B4A Library Network library v1.10 - UDP supported

Imports System
Imports System.Threading
Imports System.Net
Imports System.Net.Sockets
...
    Public UDPPort As Integer = 4444
    Public ReceivingUdpClient As UdpClient
    Public RemoteIpEndPoint As New System.Net.IPEndPoint(System.Net.IPAddress.Any, 0)
    Public ThreadReceive As System.Threading.Thread

    Private udpSendMsg As Byte() = New Byte() {}
    Private udpClient As New UdpClient
...

Sub Start
        localAddr = GetLocalIpAddress()

        'UDP

        If ReceivingUdpClient IsNot Nothing Then
            ReceivingUdpClient.Close()
        End If
        ReceivingUdpClient = New UdpClient(UDPPort)          'open a UDP port
        ReceivingUdpClient.EnableBroadcast = True
        'SendUDPMessages()
        ThreadReceive = New Thread(AddressOf ReceiveUDPMessages)        'start a thread to handle UDP i/o
        ThreadReceive.Start()
    End Sub
    
    ''' <summary>
    ''' Receive UDP broadcast message 
    ''' </summary>
    ''' <remarks></remarks>
    Public Sub ReceiveUDPMessages()
        Try
            Dim receiveBytes As [Byte]() = receivingUdpClient.Receive(RemoteIpEndPoint)
            NewClient = RemoteIpEndPoint.Address.ToString
            Dim Data As BitArray
            Data = New BitArray(receiveBytes)
            Dim strReturnData As String = BytesToString(receiveBytes)
            LOG("Receiving UDP msg: " & strReturnData)
            SendUDPMessage(ClientIP(index).Address, "UDP msg from host: " & localAddr.ToString & " " & Port.ToString)
            ReceiveUDPMessages()            'recursive call
        Catch ex As Exception
        End Try
    End Sub

    ''' <summary>
    ''' Send UPD Message directly to an IP address/port
    ''' </summary>
    ''' <param name="IPaddr"></param>
    ''' <param name="Msg"></param>
    ''' <remarks></remarks>
    Public Sub SendUDPMessage(ByVal IPaddr As IPAddress, ByVal Msg As String)
        LOG("info", "Sending: " & Msg)
        udpClient.Connect(IPaddr, UDPPort)
        udpSendMsg = StrToByteArray(Msg)
        udpClient.Send(udpSendMsg, udpSendMsg.Length) 'send a broadcast message
    End Sub

MANIFEST CONTENTS:

'This code will be applied to the manifest file during compilation.
'You do not need to modify it in most cases.
'See this link for for more information: http://www.b4x.com/forum/showthread.php?p=78136
AddManifestText(
<uses-sdk android:minSdkVersion="4" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"/>
<supports-screens android:largeScreens="true" 
    android ....

A UDP SERVICE: - requires NET library, REFLECTION library, PHONE library
#Region Module Attributes
    #StartAtBoot: False
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
    Dim UDPSocket1 As UDPSocket   
    Dim Tablet As Reflector
    Dim Device As Phone
    Dim ServerIndex As Int = -1
    Dim RequestIP As Boolean = True
    Dim UDPPort As Int = 4444
End Sub

Sub Service_Create
    Tablet.Target = Tablet.GetContext
    Tablet.Target = Tablet.RunMethod2("getSystemService", "wifi", "java.lang.String")
    Tablet.Target = Tablet.RunMethod2("createMulticastLock", "mylock", "java.lang.String")
    Tablet.RunMethod2("setReferenceCounted", False, "java.lang.boolean")     'not really necessary but safer
    Tablet.RunMethod("acquire")                                            'acquire the lock
    UDPSocket1.Initialize("UDP", UDPPort, 128)    'Port and buffer size can be changed
    ToastMessageShow("Port " & UDPPort & " initialized.",True)
End Sub

Sub Service_Start (StartingIntent As Intent)
    SendMYID
End Sub

Sub SendMYID
    If RequestIP = True Then
        RequestIP = False
        UDPSendMsg("UDP Msg from Tablet ", "255.255.255.255")
    End If
End Sub

'send the host a UDP message
Sub UDPSendMsg(msg As String, IPAddr As String)
Log("        Sending: " & msg)
    Dim Packet As UDPPacket
    Dim data() As Byte  
    data = msg.GetBytes("UTF8")
    Packet.Initialize(data, IPAddr, UDPPort)    'IP and Port can be changed
    UDPSocket1.Send(Packet)
End Sub

'Host requested our info
Sub UDP_PacketArrived (Packet As UDPPacket)
    Dim msg As String
    msg = BytesToString(Packet.Data, Packet.Offset, Packet.Length, "UTF8")
    Dim IP As String = Packet.HostAddress
Log("        Receiving: " & msg)
    StopService("")            'terminate the UDP if you don't need it anymore
End Sub

Sub Service_Destroy
    UDPSocket1.Close
    Tablet.RunMethod("release")                        ' release when not needed to save battery    
End Sub

Private udpSendMsg As Byte() = New Byte() {}
Private udpClient As New UdpClient

Sub Activity_Create(FirstTime As Boolean)
    If FirstTime Then
        UDPSocket1.Initialize("UDP", 5000, 8000)
    End If
    Activity.LoadLayout("udp")
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
End Sub
Sub UDP_PacketArrived (Packet As UDPPacket)
    Dim msg As String
    msg = BytesToString(Packet.Data, Packet.Offset, Packet.Length, "UTF8")
    Msgbox("Message received: " & msg, "")
End Sub
Sub ButtonSend_Click
    Dim Packet As UDPPacket
    Dim data() As Byte
    data = Edit.text.GetBytes("UTF8")
    Packet.Initialize(data, "192.168.178.2", 5000)
    UDPSocket1.Send(Packet)
    ToastMessageShow("Message send = " &Edit.Text, False)
End Sub

Sub Process_Globals
    Dim UDPSocket1 As UDPSocket
    Dim Server As ServerSocket
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim ButtonSend As Button
    Dim EditData As EditText
    Dim EditDest As EditText
    Dim LabelIP As Label
End Sub
Sub Activity_Create(FirstTime As Boolean)
    Dim IP As String
    If FirstTime Then
        UDPSocket1.Initialize("UDP", 5000, 8000)
        IP = Server.GetMyWifiIP
    End If
    Activity.LoadLayout("udp")
    LabelIP.Text = IP
End Sub
Sub Activity_Resume
End Sub
Sub Activity_Pause (UserClosed As Boolean)
End Sub
Sub UDP_PacketArrived (Packet As UDPPacket)
    Dim msg As String
    msg = BytesToString(Packet.Data, Packet.Offset, Packet.Length, "UTF8")
    Msgbox("Message received: " & msg, "")
End Sub
Sub ButtonSend_Click
    Dim Packet As UDPPacket
    Dim dest As String
    Dim data() As Byte
    data = EditData.text.GetBytes("UTF8")
    dest = EditDest.text
    Packet.Initialize(data, dest, 5000)
    UDPSocket1.Send(Packet)
    ToastMessageShow("Message send = " &EditData.Text, False)
End Sub

IP = Server.GetMyIP