New Feature : Service Discovery Support

The app now supports Zero-configuration networking (Zeroconf/mDNS), enabling automatic server discovery on local networks. This feature eliminates the need for clients to hardcode IP addresses and port numbers when connecting to the WebSocket server. When enabled by the app user, the server broadcasts its presence on the network using the service type "_websocket._tcp", allowing clients to discover the server automatically. Clients can now implement service discovery to locate the server dynamically, rather than relying on hardcoded network configurations.

app/build.gradle

@@ -13,8 +13,8 @@ android {
         minSdk 21
         targetSdk 34
         multiDexEnabled true
-        versionCode 33
-        versionName "6.3.2"
+        versionCode 34
+        versionName "6.4.0"
 
 
     }

app/src/main/java/github/umer0586/sensorserver/fragments/ServerFragment.kt

@@ -1,30 +1,38 @@
 package github.umer0586.sensorserver.fragments
 
+import android.annotation.SuppressLint
 import android.content.Context
 import android.content.Intent
+import android.graphics.drawable.Drawable
+import android.graphics.drawable.Icon
+import android.net.nsd.NsdServiceInfo
 import android.net.wifi.WifiManager
 import android.os.Build
 import android.os.Bundle
 import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.TextView
 import android.widget.Toast
 import androidx.core.content.ContextCompat
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.lifecycleScope
+import com.google.android.material.bottomsheet.BottomSheetDialog
+import com.google.android.material.progressindicator.LinearProgressIndicator
 import com.google.android.material.snackbar.Snackbar
 import com.permissionx.guolindev.PermissionX
 import github.umer0586.sensorserver.R
-import github.umer0586.sensorserver.customextensions.isHotSpotEnabled
 import github.umer0586.sensorserver.databinding.FragmentServerBinding
 import github.umer0586.sensorserver.service.WebsocketService
 import github.umer0586.sensorserver.service.WebsocketService.LocalBinder
 import github.umer0586.sensorserver.service.ServerStateListener
 import github.umer0586.sensorserver.service.ServiceBindHelper
+import github.umer0586.sensorserver.service.ServiceRegistrationState
 import github.umer0586.sensorserver.setting.AppSettings
 import github.umer0586.sensorserver.websocketserver.ServerInfo
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import java.net.BindException
 import java.net.UnknownHostException
@@ -36,6 +44,9 @@ class ServerFragment : Fragment(), ServerStateListener
     private lateinit var serviceBindHelper: ServiceBindHelper
     private lateinit var appSettings: AppSettings
 
+    private lateinit var bottomSheetDialog: BottomSheetDialog
+    private lateinit var bottomSheetContent: View
+
     private var _binding : FragmentServerBinding? = null
     // This property is only valid between onCreateView and
     // onDestroyView.
@@ -54,6 +65,10 @@ class ServerFragment : Fragment(), ServerStateListener
         super.onViewCreated(view, savedInstanceState)
         Log.i(TAG, "onViewCreated: ")
 
+        bottomSheetDialog = BottomSheetDialog(requireContext())
+        bottomSheetContent = layoutInflater.inflate(R.layout.bottom_sheet_dialog, null)
+        bottomSheetDialog.setContentView(bottomSheetContent)
+
 
         appSettings = AppSettings(requireContext())
 
@@ -70,6 +85,7 @@ class ServerFragment : Fragment(), ServerStateListener
             websocketService = localBinder.service
 
             websocketService?.setServerStateListener(this)
+            websocketService?.setServiceRegistrationCallBack(this::onServiceRegistrationStateChanged)
             websocketService?.checkState() // this callbacks onServerAlreadyRunning()
         }
 
@@ -150,6 +166,7 @@ class ServerFragment : Fragment(), ServerStateListener
 
         // To prevent memory leak
         websocketService?.setServerStateListener(null)
+        websocketService?.setServiceRegistrationCallBack(null)
     }
 
     override fun onServerStarted(serverInfo: ServerInfo)
@@ -252,6 +269,91 @@ class ServerFragment : Fragment(), ServerStateListener
 
