Explanation of metrics in rate limit errors

When a rate limit on your account is exceeded, we will reject new operations, such as publishing messages, until the rate limit period has passed. Therefore, messages are not discarded unpredictably within the system, and instead only new requests that cannot be completed in full by the system due to limits on your account, will be rejected.

For example, you have hit an instantaneous per second rate limit, then we will only reject new published messages for that second, and the block will be removed in the following second interval. Please note that for hourly rate limits, the limits are applied based on a clock hour as opposed to a rolling hour window, and monthly limits are applied based on a calendar month.

Error messages sent to clients once a rate limit has been imposed, will typically include the metric within the error message. See an example error message below:

Rate limit exceeded; request rejected (nonfatal); metric = channel.maxRate; interval = 2018-01-05:10:10:3; permitted rate = 5000; current rate = 5015; scope = channel:[YOUR APP ID]:[YOUR CHANNEL] (status: 429, code: 42910) (code: 42910, http status: 429)

The limit hit with this error is described by the metric attribute channel.maxRate. The following table lists out all metrics and what they represent:

Metric	Time period for block	Description
Connections
connections.hard	The block is removed as soon as the number of connections is reduced to within your account limits.	You have reached the peak number of concurrent connections allowed for your package.
connections.maxCreationRate	Within a few seconds once the rate drops.	You have exceeded the max rate of new connections allowed per second on your account. The allowed creation rate will increase as you upgrade the number of connections on your account.
Messages
messages.monthly.hard.count	The block is removed in the next calendar month.	You have reached the maximum number of messages allowed for your package in the calendar month. Find out more about how Ably counts messages.
messages.monthly.hard.data	The block is removed in the next calendar month.	You have reached the maximum bandwidth allowed for your package in the calendar month. The bandwidth allowed on your account is calculated as the total number of messages you have purchased multiplied by the default message size allowed of 2KiB. Find out more about how Ably counts message bandwidth.
messages.hourly.hard.count	The block is removed in the next clock hour.	You have reached the maximum number of messages allowed for your package in the current clock hour. Find out more about how Ably counts messages.
messages.hourly.hard.data	The block is removed in the next clock hour.	You have reached the maximum bandwidth allowed for your package in the current clock hour. The bandwidth allowed on your account is calculated as the total number of messages you have multiplied by the default message size allowed of 2KiB. Find out more about how Ably counts message bandwidth.
messages.maxRate	Within a few seconds once the rate drops.	You have reached the maximum per second rate of published and received messages allowed for your package. Find out more about how Ably counts messages. Find out why we have per second limits.
messages.maxBandwidth	Within a few seconds once the rate drops.	You have reached the maximum per second bandwidth rate for all published and received messages allowed for your package. Find out more about how Ably counts message bandwidth. Find out why we have per second limits.
connection.outboundRate	Within a few seconds once the rate drops.	The rate of outbound (subscribed) messages per second from Ably to the client has been exceeded. This will typically result in the Ably platform forcibly detaching channels for your client to reduce the rate of messages sent to that client. Consider reducing the volume of messages sent to each client as the rate is probably unsustainable for most remote clients.
connection.inboundRate	Within a few seconds once the rate drops.	The rate of incoming (published) messages per second from your client to Ably has been exceeded. This will result in Ably rejecting messages that are published. Consider reducing the volume of messages sent to Ably.
channel.maxRate	Within a few seconds once the rate drops.	You have reached the maximum per second rate of messages published on a single channel. Consider reducing the number of messages you publish per second, or shard your channel traffic across multiple channels. Please note that there is no subscribe rate limit on channels, only a publish rate limit. The rate of messages received on a channel is only limited by the total number of messages allowed on your account and the account-wide messages.maxRate limit described above. Find out more about how Ably counts messages.
channels.maxBandwidth	Within a few seconds once the rate drops.	You have reached the maximum per second bandwidth rate from messages published on a single channel. Consider reducing the number of messages you publish per second, or shard your channel traffic across multiple channels. Please note that there is no subscribe rate limit on channels, only a publish rate limit. The rate of messages received on a channel is only limited by the total number of messages allowed on your account and the account-wide messages.maxRate limit described above. Find out more about how Ably counts message bandwidth.
messages.maxSize	None	The message you have published exceeds the max message size allowed for your package. Upgrade to a paid account if you are on a free account, or contact us if you need larger messages on a paid package.
Channels
channels.hard	The block is removed as soon as the number of active channels is reduced to within your account limits.	You have reached the peak number of actively used concurrent channels allowed for your package.
connections.maxCreationRate	Within a few seconds once the rate drops.	You have exceeded the max rate of new channels allowed per second on your account. The allowed creation rate will increase as you upgrade the number of channels on your account.
channels.perConnection	The block is removed as soon as the number of attached channels is reduced by the effected client.	The realtime client has attached to the maximum number of channels allowed per connection. Find out more about the max number of channels allowed per account and how to correct common problems leading to this problem.
API requests
apiRequests.hourly.hard	The block is removed in the next clock hour.	You have exceeded the allowed number of REST API requests (excluding any token requests) in any clock hour.
apiRequests.maxRate	Within a few seconds once the rate drops.	You have exceeded the max rate of REST API requests (excluding any token requests) per second.
Token requests
tokenRequests.hourly.hard	The block is removed in the next clock hour.	You have exceeded the allowed number of token requests in any clock hour.
tokenRequests.maxRate	Within a few seconds once the rate drops.	You have exceeded the max rate of token requests per second.
Reactor
reactor.httpEvent.maxRate	Within a few seconds once the rate drops.	You have exceeded the max number of outbound HTTP requests per second using the Reactor Event feature to Serverless Functions(or custom endpoints if you have that enabled).
reactor.amqp.maxRate	Within a few seconds once the rate drops.	You have exceeded the max number of outbound messages per second using the Reactor Queues or Reactor Firehose.
reactor.webhook.maxRate	Within a few seconds once the rate drops.	You have exceeded the max number of outbound messages per second using batched webhooks.