device servers prasun dewan department of computer science university of north carolina...

Device Servers

Prasun Dewan

Department of Computer Science University of North Carolina

[email protected]

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Issues in Device Servers

Device is just a server.

So what is different?

Network

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Addressing Devices vs. Traditional Servers

Sever and network is always around - static address

Centralized heavyweight scheme acceptable to give install and give unique addresses to servers

Client expected to know traditional server address imap.cs.unc.edu

Discovery phase possible www.cnn.com logical name to physical

name can be bound dynamically

Devices may be dynamically added on ad-hoc networks - dynamic address

With so many dynamic devices and ad-hoc networks lightweight decentralized scheme needed

Client may not know or care about device server address print to the nearest printer turn off all light bulbs

Implies later binding and thus a discovery phase

4

Communicating with Device vs. Traditional Servers

Client expected to know exact server interface get mail send mail

Client may not know exact server interface palm computer controlling a

VCR it knows nothing about security system composer

substituting Axis camera with Aibot Robot, which may not share an interface

impromptu interoperability implies an interface

(capability) discovery phase

5

Communicating with Device vs. Traditional Servers

Client polls for traditional server changes New mail arrived? Cannot track fast

changing information

Client may wish to notified of device changes current channel changed, so

redisplay it Implies an eventing

mechanism that is distributed can be dynamically

discovered

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Deploying Remote User Interfaces

Run preloaded client user-interface program xmh netscape

Because of late binding, client UI program may not exist

Implies dynamic user-interface deployment

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Composing Devices

Traditional servers not composed into a single unit Not the same as

replicas

Composite device may be composed out of multiple devices security system CD

How to support composite and individual device services.

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UPnP (Universal Plug and Play) Formed in 1999 with 200 vendors

Consumer electronics,Home security, Networking, Mobile devices

Late binding Dynamic Server discovery Dynamic Interface discover Dynamic Event discovery Dynamic UI Deployment Static Service Composition

Language- and OS- Neutral Solution Avoid trojan horses

Ship data rather than code Open Use existing standards

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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

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UPNP Examples: Installing a printer

Today Attach it to server PC Load device driver Share printer Manually bind each

client to printer

Vision Just connect printer

to network

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Installing a device store

Today Attach a new disk

drive to computer

Vision Just connect drive to

network

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Intelligent Alarm clock

Today Set alarm clock

May vary depending on weekday or weekend

Set thermostat Hope meeting not

missed

Vision Alarm clock tells PC It runs script that

checks schedule and sets thermostat

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Arriving/leaving homeToday Turn on entrance light Change thermostat Play answering machine

messages Turn on TV Set channel to CNN Raise/lower blinds

depending on before/after sunset

Turn on other lights Reverse steps when

turning off light

Vision Light switch

communicates with PC, which runs script and its inverse

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Arriving/leaving townToday Manually change

thermostat Change water heater Close/open water valve Hold mail Set vacation message(s) Inform neighbour(s) Throw trash

Vision Push button saying

on vacation Could do it remotely

Must still throw trash

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Power outageToday Manually set all clocks

Vision They automatically

synchronize with an a networked atomic clock

Script runs periodically or when power comes on

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Home theater

Script to Turn on DVD Turn on TV Set it to DVD channel Set stereo to Video mode Set stereo volume to theater levels Dim lights

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Ball game

Mobile device used to: pick up traffic info on road receive commentary at stadium track player statistics order food chat with buddies at game

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Other apps

Appliance remotely fixed or set Calendars of family members

synchronized Product barcode scanned to order new

instance Presentation displayed on discovered

display devices

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UPnP Device Architecture

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Architecture/Terminology

Components Control points

Controller, usually client Device

Controlled,usually server

An actual devicemight containboth functions

DeviceDeviceDeviceDevice

ServiceServiceServiceService

Control PointControl PointControl PointControl Point

Control PointControl PointControl PointControl Point

DeviceDeviceDeviceDevice

ServiceServiceServiceService

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Architecture

UPnP Enabled Device

UPnP Enabled Device

UPnP Enabled Device

Control Point

Device

Root Device

Embedded Device

Device

Service

Service 2Service 1

Service

Service 2Service 1

Control Point

Service

StateTable

ControlServerEventServer

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Example Configuration

IP Network

Non-IP Bus/Networks

Control Point(Pocket PC)

Lightweight Device(LonWorks Thermostat)

Non-UPnP Device(X-10 Light)

UPnP Bridge

Native Device(UPnP Alarm Clock)

