UPnP

通用即插即用(UPnP)是由通用型即插即用论坛提出的一套网络协议。该协议的目标是使家庭网络（数据共享、通信和娱乐）和公司网络中的各种设备能够相互无缝连接,并简化相关网络的实现。UPnP 通过定义和发布基于开放、因特网通讯网协议标准的 UPnP 设备控制协议来实现这一目标。

UPnP 这个词是从 Plug-and-play 衍生而来的。Plug-and-play 是一种热拔插技术。

概述

UPnP 体系允许 PC 间的点对点连接、网际互连和无线设备。它是一种基于 TCP/IP、UDP 和 HTTP 的分布式、开放体系。

UPnP 使得任意两个设备能在 LAN 控制设备的管理下相互通信。其特性包括：

• 媒体和设备独立。UPnP 技术可以应用在许多媒体上，包括电话线、电线(PLC)、以太网、IR(IrDA)、RF(Wi-Fi，蓝牙)和火线。无需任务设备驱动；而是采用共同的协议。
• 用户界面(UI)控制。UPnP 技术使得设备厂商可以通过网页浏览器来控制设备并进行交互。
• 操作系统和程序语言独立。任何操作系统和程序语言均可以用于构建 UPnP产品。UPnP 并没有设定或限制运行于控制设备上的应用程序 API；OS厂商可以建立满 足他们客户需求的 API。UPnP使得厂商可以像开发常规应用程序一样来控制设备 UI 和交互。
• 基于因特网技术。UPnP 构建于 IP, TCP, UDP, HTTP, 和 XML 等许多协议之上。
• 编程控制。UPnP 体系同时支持常规应用程序编程控制。
• 扩展性。每个 UPnP 设备都可以有构建于基本体系之上、与具体设备相关的服务。

UPnP 支持零配置，"看不见的网络" 和自动检测; 任何设备能自动加入一个网络， 获取一个 IP 地址，宣布自己的名字，根据请求检查自身功能以及检测出其它设备 和它们的功能。DHCP 和 DNS 服务是可选的，并只有它们在网络上存在的时候才会 使用。设备可以自动离开网络而不会遗留下任何不需要的状态信息。

UPnP 的基础是 IP 地址解析。每一个设备都应当有一个 DHCP 客户端并在连入网 络的时候自动搜索 DHCP 服务。如果没有找到 DHCP 服务，也就是说网络是缺乏管 理状态，那么设备必须给自己设定一个地址。如果在和 DHCP 服务器交互的过程中， 设备获得了一个域名（比如通过 DNS 服务器或者 DNS 传递），那么它应当在接下 来的网络操作中使用这个域名；否则，设备应当使用它的 IP 地址。

协议

检测

给定一个 IP 地址，UPnP 网络中的第一步是检测。当一个设备被加入到网络中， UPnP 检测协议允许该设备向控制点广播自己的服务。类似地，当一个控制点加入到 网络中的时候，它也能够搜索到网络中存在的、感兴趣的设备相关信息。这两种类 型的基础交互是一种仅包含少量、重要相关设备信息或者它的某个服务。比如，类 型、标识和指向更详细信息的链接。UPnP 检测协议是基于简单服务发现协议 (SSDP) 的。

描述

UPnP 网络的下一步是描述。当一个控制点检测到一个设备时，它对该设备仍然知知 甚少。为了使控制点了解更多关于该设备的信息或者和设备进行交互，控制点必须 从设备发出的检测信息中包含的 URL 获取更多的信息。某个设备的 UPnP 描述是 XML 的方式，包括品牌、厂商相关信息，如型号名和编号、序列号、厂商名、品牌 相关 URL 等。描述还包括一个嵌入式设备和服务列表，以及控制、事件传递和存 在相关的 URL。对于每种设备，描述还包括一个命令或动作列表，包括响应何种服 务，针对各种动作的参数；这些变量刻画出运行时设备的状态信息，并通过它们的 数据类型、范围和事件来进行描述。

控制

UPnP 网络的下一步是控制。当一个控制点获取到设备描述信息之后，它就可以向该 设备发送指令了。为了实现此，控制点发送一个合适的控制消息至服务相关控制 URL(包含在设备描述中)。控制消息也是通过简单对象访问协议(SOAP)用 XML 来描 述的。类似函数调用，服务器通过返回动作相关的值来回应控制消息。动作的效果， 如果有的话，会反应在用于刻画运行中服务的相关变量。

