Channels are a fundamental concept in Pusher. Each application has a number of channels, and each client can choose which channels it subscribes to.
- A way of filtering data. For example, in a chat application there may be a channel for people who want to discuss ‘dogs’
- A way of controlling access to different streams of information. For example, a project management application would want to authorise people to get updates about ‘secret-projectX’
We strongly recommend that channels are used to filter your data and that it is not achieved using events. This is because all events published to a channel are sent to all subscribers, regardless of their event binding.
Channels don’t need to be explicitly created, and are instantiated on client demand. This means that creating a channel is easy. Just tell a client to subscribe to it.
There are 3 types of channels at the moment:
- Public channels can be subscribed to by anyone who knows their name
- Private channels should have a
private-prefix. They introduce a mechanism which lets your server control access to the data you are broadcasting
- Presence channels should have a
presence-prefix and are an extension of private channels. They let you ‘register’ user information on subscription, and let other members of the channel know who’s online
Channel Naming Conventions
Channel names may contain a maximum of 164 characters. This limit includes channel prefixes (i.e.
presence- are included in the character count).
Channel names should only include lower and uppercase letters, numbers and the following punctuation
_ - = @ , . ;
As an example this is a valid channel name:
If a channel has been subscribed to already it is possible to access channels by name, through the
var channel = pusher.channel(channelName);
- channelName (String)
- The name of the channel to retrieve