Control Point(Remote Control)

Native Device(UPnP VCR)

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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

0 Addressing0 Addressing

1 Discovery1 Discovery

2 Description2 Description

5 Presentation5 Presentation4 Eventing4 Eventing3 Control3 Control

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Vendor-specific API above

Vendor-specific OS below

UPnP Protocol Stack

UPnP Device ArchitectureUPnP Device ArchitectureUPnP Device ArchitectureUPnP Device Architecture

UDPUDPUDPUDP

IPIPIPIP

HTTPU/MUHTTPU/MUHTTPU/MUHTTPU/MUGENAGENAGENAGENA SSDPSSDPSSDPSSDP SOAPSOAPSOAPSOAP

HTTPHTTPHTTPHTTP

HTTPHTTPHTTPHTTPGENAGENAGENAGENA

TCPTCPTCPTCP

UPnP ForumUPnP ForumUPnP ForumUPnP Forum

UPnP vendorUPnP vendorUPnP vendorUPnP vendor

Multiple http servers

Name Discovery and Events

Capability Discovery

Operation Control

State Events

Schemas (Prog Lang)

Standardized Schema Instances (Types)

URLs, Model, Device # W

ire protocols

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0* Control point and device get addresses






0* Addressing0* Addressing




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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

Could use DNS and include DNS Client

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Overview -ad hoc

UPnP in action - ad hocUPnP in action - ad hoc

1. DHCP broadcast1. DHCP broadcast

(timeout)(timeout)

2. Assign AutoNet address2. Assign AutoNet address

3. DNS name multicast3. DNS name multicast

4. Announce service4. Announce service

(timeout - wait for requests)(timeout - wait for requests)

5. Discover service5. Discover service

7. Response to discover7. Response to discover

8. Get_HTTP XML8. Get_HTTP XML

9. XML content9. XML content

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Overview - configured

UPnP in action - configuredUPnP in action - configured

1. DHCP broadcast1. DHCP broadcast

2. Address from DHCP server2. Address from DHCP server

3. Name unicast to DNS server3. Name unicast to DNS server

4. Announce service to listener4. Announce service to listener

6. Directory updated by listener6. Directory updated by listener

5. Listener Get_HTTP XML5. Listener Get_HTTP XML

8. LDAP query directory8. LDAP query directory

7. Device specific negotiation7. Device specific negotiation

Se

rver

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1* Control point finds interesting device






1* Discovery1* Discovery



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1 Discovery: Pull (Active) vs. Push (Passive)

Client (Control point) could pull info Servers could be

dynamically added Needs to poll for new

devices Server (Device) could

push advertisement Control points can be

dynamically added Needs to continuously

send info, using network

Client Server

Client Server

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1 Discovery: Pull (Active) vs. Push (Passive)

SSDP Solution: Hybrid approach Advertisement has

lifetime Can simulate pure

push model HTTP over UDP

What if message gets lost?

Must send UDP message 3 times

Solution over TCP planned

Client Server

Server

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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

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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

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1 Discovery: Protocol Stack




UDPUDPUDPUDP

IPIPIPIP

HTTPMUHTTPMU(multicast)(multicast)

HTTPMUHTTPMU(multicast)(multicast) GENAGENAGENAGENA SSDPSSDPSSDPSSDP HTTPUHTTPU

(unicast)(unicast)

HTTPUHTTPU(unicast)(unicast) SSDPSSDPSSDPSSDP

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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 == upnp:rootdeviceupnp:rootdevice

NOTIFY * HTTP/1.1HOST: 239.255.255.250:1900

NOTIFY * HTTP/1.1HOST: 239.255.255.250:1900

CACHE-CONTROL: max-age = seconds until advertisement expiresLOCATION: URL for UPnP description for root deviceNT: search targetNTS: ssdp:aliveUSN: advertisement UUID

Multicast address

Port

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GENA Notification method format defined by

GENA An event delivery scheme over HTTP Allows subscription

May be used later Will allow it to be not depend on the “largely

non-existent Internet multicast infrastructure”

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Multicast Scope Entire internet

Idea to find local service Link local

Does not support bridged/routed LANS Local administrative scope

Relative address 239.255.255.250

Relative address vs local scope Relative address allows progressively larger

scopes Based on physical location?

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Location vs. USN Location needed to send messages USN a unique, location-independent ID

UUID is a USN example Decentralized assignment

Allows services to move Change IP address Change DNS name

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Byebye message Sent before device ceases to operate NTS = ssdp:byebye NT = service type

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1 Discovery: Searching Who? Control point multicasts When? Looking for device or service What?