事件通知

下一步是事件通知。一个 UPnP 描述包括一组命令列表和刻画运行时状态信息的变 量。服务在这些变量改变的时候进行更新，控制点可以进行订阅以获取相关改变。 服务通过发送事件消息来发布更新。事件消息包括一个或多个状态信息变量以及它 们的当前数值。这些消息也是采用 XML 的格式，用通用事件通知体系(GENA)进行 格式化。一个特殊的初始化消息会在控制点第一次订阅的时候发送，它包括服务相 关的变量名及值。为了支持多个控制点并存的情形，事件通知被设计成对于所有的 控制点都平行通知。因此，所有的订阅者同等地收到所有事件通知。

存在

最后一步是存在。如果设备带有存在 URL, 那么控制点可以通过它来获取设备存在 信息，即在浏览器中加载 URL，并允许用户来进行相关控制或查看操作。具体支持 哪些操作则是由存在页面和设备完成的。

UPnP AV (Audio and Video) standards

UPnP AV stands for UPnP Audio and Video, and is a grouping within the UPnP standards supervised by the DLNA (Digital Living Network Alliance), (formely: Digital Home Working Group), which is a forum of vendors and manufacturers who work in the home entertainment industry, and offer a "DLNA CERTIFIED™" branding for those products which follow their Networked Device Interoperability Guidelines. The DLNA forum members "share a vision of a wired and wireless interoperable network of Personal Computers (PC), Consumer Electronics (CE) and mobile devices in the home enabling a seamless environment for sharing and growing new digital media and content services", and is "DLNA is focused on delivering an interoperability framework of design guidelines based on open industry standards to complete the cross-industry digital convergence". On the 12th of July 2006 the UPnP Forum announced the release of 'Enhanced AV Specifications', this release was version 2 of the UPnP Audio and Video specifications (UPnP AV v2), with new MediaServer version 2.0 and MediaRenderer version 2.0 classes. These enhancements are created by adding capabilities to the UPnP AV MediaServer and MediaRenderer device classes that allow a higher level of interoperability between MediaServers and MediaRenderers from different manufacturers. Some of the early device complying to these standards where marketed by Philips under the Streamium brand name.

UPnP AV components

• UPnP MediaServer DCP - which is the UPnP-server (a 'slave' device) that share/stream media-data (like audio/video/picture/files) to UPnP-clients on the network).
• UPnP MediaServer ControlPoint - which is the UPnP-client (a 'master' device) that can auto-detect UPnP-servers on the network to browse and stream media/data-files from them.
• UPnP MediaRenderer DCP - which is a 'slave' device that can render content.
• UPnP RenderingControl DCP - control MediaRenderer settings; volume, brightness, RGB, sharpness, and more).
• UPnP Remote User Interface (RUI) client/server - which sends/receives control-commands between the UPnP-client and UPnP-server over network, (like record, schedule, play, pause, stop, etc.).
  • Web4CE (CEA 2014) for UPnP Remote UI - CEA-2014 standard designed by Consumer Electronics Association's R7 Home Network Committee. Web-based Protocol and Framework for Remote User Interface on UPnP Networks and the Internet (Web4CE). This standard allows a UPnP-capable home network device to provide its interface (display and control options) as a web page to display on any other device connected to the home network. That means that you can control a home networking device through any web-browser-based communications method for CE devices on a UPnP home network using ethernet and a special version of HTML called CE-HTML.
• QoS (Quality of Service) - is an important (but not mandatory) service function for use with UPnP AV (Audio and Video). QoS (Quality of Service) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program. Since UPnP AV is mostly to deliver streaming media that is often near real-time or real-time audio/video data which it is critical to be delivered within a specific time or the stream is interrupted. QoS (Quality of Service) guarantees are especially important if the network capacity is limited, for example public networks, like the internet.
  • QoS (Quality of Service) for UPnP consist of Sink Device (client-side/front-end) and Source Device (server-side/back-end) service functions. With classes such as; Traffic Class that indicates the kind of traffic in the traffic stream, (for example, audio or video). Traffic Identifier (TID) which identifies data packets as belonging to a unique traffic stream. Traffic Specification (TSPEC) which contains a set of parameters that define the characteristics of the traffic stream, (for example operating requirement and scheduling). Traffic Stream (TS) which is a unidirectional flow of data that originates at a source device and terminates at one or more sink device(s).

