Shared resource
Encyclopedia
In computing
, a shared resource or network share is a device or piece of information on a computer that can be remotely accessed from another computer, typically via a local area network
or an enterprise Intranet
, transparently as if it were a resource in the local machine.
Examples are shared file access (also known as disk sharing and folder sharing), shared printer access (printer sharing), shared scanner access, etc. The shared resource is called a shared disk (also known as mounted disk), shared drive volume, shared folder, shared file, shared document, shared printer or shared scanner.
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. Though, as BitTorrent and similar applications became available in the early 2000's, the term file sharing increasingly has become associated with peer-to-peer file sharing
over the Internet.
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 computer
s include distributed file system
s 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).
and Windows
PC computers. This implies that a network share can be addressed according to the following:
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 \\server\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.
s 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 network
s (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 os 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 Windows XP Home Edition operating system, english version, 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.
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, especialy for homes and small office networks.
(FTP), or the Bluetooth
or 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.
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
.
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.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, a shared resource or network share is a device or piece of information on a computer that can be remotely accessed from another computer, typically via a local area network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
or an enterprise Intranet
Intranet
An intranet is a computer network that uses Internet Protocol technology to securely share any part of an organization's information or network operating system within that organization. The term is used in contrast to internet, a network between organizations, and instead refers to a network...
, transparently as if it were a resource in the local machine.
Examples are shared file access (also known as disk sharing and folder sharing), shared printer access (printer sharing), shared scanner access, etc. The shared resource is called a shared disk (also known as mounted disk), shared drive volume, shared folder, shared file, shared document, shared printer or shared scanner.
The term file sharing traditionally means shared file access, especially in the context of operating systems and LAN
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
and Intranet
Intranet
An intranet is a computer network that uses Internet Protocol technology to securely share any part of an organization's information or network operating system within that organization. The term is used in contrast to internet, a network between organizations, and instead refers to a network...
services, for example in Microsoft Windows documentation. Though, as BitTorrent and similar applications became available in the early 2000's, the term file sharing increasingly has become associated with peer-to-peer file sharing
File sharing
File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multimedia , documents, or electronic books. It may be implemented through a variety of ways...
over the Internet.
Common file systems and protocols
Shared file and printer access require an operating systemOperating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer 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
Application layer
The Internet protocol suite and the Open Systems Interconnection model of computer networking each specify a group of protocols and methods identified by the name application layer....
(in the four or five layer TCP/IP reference model) file sharing protocol and transport layer
Transport layer
In computer networking, the transport layer or layer 4 provides end-to-end communication services for applications within a layered architecture of network components and protocols...
protocol to provide that shared access. Modern operating systems for personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
s include distributed file system
Distributed file system
Network file system may refer to:* A distributed file system, which is accessed over a computer network* Network File System , a specific brand of distributed file system...
s 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:
| Primary operating system | Application protocol | Transport protocol |
|---|---|---|
| Mac OS Mac OS Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface... |
Apple Filing Protocol Apple Filing Protocol The Apple Filing Protocol is a network protocol that offers file services for Mac OS X and original Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block , Network File System , File Transfer Protocol , and WebDAV... |
|
| Unix-like Unix-like A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification.... systems |
Network File System (NFS), SMB Server Message Block In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an... |
Transmission Control Protocol The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP... or User Datagram Protocol The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring... |
| MS-DOS MS-DOS MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating... , Windows Microsoft Windows Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal... |
SMB Server Message Block In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an... , also known as CIFS |
Transmission Control Protocol The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP... , User Datagram Protocol The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring... ), NetBIOS NetBIOS is an acronym for Network Basic Input/Output System. It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, NetBIOS is not a networking protocol... transports |
| Novell NetWare Novell NetWare NetWare is a network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, with network protocols based on the archetypal Xerox Network Systems stack.... (server) MS-DOS, Windows (client) |
NetWare Core Protocol The NetWare Core Protocol is a network protocol used in some products from Novell, Inc. It is usually associated with the NetWare operating system, but parts of it have been implemented on other platforms such as Linux, Windows NT and various flavors of Unix.It is used to access file, print,... and Service Advertising Protocol The Service Advertising Protocol is included in the Internetwork Packet Exchange protocol. SAP makes the process of adding and removing services on an IPX internetwork dynamic... |
IPX/SPX IPX/SPX stands for Internetwork Packet Exchange/Sequenced Packet Exchange. IPX and SPX are networking protocols used primarily on networks using the Novell NetWare operating systems.-Protocol Layers:... (over IPX IPX Internetwork Packet Exchange is the OSI-model Network layer protocol in the IPX/SPX protocol stack.The IPX/SPXM protocol stack is supported by Novell's NetWare network operating system. Because of Netware's popularity through the late 1980s into the mid 1990s, IPX became a popular internetworking... ), or Transmission Control Protocol The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP... |
The "primary operating system" is the operating system on which the file sharing protocol in question is most commonly used.
On Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
, a network share is provided by the Windows network component "File and Printer Sharing for Microsoft Networks", using Microsoft's SMB (Server Message Block
Server Message Block
In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an...
) protocol. Other operating systems might also implement that protocol; for example, Samba
Samba (software)
Samba is a free software re-implementation, originally developed by Andrew Tridgell, of the SMB/CIFS networking protocol. As of version 3, Samba provides file and print services for various Microsoft Windows clients and can integrate with a Windows Server domain, either as a Primary Domain...
is an SMB server running on Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems and some other non-MS-DOS/non-Windows operating systems such as OpenVMS
OpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
. Samba can be used to create network shares which can be accessed, using SMB, from computers running Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
. 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
The share can be accessed by client computers through some naming convention, such as UNC (Universal Naming Convention) used on DOSDOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
and Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
PC computers. This implies that a network share can be addressed according to the following:
- \\ServerComputerName\ShareName
where ServerComputerName is the WINS name, DNS
Domain name system
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
name or IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
of the server computer, and ShareName may be a folder or file name, or its path
Path (computing)
A path, the general form of a filename or of a directory name, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent...
. The shared folder can also be given a ShareName that is different from the folder local name at the server side. For example \\server\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
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 wormComputer worm
A computer worm is a self-replicating malware computer program, which uses a computer network to send copies of itself to other nodes and it may do so without any user intervention. This is due to security shortcomings on the target computer. Unlike a computer virus, it does not need to attach...
s 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
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
or enterprise Intranet
Intranet
An intranet is a computer network that uses Internet Protocol technology to securely share any part of an organization's information or network operating system within that organization. The term is used in contrast to internet, a network between organizations, and instead refers to a network...
. However, by means of virtual private network
Virtual private network
A virtual private network is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network....
s (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
Directory (file systems)
In computing, a folder, directory, catalog, or drawer, is a virtual container originally derived from an earlier Object-oriented programming concept by the same name within a digital file system, in which groups of computer files and other folders can be kept and organized.A typical file system may...
or file as shared, or by changing the file system permissions
File system permissions
Most current file systems have methods of administering permissions or access rights to specific users and groups of users. These systems control the ability of the users to view or make changes to the contents of the filesystem....
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 os 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 Windows XP Home Edition operating system, english version, the preshared folder is named Shared documents, typically with the path
Path (computing)
A path, the general form of a filename or of a directory name, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent...
C:\Documents and Settings\All users\Shared documents. In Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
and Windows 7, the pre-shared folder is named public documents, typically with the path C:\Users\Public\Public documents.