ST one of Service type Device type Device UUID upnp:rootdeviceupnp:rootdevice ssdp:allssdp:all

M-SEARCH * HTTP/1.1HOST: 239.255.255.250:1900

M-SEARCH * HTTP/1.1HOST: 239.255.255.250:1900MAN: "ssdp:discover"MX: seconds to delay responseST: search target

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Broadcast message Can send message to all devices

ssdp: all Network analysis tool Remote control unit

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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

HTTP/1.1 200 OKCACHE-CONTROL: max-age = seconds until advertisement expiresLOCATION: URL for UPnP description for root deviceST: search targetUSN: advertisement UUID

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Network traffic SSDP traffic on recovery after power outage.

Control points will all send discover messages. to find printer

In large companies multicast admin domain will be large Can be entire company

Need a way for SSDP to deactivate before network storms created

Even with directory services, low-level SSDP may activate

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Bandwidth requirements TP = some time period DR = # of clients sending discovery messages in TP RS = # of devices responding to each discover

message AM = average message size Bandwidth = (DR* 3 + DR*9*RS)*AM/TP

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E.g. Network traffic 100, 000 hosts 5,000 printers Requests evenly distributed over 30 second period Message size = 512 bytes Bandwidth = 585976 Megabits per second

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E.g. Network traffic 1000 hosts 50 printers Requests evenly distributed over 30 second period Message size = 512 bytes Bandwidth = 59 Megabits per second

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2* Control point learns about device capabilities






2* Description2* Description


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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




IPIPIPIP

HTTPHTTPHTTPHTTP

TCPTCPTCPTCP

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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

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XML Like HTML

Describes a tree Unlike HTML

Describes contents rather than UI Style sheets describe UI

Tags are user-defined Via Schema Language (DDT)

Supported by Web browsers

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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 <angle brackets> 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)<?xml version="1.0"?><root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase>

<device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC> <deviceType>urn:schemas-upnp-org:device:deviceType</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList> <iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL>

</device> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</root>

<?xml version="1.0"?><root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase>

<device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC> <deviceType>urn:schemas-upnp-org:device:deviceType</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList> <iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL>


</root>

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2 Description: Device (logical)<?xml version="1.0"?>

<root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase> <device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC>

<deviceType>urn:schemas-upnp-org:device:deviceType :v</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList> <iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL>


</root>

<?xml version="1.0"?>

<root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase> <device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC>

<deviceType>urn:schemas-upnp-org:device:deviceType :v</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList> <iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL>


</root>

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2 Description: Device (other)<?xml version="1.0"?>

<root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase>

<device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC> <deviceType>urn:schemas-upnp-org:device:deviceType</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList>

<iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL> </device> <specVersion> <major>1</major> <minor>0</minor> </specVersion></root>

<?xml version="1.0"?>

<root xmlns="urn:schemas-upnp-org:device-1-0"> <URLBase>base URL for all relative URLs</URLBase>

<device> <friendlyName>short user-friendly title</friendlyName> <manufacturer>manufacturer name</manufacturer> <manufacturerURL>URL to manufacturer site</manufacturerURL> <modelDescription>long user-friendly title</modelDescription> <modelName>model name</modelName> <modelNumber>model number</modelNumber> <modelURL>URL to model site</modelURL> <serialNumber>manufacturer's serial number</serialNumber> <UDN>uuid:UUID</UDN> <UPC>Universal Product Code</UPC> <deviceType>urn:schemas-upnp-org:device:deviceType</deviceType> <serviceList> <service> <serviceType>urn:schemas-upnp-org:service:serviceType:v</serviceType> <serviceId>urn:upnp-org:serviceId:serviceID</serviceId> <SCPDURL>URL to service description</SCPDURL> <controlURL>URL for control</controlURL> <eventSubURL>URL for eventing</eventSubURL> </service> Declarations for other services (if any) go here </serviceList> <deviceList>Description of embedded devices (if any) go here</deviceList>

<iconList> <icon> <mimetype>image/format</mimetype> <width>horizontal pixels</width> <height>vertical pixels</height> <depth>color depth</depth> <url>URL to icon</url> </icon> XML to declare other icons, if any, go here </iconList> <presentationURL>URL for presentation</presentationURL> </device> <specVersion> <major>1</major> <minor>0</minor> </specVersion></root>

