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.[1]
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.
DPWS standardization
The DPWS specification was initially published in May 2004 and was submitted for standardization to OASIS 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 with 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.
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[when?] 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 introduced-in-2006 "ConnectedLife.Home" 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. Further extending this work is the EU AESOPArchived 2013-04-07 at the Wayback Machine project.
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.
OSGi is an open specification and open source project under the Eclipse Foundation.
A web service (WS) is either:
Web Services Security is an extension to SOAP to apply security to Web services. It is a member of the Web service specifications and was published by OASIS.
Web Services Discovery provides access to software systems over the Internet using standard protocols. In the most basic scenario there is a Web Service Provider that publishes a service and a Web Service Consumer that uses this service. Web Service Discovery is the process of finding suitable web services for a given task.
WS-Management is a DMTF open standard defining a SOAP-based protocol for the management of servers, devices, applications and various Web services. WS-Management provides a common way for systems to access and exchange management information across the IT infrastructure.
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The Windows Communication Foundation (WCF), previously known as Indigo, is a free and open-source runtime and a set of APIs in the .NET Framework for building connected, service-oriented applications.
Web Services Dynamic Discovery (WS-Discovery) is a technical specification that defines a multicast discovery protocol to locate services on a local network. It operates over TCP and UDP port 3702 and uses IP multicast address 239.255.255.250 or ff02::c. As the name suggests, the actual communication between nodes is done using web services standards, notably SOAP-over-UDP.
Web Services Interoperability Technology (WSIT) is an open-source project started by Sun Microsystems to develop the next-generation of Web service technologies. It provides interoperability between Java Web Services and Microsoft's Windows Communication Foundation (WCF).
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Apache CXF is an open source software project developing a Web services framework. It originated as the combination of Celtix developed by IONA Technologies and XFire developed by a team hosted at the now defunct host CodeHaus in 2006. These two projects were combined at the Apache Software Foundation. The name "CXF" was derived by combining "Celtix" and "XFire".
The Microsoft Open Specification Promise is a promise by Microsoft, published in September 2006, to not assert its patents, in certain conditions, against implementations of a certain list of specifications.
Spring Roo is an open-source software tool that uses convention-over-configuration principles to provide rapid application development of Java-based enterprise software. The resulting applications use common Java technologies such as Spring Framework, Java Persistence API, Thymeleaf, Apache Maven and AspectJ. Spring Roo is a member of the Spring portfolio of projects.
OpenEJB is an open-source, embeddable and lightweight Enterprise JavaBeans Container System and EJB Server, released under the Apache License 2.0. OpenEJB has been integrated with Java EE application servers such as Geronimo and WebObjects.
Robot as a service or robotics as a service (RaaS) is a cloud computing unit that facilitates the seamless integration of robot and embedded devices into Web and cloud computing environment. In terms of service-oriented architecture (SOA), a RaaS unit includes services for performing functionality, a service directory for discovery and publishing, and service clients for user's direct access. The current RaaS implementation facilitates SOAP and RESTful communications between RaaS units and the other cloud computing units. Hardware support and standards are available to support RaaS implementation. Devices Profile for Web Services (DPWS) defines implementation constraints to enable secure Web Service messaging, discovery, description, and eventing on resource-constrained devices between Web services and devices.
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