Background Intelligent Transfer Service (BITS) is a component of
Microsoft Windows XP and later iterations of the operating systems, which facilitates asynchronous, prioritized, and throttled transfer of files between machines using idle network bandwidth. It is most commonly used by recent versions of
Windows Update
Windows Update is a Microsoft service for the Windows 9x and Windows NT families of the Microsoft Windows operating system, which automates downloading and installing Microsoft Windows software updates over the Internet. The service delivers sof ...
,
Microsoft Update,
Windows Server Update Services, and
System Center Configuration Manager to deliver
software updates to clients,
Microsoft
Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...
's anti-virus scanner
Microsoft Security Essentials (a later version of
Windows Defender) to fetch signature updates, and is also used by Microsoft's instant messaging products to transfer files. BITS is exposed through the
Component Object Model
Component Object Model (COM) is a binary-interface technology for software components from Microsoft that enables using objects in a language-neutral way between different programming languages, programming contexts, processes and machines ...
(COM) and the UWP AP
Windows.Networking.BackgroundTransfer
Technology
BITS uses idle
bandwidth to transfer data. Normally, BITS transfers data in the background, i.e., BITS will only transfer data whenever there is bandwidth which is not being used by other applications. BITS also supports resuming transfers in case of disruptions.
BITS version 1.0 supports only downloads. From version 1.5, BITS supports both downloads and uploads. Uploads require the
IIS web server, with BITS server extension, on the receiving side.
Transfers
BITS transfers files on behalf of requesting applications asynchronously, i.e., once an application requests the BITS service for a transfer, it will be free to do any other task, or even terminate. The transfer will continue in the background as long as the network connection is there and the job owner is logged in. BITS jobs do not transfer when the job owner is not signed in.
BITS suspends any ongoing transfer when the network connection is lost or the operating system is shut down. It resumes the transfer from where it left off when (the computer is turned on later and) the network connection is restored. BITS supports transfers over
SMB,
HTTP
HTTP (Hypertext Transfer Protocol) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, wher ...
and
HTTPS
Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP). It uses encryption for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protoc ...
.
Bandwidth
BITS attempts to use only spare bandwidth. For example, when applications use 80% of the available bandwidth, BITS will use only the remaining 20%. BITS constantly monitors network traffic for any increase or decrease in network traffic and
throttles its own transfers to ensure that other foreground applications (such as a
web browser
A web browser, often shortened to browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's scr ...
) get the bandwidth they need.
Note that BITS does not necessarily measure the actual bandwidth. BITS versions 3.0 and up will use
Internet Gateway Device counters, if available, to more accurately calculate available bandwidth. Otherwise, BITS will use the speed as reported by the
NIC to calculate bandwidth. This can lead to bandwidth calculation errors, for example when a fast network adapter (10 Mbit/s) is connected to the network via a slow link (56 kbit/s).
Jobs
BITS uses a queue to manage file transfers. A BITS session has to be started from an application by creating a ''Job''. A job is a container, which has one or more files to transfer. A newly created job is empty. Files must be added, specifying both the source and destination
URIs. While a download job can have any number of files, upload jobs can have only one. Properties can be set for individual files. Jobs inherit the security context of the application that creates them.
BITS provides
API
An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...
access to control jobs. A job can be programmatically started, stopped, paused, resumed, and queried for status. Before starting a job, a priority has to be set for it to specify when the job is processed relative to other jobs in the transfer queue. By default, all jobs are of ''Normal'' priority. Jobs can optionally be set to ''High'', ''Low'', or ''Foreground'' priority. Background transfers are optimized by BITS, which increases and decreases (or throttles) the rate of transfer based on the amount of idle network bandwidth that is available. If a network application begins to consume more bandwidth, BITS decreases its transfer rate to preserve the user's interactive experience, except for ''Foreground'' priority downloads.
Scheduling
BITS
schedules each job to receive only a finite
time slice, for which only that job is allowed to transfer, before it is temporarily paused to give another job a chance to transfer. Higher priority jobs get a higher chunk of time slice. BITS uses
round-robin scheduling to process jobs in the same priority and to prevent a large transfer job from blocking smaller jobs.
When a job is newly created, it is automatically ''suspended'' (or paused). It has to be explicitly ''resumed'' to be activated. ''Resuming'' moves the job to the ''queued'' state. On its turn to transfer data, it first connects to the remote server and then starts transferring. After the job's time slice expires, the transfer is temporarily paused, and the job is moved back to the ''queued'' state. When the job gets another time slice, it has to connect again before it can transfer. When the job is complete, BITS transfers ownership of the job to the application that created it.