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2 Description: Service (actns)<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList> <serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here </serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList> <serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here </serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

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2 Description: Service (vars)<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList>

<serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here

</serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList>

<serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here

</serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

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2 Description: Service (vars)<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList>

<serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable>

<stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here </serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

<?xml version="1.0"?><scpd xmlns="urn:schemas-upnp-org:service-1-0"> <actionList> <action> <name>actionName</name> <argumentList> <argument> <name>formalParameterName</name> <direction>in xor out</direction> <retval /> <relatedStateVariable>stateVariableName</relatedStateVariable> </argument> Declarations for other arguments (if any) go here </argumentList> </action> Declarations for other actions (if any) go here </actionList>

<serviceStateTable> <stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable datatype</dataType> <defaultValue>default value</defaultValue> <allowedValueRange> <minimum>minimum value</minimum> <maximum>maximum value</maximum> <step>increment value</step> </allowedValueRange> </stateVariable>

<stateVariable sendEvents=“yes” xor “no”> <name>variableName</name> <dataType>variable data type</dataType> <defaultValue>default value</defaultValue> <allowedValueList> <allowedValue>some value</allowedValue> <allowedValue>some value</allowedValue> </allowedValueList> </stateVariable> Declarations for other state variables (if any) go here </serviceStateTable> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

</scpd>

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3* Control point invokes actions on device






5 Presentation5 Presentation4 Eventing4 Eventing3* Control3* Control

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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




IPIPIPIP

SOAPSOAPSOAPSOAP

HTTPHTTPHTTPHTTP

TCPTCPTCPTCP

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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.

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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 URL:port of control URLCONTENT-TYPE: text/xml; charset="utf-8"SOAPACTION: "urn:schemas-upnp-org:service:serviceType:v#actionName"

POST path of control URL HTTP/1.1HOST: host of control URL:port of control URLCONTENT-TYPE: text/xml; charset="utf-8"SOAPACTION: "urn:schemas-upnp-org:service:serviceType:v#actionName"

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <s:Body>

</s:Body></s:Envelope>

<u:actionName xmlns:u="urn:schemas-upnp-org:service:serviceType:v"> <argumentName>in arg value</argumentName> other in args and their values (if any) go here </u:actionName>

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3 Control: Action Result Who? Device When? Action completes What?

HTTP/1.1 200 OKCONTENT-TYPE: text/xml; charset="utf-8"



HTTP/1.1 200 OKCONTENT-TYPE: text/xml; charset="utf-8"



<u:actionNameResponse xmlns:u="urn:schemas-upnp-org:service:serviceType:v"> <argumentName>out arg value</argumentName> other out args and their values (if any) go here </u:actionNameResponse>

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4* Control point listens to state changes of device





5 Presentation5 Presentation4* Eventing4* Eventing3 Control3 Control

64

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




IPIPIPIP

HTTPHTTPHTTPHTTPGENAGENAGENAGENA

TCPTCPTCPTCP

65

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

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4 Eventing: Subscribing

Who? Control point When? Before receiving any events What?SUBSCRIBE publisher path HTTP/1.1

HOST: publisher host:publisher port

SUBSCRIBE publisher path HTTP/1.1HOST: publisher host:publisher portCALLBACK: <delivery URL>NT: upnp:eventTIMEOUT: Second-requested subscription duration

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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: uuid:subscription-UUID TIMEOUT: Second-actual subscription duration

HTTP/1.1 200 OKSID: uuid:subscription-UUID TIMEOUT: Second-actual subscription duration

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4 Eventing: Notify Who? Device When? A state variable changes What?

NOTIFY delivery path HTTP/1.1HOST: delivery host:delivery portCONTENT-TYPE: text/xml

NOTIFY delivery path HTTP/1.1HOST: delivery host:delivery portCONTENT-TYPE: text/xmlNT: upnp:eventNTS: upnp:propchangeSID: uuid:subscription-UUIDSEQ: event key

<e:propertyset xmlns:e="urn:schemas-upnp-org:event-1-0"> <e:property> <variableName>new value</variableName> </e:property> Other variable names and values (if any) go here</e:propertyset>

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5* Control point controls device and/or views device status using HTML UI




5* Presentation5* Presentation4 Eventing4 Eventing3 Control3 Control

70

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 stackUPnP vendorUPnP vendorUPnP vendorUPnP vendor


IPIPIPIP

HTTPHTTPHTTPHTTP

TCPTCPTCPTCP

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Example Device (Intel Implementation)

TV Composite Control Service

Volume Power ….