NAT traversal

UPnP comes with a solution for NAT (Network Address Translation) traversal: IGD (Internet Gateway Device) protocol. NAT traversal for UPnP enables UPnP packages to pass through a router or firewall without problems and without user interaction, (that is if that router or firewall supports NAT).

Problems with UPnP

• UPnP uses HTTP over UDP (known as HTTPU and HTTPMU for unicast and multicast), even though this is not standardized and is specified only in an Internet-Draft that expired in 2001. [1]
• UPnP does not have a lightweight authentication protocol, while the available security protocols are complex. As a result, many UPnP devices ship with UPnP turned off by default as a security measure.

Future developments

The standard Devices Profile for Web Services or short DPWS, is a candidate successor for UPnP. It solves many of the problems of UPnP. A DPWS client is included in Microsoft Windows Vista as part of the Windows Rally technologies.

UPnP AV MediaServers

UPnP AV MediaServers store and share digital media, such as photographs, movies, or music. There are UPnP MediaServers available for most operating-systems and many hardware-platforms. UPnP AV MediaServers can either be categorized as software-based or hardware-based. Software-based UPnP AV MediaServers can be run on PCs (Personal-Computers), mainly on Microsoft Windows, Linux, BSD, Unix or Mac OS X. Hardware-based UPnP AV MediaServers may run on any NAS (Network Attached Storage) devices or any specific hardware for delivering media, such as a PVR (Personal Video Recorder). Currently, there are more software-based UPnP AV MediaServers than there are hardware-based, but chances are that will change in the future.

UPnP AV MediaServer software

• XBMC (Xbox Media Center), a free, open-source software media-player/media-center for Microsoft's Xbox game-console.
  • XBMC built-in UPnP client and UPnP server code are from Platinum UPnP C++ SDK (open source under GPL).
• Windows Media Connect from Microsoft - free UPnP AV MediaServer and control point (server and client) for Microsoft Windows
  • Windows Media Connect (WMC) version 2.0 can be installed for usage with Windows Media Player 10 for Windows XP
  • Windows Media Connect (WMC) version 3.0 can be installed for usage with Windows Media Player 11 for Windows XP
  • Windows Media Connect (WMC) version 4.0 already comes pre-installed on Windows Vista with its WMP version 11
• FreeNAS, a free operating-system/software (based on FreeBSD), enabling you to turn any x86-based computer into a dedicated stand-alone NAS (Network-Attached Storage) device. (FreeNAS UPnP server code is from the Portable Universal Plug and Play (UPnP) SDK project).
• AwoX mediaCTRL, a commercial DLNA 1.5 Controller, Renderer and Server for Microsoft Windows.
• MythTV, an open source HTPC and PVR software for Linux, with a built-in UPnP AV MediaServer.
• SnapStream Beyond TV (BTV), a commercial Media Control/Renderer/Server and PVR software for Windows.
• Musicmatch Jukebox, a commercial MediaServer UPnP MediaServer and music-player for Windows, (also features media organizing functionality).
• Rhapsody, by RealNetworks, a commercial UPnP MediaServer (with a online music service) for Win/Mac, (Rhapsody requires an WMDRM-ND encrypted DRM connection).
• PyMedS, a free open source Python UPnP MediaServer for Windows/Mac OS X/Linux/UNIX.
• GeeXboX, an opensource lightweight Media center has uShare for Linux.
• MediaTomb - free, open source (GPL) UPnP AV MediaServer for Linux, Mac OS X, FreeBSD and Cygwin which also runs on NAS devices. Allows users to define a custom container layout by the means of JavaScript, has a nice AJAX based UI.
• TwonkyMedia - Commercial and light-weight UPnP AV Server for Windows, Linux and embedded systems. Can be installed for instance on an NSLU2.
• Nero MediaHome - Commercial media-player/media-center software for Windows which is shipped as part of the Nero product suite, it includes a UPnP AV Server (and a UPnP AV Client). The latest version is able to capture and stream live TV and transcodes all common source file formats in real-time to other UPnP AV Clients via the UPnP AV Server.
• Fuppes - free open source UPnP MediaServer, supports transcoding of diverse audio formats to mp3. Only directory browsing supported.
• TVersity - free closed source UPnP MediaServer, currently in beta, which allows on-the-fly transcoding to wmv.
• SimpleCenter is a Java-based UPnP AV MediaServer for Windows.
• Philips Media Manager is a free closed source UPnP AV MediaServer for Windows and Macintosh that is based on Streamium
• vp UPnP MediaServer, a free feature rich UPnP AV MediaServer for Windows written in C# (needs .Net 2.0 installed).
• TVedia closed source UPnP MediaServer/Client.
• GMediaServer A UPnP MediaServer for Linux or other POSIX OS built on libupnp and licensed under the GPL.

