Subscribe for All Messages¶
This API subscribes to a channel to receive all channel messages. Message retrieval requires a separate API call documented in the Retrieve Messages section of this guide.
Method¶
POST
Endpoint URL¶
The xxxx.backendless.app is a subdomain assigned to your application. For more information see the Client-side Setup section of this documentation.
https://xxxx.backendless.app/api/messaging/<channel-name>/subscribe
where:
| Argument | Description |
|---|---|
<channel-name> |
name of the channel to subscribe to. |
Request Headers¶
Content-Type: application/json
user-token: optional value obtained as a result of the login operation.
where:
| Argument | Description |
|---|---|
Content-Type |
Must be set to application/json. This header is mandatory. |
user-token |
Optional header. Contains a value returned by Backendless in a preceding user Login API call. If user-token is set in the request, the operation will be executed with the security policy associated with the currently logged in user. This means all permissions associated with the user and the roles assigned to the user will be enforced by Backendless. |
Request Body:¶
Optional parameter is shown in [square brackets]:
{
["subscriberId" : value]
}
Response Body¶
{
"subscriptionId" : value
}
Returned subscriptionId must be used in the API call to retrieve messages for the subscription.
Errors¶
When the server-side reports an error, it returns a JSON object in the following format:
{
"message":error-message,
"code":error-code
}
Codeless Reference¶
where:
| Argument | Description |
|---|---|
id |
The unique identifier of the event listener. |
channel |
Name of the channel to subscribe to. |
selector |
A selector is a query expressed in the SQL-92 syntax and formatted as the condition part of the SQL's WHERE clause. The condition references headers in the published messages. |
message |
When a listener gets triggered, it assigns data of the message matching the where clause condition to this variable(message). |
This operation does not return a value.
The example below creates a message listener named "my-listener-1" for the "default" channel. When a message is published to the "default" channel the listener gets triggered and saves the message content to the message variable. Then the data stored in the message variable gets printed.
