Part of Hypertext Transfer Protocol - HTTP/1.1 RFC 2616 Fielding, et al. 10 Status Code Definitions. Each Status-Code is described below, including a description of which method(s) it can follow and any metainformation required in the response. This is a big update from the last time I looked into this, when I enumerated 57 Status Codes that Apache 2.x was capable of handling. This list contains 83 Status Codes that Apache recognizes. I compiled the latest 2.4.4 Apache in order to view the actual codes sent by a live server. The httpresponsecode function sets or returns the HTTP response status code. If responsecode is provided, then the previous status code will be returned. If responsecode is not provided, then the current status code will be returned. Both of these values will default to a 200 status code if used in a web server environment. HTTP response code for POST when resource already exists. Deleting a resource using http DELETE. RESTful on Play! What REST PUT/POST/DELETE calls should return by a convention? What is the HTTP response code for failed HTTP Delete operation?
If your version of PHP does not include this function:
<?php
if (!function_exists('http_response_code')) {
function http_response_code($code = NULL) {
if ($code ! NULL) {
switch ($code) {
case 100: $text = 'Continue'; break;
case 101: $text = 'Switching Protocols'; break;
case 200: $text = 'OK'; break;
case 201: $text = 'Created'; break;
case 202: $text = 'Accepted'; break;
case 203: $text = 'Non-Authoritative Information'; break;
case 204: $text = 'No Content'; break;
case 205: $text = 'Reset Content'; break;
case 206: $text = 'Partial Content'; break;
case 300: $text = 'Multiple Choices'; break;
case 301: $text = 'Moved Permanently'; break;
case 302: $text = 'Moved Temporarily'; break;
case 303: $text = 'See Other'; break;
case 304: $text = 'Not Modified'; break;
case 305: $text = 'Use Proxy'; break;
case 400: $text = 'Bad Request'; break;
case 401: $text = 'Unauthorized'; break;
case 402: $text = 'Payment Required'; break;
case 403: $text = 'Forbidden'; break;
case 404: $text = 'Not Found'; break;
case 405: $text = 'Method Not Allowed'; break;
case 406: $text = 'Not Acceptable'; break;
case 407: $text = 'Proxy Authentication Required'; break;
case 408: $text = 'Request Time-out'; break;
case 409: $text = 'Conflict'; break;
case 410: $text = 'Gone'; break;
case 411: $text = 'Length Required'; break;
case 412: $text = 'Precondition Failed'; break;
case 413: $text = 'Request Entity Too Large'; break;
case 414: $text = 'Request-URI Too Large'; break;
case 415: $text = 'Unsupported Media Type'; break;
case 500: $text = 'Internal Server Error'; break;
case 501: $text = 'Not Implemented'; break;
case 502: $text = 'Bad Gateway'; break;
case 503: $text = 'Service Unavailable'; break;
case 504: $text = 'Gateway Time-out'; break;
case 505: $text = 'HTTP Version not supported'; break;
default:
exit('Unknown http status code ' . htmlentities($code) . '');
break;
}
$protocol = (isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0');
header($protocol . ' ' . $code . ' ' . $text);
$GLOBALS['http_response_code'] = $code;
} else {
$code = (isset($GLOBALS['http_response_code']) ? $GLOBALS['http_response_code'] : 200);
}
return $code;
}
}
?>
In this example I am using $GLOBALS, but you can use whatever storage mechanism you like.. I don't think there is a way to return the current status code:
https://bugs.php.net/bug.php?id=52555
For reference the error codes I got from PHP's source code:
http://lxr.php.net/opengrok/xref/PHP_5_4/sapi/cgi/cgi_main.c#354
And how the current http header is sent, with the variables it uses:
http://lxr.php.net/opengrok/xref/PHP_5_4/main/SAPI.c#856
-->This article applies to device developers.
A device template in Azure IoT Central is a blueprint that defines the:
- Telemetry a device sends to IoT Central.
- Properties a device synchronizes with IoT Central.
- Commands that IoT Central calls on a device.
This article describes, for device developers, the JSON payloads that devices send and receive for telemetry, properties, and commands defined in a device template.
The article doesn't describe every possible type of telemetry, property, and command payload, but the examples illustrate all the key types.
Each example shows a snippet from the device model that defines the type and example JSON payloads to illustrate how the device should interact with the IoT Central application.
Note
IoT Central accepts any valid JSON but it can only be used for visualizations if it matches a definition in the device model. You can export data that doesn't match a definition, see Export IoT data to destinations in Azure.
The JSON file that defines the device model uses the Digital Twin Definition Language (DTDL) v2.
