# HTTP
The HTTPS (`http`) action sends data from an MQTT message to an HTTPS endpoint, which can point to a web application or service.
## Requirements
This rule action has the following requirements:
+ You must confirm and enable HTTPS endpoints before the rules engine can use them. For more information, see [HTTP action destinations](http-action-destination.md).
## Parameters
When you create an Amazon IoT rule with this action, you must specify the following information:
`url`
The HTTPS endpoint where the message is sent using the HTTP POST method. If you use an IP address in place of a hostname, it must be an IPv4 address. IPv6 addresses are not supported.
Supports [substitution templates](iot-substitution-templates.md): Yes
`confirmationUrl`
(Optional) If specified, Amazon IoT uses the confirmation URL to create a matching topic rule destination. You must enable the HTTP action destination before using it in an HTTP action. For more information, see [HTTP action destinations](http-action-destination.md). If you use substitution templates, you must manually create an HTTP action destination before the `http` action can be used. `confirmationUrl` must be a prefix of `url`.
The relationship between `url` and `confirmationUrl` is described by the following:
+ If `url` is hardcoded and `confirmationUrl` is not provided, we implicitly treat the `url` field as the `confirmationUrl`. Amazon IoT creates a topic rule destination for `url`.
+ If `url` and `confirmationUrl` are hardcoded, `url` must begin with `confirmationUrl`. Amazon IoT creates a topic rule destination for `confirmationUrl`.
+ If `url` contains a substitution template, you must specify `confirmationUrl` and `url` must begin with `confirmationUrl`. If `confirmationUrl` contains substitution templates, you must manually create an HTTP action destination before the `http` action can be used. If `confirmationUrl` does not contain substitution templates, Amazon IoT creates a topic rule destination for `confirmationUrl`.
Supports [substitution templates](iot-substitution-templates.md): Yes
`headers`
(Optional) The list of headers to include in HTTP requests to the endpoint. Each header must contain the following information:
`key`
The key of the header.
Supports [substitution templates](iot-substitution-templates.md): No
`value`
The value of the header.
Supports [substitution templates](iot-substitution-templates.md): Yes
The default content type is application/json when the payload is in JSON format. Otherwise, it is application/octet-stream. You can overwrite it by specifying the exact content type in the header with the key content-type (case insensitive).
`auth`
(Optional) The authentication used by the rules engine to connect to the endpoint URL specified in the `url` argument. Currently, Signature Version 4 is the only supported authentication type. For more information, see [HTTP Authorization](https://docs.amazonaws.cn/iot/latest/apireference/API_HttpAuthorization.html).
Supports [substitution templates](iot-substitution-templates.md): No
`enableBatching`
(Optional) Whether to process the HTTP action messages into a single request for a given url. Value can be true or false. For more information on batching, see [Batching HTTP action messages](http_batching.md).
Boolean value
Supports [substitution templates](iot-substitution-templates.md): No
`batchConfig`
(Optional) Configuration settings for batching. Once enabled, `batchConfig` parameters must be specified. If `batchConfig` parameters are not specified, the default values will be used.
`maxBatchOpenMs`
The maximum amount of time (in milliseconds) an outgoing message waits for other messages to create the batch. The higher the setting, the longer the latency of the batched HTTP action.
Minimum Value: 5 ms. Maximum Value: 200 ms.
Default Value: 20 ms
Supports [substitution templates](iot-substitution-templates.md): No
`maxBatchSize`
The maximum number of messages that are batched together in a single action execution.
Supports [substitution templates](iot-substitution-templates.md): No
Minimum Value: 2 messages. Maximum Value: 10 messages
Default Value: 10 messages
`maxBatchSizeBytes`
Maximum size of a message batch, in bytes.
Minimum Value: 100 bytes. Maximum Value: 131,072 bytes
Default Value: 5,120 bytes
Supports [substitution templates](iot-substitution-templates.md): No
`batchAcrossTopics`
Whether to allow batching messages from different MQTT topics into a single HTTP request. By default, only messages from the same topic are batched together. Enable this parameter for routing use cases where messages from multiple device topics are destined for the same HTTP endpoint.
Default Value: false
Supports [substitution templates](iot-substitution-templates.md): No
Messages are always batched within the scope of the same account, rule name, target HTTP endpoint URL, and billing group. Messages that differ in any of these attributes are never combined into the same batch, regardless of the `batchAcrossTopics` setting.
The default content type is application/json when the payload is in JSON format. Otherwise, it is application/octet-stream. You can overwrite it by specifying the exact content type in the header with the key content-type (case insensitive).
## Examples
The following JSON example defines an Amazon IoT rule with an HTTP action.
```
{
"topicRulePayload": {
"sql": "SELECT * FROM 'some/topic'",
"ruleDisabled": false,
"awsIotSqlVersion": "2016-03-23",
"actions": [
{
"http": {
"url": "https://www.example.com/subpath",
"confirmationUrl": "https://www.example.com",
"headers": [
{
"key": "static_header_key",
"value": "static_header_value"
},
{
"key": "substitutable_header_key",
"value": "${value_from_payload}"
}
]
}
}
]
}
}
```
```
"http": {
"url": "https://www.example.com/subpath",
"confirmationUrl": "https://www.example.com",
"headers": [
{
"key": "Content-Type",
"value": "application/json"
}
],
"enableBatching": true,
"batchConfig": {
"maxBatchOpenMs": 123,
"maxBatchSize": 5,
"maxBatchSizeBytes": 131072,
}
},
"errorAction": {
"http": {
"url": "https://www.example.com/subpath",
"confirmationUrl": "https://www.example.com"
// batchConfig is not allowed here
}
}
```
## HTTP action retry logic
The Amazon IoT rules engine retries the HTTP action according to these rules:
+ The rules engine tries to send a message at least once.
+ The rules engine retries at most twice. The maximum number of tries is three.
+ The rules engine does not attempt a retry if:
+ The previous try provided a response larger than 16,384 bytes.
+ The downstream web service or application closes the TCP connection after the try.
+ The total time to complete a request with retries exceeded the request timeout limit.
+ The request returns an HTTP status code other than 429, 500-599.
**Note**
[Standard data transfer costs](http://www.amazonaws.cn/ec2/pricing/on-demand/) apply to retries.
## See also
+ [Batching HTTP action messages](http_batching.md)
+ [HTTP action destinations](http-action-destination.md)
+ [Route data directly from Amazon IoT Core to your web services](https://amazonaws-china.com/blogs/iot/route-data-directly-from-iot-core-to-your-web-services/) in the *Internet of Things on Amazon* blog