WURFL Patch File Applying your local fixes to the WURFL by Luca Passani      passani at eunet dot no      luca dot passani at openwave dot com While everyone can patch their own copy of the WURFL file for their own purposes, real applications may find this approach hard to manage. The idea behind WURFL is that you get a newer version of the WURFL file as more accurate information becomes available and is added to the WURFL file. Modifying one's private copy of the WURFL makes the update process error-prone and hard to manage. The introduction of the WURFL 'patch file' helps with this. Developers can add a 'wurfl_patch.xml' file to their system, which stores modified/enhanced groups and capability lists for new or existing WURFL devices. When the WURFL is parsed, the patch file is also imported to build a modified version of the device database. When to use the patch There may be different reasons why one wishes to use a patch file. Here are some (there may be others): An existing device contains wrong data You fix your local version of the WURFL by overriding existing devices and defining new capabilities (or overriding existing ones). In this case, you may want to tell the WURFL maintainer about your findings, so we can fix the official WURFL for the whole community. Your application is very specific You need capabilities which are not in the WURFL and are unlikely to be added (i.e. the WURFL is too general for your needs). You define the capabilities in the patch file and update your WURFL without interference. Capabilities are OK, but you have your own reasons to assign them different values You can use the WURFL file to override those capability values and still update the WURFL independently What does the patch file look like? The patchfile is very similar to the WURFL itself (but hopefully much shorter!). Bialetti is an Italian coffee-maker manufacturer. I'll add coffee-maker support for the WURFL with a patch: wurfl_patch.xml <wurfl_patch> <devices> <device user_agent="" fall_back="root" id="generic"> <group id="magical_powers"> <capability name="makes_good_coffee" value="false" /> <capability name="average_coffee_preparation_time" value="0" /> </group> <group id="display"> <capability name="resolution_height" value="200"/> <capability name="lucas_capa" value="0"/> </group> <group id="new_group"> <capability name="new_capa1" value="false"/> <capability name="new_capa2" value="0"/> </group> </device> <device user_agent="Nokia 20" fall_back="generic" id="nokia_generic_series20"> <group id="new_group"> <capability name="new_capa1" value="true"/> <capability name="new_capa2" value="34832798"/> </group> <group id="display"> <capability name="resolution_height" value="3300"/> </group> </device> <!-- Adding a Coffeee Pot to the WURFL --> <device id="bialetti_ver61" user_agent="Bialetti 6.1" fall_back="generic"> <group id="magical_powers"> <capability name="makes_good_coffee" value="true" /> <capability name="average_coffee_preparation_time" value="5" /> </group> <group id="display"> <capability name="resolution_width" value="190"/> <capability name="resolution_height" value="140"/> <capability name="lucas_capa" value="34832798"/> </group> </device> </devices> </wurfl_patch> There are a few things to observe about the patch file: wurfl_patch and devices enclose the patch If you add new groups and or capabilities to the WURFL for some devices, you *must* initialize them by overriding generic values and providing corresponding groups and capabilities with the values for unrecognized devices. If the 'id' of a certain device already exists, then you are overriding an existing device. Otherwise, it's effectively a new device you are defining. If you override an existing device, you are not allowed to change the User Agent string associated to the device by the WURFL. If you are defining a new device, you must provide a User Agent string. If you override an existing device, the capabilities you introduce are either: added to the list of capabilities for that device (the capability was not previously defined in the original device). used to modify the value of the capability (the capability was previously defined in the original device) Of course, this happens automatically, so your patch will keep working even if the capabilities in the patch are added to the official WURFL version. Example: Let's assume we have a wurfl_patch.xml file like the one above and a mini wurfl.xml file like the one which follows: <?xml version="1.0" encoding="UTF-8" ?> <wurfl> <devices> <device fall_back="root" id="generic" user_agent=""> <group id="wml_ui"> <capability name="access_key_support" value="false" /> <capability name="wrap_mode_support" value="false" /> </group> <group id="display"> <capability name="resolution_width" value="90" /> <capability name="resolution_height" value="40" /> </group> </device> <device user_agent="Nokia 20" fall_back="generic" id="nokia_generic_series20"> <group id="display"> <capability name="resolution_width" value="260" /> <capability name="resolution_height" value="440" /> </group> </device> <device user_agent="Nokia 30" fall_back="nokia_generic_series20" id="nokia_generic_series30"> <group id="wml_ui"> <capability name="access_key_support" value="true" /> </group> <group id="display"> <capability name="resolution_width" value="96" /> <capability name="resolution_height" value="65" /> </group> </device> <device user_agent="Nokia 40" fall_back="nokia_generic_series30" id="nokia_generic_series40"> <group id="display"> <capability name="resolution_width" value="128" /> <capability name="resolution_height" value="128" /> </group> </device> <device user_agent="Nokia 60" fall_back="nokia_generic_series40" id="nokia_generic_series60"> <group id="wml_ui"> <capability name="access_key_support" value="false" /> </group> </device> </devices> </wurfl> The merged patch file (i.e. wurfl.xml patched with wurfl_patch.xml) will be equivalent to this: <?xml version="1.0" encoding="UTF-8"?> <wurfl> <devices> <device fall_back="root" id="generic" user_agent=""> <group id="wml_ui"> <capability name="access_key_support" value="false"/> <capability name="wrap_mode_support" value="false"/> </group> <group id="display"> <capability name="resolution_width" value="90"/> <capability name="resolution_height" value="200"/> <capability name="lucas_capa" value="0"/> </group> <group id="magical_powers"> <capability name="makes_good_coffee" value="false"/> <capability name="average_coffee_preparation_time" value="0"/> </group> <group id="new_group"> <capability name="new_capa1" value="false"/> <capability name="new_capa2" value="0"/> </group> </device> <device user_agent="Nokia 20" fall_back="generic" id="nokia_generic_series20"> <group id="display"> <capability name="resolution_width" value="260"/> <capability name="resolution_height" value="3300"/> </group> <group id="new_group"> <capability name="new_capa1" value="true"/> <capability name="new_capa2" value="34832798"/> </group> </device> <device user_agent="Nokia 30" fall_back="nokia_generic_series20" id="nokia_generic_series30"> <group id="wml_ui"> <capability name="access_key_support" value="true"/> </group> <group id="display"> <capability name="resolution_width" value="96"/> <capability name="resolution_height" value="65"/> </group> </device> <device user_agent="Nokia 40" fall_back="nokia_generic_series30" id="nokia_generic_series40"> <group id="display"> <capability name="resolution_width" value="128"/> <capability name="resolution_height" value="128"/> </group> </device> <device user_agent="Nokia 60" fall_back="nokia_generic_series40" id="nokia_generic_series60"> <group id="wml_ui"> <capability name="access_key_support" value="false"/> </group> </device> <device id="bialetti_ver61" user_agent="Bialetti 6.1" fall_back="generic"> <group id="magical_powers"> <capability name="makes_good_coffee" value="true"/> <capability name="average_coffee_preparation_time" value="5"/> </group> <group id="display"> <capability name="resolution_width" value="190"/> <capability name="resolution_height" value="140"/> <capability name="lucas_capa" value="34832798"/> </group> </device> </devices> </wurfl>

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