Web Services Discovery andWeb Services Devices Profile

Toby NixonCo-Chair, OASIS WS-DD TCtoby.nixon@microsoft.com

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Networked Device Standards“The Great Thing about Standards is… … there are so many to choose from!”

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Industry Challenges• Non-interoperable or gateways required

– And often gateways not available• Proprietary physical interfaces• Tied to single physical layers• Non-standard link protocols• Platform- or runtime-specific• Not extendable

– Limited opportunity for innovation• Not scalable• Limited, if any, development tools• Security

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Web Services• Interoperable machine-to-machine interaction

over a network– Programmatic interfaces

• Messages formatted using XML (Extensible Markup Language)

• Simple Object Access Protocol (SOAP)• Web Services Description Language (WSDL)

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Benefits of Web Services• Work on any physical network• Standard protocols: TCP/UDP/IP, HTTP, XML• Not platform- or runtime-specific• Scalable from smallest device to the internet• Extendable by vendors and orgs• Excellent development tools from many

vendors, and many trained developers• Secure• High performance• Many infrastructure components available• Leverage industry investments

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UPnP – 1st Generation• Rolled out in 1999 – UPnP Forum created

– 10th Anniversary is this fall

• Web services were in their infancy– HTTP, XML, SOAP… not much else– UPnP is based on an early snapshot

• But many benefits from just these basics, so industry moved ahead with UPnP adoption– Most adoption for NAT traversal and media sharing– UPnP supported in Windows since Windows ME

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UPnP Status• UPnP Forum now has over 880 members

– UPnP Forum was incorporated in January, 2009

• 72 UPnP specifications were published as ISO/IEC standards in December, 2008– UPnP Device Architecture 1.0– DCPs: Basic Device, AVv1, AVv2, Digital Security Camera,

HVAC, Lighting, Internet Gateway, Printer, Scanner, QOSv1, QOSv2, RemoteUI, Device Security

• New specifications not yet submitted to ISO/IEC– Done: UDA 1.1, Low Power, AVv3 and QOSv3– Work in Progress: Remote Access, Content Sync, Device

Management, Telephony, AVv4

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DPWS – 2nd Generation• UPnP 2.0 was proposed in 2002

– Full alignment with Web Services architecture– Lightweight profile of Web Services specifications

appropriate for embedded device applications– Work suspended because some specs not ready,

including Discovery and Eventing• Work started on Devices Profile for Web

Services, WS-Discovery, and WS-Eventing– BEA, Canon, Computer Associates, IBM, Intel,

Lexmark, Microsoft, Ricoh, SoftwareAG, and TIBCO worked on various components

– Industry workshops and plugfests– DPWS first published in 2004

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How It Works• Addressing – automatic assignment• Discovery – automatically find devices• Description – what can the device do?• Control – invoke device functions• Eventing – monitor device state• Presentation – use device’s web interface• Security – authentication, integrity, privacy

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Addressing• Address assignment not detailed in DPWS

– But typical implementations all work the same way

• IPv4– Attempt DHCP address assignment– If fails, use “Auto-IP” (RFC 3927) self-assigned local

address (169.254/16)– Check periodically for DHCP server– Static IP addresses also permitted

• IPv6– Obtain address from DHCP or Router– Or use self-assigned Unique Local Address (RFC 4193)

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Discovery• WS-Discovery

– Being standardized in OASIS WS-DD along with DPWS

• Device multicasts “Hello” when joins network• Client requests address using “Resolve”

– Device responds using “ResolveMatch”

• Clients can search using multicast “Probe”– Devices respond using “ProbeMatch”

• Device multicasts “Bye” when leaving• WS-Discovery also defines “discovery proxy”

server role for managed networks, scalability

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Description• Client uses WS-Transfer to Get device

description information– ThisModel: e.g. manufacturer name, model number– ThisDevice: user-assigned name, serial number,

firmware version– Relationship: List of device types and services

available on device, and their WS-Addressing EPRs

• Client can use WS-MetadataExchange GetMetadata to download WSDLs for services– Data types, Port types, Operations, Messages– Used more at development time rather than run time

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Control• Actions defined in the service WSDL are

invoked using SOAP over HTTP• Responses returned using SOAP over HTTP

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Eventing• WS-Eventing

– Being standardized in W3C WS-ResourceAccess WG

• Clients Subscribe to event notifications– Address to deliver events– Desired duration of subscription– Optional filter expressing events of interest

