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Data exchange - OnDataEvent

A data exchange between a connected clients can be arranged using Session.sendData() client function and OnDataEvent REST hook. If clients sessionId is known, an arbitrary data can be sent to the client using /rest-api/data/send REST API query.

Sending data to the server

 

  1. Client sends an arbitrary data object to server using the direct method Session.sendData()
  2. WCS sends /OnDataEvent REST hook to backend server
  3. Backend server returns 200 OK
  4. WCS sends SESSION_STATUS.SEND_DATA_STATUS with ACCEPTED value to the client

Example:

POST /rest/my_api/OnDataEvent HTTP/1.1
Accept: application/json
Content-Type: application/json;charset=UTF-8
User-Agent: Java/1.8.0_111
Host: 192.168.1.101
Connection: keep-alive
Content-Length: 218

{
    "nodeId":"Hw47CFMBEchVOpBMDr29IxjudnJ1sjOY@192.168.1.101",
    "appKey":"defaultApp",
    "sessionId":"/192.168.1.102:55839/192.168.1.101:8443",
    "operationId":"d1999750-fde9-11e6-9f1b-913210792931",
    "payload":{
        "message":"hello"
    }
}

HTTP/1.1 200 OK
Date: Tue, 28 Feb 2017 19:12:14 GMT
Server: Apache/2.2.15 (CentOS)
X-Powered-By: PHP/5.3.3
Content-Length: 220
Connection: close
Content-Type: application/json

{
    "nodeId":"Hw47CFMBEchVOpBMDr29IxjudnJ1sjOY@192.168.1.101",
    "appKey":"defaultApp",
    "sessionId":"/192.168.1.102:55839/192.168.1.101:8443",
    "operationId":"d1999750-fde9-11e6-9f1b-913210792931",
    "payload":{
        "message":"hello"
    }
}

Error handling

To make WCS react to the error, set restOnError: FAIL in the settings of the OnDataEvent method, in restClientConfig when establishing the connection.

  1. Client sends an arbitrary data object to server using the direct method Session.sendData()
  2. WCS sends /OnDataEvent REST hook to backend server
  3. Backend server returns 403 Forbidden
  4. WCS sends SESSION_STATUS.SEND_DATA_STATUS with FAILED value to the client

Example:

POST /rest/my_api/OnDataEvent HTTP/1.1
Accept: application/json
Content-Type: application/json;charset=UTF-8
User-Agent: Java/1.8.0_111
Host: 192.168.1.101
Connection: keep-alive
Content-Length: 218

{
    "nodeId":"Hw47CFMBEchVOpBMDr29IxjudnJ1sjOY@192.168.1.101",
    "appKey":"defaultApp",
    "sessionId":"/192.168.1.102:25789/192.168.1.101:8443",
    "operationId":"d0149310-fdeb-11e6-9b58-9509528e5d66",
    "payload":{
        "message":"hello"
    }
}

HTTP/1.1 403 Forbidden
Date: Tue, 28 Feb 2017 19:26:30 GMT
Server: Apache/2.2.15 (CentOS)
X-Powered-By: PHP/5.3.3
Content-Length: 0
Connection: close
Content-Type: text/html; charset=UTF-8

Sending data to connected client

There is a way to send a direct message to a connected client with REST API query http://host:8081/rest-api/data/send

To do this, pass the following JSON object

{  
   "nodeId":"",
   "sessionId":"/192.168.1.102:25789/192.168.1.101:8443",
   "operationId":"",
   "payload":{  
      "test":"test"
   }
}

Where sessionId is connected client session identifier that is received on backend while REST hook /connect handling.

In this case, the connected client receives the custom object where you can put any data, for example {"test":"test"} as shown above.

The client receives the SESSION_STATUS.APP_DATA event.