HTTP Server Simple WebSocket Demonstration
ws://deviceName/stream that causes the device to open a WebSocket. For more on the WebSocket API, see Mozilla WebSocket API.
With the socket open, you can send and receive messages between the client and the ZentriOS device.
At the ZentriOS device end, in command mode, you can read messages with stream_read and send messages with stream_write. In stream mode, data streams directly to and from the WebSocket.
Open a ZentriOS terminal.
Configure ZentriOS Device
Configure as follows:
Note:The network.buffer.rxtx_ratio setting is necessary only for the Numbat, which has a smaller memory. See Memory.
After rebooting, the ZentriOS Terminal displays messages similar to:
[Associating to Zentri] > Obtaining IPv4 address via DHCP IPv4 address: 10.5.6.55 Starting mDNS mDNS domain: mymodule.local HTTP and REST API server listening on port: 80 [Associated]
Download and Launch the HTML page
Download the HTTP Server Simple WebSocket Demonstration web page: http_server_ws_simple.html.
Run this page in a web browser to act as the client. You can run it as a
Open the browser development tools to view the web page console log.
The web page has input boxes for the device IP or name, and for a message to send from the client.
By default, the ZentriOS device bus mode is
command. You issue commands to read from and write to the WebSocket.
In the web page
Device IP or Name input box, specify the mDNS name or the IP address of the module. If you used the command sequence above, the mDNS name is the default,
Open WebSocket button to open the WebSocket.
The web page session log indicates a successful connection.
In the ZentriOS Terminal, ZentriOS indicates a connection has been opened with a response similar to:
> [2015-02-12 | 06:12:09: Opened: 0]
The stream_list command displays a list of open streams, similar to:
> list ! # Type Info # 0 WEBS 10.5.6.55:80 10.5.6.60:63745
In the web page, enter a message in the
Message input box and press Enter to send the message.
In the ZentriOS Terminal, view the message by issuing the command:
read 0 1000
The first argument is the stream id, and should be modified depending on the WebSocket stream. See stream_read. The response is similar to:
To send a message back to the web page via the WebSockets, in the ZentriOS Terminal issue the command:
write 0 5 Hello
Press Enter after typing 'write 0 5', then type the text of the message,
hello. The first argument is the stream id, and should be modified depending on the WebSocket stream. See stream_write.
The web page message log shows the message received.
Now, in the ZentriOS Terminal, switch to stream mode:
set bus.mode stream save reboot
The ZentriOS device reboots in stream mode and displays messages indicating the the HTTP server and mDNS are running.
In the web page, open a new WebSocket.
When the WebSocket opens successfully, send a message to the device from the web page. It appears immediately on the ZentriOS Terminal console.
Type a message on the ZentriOS Terminal console. Depending on terminal echo settings, it may not appear on the terminal, but each character you type is streamed directly to the the web page message log, via the WebSocket connection.
Using Multiple Websockets
Note that you can handle multiple streams only in command mode. To read from and write to the individual streams, you have to identify the stream with the
<handle> argument to the read or write command. For example, here is a sample session where stream 0 corresponds to websocket A, and stream 1 corresponds to websocket B:
> [2015-05-04 | 23:56:40: Opened: 0] > [2015-05-04 | 23:56:52: Opened: 1] > list ! # Type Info # 0 WEBS 10.5.6.108:80 10.5.6.153:54997 # 1 WEBS 10.5.6.108:80 10.5.6.153:55000 > read 0 1000 Hello from WebSocket A > write 0 17 Hello WebSocket A Success > Ready > read 1 1000 Hello from WebSocket B > write 1 17 Hello WebSocket B Success
The WebSocket is initialized in the
initWebSocket() function, with the line:
ws = new WebSocket('ws://'+ipName+'/stream')
In the same function, calls to the WebSocket
onmessage functions set callbacks for those events.
sendMessage function, a call to the WebSocket
send method sends the message to the device.
|2015-May-05||Added note on connecting multiple websockets||2.0+|