Elgar Publishing
. p. 7.
ISBN
978-1849805049
. Retrieved
2015-08-16
.
- ^
Kirstein, P.T. (1999).
"Early experiences with the Arpanet and Internet in the United Kingdom"
(PDF)
.
IEEE Annals of the History of Computing
.
21
(1): 38?44.
doi
:
10.1109/85.759368
.
ISSN
1934-1547
.
S2CID
1558618
. Archived from
the original
(PDF)
on 2020-02-07.
- ^
"30 years of the international internet"
.
BBC News
. 19 November 2003
. Retrieved
22 June
2012
.