wpilib-nt-client

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
    }[]
}