Table of Contents

Communication

Once the WebSocket has been set up, data can be sent and received. Commands are implemented using Command constructs, and Responses can be implemented using Response constructs. This is identical to the way in which serial connections work.

For traditional request/response communication, a command and response can be combined in a pair. Similar to HTTP, when a response is not received, the connection will time out.

However, the most common use case will be to send an initial request, after which the WebSocket server will periodically send data to DataMiner. In this case, you only need to add the command to the pair, similar to smart-serial connections.

Examples

In each of the examples below, the following needs to be defined:

  • Command
  • Response
  • Pair

Traditional Request/Response

For a traditional request/response setup, the pair needs to have both a command and a response. In this example, the command is stored in parameter 11, and the response will be saved in parameter 1.

<Commands>
    <Command id="1">
        <Name>Websocket Command #1</Name>
        <Description>Command to send over WebSocket for Instance 1</Description>
        <WebSocketMessageType>text</WebSocketMessageType>
        <Content>
            <Param>11</Param>
        </Content>
    </Command>
</Commands>

<Responses>
    <Response id="1" options="Connection:0">
        <Name>Websocket Response #1</Name>
        <Description>Response received over WebSocket for Instance 1</Description>
        <Content>
            <Param>1</Param>
        </Content>
    </Response>
</Responses>

<Pairs>
    <Pair id="1">
        <Name>Instance 1</Name>
        <Description>Instance 1</Description>
        <Content>
            <Command>1</Command>
            <Response>1</Response>
        </Content>
    </Pair>
</Pairs>

Receive push messages

In this case, the pair cannot have a response defined.

In the example below, the traditional request/response structure still works. The command is sent out, and every response coming from Connection:0 will be saved in parameter 1.

<Commands>
    <Command id="1">
        <Name>Websocket Command #1</Name>
        <Description>Command to send over WebSocket for Instance 1</Description>
        <WebSocketMessageType>text</WebSocketMessageType>
        <Content>
            <Param>11</Param>
        </Content>
    </Command>
</Commands>

<Responses>
    <Response id="1" options="Connection:0">
        <Name>Websocket Response #1</Name>
        <Description>Response received over WebSocket for Instance 1</Description>
        <Content>
            <Param>1</Param>
        </Content>
    </Response>
</Responses>

<Pairs>
    <Pair id="1">
        <Name>Instance 1</Name>
        <Description>Instance 1</Description>
        <Content>
            <Command>1</Command>
        </Content>
    </Pair>
</Pairs>

Multiple WebSockets

In this example, there are two WebSocket connections. The responses have an option defined to distinguish between the two connections:

  • Messages coming from the first WebSocket will be saved in parameter 1.
  • Messages coming from the second WebSocket will be saved in parameter 2.

If determining the source connection of the messages is important, you can adjust your logic according to the parameter in which the messages were stored.

<Commands>
    <Command id="1">
        <Name>Websocket Command #1</Name>
        <Description>Command to send over WebSocket for Instance 1</Description>
        <WebSocketMessageType>text</WebSocketMessageType>
        <Content>
            <Param>11</Param>
        </Content>
    </Command>
    <Command id="2">
        <Name>Websocket Command #2</Name>
        <Description>Command to send over WebSocket for Instance 2</Description>
        <WebSocketMessageType>text</WebSocketMessageType>
        <Content>
            <Param>12</Param>
        </Content>
    </Command>
</Commands>

<Responses>
    <Response id="1" options="Connection:0">
        <Name>Websocket Response #1</Name>
        <Description>Response received over WebSocket for Instance 1</Description>
        <Content>
            <Param>1</Param>
        </Content>
    </Response>
    <Response id="2" options="Connection:1">
        <Name>Websocket Response #2</Name>
        <Description>Response received over WebSocket for Instance 2</Description>
        <Content>
            <Param>2</Param>
        </Content>
    </Response>
</Responses>

<Pairs>
    <Pair id="1">
        <Name>Instance 1</Name>
        <Description>Instance 1</Description>
        <Content>
            <Command>1</Command>
        </Content>
    </Pair>
    <Pair id="2">
        <Name>Instance 2</Name>
        <Description>Instance 2</Description>
        <Content>
            <Command>2</Command>
        </Content>
    </Pair>
</Pairs>
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