This page is currently a braindump of CardDAV related information. If there is a library for this in the language you’re using, you’re probably better off using that.

CardDAV has a lot of functionality, but depending on your purposes you can keep your code simple and get the job done easily. With critical information such as address books, it is usually a good idea to keep your access read only. If you mess up with read only access, you just read incorrectly. But if you mess up when trying to read/delete contacts, you risk losing user data.

Daytime is an almost extinct protocol that can be used to get the current time from a server. It is defined by RFC867. It can be used over TCP or UDP.

TCP Connections

The server should listen on TCP port 13. When it accepts a new connection, it should send the current time in an UNSPECIFIED format, discard any received data and close the connection.

The project URL entered into BOINC is just a human-readable (X)HTML page. The RPC communication happens on a separate endpoint. This endpoint is located by fetching the project URL and looking for a specific tag.

There are two different ways to find the tag. It is recommended to implement both of them to maximize compatibility.