UPnP Device Architecture

1
UPnP Device Architecture
2
Networking is easy, except

• Ad hoc networks don't have resources just for the
  sake of the network
• E.g., DHCP, DNS, directory,
• Network is unreliable
• Nodes added / removed unpredictably
• Programs need to talk to programs
• But software is heterogeneous
• One size doesn't fit all
• Must upgrade system piece at a time

3
UPnP Strategy

• Just send data over the network
• (No executables)
• Minimize version issues
• Minimize security issues
• Keep implementation private
• Be agnostic re programming language, OS
• Update implementation w/o affecting interop
• Improve performance
• Reduce footprint
• Improve capabilities
• Agree on meaning / format of data
• Choose substrate of proven protocols
• Define device (service) specific protocols in a
  Forum

4
UPnP Tactics

• Start simple
• Build in only universal things that everybody
  needs (and can live with)
• Add as needed
• Minimize requirements
• Basic IP network connectivity
• Common HTTP protocol stack
• Leverage existing standards
• HTTP, XML

5
Goals

• Describe the protocols for communication between
• Control points
• Controller, usually client
• Device
• Controlled,usually server
• An actual devicemight containboth functions

6
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

7
UPnP Protocol Stack

• Vendor-specific API above
• Vendor-specific OS below

Vendor-specific physical net
8
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
9
0 Addressing

• Control point and device get address
• Use a DHCP server
• Else use Auto IP
• What is Auto IP?
• IETF Draft Automatically Choosing an IP Address
  in an Ad-Hoc IPv4 Network
• What steps does it take?
• Pick an address in 169.254/16 range
• Check to see if it is used (ARP)
• Periodically check for DHCP server

10
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
11
1 Discovery

• Control point finds interesting device
• 0 get address
• 1 discover device
• Advertise / find typed devices (services)
• Guarantee of minimal capabilities
• Simple

• Devices
• Advertise when added
• Refresh advertisements (cf. lease)
• Cancel advertisements when removed
• Control points search as needed
• Devices respond
• Control points filter

12
1 Discovery Protocol Stack
13
1 Discovery SSDP Sidebar

• What is SSDP?
• IETF Draft Simple Service Discovery Protocol
• Key design principles
• Administratively-scoped multicast
• Unicast responses
• UDP
• Very simple advertisements
• Very simple search

14
1 Discovery Advertising

• Who? Device multicasts
• When? Added or refresh (cf. lease)
• What?
• 1 time / service type with NT service type
• 1 time / device type with NT device type
• 1 time / device with NT device UUID
• 1 time with NT upnprootdevice

NOTIFY HTTP/1.1HOST 239.255.255.2501900
CACHE-CONTROL max-age seconds until
advertisement expiresLOCATION URL for UPnP
description for root device
NT search targetNTS ssdpaliveUSN
advertisement UUID
15
1 Discovery Searching

• Who? Control point multicasts
• When? Looking for device or service
• What?
• ST one of
• Service type
• Device type
• Device UUID
• upnprootdevice
• ssdpall

M-SEARCH HTTP/1.1HOST 239.255.255.2501900
MAN "ssdpdiscover"MX seconds to delay response
ST search target
16
1 Discovery Responding

• Who? Device unicasts
• When? If ST matches an NT
• What?
• 1 time for each NT that matches
• Very simple matching

HTTP/1.1 200 OKCACHE-CONTROL max-age seconds
until advertisement expires
LOCATION URL for UPnP description for root
deviceST search targetUSN advertisement UUID
17
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
18
2 Description

• Control point learns about device capabilities
• 0 get address
• 1 discover device
• get URL for description
• 2 retrieve descr
• get URL for service description
• Declare capabilities

• Protocol stack

19
2 Description

• Device description
• Type
• Physical container
• Logical container
• For each service
• Type
• URL for description
• URL for control
• URL for eventing
• UI
• Icons
• URL for presentation

• Services
• Functional units within devices
• Service description
• Actions
• State variables
• Actual (vs. designed) implementation
• Expressed in XML