     }
 
+    @SuppressLint("SetTextI18n")
+    private fun onServiceRegistrationStateChanged(
+        serviceRegistrationState: ServiceRegistrationState,
+        serivceInfo: NsdServiceInfo?,
+        errorCode: Int?
+    ) {
+
+        lifecycleScope.launch(Dispatchers.Main) {
+
+            val messageText = bottomSheetContent.findViewById<TextView>(R.id.message)
+            val progressIndicator =
+                bottomSheetContent.findViewById<LinearProgressIndicator>(R.id.progress_indicator)
+
+
+            when (serviceRegistrationState) {
+                ServiceRegistrationState.REGISTERING -> {
+                    messageText.text = "Registering..."
+                    bottomSheetDialog.show()
+                    progressIndicator.show()
+
+                }
+
+                ServiceRegistrationState.REGISTRATION_SUCCESS -> {
+
+                    messageText.text = "Successfully registered"
+                    delay(2000L)
+                    showToastMessage("Service Discoverable !")
+                    bottomSheetDialog.dismiss()
+                    progressIndicator.hide()
+
+                }
+
+                ServiceRegistrationState.UNREGISTERING -> {
+
+                    messageText.text = "Unregistering..."
+                    bottomSheetDialog.show()
+                    progressIndicator.show()
+
+                }
+
+                ServiceRegistrationState.REGISTRATION_FAIL -> {
+
+                    messageText.text = "Registration Failed"
+                    delay(2000L)
+                    showToastMessage("Service Not Discoverable")
+                    bottomSheetDialog.show()
+                    progressIndicator.hide()
+
+                }
+
+                ServiceRegistrationState.UNREGISTRATION_SUCCESS -> {
+
+                    messageText.text = "Successfully unregistered"
+                    delay(2000L)
+                    showToastMessage("Service Not Discoverable")
+                    bottomSheetDialog.dismiss()
+                    progressIndicator.hide()
+
+
+                }
+
+                ServiceRegistrationState.UNREGISTRATION_FAIL -> {
+
+                    messageText.text = "Unregistration Failed"
+                    delay(2000L)
+                    showToastMessage("Failed to unregister service")
+                    bottomSheetDialog.show()
+                    progressIndicator.hide()
+
+                }
+            }
+        }
+
+    }
+
+    private fun showToastMessage(message: String){
+        lifecycleScope.launch(Dispatchers.Main) {
+            Toast.makeText(
+                requireContext(),
+                message,
+                Toast.LENGTH_SHORT
+            ).show()
+        }
+    }
+
     companion object
     {
         private val TAG: String = ServerFragment::class.java.simpleName

app/src/main/java/github/umer0586/sensorserver/fragments/SettingsFragment.kt

@@ -26,6 +26,7 @@ class SettingsFragment : PreferenceFragmentCompat()
     private var  hotspotPref : SwitchPreferenceCompat? = null
     private var  localHostPref : SwitchPreferenceCompat? = null
     private var  allInterfacesPref : SwitchPreferenceCompat? = null
+    private var  discoverablePref : SwitchPreferenceCompat? = null
 
 
     override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?)
@@ -39,9 +40,29 @@ class SettingsFragment : PreferenceFragmentCompat()
         handleAllInterfacesPreference()
         handleSamplingRatePreference()
         handleHotspotPref()
+        handleDiscoverablePref()
 
     }
 
+    private fun handleDiscoverablePref() {
+        discoverablePref = findPreference(getString(R.string.pref_key_discoverable))
+        discoverablePref?.isChecked = appSettings.isDiscoverableEnabled()
+
+        discoverablePref?.setOnPreferenceChangeListener { _, newValue ->
+            appSettings.saveDiscoverable(newValue as Boolean)
+
+            if(newValue == true)
+            {
+                localHostPref?.apply {
+                    isChecked = false
+                    appSettings.enableLocalHostOption(false)
+                }
+            }
+
+            return@setOnPreferenceChangeListener true
+        }
+    }
+
     private fun handleHttpPortPreference()
     {
         val httpPortNoPref = findPreference<EditTextPreference>(getString(R.string.pref_key_http_port_no))
@@ -147,7 +168,7 @@ class SettingsFragment : PreferenceFragmentCompat()
     {
         localHostPref = findPreference(getString(R.string.pref_key_localhost))
 
-        localHostPref?.setOnPreferenceChangeListener { preference, newValue ->
+        localHostPref?.setOnPreferenceChangeListener { _, newValue ->
             val newState = newValue as Boolean
             appSettings.enableLocalHostOption(newState)
 
@@ -162,6 +183,11 @@ class SettingsFragment : PreferenceFragmentCompat()
                     isChecked = false
                     appSettings.listenOnAllInterfaces(false)
                 }
+
+                discoverablePref?.apply {
+                    isChecked = false
+                    appSettings.saveDiscoverable(false)
+                }
             }
 
 

app/src/main/java/github/umer0586/sensorserver/service/WebsocketService.kt

@@ -7,6 +7,8 @@ import android.app.Service
 import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
+import android.net.nsd.NsdManager
+import android.net.nsd.NsdServiceInfo
 import android.net.wifi.WifiManager
 import android.os.Binder
 import android.os.Build
@@ -36,6 +38,15 @@ interface ServerStateListener
     fun onServerAlreadyRunning(serverInfo: ServerInfo)
 }
 
+enum class ServiceRegistrationState{
+    REGISTERING,
+    REGISTRATION_SUCCESS,
+    REGISTRATION_FAIL,
+    UNREGISTERING,
+    UNREGISTRATION_SUCCESS,
+    UNREGISTRATION_FAIL
+}
+
 class WebsocketService : Service()
 {
 
