Facility Control

Hi

I am writing an AMP protocol control UI in Dashboard. I can see how to send the binary bytes using writeAsBytes(myByteArray).

What I can't see is how to receive the variable length response. If I set the listener to have a fixed length of 1 byte, I receive an event for each byte in the response. Problem is I don't know when there are no more bytes to read. Is there a way to get at the underlying socket object to probe the receive buffer?

I'm currently using event.getBytes().  I was hoping calling that until I received no more data would work, but it just return the same 1 byte (my listener is set to return 1 byte per message event). 

Thanks

Simon

Hi Simon

The key to this is to select "Stop all receive/task execution on pause" for the listener and use ogscript.createMessageParser(this.getInputStream()) inside of your listener's code. This will allow you to read directly from the wire instead of waiting for messages to be complete:

<abs contexttype="opengear" gridsize="20" id="_top">
   <meta>
      <params>
         <param access="1" maxlength="0" name="Message Type 1" oid="Message_Type_1" type="STRING" value="Test 1" widget="text"/>
         <param access="1" maxlength="0" name="Message Type 2" oid="Message_Type_2" type="STRING" value="Test 2" widget="text"/>
      </params>
      <api>function sendMessageToListener(type, message)
{
   var mb = ogscript.createMessageBuilder();
   mb.writeShort(type);
   mb.writeShort(message.length);
   mb.writeString(message);
   rosstalk.sendBytes('localhost', 2244, mb.toByteArray(), null);
}
</api>
      <listener autostart="true" blockingpause="true" delimiter="2" delimitertype="fixedlen" listenport="2244">
         <task tasktype="ogscript">if (event.isMessageEvent())
{
   var cmdTypeBytes = event.getBytes();
   var commandType = cmdTypeBytes[0] &lt;&lt; 8 | cmdTypeBytes[1];
   var messageParser = ogscript.createMessageParser(this.getInputStream());
   var length = messageParser.readShort();
   var string = messageParser.readString(length);

   ogscript.rename('output', 'TYPE: ' + commandType + ' MESSAGE: ' + string);
}</task>
      </listener>
   </meta>
   <param expand="true" height="40" left="80" oid="Message_Type_1" top="40" width="320"/>
   <param expand="true" height="40" left="80" oid="Message_Type_2" top="100" width="320"/>
   <button buttontype="push" height="40" left="400" name="Go" top="40" width="60">
      <task tasktype="ogscript">sendMessageToListener(1, params.getValue('Message_Type_1', 0));
</task>
   </button>
   <button buttontype="push" height="40" left="400" name="Go" top="100" width="60">
      <task tasktype="ogscript">sendMessageToListener(2, params.getValue('Message_Type_2', 0));
</task>
   </button>
   <label height="60" id="output" left="0" style="txt-align:west" top="140" width="1340"/>
</abs>

Also, for mixing Binary and ASCII, the list of available methods on the message builder/parser is available in the script palette:

var messageBuilder = ogscript.createMessageBuilder();
/*
* messageBuilder.writeByteArray(bytesArray);
* messageBuilder.writeByteArray(bytesArray, offset, length);
* messageBuilder.writeBoolean(boolVal);
* messageBuilder.writeByte(byteVal);
* messageBuilder.writeShort(shortVal);
* messageBuilder.writeChar(charVal);
* messageBuilder.writeInt(intVal);
* messageBuilder.writeLong(longVal);
* messageBuilder.writeFloat(floatVal);
* messageBuilder.writeDouble(doubleVal);
* messageBuilder.writeLine(strVal);
* messageBuilder.writeString(strVal);
* messageBuilder.writeUTF(strVal); //includes 2-byte length count
*/
var bytes = messageBuilder.toByteArray();


var messageReader = ogscript.createMessageParser(messageBytes);
/*
* var byteArray = messageReader.readBytes(length);
* messageReader.skipBytes(length);
* var boolVal = messageReader.readBoolean();
* var byteVal = messageReader.readByte();
* var byteVal = messageReader.readUnsignedByte();
* var shortVal = messageReader.readShort();
* var shortVal = messageReader.readUnsignedShort();
* var charVal = messageReader.readChar();
* var intVal = messageReader.readInt();
* var longVal = messageReader.readLong();
* var floatVal = messageReader.readFloat();
* var doubleVal = messageReader.readDouble();
* var str = messageReader.readUTF(); //includes 2-byte length count
* var str = messageReader.readLine(); //read bytes until newline character is reached
* var str = messageReader.readString(length); //without 2-byte length count
*/

Thanks James. It's almost what I needed, but gave me enough to figure the rest out! I have kept the delimiter set to 1 byte.

Here is my code now. It will allow for any length of response that I can then parse, and pass onto a messageParser if need be.

if (event.isMessageEvent())
{
ogscript.debug("Dyno data");
var data = [];

//we need to get the first byte the normal way
data.push(event.getBytes()[0]);
var stream = this.getInputStream();
ogscript.debug("Data available: " + stream.available());

//get the rest of the bytes in the message and add to our array
while( stream.available())
{
data.push(stream.read());
}

//what we got?
for(var i = 0; i< data.length; i++)
{
ogscript.debug(data[i]);
}
return;

}

I don't have access to real hardware yet, just a simple TCP server, but it's proved what I need

Thanks

@Simon, this is awesome.
This code makes getting messages much easier, no need to mess with delimiter type and value. Thanks to available() method. I wonder why this is not preffered way to get any response, instead of using delimiter. But, in fact, i didn't found info about that method, not in ogscript pdf's, nor in that forum. Actually, your topic is uniq in that case.

Congratulations, and thanks for posting that code, i already integrated it in some panels and i think this is much easier way to get messages via listener.

Alex.