A new commercial offering from Thomas Milius is CaxDAV, which can be used to synchronise calendars and addresses between local clients and servers that support the CalDAV/CardDAV protocols.
Both CalDAV and CardDAV are extensions to the WebDAV protocol, which is short for Web Distributed Authoring and Versioning. WebDAV was intended as a system that would allow users to perform various actions on files on remote servers, with properties recorded about what actions they carried out; the essence of versioning, allowing revisions to be tracked.
The CalDAV protocol extends WebDAV specifically for scheduling data using the iCalendar format, while CardDAV extension covers contact data using the vCard format.
CaxDAV can take files in vCard (also known as VCF or Virtual Contact File) format, and iCalendar (ICS or Internet Calendaring and Scheduling) format – both of which I believe can be exported from Organizer, for example – and is able to synchronise them with any servers in a pre-defined list.
If the remotely held addresses and schedules appear to have changed asynchronously, CaxDAV will record the changes so that they can be passed back to the local application that looks after them – it is then up to that application to evaluate the changes and, if necessary, update its records.
Thomas is selling CaxDAV through his company Stader Softwareentwicklung GmbH (English version) and has priced it at €29.75 (€30.00 for customers in the UK). The slight difference in prices reflects the slightly higher rate of VAT in the UK than in Germany.