@@ -46,6 +57,9 @@ class WebsocketService : Service()
     private var connectionsChangeCallBack: ((List<WebSocket>) -> Unit)? = null
     private var connectionsCountChangeCallBack: ((Int) -> Unit)? = null
 
+    private lateinit var nsdManager : NsdManager
+    private var serviceRegistrationCallBack: ((ServiceRegistrationState, NsdServiceInfo?, Int?) -> Unit)? = null
+
     private lateinit var appSettings: AppSettings
 
     // Binder given to clients
@@ -73,6 +87,7 @@ class WebsocketService : Service()
     {
         super.onCreate()
         Log.d(TAG, "onCreate()")
+        nsdManager = (getSystemService(Context.NSD_SERVICE) as NsdManager)
         createNotificationChannel()
         appSettings = AppSettings(applicationContext)
         broadcastMessageReceiver = BroadcastMessageReceiver(applicationContext)
@@ -188,6 +203,9 @@ class WebsocketService : Service()
             val notification = notificationBuilder.build()
             startForeground(ON_GOING_NOTIFICATION_ID, notification)
 
+            if(appSettings.isDiscoverableEnabled())
+                makeServiceDiscoverable(serverInfo.port)
+
         }
         sensorWebSocketServer?.onStop {
 
@@ -196,6 +214,9 @@ class WebsocketService : Service()
             //remove the service from foreground but don't stop (destroy) the service
             //stopForeground(true)
             stopForeground()
+
+            if(appSettings.isDiscoverableEnabled())
+                makeServiceNotDiscoverable()
         }
 
         sensorWebSocketServer?.onError { exception ->
@@ -363,6 +384,47 @@ class WebsocketService : Service()
 
     }
 
+    private val serviceRegistrationListener = object : NsdManager.RegistrationListener {
+
+        override fun onRegistrationFailed(serviceInfo: NsdServiceInfo?, errorCode: Int) {
+            serviceRegistrationCallBack?.invoke(ServiceRegistrationState.REGISTRATION_FAIL,serviceInfo,errorCode)
+        }
+
+        override fun onUnregistrationFailed(serviceInfo: NsdServiceInfo?, errorCode: Int) {
+            serviceRegistrationCallBack?.invoke(ServiceRegistrationState.UNREGISTRATION_FAIL,serviceInfo,errorCode)
+        }
+
+        override fun onServiceRegistered(serviceInfo: NsdServiceInfo?) {
+            serviceRegistrationCallBack?.invoke(ServiceRegistrationState.REGISTRATION_SUCCESS,serviceInfo,null)
+        }
+
+        override fun onServiceUnregistered(serviceInfo: NsdServiceInfo?) {
+            serviceRegistrationCallBack?.invoke(ServiceRegistrationState.UNREGISTRATION_SUCCESS,serviceInfo,null)
+        }
+
+    }
+
+    private fun makeServiceDiscoverable(portNo : Int){
+        val serviceInfo = NsdServiceInfo().apply {
+            serviceName = "SensorServer"
+            serviceType = "_websocket._tcp"
+            port = portNo
+        }
+        nsdManager.registerService(serviceInfo, NsdManager.PROTOCOL_DNS_SD, serviceRegistrationListener)
+        serviceRegistrationCallBack?.invoke(ServiceRegistrationState.REGISTERING,serviceInfo,null)
+    }
+
+    private fun makeServiceNotDiscoverable(){
+        nsdManager.unregisterService(serviceRegistrationListener)
+        serviceRegistrationCallBack?.invoke(ServiceRegistrationState.UNREGISTERING,null,null)
+    }
+
+
+    fun setServiceRegistrationCallBack(callBack: ((ServiceRegistrationState, NsdServiceInfo?, Int?) -> Unit)?){
+        serviceRegistrationCallBack = callBack
+    }
+
+
 
 
 }

app/src/main/java/github/umer0586/sensorserver/setting/AppSettings.kt

@@ -101,12 +101,26 @@ class AppSettings(context: Context)
         return sharedPreferences.getBoolean(context.getString(R.string.pref_key_all_interface), false)
     }
 
+    fun saveDiscoverable(state: Boolean)
+    {
+        sharedPreferences.edit()
+            .putBoolean(context.getString(R.string.pref_key_discoverable), state)
+            .apply()
+
+    }
+
+    fun isDiscoverableEnabled() : Boolean
+    {
+        return sharedPreferences.getBoolean(context.getString(R.string.pref_key_discoverable), DEFAULT_DISCOVERABLE)
+    }
+
     companion object
     {
 
 
         private const val DEFAULT_WEBSOCKET_PORT_NO = 8080
         private const val DEFAULT_HTTP_PORT_NO = 9090
         private const val DEFAULT_SAMPLING_RATE = 200000
+        private const val DEFAULT_DISCOVERABLE = false
     }
 }