20
2 Description XML Sidebar

• What is XML?
• W3C Recommendation Extensible Markup Language
• "Universal format for structured documents and
  data on the Web."
• Field names in ltangle bracketsgt
• Field values between names
• Defines 24 data types
• ui1, ui2, ui4, i1, i2, i4, int
• r4, r8, number, fixed.14.4, float
• char, string
• date, dateTime, dateTime.tz, time, time.tz
• boolean
• bin.base64, bin.hex
• uri
• uuid

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2 Description Device (phys)
lt?xml version"1.0"?gtltroot xmlns"urnschemas-upn
p-orgdevice-1-0"gt   ltURLBasegtbase URL for all
relative URLslt/URLBasegt  ltdevicegt   
ltfriendlyNamegtshort user-friendly
titlelt/friendlyNamegt    ltmanufacturergtmanufacture
r namelt/manufacturergt    ltmanufacturerURLgtURL to
manufacturer sitelt/manufacturerURLgt   
ltmodelDescriptiongtlong user-friendly
titlelt/modelDescriptiongt    ltmodelNamegtmodel
namelt/modelNamegt    ltmodelNumbergtmodel
numberlt/modelNumbergt    ltmodelURLgtURL to model
sitelt/modelURLgt    ltserialNumbergtmanufacturer's
serial numberlt/serialNumbergt   
ltUDNgtuuidUUIDlt/UDNgt    ltUPCgtUniversal Product
Codelt/UPCgt    ltdeviceTypegturnschemas-upnp-orgde
vicedeviceTypelt/deviceTypegt   
ltserviceListgt      ltservicegt       
ltserviceTypegturnschemas-upnp-orgserviceserviceT
ypevlt/serviceTypegt        ltserviceIdgturnupnp-or
gserviceIdserviceIDlt/serviceIdgt       
ltSCPDURLgtURL to service descriptionlt/SCPDURLgt    
    ltcontrolURLgtURL for controllt/controlURLgt     
   lteventSubURLgtURL for eventinglt/eventSubURLgt   
   lt/servicegt      Declarations for other
services (if any) go here    lt/serviceListgt   
ltdeviceListgtDescription of embedded devices (if
any) go herelt/deviceListgt    lticonListgt     
lticongt        ltmimetypegtimage/formatlt/mimetypegt 
       ltwidthgthorizontal pixelslt/widthgt       
ltheightgtvertical pixelslt/heightgt       
ltdepthgtcolor depthlt/depthgt        lturlgtURL to
iconlt/urlgt      lt/icongt      XML to declare
other icons, if any, go here    lt/iconListgt   
ltpresentationURLgtURL for presentationlt/presentatio
nURLgt  lt/devicegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/rootgt
22
2 Description Device (logical)
lt?xml version"1.0"?gtltroot xmlns"urnschemas-upn
p-orgdevice-1-0"gt  ltURLBasegtbase URL for all
relative URLslt/URLBasegt  ltdevicegt   
ltfriendlyNamegtshort user-friendly
titlelt/friendlyNamegt    ltmanufacturergtmanufacture
r namelt/manufacturergt    ltmanufacturerURLgtURL to
manufacturer sitelt/manufacturerURLgt   
ltmodelDescriptiongtlong user-friendly
titlelt/modelDescriptiongt    ltmodelNamegtmodel
namelt/modelNamegt    ltmodelNumbergtmodel
numberlt/modelNumbergt    ltmodelURLgtURL to model
sitelt/modelURLgt    ltserialNumbergtmanufacturer's
serial numberlt/serialNumbergt   
ltUDNgtuuidUUIDlt/UDNgt    ltUPCgtUniversal Product
Codelt/UPCgt    ltdeviceTypegturnschemas-upnp-orgde
vicedeviceType vlt/deviceTypegt   
ltserviceListgt      ltservicegt       
ltserviceTypegturnschemas-upnp-orgserviceserviceT
ypevlt/serviceTypegt        ltserviceIdgturnupnp-or
gserviceIdserviceIDlt/serviceIdgt       
ltSCPDURLgtURL to service descriptionlt/SCPDURLgt    
    ltcontrolURLgtURL for controllt/controlURLgt     
   lteventSubURLgtURL for eventinglt/eventSubURLgt   
