AdmissionWebhooks are HTTP callbacks that query the control server to control publishing and playback admission requests.
Users can use the AdmissionWebhook for a variety of purposes, including customer authentication, tracking published streams, hide app/stream names, logging and more.
AdmissionWebhooks can be set up on VirtualHost, as shown below.
| Key | Description |
|---|---|
ControlServerUrl | The HTTP Server to receive the query. HTTP and HTTPS are available. |
SecretKey | The secret key used when encrypting with HMAC-SHA1 For more information, see Security. |
Timeout | Time to wait for a response after request (in milliseconds) |
Enables | Enable Providers and Publishers to use AdmissionWebhooks |
AdmissionWebhooks send HTTP/1.1 request message to the configured user's control server when an encoder requests publishing or a player requests playback. The request message format is as follows.
The message is sent in POST method and the payload is in application/json format. X-OME-Signature is a base64 url safe encoded value obtained by encrypting the payload with HMAC-SHA1 so that the ControlServer can validate this message. See the Security section for more information on X-OME-Signature.
Here is a detailed explanation of each element of Json payload:
| Element | Sub-Element | Description |
|---|---|---|
client | Information of the client who requested the connection. | |
address | Client's IP address | |
port | Client's Port number | |
user_agent (optional) | Client's User_Agent | |
request | Information about the client's request | |
direction | incoming : A client requests to publish a stream outgoing : A client requests to play a stream | |
protocol | webrtc, srt, rtmp, llhls, thumbnail | |
status | opening : A client requests to open a stream closing : A client closed the stream | |
url | url requested by the client | |
new_url (optional) | url redirected from user's control server (status "closing" only) | |
time | time requested by the client (ISO8601 format) |
The control server may need to validate incoming http requests for security reasons. To do this, the AdmissionWebhooks module puts the X-OME-Signature value in the HTTP request header. X-OME-Signature is a base64 url safe encoded value obtained by encrypting the payload of an HTTP request with the HMAC-SHA1 algorithm using the secret key set in <AdmissionWebhooks><SecretKey> of the configuration.
As shown below, the trigger condition of request is different for each protocol.
| Protocol | Condition |
|---|---|
WebRTC | When a client requests Offer SDP |
RTMP | When a client sends a publish message |
SRT | When a client send a streamid |
LLHLS | When a client requests a playlist (llhls.m3u8) |
The engine in the closing state does not need any parameter in response. To the query just answer with empty json object.
ControlServer must respond with the following Json format. In particular, the "allowed" element is required.
| Element | Description |
|---|---|
allowed (required) | true or false Allows or rejects the client's request. |
new_url (optional) | Redirects the client to a new url. However, the |
lifetime (optional) | The amount of time (in milliseconds) that a client can maintain a connection (Publishing or Playback)
HTTP based streaming (HLS, DASH, LLDASH) does not keep a connection, so this value does not apply. |
reason (optional) | If allowed is false, it will be output to the log. |
new_url redirects the original request to another app/stream. This can be used to hide the actual app/stream name from the user or to authenticate the user by inserting additional information instead of the app/stream name.
For example, you can issue a WebRTC streaming URL by inserting the user ID as follows: ws://domain.com:3333/user_id It will be more effective if you issue a URl with the encrypted value that contains the user ID, url expiration time, and other information.
After the Control Server checks whether the user is authorized to play using user_id, and responds with ws://domain.com:3333/app/sport-3 to new_url, the user can play app/sport-3.
If the user has only one hour of playback rights, the Control Server responds by putting 3600000 in the lifetime.
