To establish a standard and to proof that it is actually implementable the creator usually develops a reference implementation. For ISO standards this is even mandatory.
The same thing happened with the SyncML specification. A reference toolkit (RTK) was published with a very unrestrictive license on the web site.
After the standard established itself, however the policy for the toolkit changed. First, the newer toolkit (now called SCTS) was only available to attendees of a so-called syncfest. Then, they decided to take the toolkit totally off the web site and make it available with “promoter membership” only. The only problem with that is that this promoter membership currently costs $20.000 per year. For this reason, the version described here is the last freely available one.
The RTK is written in pure C. It takes care of the parsing of the XML commands and the creation of SyncML messages. This is equivalent to the core layer of sync4j. It also implements basic transports.
Using the RTK requires an in-depth knowledge of the SyncML specifications. Most commands are simply mapped to C functions.
The RTK would have been a good base for the start of own projects. Its major shortcomings are the use of plain C and the need of deeper knowledge. But since the current versions are not free anymore, this opportunity ceased to exist.