Since version 3.3, vObject has support for parsing and generating iTip
messages. Currently only
VEVENT is supported.
What is an iTip message?
iTip is defined in rfc5546. iTip messages are a type of iCalendar messages, that are typically used for scheduling (invites and replies and such).
You can recognize an iTip message from a standard iCalendar message by the
fact that it will have a
METHOD property. Here's a minimal example of an
BEGIN:VCALENDAR VERSION:2.0 METHOD:REQUEST BEGIN:VEVENT UID:foobar ORGANIZER:email@example.com ATTENDEE:firstname.lastname@example.org SEQUENCE:1 END:VEVENT END:VCALENDAR
Here's an example of a response to that invite:
BEGIN:VCALENDAR VERSION:2.0 METHOD:REPLY BEGIN:VEVENT UID:foobar ORGANIZER:email@example.com ATTENDEE;PARTSTAT=ACCEPTED:firstname.lastname@example.org SEQUENCE:1 END:VEVENT END:VCALENDAR
These types of messages are often sent over email. This is called iMip. CalDAV servers also deal with iTip, this is defined in rfc6638.
There are very strictly defined semantics on how Calendar agents are supposed to generate and process these. VObject provides some help with this.
Generating iTip messages
Generating iTip messages works based on the following three scenarios:
- A user creates an event,
- A user updates an event,
- A user deletes an event.
For each of those scenarios, we need to figure out:
- Is the user an attendee or organizer for that event?
- If the user is an attendee, did the attendee update their participation status?
- If the user is an organizer, do the attendees need to know about any updates?
- And so on.
There's quite a few possible scenarios, including organizers adding or removing attendees, resulting into various requests, cancellations and replies.
Here's an example to generate these messages:
$broker = new Sabre\VObject\ITip\Broker(); $messages = $broker->parseEvent( $newCalendar, 'email@example.com', $oldCalendar );
$oldCalendar should either be a
null, it will be treated as a new object, if
null, it will be treated as if the user deleted the object.
The returned value (
$messages) is an array of
objects. Each object carries all the relevant information to deliver the
object using email or otherwise.
Parsing iTip messages
The broker can also parse incoming iTip messages. This happens for example when:
- You receive an invite,
- You get an update for an invite,
- You send a reply to an invite,
- You receive a cancellation for an invite.
The broker can parse these incoming messages, and update an existing calendar object (or create a new one).
To do this, you will need a fully populated
object, and some existing calendar object (or not at all if it's an invite
to a new event).
$broker = new Sabre\VObject\ITip\Broker(); $broker->processMessage( $message, $oldCalendar );
This will update