W3C MWI DDWG - Workshop on the Implementation of a Device Description Repository

Volantis Systems Ltd. Position Paper

Jennifer Bursack & Martin Jones
Volantis Systems Ltd.
1 Chancellor Court
Occam Road
Surrey Research Park
Guildford GU2 7YT
United Kingdom
+44 (1483) 739701


New mobile, web-enabled devices are pushed to the global market nearly on a daily basis. These devices do not just originate from the larger players in the mobile industry such as Nokia and Samsung, but also from less well-known manufacturers such as Xcute, Wonki and OKWap.

Tracking the capabilities of these devices has become an intensive process that requires much research time. To render a page at a high level of quality to each device requires accurate knowledge of many attributes of the device. Examples include the usable display width, support for downloads, CSS capabilities, video capabilities, etc.

The User Agent Profile (UAProf) specification was designed as a way of describing a phone's functionality using XML (RDF) and CC/PP. It has been adopted by most device manufacturers, though not all. Commonly, these XML files are stored on the manufacturer's website in a directory which contains all the profiles provided by that manufacturer. The UAProf location is specified in requests from a device using HTTP headers, via a URL that is hard-coded into the user agent.

Existing mechanisms such as UAProf have several shortcomings from the perspective of those who wish to do the best possible job of content adaptation.

Issues with current device descriptions

Availability of Device Descriptions

There are still many manufacturers that do not provide UAProf profiles for their devices. This is particularly true for non-GSM handsets, which despite having a minority market share, still account for hundreds of millions of devices globally. Also from time to time, device manufacturers go out of business, their web sites are shut down and their profiles become inaccessible (example: Sendo, the former UK-based device manufacturer).

Most manufacturers do not indicate the existence of new profiles by any method other than building the URLs into the devices that are shipped. This means that the details held within new profiles can remain elusive until the device becomes physically available.

The best way to create accurate descriptions for devices that do not supply UAProf information is to physically test the device. However it can be difficult and expensive to do this in a timely manner due to the location, availability, and network capabilities of the device.

Quality of Device Descriptions

If a profile exists for a device, Volantis will usually try to use this as an initial information source to populate the Volantis Device Database However some manufacturers do not follow all of the proper rules when creating the UAProf profile, so the documents are sometimes invalid and must be repaired before being imported. The availability of CC/PP or UAProf validation services has improved the situation but it still happens surprisingly often.

Furthermore, the information provided in a UAProf profile is often far from 100% accurate, and this situation does not seem to be improving. In fact, Volantis has noticed a rise in the amount of inaccurate UAProfile data over the last year. Even though issues may be corrected in later version of the UAProf, it can be difficult to determine when corrections have been made because the version control of UAProf documents is not standardized,

One source of inaccuracy is that the meanings of some of the UAProf attributes are not very clearly defined in the specifications. This can lead to differences in interpretation. As an example, while most profiles report the physical display dimensions, some report the dimensions of the area that is usable by the browser for displaying content.

Level of Detail in Device Descriptions

UAProfiles do supply a lot of useful information, but they still lack many details which may be vital in order to render web content in the best possible way.

These missing, or weakly represented details include items such as:

In some cases, more of this information can be obtained by referring to developer documentation provided by the manufacturer. However, this never covers all the required attributes, and many manufacturers do not supply any developer documentation at all. In most cases, the required level of detail can only be acquired through testing the device.


The ability of Volantis products to provide good quality rendering on a very wide range of real-world devices is largely dependent on the quality of the device information that is held in the Volantis Device Database. Volantis' goal is therefore to provide the most comprehensive and accurate information possible in the Volantis device database and device update service. As part of this effort, the Volantis Device team collects information from multiple sources and physically tests devices, covering a significant proportion of the global device landscape in order to validate the correctness of the data.

For the reasons described above, current public sources of information, while valuable, are insufficient and have to be supplemented by various means, all of which consume resources. Much of the information in the Volantis Device Database is of the kind that could be provided by public, shared sources of device descriptions, but more than half of the 530+ attributes are designed to provide more detailed data, which extends beyond what could reasonably be provided by publicly maintained databases. These detailed descriptions of behaviour are key to helping Volantis products fine-tune the adaptation of content to over 3000 device models.

Volantis would prefer to be in a position to concentrate its efforts on adding higher levels of detail to existing sources of commonly-known core device descriptions, rather than having to expend effort (duplicated by others) on establishing correct basic device descriptions.

Volantis believes that a general improvement in the quality and availability of basic device descriptions will ultimately benefit all of the stakeholders in the mobile web ecosystem.

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