• Service sends SOAP messages to client to deliver event notifications

• Client can Renew subscription, or Unsubscribe• Service can send SubscriptionEnd to

terminate subscription before expiration

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Presentation• Enables web interface to device• PresentationURL is included in ThisModel

metadata element• Client uses browser (HTTP GET) to use device’s

web interface• Metadata also includes

– ManufacturerURL– ModelURL

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Security• Optional• Secure devices must have X.509v3 certificate

– Should be unique for each device instance• Based on SSL/TLS (https://)

– Establish secure channel for description, control, and eventing for authentication, integrity, and confidentiality

– Device can require either X.509 certification or username/password authentication of client

• Multicast WS-Discovery messages authenticated and integrity-checked using Compact XML Signatures

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UPnP – DPWS Comparison

UPnP DPWS

Addressing DHCP, AutoIP Not Defined

Discovery SSDP WS-Discovery

Description UDA Schema WSDL

Control SOAP 0.9, 1.1 SOAP 1.2

Eventing GENA WS-Eventing

Presentation HTTP, HTML HTTP, HTML

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DPWS – Subset of WS-* Suite

Assurances

Messaging

SOAP

WS-Security

MTOM

Metadata

WSDL

UDDI

WS-Metadata Exchange

WS-Discovery

WS-Transfer WS-Enumeration WS-Eventing

XML Schema

WS-ReliableMessaging WS-Coordination

WS-AtomicTransactionWS-Trust

WS-SecureConversation

Infrastructureand ProfilesWS-ManagementWS-Federation Devices

Profile

Foundation

SOAP / HTTP

SOAP / UDP

MIME

XML Infoset

XML 1.0 XMLNamespaces

Workshop Submitted StandardMember Sub

WS-Addressing

WS-Policy

Non-DPWS

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DPWS Standardization• OASIS WS-DD TC

– Web Services Discovery and Web Services Devices Profile Technical Committee

– http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=ws-dd

– Co-proposed by CA, Canon, Lexmark, Microsoft, Nortel, Novell, Progress Software, Red Hat, Ricoh, Schneider Electric, Software AG, and WSO2

• DPWS, WS-Discovery, and SOAP-over-UDP– Not any specific device classes

• First Meeting September, 2008 in Redmond• Quarterly face-to-face meetings, weekly calls• Original Goal: Completion by 2nd quarter 2009• OASIS Final Approval vote is June 16-30, 2009

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DPWS Standardization• WS-DD Charter Clarified May 7, 2009

– TC will continue in maintenance mode until closed– Update DPWS to refer to W3C Recommendation

versions of WS-Eventing, WS-Transfer, and WS-MetadataExchange; profile as necessary

– Update to WS-I Basic Profile 2.0 if available– Deferred issues, spec issues, errata– Further work on Security if needed– DPWS 1.2 completion dependent on completion of

work in W3C WS-ResourceAccess WG

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DPWS Stacks• Microsoft

– Windows Vista and Windows 7• Printers, Scanners, Conference room projectors• Discovery of computers and users

– Windows Embedded CE 6.0 R2– Windows XP Embedded– .net Micro Framework 3.0– Biztalk Server 2008

• RFID readers

• Other stacks– Levitate, Peerless, SOA4D, gSOAP, eSOL, DotVision,

DPWS4J

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DPWS Implementations• Printers and Scanners

– Canon, HP, Xerox, Epson, Lexmark, Brother, Konica-Minolta, Fuji-Xerox, Toshiba, Ricoh, others

• Projectors– Epson, NEC, Toshiba– Several others coming

• Industrial and home control– Schneider, Hager, LeGrand, Beckhoff, Vantage– Exceptional Innovation

• Audio, Video, home control, hotel control• Over 1000 deployments in USA

– Disney Home of Tomorrow• Thousands of devices, 50K visitors in first week

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Future DPWS Applications• Point of Service• Energy Management• Network Infrastructure• Healthcare• Hospitality• Factory Automation• Mobile devices• Automotive• Many more…

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What About Device Schemas?• OASIS WS-DD will not define device class

specifications/schemas – outside of scope• No SIG or other organization for DPWS

– Nothing like UPnP Forum for DPWS– No DPWS-specific certification or logo program

• Individual device classes might have them• Any organization can reference DPWS

– Device schema specifications should be prepared in the most appropriate existing industry organization

– OASIS would be a great home for a device class when no other organization takes ownership

• Your organization can start today!

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Thanks!

Questions?