Devices Profile for Web Services
Encyclopedia
The Devices Profile for Web Services (DPWS) defines a minimal set of implementation constraints to enable secure Web Service
messaging, discovery, description, and eventing on resource-constrained devices.
Its objectives are similar to those of Universal Plug and Play
(UPnP) but, in addition, DPWS is fully aligned with Web Services technology and includes numerous extension points allowing for seamless integration of device-provided services in enterprise-wide application scenarios.
in July 2008. DPWS 1.1 was approved as OASIS Standard together with WS-Discovery 1.1 and SOAP-over-UDP 1.1 on June 30 2009.
DPWS defines an architecture in which devices run two types of services: hosting services and hosted services. Hosting services are directly associated to a device, and play an important part in the device discovery process. Hosted services are mostly functional and depend on their hosting device for discovery.
In addition to these hosted services, DPWS specifies a set of built-in services:
DPWS builds on the following core Web Services standards: WSDL
1.1, XML Schema, SOAP
1.2, WS-Addressing
, and further comprises WS-MetadataExchange
, WS-Transfer
, WS-Policy
, WS-Security
, WS-Discovery and WS-Eventing
.
Microsoft
's Windows Vista
and Windows Embedded CE6R2 platforms natively integrate DPWS with a stack called WSDAPI, included as part of the Windows Rally
technologies. Support for OSGi
is on the way.
For many manufacturers, the first step towards DPWS adoption is the creation of a small “device bridge” between their native, usually proprietary, code and Web Services. At least 117 automation and AV products from 37 different vendors currently support DPWS either natively or through a bridge. At the International Security Controls (ISC) trade show, a major security company demonstrated a security system that supported DPWS, while the Kitchen and Bath Show (KBIS) saw two major appliance manufacturers demonstrating washers and dryers that communicated using DPWS. A communicative oven has been demonstrated at the International Building Show for the past two years. An even greater sign of the drive towards market acceptance of DPWS is the recent ConnectedLife. Home automation package offered by US retailer Best Buy. The package uses automation software and controllable devices that leverage DPWS for communications.
Also stemming from the SIRENA project, the "Web Services for Devices" (WS4D.org) Website provides information, downloads and news about three DPWS implementations: one C implementation integrating gSOAP, one Java implementation using Axis, and another Java implementation that can use different Java editions, including Java ME.
Following the SIRENA project, a new European research project from ITEA, named SODA (Service Oriented Device and Delivery Architecture), went further into the development and implementation of an embedded DPWS stack for devices and associated tools.
The EU Research Project SOCRADES composed by heavyweights like ABB, SAP, Schneider Electric, and Siemens, are focusing on implementing, testing and piloting prototypes of DPWS-enabled devices in the industrial automation domain.
There are several proposals and/or projects having worked on an integration of DPWS with OSGi
, i.e. mainly providing an implementation for this Java
framework.
Web service
A Web service is a method of communication between two electronic devices over the web.The W3C defines a "Web service" as "a software system designed to support interoperable machine-to-machine interaction over a network". It has an interface described in a machine-processable format...
messaging, discovery, description, and eventing on resource-constrained devices.
Its objectives are similar to those of Universal Plug and Play
Universal Plug and Play
Universal Plug and Play is a set of networking protocols for primarily residential networks without enterprise class devices that permits networked devices, such as personal computers, printers, Internet gateways, Wi-Fi access points and mobile devices to seamlessly discover each other's presence...
(UPnP) but, in addition, DPWS is fully aligned with Web Services technology and includes numerous extension points allowing for seamless integration of device-provided services in enterprise-wide application scenarios.
DPWS Standardization
The DPWS specification was initially published in May 2004 and was submitted for standardization to OASISOASIS (organization)
The Organization for the Advancement of Structured Information Standards is a global consortium that drives the development, convergence and adoption of e-business and web service standards...
in July 2008. DPWS 1.1 was approved as OASIS Standard together with WS-Discovery 1.1 and SOAP-over-UDP 1.1 on June 30 2009.
DPWS defines an architecture in which devices run two types of services: hosting services and hosted services. Hosting services are directly associated to a device, and play an important part in the device discovery process. Hosted services are mostly functional and depend on their hosting device for discovery.
In addition to these hosted services, DPWS specifies a set of built-in services:
- Discovery services: used by a device connected to a network to advertise itself and to discover other devices. Support of discovery has led some to dub DPWS as "the USB for Ethernet."
- Metadata exchange services: provide dynamic access to a device’s hosted services and to their metadata.
- Publish/subscribe eventing services: allowing other devices to subscribe to asynchronous event messages produced by a given service.
DPWS builds on the following core Web Services standards: WSDL
Web Services Description Language
The Web Services Description Language is an XML-based language that is used for describing the functionality offered by a Web service. A WSDL description of a web service provides a machine-readable description of how the service can be called, what parameters it expects and what data structures...