For sample device code that shows some of these payloads in use, see the Create and connect a client application to your Azure IoT Central application tutorial.
View raw data
IoT Central lets you view the raw data that a device sends to an application. This view is useful for troubleshooting issues with the payload sent from a device. To view the raw data a device is sending:
- Navigate to the device from the Devices page.
- Select the Raw data tab:On this view, you can select the columns to display and set a time range to view. The Unmodeled data column shows data from the device that doesn't match any property or telemetry definitions in the device template.
Telemetry
Telemetry in components
If the telemetry is defined in a component, add a custom message property called
$.sub
with the name of the component as defined in the device model. To learn more, see Tutorial: Create and connect a client application to your Azure IoT Central application.Primitive types
This section shows examples of primitive telemetry types that a device streams to an IoT Central application.
The following snippet from a device model shows the definition of a
boolean
telemetry type:A device client should send the telemetry as JSON that looks like the following example:
The following snippet from a device model shows the definition of a
string
telemetry type:A device client should send the telemetry as JSON that looks like the following example:
The following snippet from a device model shows the definition of an
integer
telemetry type:A device client should send the telemetry as JSON that looks like the following example:
The following snippet from a device model shows the definition of a
double
telemetry type:A device client should send the telemetry as JSON that looks like the following example:
The following snippet from a device model shows the definition of a
dateTime
telemetry type:A device client should send the telemetry as JSON that looks like the following example -
DateTime
types must be in ISO 8061 format:The following snippet from a device model shows the definition of a
duration
telemetry type:A device client should send the telemetry as JSON that looks like the following example - durations must be in ISO 8601 format:
Complex types
This section shows examples of complex telemetry types that a device streams to an IoT Central application.
The following snippet from a device model shows the definition of a
geopoint
telemetry type:Note
The geopoint schema type is not part of the Digital Twins Definition Language specification. IoT Central currently supports the geopoint schema type and the location semantic type for backwards compatibility.
A device client should send the telemetry as JSON that looks like the following example. IoT Central displays the value as a pin on a map:
The following snippet from a device model shows the definition of an
Enum
telemetry type:A device client should send the telemetry as JSON that looks like the following example. Possible values are
0
, 1
, and 2
that display in IoT Central as Item1
, Item2
, and Item3
:The following snippet from a device model shows the definition of an
Object
telemetry type. This object has three fields with types dateTime
, integer
, and Enum
:A device client should send the telemetry as JSON that looks like the following example.
DateTime
types must be ISO 8061 compliant. Possible values for Property3
are 0
, 1
, and that display in IoT Central as Item1
, Item2
, and Item3
:The following snippet from a device model shows the definition of a
vector
telemetry type:A device client should send the telemetry as JSON that looks like the following example:
Event and state types
This section shows examples of telemetry events and states that a device sends to an IoT Central application.
The following snippet from a device model shows the definition of a
integer
event type:A device client should send the event data as JSON that looks like the following example:
The following snippet from a device model shows the definition of a
integer
state type:A device client should send the state as JSON that looks like the following example. Possible integer state values are
1
, 2
, or 3
:Properties
Note
The payload formats for properties applies to applications created on or after 07/14/2020.
Properties in components
If the property is defined in a component, wrap the property in the component name. The following example sets the
maxTempSinceLastReboot
in the thermostat2
component. The marker __t
indicates that this a component:To learn more, see Tutorial: Create and connect a client application to your Azure IoT Central application.
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Primitive types
![Http_response_code Http_response_code](/uploads/1/3/7/5/137556028/126662692.jpg)
This section shows examples of primitive property types that a device sends to an IoT Central application.
The following snippet from a device model shows the definition of a
boolean
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
The following snippet from a device model shows the definition of a
boolean
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
The following snippet from a device model shows the definition of a
date
property type:Http_response_code(200)
A device client should send a JSON payload that looks like the following example as a reported property in the device twin.
Date
types must be ISO 8061 compliant:The following snippet from a device model shows the definition of a
duration
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin - durations must be ISO 8601 Duration compliant:
The following snippet from a device model shows the definition of a
float
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
The following snippet from a device model shows the definition of a
string
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
Complex types
This section shows examples of complex property types that a device sends to an IoT Central application.
The following snippet from a device model shows the definition of a
geopoint
property type:Note
The geopoint schema type is not part of the Digital Twins Definition Language specification. IoT Central currently supports the geopoint schema type and the location semantic type for backwards compatibility.
