WPI NetworkTables Client for Node
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README.md

WPILIB Network Tables Client

This client uses version 3.0 of the Network Tables Protocol. With a failover to 2.0

Installation

npm install wpilib-nt-client

Usage

// Decleration
const ntClient = require('wpilib-nt-client');

const client = new ntClient.Client()

// Connects the client to the server on team 3571's roborio
client.start((isConnected, err) => {
    // Displays the error and the state of connection
    console.log({ isConnected, err });
}, 'roborio-3571.local');

// Adds a listener to the client
client.addListener((key, val, type, id) => {
    console.log({ key, val, type, id });
})

Constructor

  • Client()
    • Standard Constructor
  • Client(options)
    • options an object containing is strictInput with a boolean value
      • strictInput Does not try to correct incorrect types

Properties

  • .start((connected, err, is2_0) => any, address, port)
    • Connects the client to a specific address and port
    • connected - True if the client has successfully completed its handshake
    • err - Contains the error if one has occurred
    • is2_0 - True if the client had to failover to 2.0 of the Network Tables protocol
    • address - The address of the Server. Defaults to loopback
    • port - The port of the server
  • .stop()
    • Tries to stop the client by sending a fin packet
  • .destroy()
    • Closes the connection forcefully
  • .setReconnectDelay(delay)
    • delay set the delay before trying to reconnect
    • If the dellay is less than 20 than it wll not attempt reconnect
  • .addListener((key, value, valueType, type, id, flags) => any, getCurrent)
    • Adds a callback to be called when a value has been added, updated, or deleted, and returns the Listener
    • key - The Key for the Entry
    • value - The value associated with the key
    • valueType - The type of the value Possible Types are listed Bellow
    • type - The type of the callback. Possible Types are: "add", "update", "delete", "flagChange"
    • id - The ID of the Entry
    • flags - The flags of the Entry
    • getCurrent - immediatly callback if connected with known entries
  • .removeListener(listener)
    • Removes the specified listener
    • listener - The Listener returned from .addListener()
  • .isConnected()
    • Returns true if the client is connected and has completed its handshake
  • .uses2_0()
    • Returns true if the client has switched to using version 2.0 of the NetworkTables protocol
  • .getKeyID(key)
    • Returns the ID of a key or All of the keys if key is left out
  • .getEntry(id)
    • Returns an Entry identified with an ID
  • .Assign(val, name, persist)
    • Sets a new Entry
    • val - The Value being added
    • name - The Key for the Entry
    • persist - An optional boolean value of whether the value shoud stay on the server after a restart
    • Can return an error if type is an RPC
  • .Update(id, val)
    • id - The ID of the Entry to be updated
    • val - The new Value
    • Can Return an error if the Entry does not exist ot the value is of the wrong type
  • Flag(id, persist)
    • Updates the persist flag
    • id - The ID of the Entry to be updated
    • persist - An optional boolean value of whether the value shoud stay on the server after a restart
    • Can return an error if the Entry does not exist
  • .Delete(id)
    • Deletes an Entry
    • id - The ID of the entry being Deleted
    • Can Return an error if the Entry does not exist
  • .DeleteAll()
    • Deletes all of the Entries
    • Returns an error if the type is the client is using 2.0
  • .RPCExec(id, val, (result) => any)
    • Calls a Remote Procedure
    • id - The ID of the procedure
    • val - The Parameters of the Procedure
    • result - The result of the call
    • Can Return an error of parameter type does not corespond to the definition, the Entry is not an RPC, or the Entry does not Exist
  • .write(buf)
    • Sends a Message dirrectly to the server
    • DO NOT USE unless you know what you are doing

Types

  • valueType
    • Boolean
    • Number
    • String
    • Buffer
    • BooleanArray
    • NumberArray
    • StringArray
    • RPC
  • valueID
    • 0x00 : "Boolean"
    • 0x01 : "Number"
    • 0x02 : "String"
    • 0x03 : "Buffer"
    • 0x10 : "BooleanArray"
    • 0x11 : "NumberArray"
    • 0x12 : "StringArray"
    • 0x20 : "RPC"

In 2.0

  • Delete does not work
  • Flags do not exist
  • RPC does not exist

RPC Entry Definition

Remote Procedure Call

RPC:{
    // The name of the Call
    name,
    // The parameters of the call
    par:{
        // The Id of the type of the parameter
        typeId,
        // The name of the Type of the parameter
        typeName,
        // Name of the Parameter
        name,
        // Default value for the parameter
        default
    }[],
    // The format of the results
    results:{
        // The Id of the type of the result
        typeId,
        // The name of the Type of the result
        typeName,
        // The name of the result
        name
    }[]
}