4. Using UAProf (User Agent Profile) to Detect User Agent Types and Device Capabilities
4.1. Introduction
UAProf (User agent profile) is an XML document that contains information about the user agent type and device capabilities. It is a standard defined and maintained by the Open Mobile Alliance (formerly the WAP Forum).
UAProf was created according to the CC/PP (Composite Capabilities/Preferences Profiles) framework with RDF (Resource Description Framework) as the schema. Both CC/PP and RDF were defined by the W3C (World Wide Web Consortium).
User agent profiles are stored in a server called the profile repository. Very often a profile repository is maintained by a mobile device manufacturer. For example, the user agent profiles describing the capabilities of Nokia cell phones are stored in a profile repository maintained by Nokia.
The URL that points to the user agent profile of a mobile device can be found in the headers of requests sent by the mobile device. Very often the URL is located in the x-wap-profile header or the Profile header. For example, the value of the x-wap-profile header generated by a Nokia 6230i cell phone is:
"http://nds1.nds.nokia.com/uaprof/N6230ir200.xml"
A user agent profile contains a number of components and each component has a number of attributes. For example, if you download and open Nokia 6230i's user agent profile, you will find the ScreenSize attribute under the HardwarePlatform component, like this:
...
<prf:component>
<rdf:Description
rdf:ID="HardwarePlatform">
<rdf:type
rdf:resource= "http://www.openmobilealliance.org/tech/profiles/UAPROF/ccppschema-20021212#HardwarePlatform"/>
...
<prf:ScreenSize>208x208</prf:ScreenSize>
...
</rdf:Description>
</prf:component>
...
From the above user agent profile, we know that Nokia 6230i cell phones have a screen size of 208 pixels x 208 pixels.
The latest approved UAProf specification is WAP-248-UAProf-20011020-a, which is part of WAP 2.0. The newest version is OMA-UAProf-V2_0_20030520-C1, which is still in the candidate phase.
4.2. Where to Find the URL of the UAProf Document of a Mobile Device
As mentioned earlier, the URL of the UAProf document of a mobile device can very often be found in the HTTP headers x-wap-profile or Profile. For example, if you look inside the HTTP requests sent by Nokia 6230i, you will find the following line:
x-wap-profile: "http://nds1.nds.nokia.com/uaprof/N6230ir200.xml"
If you cannot find the x-wap-profile header and the Profile header in an HTTP request, you may find the URL of the UAProf document by following the steps below:
1. Check if there are any Opt headers in the HTTP request. If yes, read the value of the Opt header that contains the URL "http://www.w3.org/1999/06/24-CCPPexchange". The Opt header should contain something like this:
"http://www.w3.org/1999/06/24-CCPPexchange" ; ns=80
2. Extract the namespace number in the Opt header. In the above example, the namespace number is 80.
3. The URL of the UAProf document should be found in the NAMESPACE-Profile header, where NAMESPACE is the namespace number you found in the Opt header. For example:
80-Profile: "http://wap.sonyericsson.com/UAprof/T68R502.xml"
Note that not all mobile devices support UAProf and so you may not be able to find the URL of the UAProf document in HTTP headers. If the mobile device does not support UAProf, you can still find out certain information about the user agent using traditional HTTP headers such as Accept, Accept-Charset, Accept-Language and User-Agent.
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