BITS includes a built-in mechanism for error handling and recovery attempts. Errors can be either ''fatal'' or ''transient''; either moves a job to the respective state. A ''transient'' error is a temporary error that resolves itself after some time. For a transient error, BITS waits for some time and then retries. For ''fatal'' errors, BITS transfers control of the job to the creating application, with as much information regarding the error as it can provide.
Command-line interface tools
BITSAdmin command
Microsoft provides a BITS Administration Utility (
BITSAdmin
)
command-line utility
In economics, utility is a measure of a certain person's satisfaction from a certain state of the world. Over time, the term has been used with at least two meanings.
* In a normative context, utility refers to a goal or objective that we wish ...
to manage BITS jobs. The utility is part of
Windows Vista
Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, released five years earlier, which was then the longest time span between successive releases of Microsoft W ...
and later. It is also available as a part of the ''Windows XP Service Pack 2 Support Tools'' or ''Windows Server 2003 Service Pack 1 Support Tools''.
Usage example:
C:\>bitsadmin /transfer myDownloadJob /download /priority normal https://example.com/file.zip C:\file.zip
PowerShell BitsTransfer
In
Windows 7
Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was Software release life cycle#Release to manufacturing (RTM), released to manufacturing on July 22, 2009, and became generally available on October 22, ...
, the
BITSAdmin
utility is deprecated in favor of
Windows PowerShell cmdlets. The
BitsTransfer
PowerShell module provides eight cmdlets with which to manage BITS jobs.
The following example is the equivalent of the BITSAdmin example above:
PS C:\> Start-BitsTransfer -Source "https://example.com/file.zip" -Destination "C:\file.zip" -DisplayName "myDownloadJob"
List of non-Microsoft applications that use BITS
*
AppSense – Uses BITS to install Packages on clients.
* BITS Download Manager – A
download manager
A download manager is a type of software that manages the downloading of files from the Internet, which may be built into a web browser, or as a standalone program.
Functions
A download manager manages files being downloaded from the internet. ...
for Windows that creates BITS Jobs.
* BITSync – An
open source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
utility that uses BITS to perform
file synchronization on
Server Message Block network shares.
* ''
Civilization V'' – Uses BITS to download
mod packages.
*
Endless OS installer for Windows – Uses BITS to download OS images.
* ''
Eve Online'' – Uses BITS to download all the patches post-Apocrypha (March 10, 2009). It is also now used in the client repair tool.
* Some
Google
Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
services including
Chrome,
Gears,
Pack,
Flutter updater and
YouTube Uploader used BITS.
*
Firefox
Mozilla Firefox, or simply Firefox, is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary, the Mozilla Corporation. It uses the Gecko rendering engine to display web pages, which implements curr ...
(since version 68) for updates.
*
KBOX Systems Management Appliance – A
systems management
Systems management is enterprise-wide System administration, administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunic ...
appliance that can use BITS to deliver files to Windows systems.
*
RSS Bandit – Uses BITS to download attachments in web feeds.
* Oxygen media platform – Uses BITS to distribute Media Content and Software Updates.
* SharpBITS – An
open source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
download manager
A download manager is a type of software that manages the downloading of files from the Internet, which may be built into a web browser, or as a standalone program.
Functions
A download manager manages files being downloaded from the internet. ...
for Windows that handles BITS jobs.
* WinBITS – An
open source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
Downloader for Windows that downloads files by creating BITS Jobs.
*
Novell ZENworks Desktop Management – A
systems management
Systems management is enterprise-wide System administration, administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunic ...
software that can use BITS to deliver application files to workstations.
* Specops Deploy/App – A
systems management
Systems management is enterprise-wide System administration, administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunic ...
software that (when available) uses BITS for delivering packages to the clients in the background.
FTP Download- Download files using the ftp protocol. Support downloads from servers with expired certificates (ex. old websites). Written in UWP and available on the official Microsoft Store.
See also
*
List of Microsoft Windows components
*
Comparison of file transfer protocols
References
External links
Background Intelligent Transfer Service in Windows Server 2008Fix Background Intelligent Transfer Service in Windows 10BITS version historybitsadmin , Microsoft Docs
{{Microsoft APIs
Distributed data storage
Network file transfer protocols
Hypertext Transfer Protocol clients
Windows services
Windows administration