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External

Note

This is still in the early stages, so if you find any issues or have any suggestion, please feel free to raise it over on GitHub!

Pode has support to connect to external WebSocket servers, and has the ability to receive and send messages to/from them. This is useful if you want to connect to external metrics servers to update dashboards; send messages to external WebSockets; or even create a bot.

Connecting

You can connect to an external WebSocket either in the main Start-PodeServer script, or adhoc in Routes, Timers, etc. If you opt to connect adhoc, then you'll need to pass WebSockets to -EnablePool:

Start-PodeServer -EnablePool WebSockets {
    # ...
}

The function to use to connect to external WebSockets is Connect-PodeWebSocket, this expects a -Name, -Url, and a -ScriptBlock. The scriptblock is what will be invoked when a message is received from the WebSocket server.

Important

The -Url should begin with either ws:// or wss://

For example, if you have a WebSocket server running at ws://localhost:8091 (like the web-signal.ps1 example) then you can connect to it like below:

Connect-PodeWebSocket -Name 'Example' -Url 'ws://localhost:8091' -ScriptBlock {
    $WsEvent.Request | Out-Default
}

This will simply output the message received from the WebSocket to the terminal. You'll notice the $WsEvent variable; this works like $WebEvent and others, and will contain details about the current event - mostly just the Request object and the Data received. By default the data received will be parsed from JSON, but you can customise this using the -ContentType parameter on Connect-PodeWebSocket.

Pre-Call

Sometimes you might need to make a call to a REST API first to retrieve the WebSocket URL to connect. The best way to achieve this is to just make an Invoke-RestMethod call first, then pass the URL into Connect-PodeWebSocket:

$response = Invoke-RestMethod -Url 'https://example.com/websocket/get_url'

Connect-PodeWebSocket -Name 'Example' -Url $response.url -ScriptBlock {
    $WsEvent.Request | Out-Default
}

Disconnect

When you're done with a WebSocket, you can optionally call Disconnect-PodeWebSocket to close the connection. This can be called from within the scriptblock of Connect-PodeWebSocket, or by passing the -Name of the WebSocket to close directly.

Reconnect

If at any point you need to reset a WebSocket connection, because the connection has/will expire and you have a new URL, then you can call Reset-PodeWebSocket. If called without -Url then it will attempt to reconnect using the existing connection details, or it will attempt to reconnect but use the new URL instead.

An example of this could be how Slack's Real Time Messaging works, where a new URL to connect to will be sent as a WebSocket message. You'll need to called Reset-PodeWebSocket using this new URL for the Slack connection to continue.

Or, you might have to reset an existing connection on the same details because the connection dropped.

Send Message

You can also send messages back to a connected WebSocket by using Send-PodeWebSocket. This will need the -Name of the WebSocket to send the message, and naturally the -Message itself.

For example, using the connect example above, we can extend this to send back a response instead of outputting to the terminal:

Connect-PodeWebSocket -Name 'Example' -Url 'ws://localhost:8091' -ScriptBlock {
    Send-PodeWebSocket -Message @{ message = $WsEvent.Request.Body }
}

If the -Message is a hashtable or a psobject then Pode will auto-convert these to JSON (unless a different -ContentType was supplied on Connect-PodeWebSocket). Or, you can supply a raw string message that will be used instead, with no auto-conversion.

Tip

In the scope of Connect-PodeWebSocket you don't need to supply the -Name on Send-PodeWebSocket.

WebSocket Event

When connecting to external WebSocket servers, the $WsEvent is a HashTable that is available for you to use - much like the $WebEvent object for normal routes.

This $WsEvent object has the following properties:

Name Type Description
Data hashtable Contains the message data received from the WebSocket
Lockable hashtable A synchronized hashtable that can be used with Lock-PodeObject
Request object The raw Request object
Timestamp datetime The current date and time of the received data
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