UPnP AV MediaServer hardware

• Xbox game-console with XBMC (Xbox Media Center) software, which is a free open-source software multimedia-player.
  • XBMC built-in UPnP client and UPnP server code are from Platinum UPnP C++ SDK (open source under GPL).
• ICY BOX IB-NAS1000, smal SOHO NAS with a 30 days trial version of TwonkyMedia (can be activated for lifetime)
• ICY BOX IB-NAS2000, smal SOHO NAS with 30 days trial version of TwonkyMedia (can be activated for lifetime)
• NSLU2, a hacked/modded version running ushare (a free open source UPnP MediaServer for Linux), (connect USB 2.0 drives to the NSLU2 and share).
• HP Media Vault,wikipedia entry a NAS box from HP has a built-in UPnP AV server.
• UPnP Home Automation system, UPnP domotics.
• Infrant ReadyNAS NV+, a NAS box from Infrant Technologies that supports UPnP AV.
• DLink - DNS-323 and DSM-G600, NAS boxes from D-Link that support UPnP AV.
• Linksys WRTSL54GS, All-in-one internet-sharing router, access point, and network storage link.
• Synology DS-106 Disk Station, a NAS from Synology that supports UPnP AV.
• Maxtor Shared Storage Plus drive includes a built-in Mediabolic UPnP server. The Twonky UPnP server is also available for this drive.

UPnP AV clients (ControlPoint)

UPnP MediaServer ControlPoint is the UPnP-client (a 'master' device) that function as digital audio/video players, which can auto-detect UPnP-servers on the network to browse and stream media/data-files from them.

UPnP control points and player software

• Playstation 3 game-console with OS version 1.8 or later.
• XBMC (Xbox Media Center), a free, open-source software media-player/media-center for Microsoft's Xbox game-console.
  • XBMC built-in UPnP client and UPnP server code are from Platinum UPnP C++ SDK (open source under GPL).
• InterVideo WinDVD, a commercial DVD-Video and video-files playback software for Windows.
• CyberLink PowerDVD, a commercial DVD-Video and video-files playback software for Windows.
• AwoX mediaCTRL, a commercial DLNA 1.5 Controller, Renderer and Server for Microsoft Windows.
• LobsterTunes, a commercial, fully featured Music Player for Windows Mobile Smartphones (including Treo) that also plays internet Radio and TV.
• Musicmatch Jukebox, a commercial MediaServer UPnP MediaServer and music-player for Microsoft Windows.
• Yahoo! Music Jukebox, a free MediaServer UPnP MediaServer and music-player for Microsoft Windows.
• VideoLAN Network Client (VLC), a free, open-source and cross-platform media player that has a UPnP-client (via the CyberLink UPnP plugin).
• Winamp, a free media player for Microsoft Windows, using the commercial On2Share UPnP plug-in.
• Windows Media Player, included with Windows, using the free Windows Media Connect or the commercial On2Share UPnP plug-in.
• GeeXboX, an open source lightweight Media center Livecd no installation required.
• Cidero, an open source UPnP Control Point and an UPnP internet radio gateway.
• Nero MediaHome - Commercial media-player/media-center software for Windows which is shipped as part of the Nero product suite, it includes a UPnP AV Client (and a UPnP AV Server). The latest version is able to capture and stream live TV and transcodes all common source file formats in real-time to other a UPnP AV Clients via the UPnP AV Server.
• Nero ShowTime a commercial media-player.
• Windows Media Connect from Microsoft - free UPnP AV MediaServer and Control Point (server and client) for Microsoft Windows
  • Windows Media Connect (WMC) version 2.0 can be installed for usage with Windows Media Player 10 for Windows XP
  • Windows Media Connect (WMC) version 3.0 can be installed for usage with Windows Media Player 11 for Windows XP
  • Windows Media Connect (WMC) version 4.0 already comes pre-installed on Windows Vista with its WMP version 11