1.1, XML Schema, SOAP
SOAP
SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks...
1.2, WS-Addressing
WS-Addressing
WS-Addressing or Web Services Addressing is a specification of transport-neutral mechanisms that allow web services to communicate addressing information...
, and further comprises WS-MetadataExchange
WS-MetadataExchange
WS-MetaDataExchange is a Web Services protocol specification, published by BEA Systems, IBM, Microsoft, and SAP. WS-MetaDataExchange is part of theWS-Federation roadmap; and is designed to work in conjunction with WS-Addressing, WSDL and WS-Policy to allow retrieval of metadataabout a Web...
, WS-Transfer
WS-Transfer
WS-Transfer is a specification defining the transfer of an XML-representation of an WS-addressable resource, as well as creating and deleting such resources.The Candidate Recommendation specification summarize the scope like this:...
, WS-Policy
WS-Policy
WS-Policy is a specification that allows web services to use XML to advertise their policies and for web service consumers to specify their policy requirements.WS-Policy is a W3C recommendation as of September 2007....
, WS-Security
WS-Security
WS-Security is a flexible and feature-rich extension to SOAP to apply security to web services. It is a member of the WS-* family of web service specifications and was published by OASIS....
, WS-Discovery and WS-Eventing
WS-Eventing
WS-Eventing defines a protocol for web services to subscribe to another web service, or to accept a subscription from another web service. It is used to provide asynchronous notifications to interested parties.-External links:**...
.
Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
's Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...
and Windows Embedded CE6R2 platforms natively integrate DPWS with a stack called WSDAPI, included as part of the Windows Rally
Windows Rally
Windows Rally is a set of technologies from Microsoft intended to simplify the setup and maintenance of wired and wireless network-connected devices. They aim to increase reliability and security of connectivity for users who connect the devices to the Internet or to computers running Microsoft...
technologies. Support for OSGi
OSGi
The Open Services Gateway initiative framework is a module system and service platform for the Java programming language that implements a complete and dynamic component model, something that does not exist in standalone Java/VM environments...
is on the way.
Use Cases
Because DPWS supports dynamic discovery, and is part of the evolving vision of distributed applications that leverage WS-* standards, its application to automation environments is clear. At the 2007 Consumer Electronics Show, a “Next Gen” home was highlighted by an automation system, Life|ware from Exceptional Innovation, that uses DPWS to communicate with a lighting system, audio distribution system, security system, motorized shades, security cameras, thermostats, washers and dryers, and a motorized television mount. The show demonstrated tremendous consumer interest in the prospect of bringing controllable devices into the same environment as digital entertainment, and manufacturers are taking notice.For many manufacturers, the first step towards DPWS adoption is the creation of a small “device bridge” between their native, usually proprietary, code and Web Services. At least 117 automation and AV products from 37 different vendors currently support DPWS either natively or through a bridge. At the International Security Controls (ISC) trade show, a major security company demonstrated a security system that supported DPWS, while the Kitchen and Bath Show (KBIS) saw two major appliance manufacturers demonstrating washers and dryers that communicated using DPWS. A communicative oven has been demonstrated at the International Building Show for the past two years. An even greater sign of the drive towards market acceptance of DPWS is the recent ConnectedLife. Home automation package offered by US retailer Best Buy. The package uses automation software and controllable devices that leverage DPWS for communications.
Research Projects driving DPWS adoption
Within the SIRENA project, under the auspices of the European research initiative ITEA, Schneider Electric produced an early DPWS implementation targeted at embedded devices. This implementation was open-sourced through the SOA4D.org (SOA for Devices) Website, from which the DPWS stack (both C and Java versions) and its add-ons (like WS-Management and WS-Security implementations) can be freely downloaded.Also stemming from the SIRENA project, the "Web Services for Devices" (WS4D.org) Website provides information, downloads and news about three DPWS implementations: one C implementation integrating gSOAP, one Java implementation using Axis, and another Java implementation that can use different Java editions, including Java ME.
Following the SIRENA project, a new European research project from ITEA, named SODA (Service Oriented Device and Delivery Architecture), went further into the development and implementation of an embedded DPWS stack for devices and associated tools.
The EU Research Project SOCRADES composed by heavyweights like ABB, SAP, Schneider Electric, and Siemens, are focusing on implementing, testing and piloting prototypes of DPWS-enabled devices in the industrial automation domain.
There are several proposals and/or projects having worked on an integration of DPWS with OSGi
OSGi
The Open Services Gateway initiative framework is a module system and service platform for the Java programming language that implements a complete and dynamic component model, something that does not exist in standalone Java/VM environments...
, i.e. mainly providing an implementation for this Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
framework.