Chrome Native Messaging Host VB.Net - vb.net

Question

I have had a hard time finding any support for Chrome Native Messaging Hosts in VB.Net, after much trial and error I have put together something that works for a single message at a time. However I have not been able to get the
While OpenStandardStreamIn() IsNot Nothing
part to work. If anyone has any suggestions...
OTHERWISE THIS CODE WORKS GREAT, for anyone else like me looking for a VB.Net Native Message Host:
Also, this uses Newtonsoft.Json Lib for JSON serializing...
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Threading.Tasks
Imports System.Diagnostics
Imports System.Runtime.InteropServices
Module Module1
Public Sub Main(ByVal args As String())
'create response as an array so it can be easily converted JSON
Dim ResponseString() As String = {""}
' get input from chrome extension
Dim InputString As String = OpenStandardStreamIn()
' Do whatever you want with Input, then prepare Response
ResponseString(0) = DO_SOMETHING(InputString)
' Send Response to Chrome
OpenStandardStreamOut(ResponseString)
End Sub
Public Function OpenStandardStreamIn() As String
Dim MsgLength As Integer = 0
Dim InputData As String = ""
Dim LenBytes As Byte() = New Byte(3) {} 'first 4 bytes are length
Dim StdIn As System.IO.Stream = Console.OpenStandardInput() 'open the stream
StdIn.Read(LenBytes, 0, 4) 'length
MsgLength = System.BitConverter.ToInt32(LenBytes, 0) 'convert length to Int
Dim Buffer As Char() = New Char(MsgLength - 1) {} 'create Char array for remaining bytes
Using Reader As System.IO.StreamReader = New System.IO.StreamReader(StdIn) 'Using to auto dispose of stream reader
While Reader.Peek() >= 0 'while the next byte is not Null
Reader.Read(Buffer, 0, Buffer.Length) 'add to the buffer
End While
End Using
InputData = New String(Buffer) 'convert buffer to string
Return InputData
End Function
Private Sub OpenStandardStreamOut(ByVal ResponseData() As String) 'fit the response in an array so it can be JSON'd
Dim OutputData As String = ""
Dim LenBytes As Byte() = New Byte(3) {} 'byte array for length
Dim Buffer As Byte() 'byte array for msg
OutputData = Newtonsoft.Json.JsonConvert.SerializeObject(ResponseData) 'convert the array to JSON
Buffer = System.Text.Encoding.UTF8.GetBytes(OutputData) 'convert the response to byte array
LenBytes = System.BitConverter.GetBytes(Buffer.Length) 'convert the length of response to byte array
Using StdOut As System.IO.Stream = Console.OpenStandardOutput() 'Using for easy disposal
StdOut.WriteByte(LenBytes(0)) 'send the length 1 byte at a time
StdOut.WriteByte(LenBytes(1))
StdOut.WriteByte(LenBytes(2))
StdOut.WriteByte(LenBytes(3))
For i As Integer = 0 To Buffer.Length - 1 'loop the response out byte at a time
StdOut.WriteByte(Buffer(i))
Next
End Using
End Sub
End Module
From the Chrome Extension, open a connection, send a message, and once a response is received the host will close. Check our Chrome's Dev page for a sample app/extension: https://developer.chrome.com/apps/nativeMessaging
I hope this helps somebody, and please let me know if you make any improvements!

Answer 1

Sub Main() ' Recursive Version
Try
Dim stdin As Stream = Console.OpenStandardInput()
Dim stdout As Stream = Console.OpenStandardOutput()
Dim MsgLength As Integer = 0
Dim InputData As String = ""
Dim LenBytes As Byte() = New Byte(3) {}
stdin.Read(LenBytes, 0, 4)
MsgLength = BitConverter.ToInt32(LenBytes, 0)
Dim Buffer As Byte() = New Byte(MsgLength - 1) {}
stdin.Read(Buffer, 0, Buffer.Length)
InputData = Encoding.UTF8.GetString(Buffer)
Dim Str As String = Newtonsoft.Json.JsonConvert.SerializeObject("[" & Now & "] Arrrr!")
Dim buff() As Byte = Encoding.UTF8.GetBytes(Str)
stdout.Write(BitConverter.GetBytes(buff.Length), 0, 4)
stdout.Write(buff, 0, buff.Length)
Main()
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical, "Oh, Snap!")
End Try
End Sub