upnp Device Architecture

Transcription

1 upnp and DLNA

2 upnp Device Architecture defines an architecture for pervasive peer-to-peer network connectivity of intelligent appliances, wireless devices, and PCs of all form factors easy-to-use, flexible, standards-based connectivity to adhoc or unmanaged networks Specifications UPnP Device Architecture ( formerly known as DCP Framework ) zero-configuration "invisible" networking automatic discovery for a breadth of device categories Basis Internet protocols such as IP, TCP, UDP, HTTP, and XML.

3 upnp Protocol Stack ALL MESSAGES are based on the HTTP protocol SSDP : Simple Service Discovery Protocol GENA : General Event Notification Architecture upnp is based on IP protocols. UPnP general device classification Controlled devices ( or devices ) : server Control Points Glossary Device : logical device. Service : logical functional unit. Smallest units of control. (action/ variables)

4 UPnP Steps 0. Addressing DHCP, static IP assignment or AUTO IP. 1. Discovery Discovery message format, including URL for description. How devices advertise. How control points search devices. 2. Description Expressed in XML, and can be accessed via HTML using URL. Includes device information Includes URL for control, eventing and presentation. Includes variables to model the state of the service at runtime. 3. Control Expressed in XML using SOAP. Returns any action-specific values. May change the variables.

5 UPnP Steps 4. Eventing Subscription and Update Update : by service if variable changes. Subscription : by control point to the service. Multicast Eventing when events which are not relevant to specific UPnP interactions should be delivered to control points to inform users. when multiple controlled devices want to inform multiple other control points Retransmission. 5. Presentation Presentation to User using a Browser. URL for presentation is in Description message User may access to that URL with a browser and control the device or view device status.

6 Step0 : Addressing All DHCP-compatible device should have IP address. UPnP and DLNA is based on IPv4 IPv6 compatibility is written in annex of UDA Addressing Should support DHCP. Auto-IP : /16 address range. Link-local address (RFC3927) May use static IP address.

7 Step 1 : DISCOVERY

8 Step 1 : DISCOVERY UPnP Discovery Protocol Based on SSDP protocol Control point : search for devices Device : advertise its service to control points Device (server) MUST Multicast discovery messages when added to the network. Standard multicast address in SSDP : Control Point (client) MAY Multicast discovery messages when added to the network. Standard port for SSDP : 1900 Bonjour, ZeroConfig, SSDP?

9 Step 1 : DISCOVERY SSDP Message Format SSDP is in the HTTTP header field. SSDP Start-line SSDP message header fields SSDP header field extensions UUID DCE variant of Universal Unique Identifiers (UUIDs), The Open group, 1997, Available at:

10 Step 1 - Advertisement NT : Notification Type upnp:rootdevice uuid:device-uuid urn:schemas-upnp-org:device:devicetype:ver urn:schemas-upnp-org:service:servicetype:ver urn:domain-name:device:devicetype:ver urn:domain-name:service:servicetype:ver NTS : ssdp:alive CACHE-COBTROL : should be greater than USN : Unique Service Name. uuid:device-uuid::upnp:rootdevice uuid:device-uuid etc.

11 Step 1 - Advertisement

12 Step 1 - Advertisement Device unavailable -- NOTIFY with ssdp:byebye Device Update NOTIFY with ssdp:update

13 Step 1 - Search Search Request : M-SEARCH Search Response

14 Step 2 : Description Description : Information about device and service Device Description : for physical and logical containers Vendor-specific information. Service type Service name URLs (service description, control and eventing for each service) URS for presentation (of the aggregate) Service Description Actions and arguments To control a service (action) and get a response (argument)

15 Device Description

16 Service Description scpd : service control protocol description

17 HTTP

18 Based on SOAP protocol. Step 3 : Control

19 SOAP 1.1 UPnP Profile

20 HTTP Retrieved by description

21 HTTP

22 Step 4 : Eventing Unicast Eventing Subscription model Control Point subscribes to a variable of a service. Service sends an event when variable changes. Multicast Eventing Service multicasts an event when variable changes to multicast group. Publisher-Subscriber-Receiver Publisher : service (source of events) Subscriber : control point (destination of events) Receiver : control point or controlled device, listener of multicast device

23 Step 4 : Eventing

24 Step 4 : Eventing Subscriber information Publisher Unique subscription identifier Delivery URL for event messages Event key Subscription duration HTTP version of subscriber Subscriber Sends subscription message to a service URL for the publisher, service id for the publisher and delivery URL for event messages. MAY include duration. Subscription : to a Service. All the variables of a service will be used for eventing. No individual subscription of a variable of a service.

25 Unicast Eventing Publisher Send respond to the subscriber : Unique ID and duration Initial event message ASAP after the subscription is accepted. Names and current value of all evented variables. Subscription Renewal By subscriber No delivery URL in its message

26 Unicast Eventing

27 Unicast Eventing

28 Multicast Eventing A HTTP-like message : since it is sent via UDP On a ONE single UDP payload : If big, several UDP message can be sent. fragmentation is done by UPnP, not by UDP. Can be retransmitted as defined by UPnP

29 Unicast Event : HTTP

30 Multicast Event : HTTP

31 Step 5 : Presentation