UPnP control point hardware

• Philips RC9800i
• Philips Streamium range of products
• Logik IR100 (Reciva Based Radio)

UPnP media render hardware

• Playstation 3 game-console with OS version 1.8 or later through the Cross Media Bar
• Xbox game-console with XBMC (Xbox Media Center) software, which is a free open-source software multimedia-player.
  • XBMC built-in UPnP client and UPnP server code are from Platinum UPnP C++ SDK (open source under GPL).
• Xbox 360 game-console through the Xbox 360 Dashboard
• Buffalo Technology LinkTheater™ DVD (PC-P3LWG/DVD), a (wireless) networked High-Definition DVD and video/music-files player in standalone set-top design.
• Buffalo Technology LinkTheater™ A&G ()PC-P4LWAG, a (wireless) networked High-Definition video/music-files player in standalone set-top design.
• D-Link MediaLounge DSM-750, a (wireless) networked High-Definition video/music player in standalone set-top design.
• D-Link MediaLounge DSM-520, a (wireless) networked High-Definition video/music player in standalone set-top design.
• D-Link MediaLounge DSM-510, a (wireless) networked High-Definition video/music player in standalone set-top design.
• D-Link MediaLounge DSM-320RD, a (wireless) networked DVD and video/music-files player in standalone set-top design.
• D-Link MediaLounge DSM-320, a (wireless) networked video/music-files player in standalone set-top design.
• GoVideo D2730 Networked DVD, a networked DVD-Video player in standalone set-top design.
• Helios Z1000, a networked in standalone set-top design.
• Helios X3000, a networked High-Definition DVD-Video player in standalone set-top design.
• Helios X5000, a networked High-Definition DVD-Video player and Audio system in standalone set-top design.
• NETGEAR Digital Entertainer HD EVA8000, a (wireless) networked High-Definition video/music/foto/youTube/RSS feeds playing standalone Media Player with 1080P HDMI interface.
• Roku SoundBridge M2000, a small (wireless) networked music player.
• Roku SoundBridge M1001, a small (wireless) networked music player.
• Roku SoundBridge Radio M1000, a small (wireless) networked music player (no longer in production).
• Roku SoundBridge M500, a small (wireless) networked music player (no longer in production).
• Zensonic Z500, a (wireless) networked High-Definition DVD and video/music-files player in standalone set-top design.
• Ziova CS505, a (wireless) networked High-Definition DVD and video/music-files player in standalone set-top design.
• Ziova CS510, a (wireless) networked High-Definition video/music-files player in standalone set-top design.

See also

Zeroconf

Bonjour

NAT-PMP

Jini

SNMP

OSGi

Service Location Protocol

Salutation

CORBA

a list of Service discovery protocols (including SSDP, used by UPnP)

for a list of technologies, applications and products that support UPnP, see the linked pages to this article

File Area Networking

Storage area network

Network attached storage

Data Storage Server

List of network protocols

Protocol (computing)

Network architecture

Connection-oriented protocol

Connectionless protocol

Congestion collapse

Tunneling protocol

References

• UPnP™ Forum Universal Plug and Play Device Standards
• Golden G. Richard: Service and Device Discovery : Protocols and Programming, McGraw-Hill Professional, ISBN 0-07-137959-2
• Michael Jeronimo, Jack Weast: UPnP Design by Example: A Software Developer's Guide to Universal Plug and Play, Intel Press, ISBN 0-9717861-1-9

External links

Documentation

• UPnP™ Forum
• DLNA (Digital Living Network Alliance)
• The Jini, Vision
• technique comparison
• Microsoft WHDC UPnP webpage & links
• Universal Plug and Play in Windows XP

News

• Security firm predicts Microsoft Windows UPnP exploit by the end of the week at The Inquirer (Wednesday, 11 April 2007)
  • Microsoft security updates for April 2007 to fix the above Microsoft Windows UPnP security issue.