A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
The following snippet from a device model shows the definition of an
Enum
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin. Possible values are
0
, 1
, and that display in IoT Central as Item1
, Item2
, and Item3
:The following snippet from a device model shows the definition of an
Object
property type. This object has two fields with types string
and integer
:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
![Http_response_code 500 Http_response_code 500](/uploads/1/3/7/5/137556028/284135527.png)
The following snippet from a device model shows the definition of an
vector
property type:A device client should send a JSON payload that looks like the following example as a reported property in the device twin:
Writable property types
This section shows examples of writable property types that a device receives from an IoT Central application.
If the writable property is defined in a component, the desired property message includes the component name. The following example shows the message requesting the device to update the
targetTemperature
in the thermostat2
component. The marker __t
indicates that this a component:To learn more, see Tutorial: Create and connect a client application to your Azure IoT Central application.
IoT Central expects a response from the device to writable property updates. The response message should include the
ac
and av
fields. The ad
field is optional. See the following snippets for examples.ac
is a numeric field that uses the values in the following table:Value | Label | Description |
---|---|---|
'ac': 200 | Completed | The property change operation was successfully completed. |
'ac': 202 or 'ac': 201 | Pending | The property change operation is pending or in progress |
'ac': 4xx | Error | The requested property change wasn't valid or had an error |
'ac': 5xx | Error | The device experienced an unexpected error when processing the requested change. |
av
is the version number sent to the device.ad
is an option string description.The following snippet from a device model shows the definition of a writable
string
property type:The device receives the following payload from IoT Central:
The device should send the following JSON payload to IoT Central after it processes the update. This message includes the version number of the original update received from IoT Central. When IoT Central receives this message, it marks the property as synced in the UI:
The following snippet from a device model shows the definition of a writable
Enum
property type:The device receives the following payload from IoT Central:
The device should send the following JSON payload to IoT Central after it processes the update. This message includes the version number of the original update received from IoT Central. When IoT Central receives this message, it marks the property as synced in the UI:
Commands
If the command is defined in a component, the name of the command the device receives includes the component name. For example, if the command is called
getMaxMinReport
and the component is called thermostat2
, the device receives a request to execute a command called thermostat2*getMaxMinReport
.The following snippet from a device model shows the definition of a command that has no parameters and that doesn't expect the device to return anything:
The device receives an empty payload in the request and should return an empty payload in the response with a
200
Azure devops github desktop. HTTP response code to indicate success.The following snippet from a device model shows the definition of a command that has an integer parameter and that expects the device to return an integer value:
The device receives an integer value as the request payload. The device should return an integer value as the response payload with a
200
HTTP response code to indicate success.The following snippet from a device model shows the definition of a command that has an object parameter and that expects the device to return an object. In this example, both objects have integer and string fields:
The following snippet shows an example request payload sent to the device:
The following snippet shows an example response payload sent from the device. Use a
200
HTTP response code to indicate success:Long running commands
Http Response Code 404
The following snippet from a device model shows the definition of a command. The command has an integer parameter and expects the device to return an integer value:
The device receives an integer value as the request payload. If the device needs time to process this command, it should return an empty response payload with a
202
HTTP response code to indicate the device has accepted the request for processing.When the device has finished processing the request, it should send a property to IoT Central that looks like the following example. The property name must be the same as the command name:
Offline commands
In the IoT Central web UI, you can select the Queue if offline option for a command. Offline commands are one-way notifications to the device from your solution that are delivered as soon as a device connects. Offline commands can have a request parameter but don't return a response.
The Queue if offline setting isn't included if you export a model or interface from the device template. You can't tell by looking at an exported model or interface JSON that a command is an offline command.
Offline commands use IoT Hub cloud-to-device messages to send the command and payload to the device.
The payload of the message the device receives is the raw value of the parameter. A custom property called
method-name
stores the name of the IoT Central command. The following table shows some example payloads:IoT Central request schema | Example payload received by device |
---|---|
No request parameter | @ |
Double | 1.23 |
String | sample string |
Object | {'StartTime':'2021-01-05T08:00:00.000Z','Bank':2} |
The following snippet from a device model shows the definition of a command. The command has an object parameter with a datetime field and an enumeration:
Http Response Code 503
If you enable the Queue if offline option in the device template UI for the command in the previous snippet, then the message the device receives includes the following properties:
Property name | Example value |
---|---|
custom_properties | {'method-name': 'GenerateDiagnostics'} |
data | {'StartTime':'2021-01-05T08:00:00.000Z','Bank':2} |
Next steps
Http Response Code 503
As a device developer, now that you've learned about device templates, a suggested next steps is to read Get connected to Azure IoT Central to learn more about how to register devices with IoT Central and how IoT Central secures device connections.