Picture Service Color Tint Contrast ….

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Example Composition

<?xml version="1.0" ?>

<root xmlns="urn:schemas-upnp-org:device-1-0">

<specVersion>

<major>1</major>

<minor>0</minor>

</specVersion>

<URLBase>http://192.168.0.4:5431</URLBase>

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Example Composition<device>

<deviceType>urn:schemas-upnp- org:device:tvdevice:1</deviceType>

<friendlyName>UPnP Television Emulator</friendlyName>

<manufacturer>TV Manufacturer Name</manufacturer>

<manufacturerURL>http://www.manufacturer.com</manufacturerURL>

<modelDescription>UPnP Television Device Emulator 1.0</modelDescription>

<modelName>TVEmulator</modelName>

<modelNumber>1.0</modelNumber>

<modelURL>http://www.manufacturer.com/TVEmulator/</modelURL>

<serialNumber>123456789001</serialNumber>

<UDN>uuid:Upnp-TVEmulator-1_0-1234567890001</UDN>

<UPC>123456789</UPC>

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Example Service Composition<serviceList> <service> <serviceType>urn:schemas-upnp-org:service:tvcontrol:1</serviceType> <serviceId>urn:upnp-org:serviceId:tvcontrol1</serviceId> <controlURL>/upnp/control/tvcontrol1</controlURL> <eventSubURL>/upnp/event/tvcontrol1</eventSubURL> <SCPDURL>/tvcontrolSCPD.xml</SCPDURL> </service> <service> <serviceType>urn:schemas-upnp-org:service:tvpicture:1</serviceType> <serviceId>urn:upnp-org:serviceId:tvpicture1</serviceId> <controlURL>/upnp/control/tvpicture1</controlURL> <eventSubURL>/upnp/event/tvpicture1</eventSubURL> <SCPDURL>/tvpictureSCPD.xml</SCPDURL> </service> </serviceList>

</device>

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Example Service

<?xml version="1.0" ?> <scpd xmlns="urn:schemas-upnp-org:service-1-0"> <specVersion> <major>1</major> <minor>0</minor> </specVersion>

76

Example Action List

<actionList> <action> <name>PowerOn</name> </action> <action> <name>SetChannel</name>

<argumentList> <argument>

<name>Channel</name> <relatedStateVariable>Channel</relatedStateVariable> <direction>in</direction>

</argument> </argumentList>

</action> ….

<actionList>

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Example Variables<serviceStateTable> <stateVariable sendEvents="yes"> <name>Power</name> <dataType>Boolean</dataType> <defaultValue>0</defaultValue> </stateVariable> <stateVariable sendEvents="yes"> <name>Channel</name> <dataType>i4</dataType> <allowedValueRange> <minimum>1</minimum> <maximum>100</maximum> <step>1</step> </allowedValueRange> <defaultValue>1</defaultValue> </stateVariable> …..</serviceStateTable>

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Example Presentation

Described using HTML

79

Example Server CodeObject processMessages (Message message) {

switch (message.kind) case GET_VAR_REQUEST:

switch ((GetVarMessage) message).varName) case “Channel”: message.result = getChannel();

… case ACTION_REQUEST:

actionMessage = (ActionMessage) message.switch (actionMessage.actionName) case “setChannel”: setChannel(parseString(actionMessage.params[0])) …

}int channel;int getChannel () { return curentChannel};void setChannel (int newChannel) { channel = newChannel; UPnP.announce(“Channel”, toString(getChannel());}...

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Another Example: Composite greater than sum of parts

TV Composite Simply combines services

CD Composite Adds services Record with fields vs Object with instance

variables

81

CD Example

(empty)

disc

(empty)

disc

disc

disc

disc

carousel

disc tray

(empty)

(empty)

disc

disc

disc tray door(closed)

CD Composite

Power

Player

Changer

Audio

•When disc insertion event received play CD• Play random (CD)

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Elaborate Scenario New DVD player connected to network

Assigns itself an IP address after looking for DHCP several times or Auto-IP

Sends advertisement, possibly multiple times because UDP

Father brings laptop home Assigns address and sends advertisement

Video remote control started Searches for and displays Video devices

83

Elaborate Scenario DVD selected by father

Controller retrieves description/presentation URL

User can choose between using URL or controller UI

Run invoked on DVD Run time of current disc can be queried Clock flashing Retrieves clock synchronizer from disk server Clock synchronizer finds clocks and syncs

them

84

Elaborate Scenario Father prints file Printer out ink message appears on father’s

and son’s computers Son fixes it. Needs printer in room to print HW Disconnects printer