   lt/servicegt      Declarations for other
services (if any) go here    lt/serviceListgt   
ltdeviceListgtDescription of embedded devices (if
any) go herelt/deviceListgt    lticonListgt     
lticongt        ltmimetypegtimage/formatlt/mimetypegt 
       ltwidthgthorizontal pixelslt/widthgt       
ltheightgtvertical pixelslt/heightgt       
ltdepthgtcolor depthlt/depthgt        lturlgtURL to
iconlt/urlgt      lt/icongt      XML to declare
other icons, if any, go here    lt/iconListgt   
ltpresentationURLgtURL for presentationlt/presentatio
nURLgt  lt/devicegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/rootgt
23
2 Description Device (other)
lt?xml version"1.0"?gtltroot xmlns"urnschemas-upn
p-orgdevice-1-0"gt   ltURLBasegtbase URL for all
relative URLslt/URLBasegt  ltdevicegt   
ltfriendlyNamegtshort user-friendly
titlelt/friendlyNamegt    ltmanufacturergtmanufacture
r namelt/manufacturergt    ltmanufacturerURLgtURL to
manufacturer sitelt/manufacturerURLgt   
ltmodelDescriptiongtlong user-friendly
titlelt/modelDescriptiongt    ltmodelNamegtmodel
namelt/modelNamegt    ltmodelNumbergtmodel
numberlt/modelNumbergt    ltmodelURLgtURL to model
sitelt/modelURLgt    ltserialNumbergtmanufacturer's
serial numberlt/serialNumbergt   
ltUDNgtuuidUUIDlt/UDNgt    ltUPCgtUniversal Product
Codelt/UPCgt   ltdeviceTypegturnschemas-upnp-orgdev
icedeviceTypelt/deviceTypegt   
ltserviceListgt      ltservicegt       
ltserviceTypegturnschemas-upnp-orgserviceserviceT
ypevlt/serviceTypegt        ltserviceIdgturnupnp-or
gserviceIdserviceIDlt/serviceIdgt       
ltSCPDURLgtURL to service descriptionlt/SCPDURLgt    
    ltcontrolURLgtURL for controllt/controlURLgt     
   lteventSubURLgtURL for eventinglt/eventSubURLgt   
   lt/servicegt      Declarations for other
services (if any) go here    lt/serviceListgt   
ltdeviceListgtDescription of embedded devices (if
any) go herelt/deviceListgt    lticonListgt     
lticongt        ltmimetypegtimage/formatlt/mimetypegt 
       ltwidthgthorizontal pixelslt/widthgt       
ltheightgtvertical pixelslt/heightgt       
ltdepthgtcolor depthlt/depthgt        lturlgtURL to
iconlt/urlgt      lt/icongt      XML to declare
other icons, if any, go here    lt/iconListgt   
ltpresentationURLgtURL for presentationlt/presentatio
nURLgt  lt/devicegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/rootgt
24
2 Description Service (actns)
lt?xml version"1.0"?gtltscpd xmlns"urnschemas-upn
p-orgservice-1-0"gt  ltactionListgt   
ltactiongt      ltnamegtactionNamelt/namegt     
ltargumentListgt        ltargumentgt         
ltnamegtformalParameterNamelt/namegt         
ltdirectiongtin xor outlt/directiongt         
ltretval /gt          ltrelatedStateVariablegtstateVa
riableNamelt/relatedStateVariablegt       
lt/argumentgt       Declarations for other
arguments (if any) go here     
lt/argumentListgt    lt/actiongt    Declarations
for other actions (if any) go here 
lt/actionListgt  ltserviceStateTablegt   
ltstateVariable sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable datatypelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueRangegt        ltminimumgtminimum
valuelt/minimumgt        ltmaximumgtmaximum
valuelt/maximumgt        ltstepgtincrement
valuelt/stepgt      lt/allowedValueRangegt   
lt/stateVariablegt    ltstateVariable
sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable data typelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueListgt        ltallowedValuegtsome
valuelt/allowedValuegt        ltallowedValuegtsome
valuelt/allowedValuegt      lt/allowedValueListgt   
lt/stateVariablegt    Declarations for other
state variables (if any) go here 
lt/serviceStateTablegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/scpdgt
25
2 Description Service (vars)
lt?xml version"1.0"?gtltscpd xmlns"urnschemas-upn
p-orgservice-1-0"gt  ltactionListgt   
ltactiongt      ltnamegtactionNamelt/namegt     
ltargumentListgt        ltargumentgt         
ltnamegtformalParameterNamelt/namegt         
ltdirectiongtin xor outlt/directiongt         
ltretval /gt          ltrelatedStateVariablegtstateVa
riableNamelt/relatedStateVariablegt       
lt/argumentgt       Declarations for other
arguments (if any) go here     
lt/argumentListgt    lt/actiongt    Declarations
for other actions (if any) go here 
lt/actionListgt  ltserviceStateTablegt   
ltstateVariable sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable datatypelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueRangegt        ltminimumgtminimum
valuelt/minimumgt        ltmaximumgtmaximum
valuelt/maximumgt        ltstepgtincrement
valuelt/stepgt      lt/allowedValueRangegt   
lt/stateVariablegt    ltstateVariable
sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable data typelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueListgt        ltallowedValuegtsome
valuelt/allowedValuegt        ltallowedValuegtsome
valuelt/allowedValuegt      lt/allowedValueListgt   
lt/stateVariablegt    Declarations for other
state variables (if any) go here 
lt/serviceStateTablegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/scpdgt
26
2 Description Service (vars)
lt?xml version"1.0"?gtltscpd xmlns"urnschemas-upn
p-orgservice-1-0"gt  ltactionListgt   
ltactiongt      ltnamegtactionNamelt/namegt     
ltargumentListgt        ltargumentgt         
ltnamegtformalParameterNamelt/namegt         
ltdirectiongtin xor outlt/directiongt         
ltretval /gt          ltrelatedStateVariablegtstateVa
riableNamelt/relatedStateVariablegt       
lt/argumentgt       Declarations for other
arguments (if any) go here     
lt/argumentListgt    lt/actiongt    Declarations
for other actions (if any) go here 
lt/actionListgt  ltserviceStateTablegt   
ltstateVariable sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable datatypelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueRangegt        ltminimumgtminimum
valuelt/minimumgt        ltmaximumgtmaximum
valuelt/maximumgt        ltstepgtincrement
valuelt/stepgt      lt/allowedValueRangegt   
lt/stateVariablegt    ltstateVariable
sendEventsyes xor nogt     
ltnamegtvariableNamelt/namegt     
ltdataTypegtvariable data typelt/dataTypegt     
ltdefaultValuegtdefault valuelt/defaultValuegt     
ltallowedValueListgt        ltallowedValuegtsome
valuelt/allowedValuegt        ltallowedValuegtsome
valuelt/allowedValuegt      lt/allowedValueListgt   
lt/stateVariablegt    Declarations for other
state variables (if any) go here 
lt/serviceStateTablegt  ltspecVersiongt   
ltmajorgt1lt/majorgt ltminorgt0lt/minorgt 
lt/specVersiongtlt/scpdgt
27
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
28
3 Control

