Ably FAQs

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Ably FAQs

Channels

Channels

Details on channel functionality, limits, and best practices

Messages

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

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

Reliable message ordering for connected clients

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

How do I send emojis over Ably

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

Do you binary encode your messages for greater efficiency?

Can I send messages between clients without using channels?

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

Are messages recovered if my connection drops?

Am I able to check who has read published messages?

Client-specified message ID restrictions for multiple messages published atomically

What is Idempotent Publishing?

Can I store messages on specific channels?

I'm not receiving messages, how do I debug that?

Can I see messages sent by Channel or ClientID?

How does Ably count and bill for messages?

How can I reduce my message count?

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Subscribing and publishing

Subscription filters

Is there a maximum number of channels per connection?

Can I attach and subscribe to channels using wildcards?

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

Private/direct messages between users and group chat

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Presence

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

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

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

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

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

Can I change the length of the presence timeout?

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

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?

Are there restrictions on channel names?

General

How are channels opened and closed?

How to limit user numbers in channels

What does it mean if I see 'Channel Region Inactive' in my logs on the Dev Console?

History

Can I make a History Call to several Channels Simultaneously?

Common misconceptions around Ably History

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

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

Occupancy

Can I still use occupancy if the library I am using doesn't yet support channel parameters?

Metadata and statistics

How can I see which channels are currently active?