Bye bye message sent and seen by father Moves printer to room

IP assignment and advertisement Mother presses button for mood control

Lights get dimmed, shades down, soft music starts, laptop shuts down

85

Issues raised by UPnP

0 Control point and device get addresses (Auto IP)1 Control point finds interesting device (push/pull multicast,

type)2 Control point learns about device capabilities (XML)3 Control point invokes actions on device (SOAP)4 Control point listens to state changes of device (GENA)5 Control point controls device and/or views device status

using HTML UI





86


Scaling problem of multicast-based discovery Auto Shut off problem

Simple-minded search Lack of access and concurrency control Static, manual, procedural service composition Device-independent UI No programmer-defined types High programming and maintenance costs

87

Auto-Shutoff

Auto Shut off problem Network storm when devices reboot in sync Combine address discovery and routing

88

Simple-minded Search Facilities

Choices All Service type Device Type Specific

Complex queries Attributes?

89

Lack of Control Ignores access control.

prevents accidents turning on neighbor’s TV

prevents intentional sabotage opening garage door to steal

Classic AC applicable? Ignores concurrency control.

Two remote users concurrently setting thermostat Two users editing VCR settings offline Classic CC applicable? Mobile CC applicable?

90

Static, Manual, Procedural Composition

Dynamic collections e.g. All lamps in a room All services explicitly statically enumerated in UPnP Must create a new description when new service added

to collection new lamp to room

Declarative/automatic composition issue when composite greater than sum of parts low-level procedural code to add functionality in UPnP

play CD when disc inserted set printer output to camera distribute multi-media presentation to audio and video

devices

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Device-Independent UI

Fixed UI for all devices may wish one specific to interactive computer used

palm computers and laptops have different form factors and I/O capabilities

may wish to show each variable in separate screen. the kind of interactive computer may not be known

when service defined

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No Programmer-Defined Types XML 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

93

No Programmer-Defined Types Only supports predefined types

state variables action parameters

No way to model dynamic composites

Dynamic programmer-defined collection

94

High Programming Cost Device developer must:

define the XML-based external representation of the device

translate the client operation-invocation and variable-access requests to local operation-invocations

announce variable change notifications Exporting functionality requires more code than

implementing it in example Intel device not counting UI code

Cost proportional to complexity of type. Reason for not allowing complex types?

95

High Maintenance Cost Information repeated multiple times

operation implementation code action list state variable table message processing code event announcement code

All repetitions must be changed tedious error-prone

Channel -> Current Channel requires 9 changes!

96

Changed Action List<actionList> <action> <name>PowerOn</name> </action> <action> <name>SetCurrentChannel</name> <argumentList> <argument>

<name>CurrentChannel</name> <relatedStateVariable>CurrentChannel</relatedStateVariable>

<direction>in</direction> </argument> </argumentList>

</action> ….

<actionList>

97

Changed State Variable Table<serviceStateTable> <stateVariable sendEvents="yes"> <name>Power</name> <dataType>Boolean</dataType> <defaultValue>0</defaultValue> </stateVariable> <stateVariable sendEvents="yes"> <name>CurrentChannel</name> <dataType>i4</dataType> <allowedValueRange> <minimum>1</minimum> <maximum>100</maximum> <step>1</step> </allowedValueRange> <defaultValue>1</defaultValue> </stateVariable> …..</serviceStateTable>

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Changed Server CodeObject processMessages (Message message) {

switch (message.kind) case GET_VAR_REQUEST: switch ((GetVarMessage) message).varName) case “CurrentChannel”: message.result = getCurrentChannel();

… case ACTION_REQUEST: actionMessage = (ActionMessage) message. switch (actionMessage.actionName)

case “setCurrentChannel”: setCurrentChannel(parseString(actionMessage.params[0]))

…}int channel;int getCurrentChannel () {return channel};void setCurrentChannel (int newChannel) { channel = newChannel; UPnP.announce(“CurrentChannel”, toString(getCurrentChannel());}...

99

Ideal Developer Effort

int getChannel () { return channel};void setChannel (int newChannel) { channel = newChannel;}...

100


Scaling problem of multicast-based discovery Auto Shut off problem

Simple-minded search Lack of access and concurrency control Static, manual, procedural service composition Device-independent UI No programmer-defined types High programming and maintenance costs

device servers prasun dewan department of computer science university of north carolina...

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