• Control point invokes actions on device
• 0 get address
• 1 discover device
• 2 retrieve descr
• get URL for control
• 3 send actions to device

• Protocol stack

29
3 Control SOAP Sidebar

• What is SOAP?
• IETF Draft Simple Object Access Protocol
• "Lightweight, XML-based protocol for exchange of
  information in a decentralized, distributed
  environment."
• Envelope defines a framework for describing what
  is in a message and how to process it.
• Convention represent remote procedure calls and
  responses.

30
3 Control Invoke Action

• Who? Control point
• When? To invoke action on device
• What?

POST path of control URL HTTP/1.1HOST host of
control URLport of control URLCONTENT-TYPE
text/xml charset"utf-8"SOAPACTION
"urnschemas-upnp-orgserviceserviceTypevaction
Name"
ltsEnvelope xmlnss"http//schemas.xmlsoap.org/so
ap/envelope/"    sencodingStyle"http//schemas.
xmlsoap.org/soap/encoding/"gt  ltsBodygt  
lt/sBodygtlt/sEnvelopegt
    ltuactionName xmlnsu"urnschemas-upnp-orgse
rviceserviceTypev"gt      ltargumentNamegtin arg
valuelt/argumentNamegt      other in args and
their values (if any) go here    lt/uactionNamegt
31
3 Control Action Result

• Who? Device
• When? Action completes
• What?

HTTP/1.1 200 OKCONTENT-TYPE text/xml
charset"utf-8" ltsEnvelope xmlnss"http//schem
as.xmlsoap.org/soap/envelope/"   
sencodingStyle"http//schemas.xmlsoap.org/soap/e
ncoding/"gt  ltsBodygt   lt/sBodygtlt/sEnvelop
egt
    ltuactionNameResponse
xmlnsu"urnschemas-upnp-orgserviceserviceType
v"gt      ltargumentNamegtout arg
valuelt/argumentNamegt      other out args and
their values (if any) go here   
lt/uactionNameResponsegt
32
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
33
4 Eventing

• Control point listens to state changes of device
• 0 get address
• 1 discover device
• 2 retrieve descr
• get URL for eventing
• 4 subscribe to events from device
• Basic push model
• Simple

• Protocol stack

34
4 Eventing GENA Sidebar

• What is GENA?
• IETF Draft General Event Notification
  Architecture
• "Send and receive notifications using HTTP over
  TCP/IP and administratively-scoped multicast
  UDP."
• SUBSCRIBE to notifications
• UNSUBSCRIBE
• NOTIFY
• Of device availability
• Of state variable changes

35
4 Eventing Subscribing

• Who? Control point
• When? Before receiving any events
• What?

SUBSCRIBE publisher path HTTP/1.1HOST publisher
hostpublisher port
CALLBACK ltdelivery URLgtNT upnpeventTIMEOUT
Second-requested subscription duration
36
4 Eventing Subscription

• Who? Device
• When? Accepts subscription
• What?
• Device immediately sends a special, initial event
  to control point with the value of all evented
  variables

HTTP/1.1 200 OKSID uuidsubscription-UUID
TIMEOUT Second-actual subscription duration
37
4 Eventing Notify

• Who? Device
• When? A state variable changes
• What?

NOTIFY delivery path HTTP/1.1HOST delivery
hostdelivery portCONTENT-TYPE
text/xml
NT upnpeventNTS upnppropchange
SID uuidsubscription-UUIDSEQ event key
ltepropertyset xmlnse"urnschemas-upnp-orgevent
-1-0"gt  ltepropertygt    ltvariableNamegtnew
valuelt/variableNamegt  lt/epropertygt  Other
variable names and values (if any) go
herelt/epropertysetgt
38
Steps to UPnP Networking

• 0 Control point and device get addresses
• 1 Control point finds interesting device
• 2 Control point learns about device capabilities
• 3 Control point invokes actions on device
• 4 Control point listens to state changes of
  device
• 5 Control point controls device and/or views
  device status using HTML UI

5 Presentation
4 Eventing
3 Control
2 Description
1 Discovery
0 Addressing
39
5 Presentation

• Control point controls device and/or views device
  status using HTML UI
• 0 get address
• 1 discover device
• 2 retrieve descr
• get URL for presentation
• 5 load presentation page
• (Don't constrain implementation)

• Protocol stack

40
Summary

• UPnP says
• Just send data
• Keep implementation private
• Agree on content / format of data
• UPnP is
• Web-based protocols
• Tailored by a Forum for device (service) types
• That are API, OS, physical network neutral
• For discovery, description, control, eventing
• (And simple HTML UI too)
• For more information
• Resources http//www.upnp.org
• Questions? mailtoUPNPWORLD_at_FORUM.UPNP.ORG