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Ably Help Center

Channels

Channels

Details on channel functionality, limits, and best practices

Can I see messages sent by Channel or ClientID?

Messages

How do I send emojis over Ably

How long are messages stored for?

What is the maximum message size?

Reliable message ordering for connected clients

Is it possible to prevent messages published being echoed back to the publishing client?

How synchronized / up to date is channel history between datacenters / regions?

How do I enable history? My messages are not being stored for longer than a few minutes.

Do you binary encode your messages for greater efficiency?

Can I store my messages for longer?

Can I store messages on specific channels?

Can I send messages between clients without using channels?

Can I send media stream through Ably?

Can I delete messages which have been persisted through the history API?

Can I be notified over HTTP when a channel is created or closed?

Can a published message be pushed to a mobile device using Mobile Push Notifications (GCM or APN)?

Are messages recovered if my connection drops?

Am I able to check who has read published messages?

Is it possible to check if a specific message has been delivered to a device?

Client-specified message ID restrictions for multiple messages published atomically

What is Idempotent Publishing?

Can messages be consumed using a more traditional streaming API akin to Kafka or SSE?

Is it possible to check if a specific message has been delivered to a device?

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Subscribing and publishing

Is there a maximum number of channels per connection?

How do I subscribe or unsubscribe for messages on channels?

Does an attached channel receive messages even if subscribe has not been called?

Can I attach and subscribe to channels using wildcards?

Presence

What happens if I exceed the number of members present on a channel?

How can I see which channels are currently active?

How can I implement presence subscriptions efficiently, in terms of limits?

Why don't presence members leave as soon as I close a tab?

Can I change the length of the presence timeout?

Can a single user be present multiple times on the same channel?

Can I change my connection's clientId after connecting?

Can I use webhooks or other rules to maintain an external copy of the presence set of a channel or channels?

What happens to the presence status of a client that abruptly disconnects?

I don't understand why I see so many presence messages in my stats.

Can I be notified over HTTP when someone enters or leaves a channel?

Why do you have a limit on the number of members present on a channel?

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Namespaces and naming

What is a channel namespace and how can I use them?

What restrictions exist for the name field of a channel namespaces?

Are channel names and channel namespaces case-sensitive?

What restrictions are there on channel names?

General

How are channels opened and closed?