Workgroup topology or centralized server
In home and small office networks, a decentralizedDecentralized computing
Decentralized computing is the allocation of resources, both hardware and software, to each individual workstation, or office location. In contrast, centralized computing exists when the majority of functions are carried out, or obtained from a remote centralized location. Decentralized computing...
approach is often used, where every user may make their local folders and printers available to others. This approach is sometimes denoted a Workgroup
Workgroup (Computer networking)
A workgroup is Microsoft's terminology for a peer-to-peer Windows computer network.Microsoft operating systems in the same workgroup may allow each other access to their files, printers, or Internet connection...
or peer-to-peer
Peer-to-peer
Peer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads among peers. Peers are equally privileged, equipotent participants in the application...
network topology, since the same computer may be used as client as well as server.
In large enterprise networks, a centralized file server
File server
In computing, a file server is a computer attached to a network that has the primary purpose of providing a location for shared disk access, i.e. shared storage of computer files that can be accessed by the workstations that are attached to the computer network...
or print server
Print server
A print server, or printer server, is a device that connects printers to client computers over a network. It can accept print jobs from the computers and send the jobs to the appropriate printers....
, 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
File server
In computing, a file server is a computer attached to a network that has the primary purpose of providing a location for shared disk access, i.e. shared storage of computer files that can be accessed by the workstations that are attached to the computer network...
or print server
Print server
A print server, or printer server, is a device that connects printers to client computers over a network. It can accept print jobs from the computers and send the jobs to the appropriate printers....
remote computer passively waits for requests to start a communication session
In very large networks, a Storage Area Network
Storage area network
A storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...
(SAN) approach may be used.
Online storage on a server outside the local network is currently an option, especialy for homes and small office networks.
Difference from file transfer
Shared file access should not be confused with file transfer using the file transfer protocolFile Transfer Protocol
File Transfer Protocol is a standard network protocol used to transfer files from one host to another host over a TCP-based network, such as the Internet. FTP is built on a client-server architecture and utilizes separate control and data connections between the client and server...
(FTP), or the Bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
or IRDA
IRDA
IRDA may refer to:* Infrared Data Association, in information and communications technology , a standard for communication between devices over short distances using infrared signals...
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.
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
Concurrency control
In information technology and computer science, especially in the fields of computer programming , operating systems , multiprocessors, and databases, concurrency control ensures that correct results for concurrent operations are generated, while getting those results as quickly as possible.Computer...
or locking
Lock (computer science)
In computer science, a lock is a synchronization mechanism for enforcing limits on access to a resource in an environment where there are many threads of execution. Locks are one way of enforcing concurrency control policies.-Types:...
of a remote file while a user is editing it, and file system permissions
File system permissions
Most current file systems have methods of administering permissions or access rights to specific users and groups of users. These systems control the ability of the users to view or make changes to the contents of the filesystem....
.
Difference from synchronization
Shared file access involves but should not be confused with file synchronizationFile synchronization
File synchronization in computing is the process of ensuring that computer files in two or more locations are updated via certain rules....
and other information synchronization. Internet based information synchronization may for example use the SyncML
SyncML
SyncML is the former name for a platform-independent information synchronization standard. The project is currently referred to as Open Mobile Alliance Data Synchronization and Device Management...
language. Shared file access is based on server side pushing of folder information, and is normally used over an "always on" Internet socket
Internet socket
In computer networking, an Internet socket or network socket is an endpoint of a bidirectional inter-process communication flow across an Internet Protocol-based computer network, such as the Internet....
. 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
Cache
In computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
of remote files, allowing offline access and synchronization when reconnected.
See also
- Client portalClient portalA client portal is an electronic gateway to a collection of digital files, services, and information, accessible over the Internet through a web browser.The term is most often applied to a sharing mechanism between an organization and its clients...
s - Distributed file systemDistributed file systemNetwork file system may refer to:* A distributed file system, which is accessed over a computer network* Network File System , a specific brand of distributed file system...
s - File area network
- List of file systems, distributed file systems section
- Network file systemNetwork File SystemNetwork File System is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing...
s - Network-attached storageNetwork-attached storageNetwork-attached storage is file-level computer data storage connected to a computer network providing data access to heterogeneous clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements...
(NAS)