List SUSI.AI Devices in Admin Panel

In this blog I’ll be explaining about the Devices Tab in SUSI.AI Admin Panel. Admins can now view the connected devices of the users with view, edit and delete actions. Also the admins can directly view the location of the device on the map by clicking on the device location of that user.


List Devices

Admin device Tab

Devices tab displays device name, macId, room, email Id, date added, last active, last login IP and location of the device. loadDevices function is called on componentDidMount which calls the fetchDevices API which fetches the list of devices from /aaa/getDeviceList.json endpoint. List of all devices is stored in devices array. Each device in the array is an object with the above properties. Clicking on the device location opens a popup displaying the device location on the map.

loadDevices = () => {
     .then(payload => {
       const { devices } = payload;
       let devicesArray = [];
       devices.forEach(device => {
         const email =;
         const devices = device.devices;
         const macIdArray = Object.keys(devices);
         const lastLoginIP =
           device.lastLoginIP !== undefined ? device.lastLoginIP : '-';
         const lastActive =
           device.lastActive !== undefined
             ? new Date(device.lastActive).toDateString()
             : '-';
         macIdArray.forEach(macId => {
           const device = devices[macId];
           let deviceName = !== undefined ? : '-';
           deviceName =
             deviceName.length > 20
               ? deviceName.substr(0, 20) + '...'
               : deviceName;
           let location = 'Location not given';
           if (device.geolocation) {
             location = (
           const dateAdded =
             device.deviceAddTime !== undefined
               ? new Date(device.deviceAddTime).toDateString()
               : '-';
           const deviceObj = {
               device.geolocation !== undefined
                 ? device.geolocation.latitude
                 : '-',
               device.geolocation !== undefined
                 ? device.geolocation.longitude
                 : '-',
         loadingDevices: false,
         devices: devicesArray,
     .catch(error => {

View Device

User Device Page

View action redirects to users /mydevices?email<email>&macid=<macid>. This allows admin to have full control of the My devices section of the user. Admin can change device details and delete device. Also admin can see all the devices of the user from the ALL tab. To edit a device click on edit icon in the table, update the details and click on check icon. To delete a device click on the delete device which then asks for confirmation of device name and on confirmation deletes the device.

Edit Device

Edit Device Dialog

Edit actions opens up a dialog modal which allows the admin to update the device name and room. Clicking on the edit button calls the modifyUserDevices API which takes in email Id, macId, device name and room name as parameters. This calls the API endpoint /aaa/modifyUserDevices.json.

 handleChange = event => {
   this.setState({ []: });

 render() {
   const { macId, email, handleConfirm, handleClose } = this.props;
   const { room, deviceName } = this.state;
   return (
       <DialogTitle>Edit Device Details for {macId}</DialogTitle>
           label="Device Name"
           style={{ marginRight: '20px' }}
           onClick={() => handleConfirm(email, macId, room, deviceName)}>
         <Button key={2} color="primary" onClick={handleClose}>

Delete Device

Delete Device Dialog

Delete action opens up a confirm delete dialog modal. To delete a device enter the device name and click on delete. This calls the confirmDelete function which calls the removeUserDevice API which takes in email Id and macId as parameters. This API hits the endpoint /aaa/removeUserDevices.json.

confirmDelete = () => {
   const { actions } = this.props;
   const { macId, email } = this.state;
   removeUserDevice({ macId, email })
     .then(payload => {
         snackBarMessage: payload.message,
         snackBarDuration: 2000,
         loadingDevices: true,
     .catch(error => {
         snackBarMessage: `Unable to delete device with macID ${macId}. Please try again.`,
         snackBarDuration: 2000,

To conclude, admin can now view all the connected SUSI.AI devices along with the user details and location. They can also access users My Devices tab in Dashboard and update and delete devices.


Continue ReadingList SUSI.AI Devices in Admin Panel

Displaying Private Skills and Drafts on SUSI.AI

The ListPrivateSkillService and ListPrivateDraftSkillService endpoint was implemented on SUSI.AI Server for SUSI.AI Admins to view the bots and drafts created by users respectively. This allows admins to monitor the bots and drafts created by users, and delete the ones which violate the guidelines. Also admins can see the sites where the bot is being used.

The endpoint of both ListPrivateSkillService and ListPrivateDraftSkillService is of GET type. Both of them have a compulsory access_token parameter but ListPrivateSkillService has an extra optional search parameter.

  • access_token(necessary): It is the access_token of the logged in user. It means this endpoint cannot be accessed in anonymous mode. 
  • search: It fetches a bot with the searched name.

The minimum user role is set to OPERATOR.

API Development


For creating a list, we need to access each property of botDetailsObject, in the following manner:

Key → Group  → Language → Bot Name  → BotList

The below code iterates over the uuid of all the users having a bot, then over different groupNames,languageNames, and finally over the botNames. If search parameter is passed then it searches for the bot_name in the language object. Each botDetails object consists of bot name, language, group and key i.e uuid of the user which is then added to the botList array.

       JsonTray chatbot = DAO.chatbot;
       JSONObject botDetailsObject = chatbot.toJSON();
       JSONObject keysObject = new JSONObject();
       JSONObject groupObject = new JSONObject();
       JSONObject languageObject = new JSONObject();
       List botList = new ArrayList();
       JSONObject result = new JSONObject();

       Iterator Key = botDetailsObject.keys();
       List keysList = new ArrayList();

       while (Key.hasNext()) {
           String key = (String);

       for (String key_name : keysList) {
           keysObject = botDetailsObject.getJSONObject(key_name);
           Iterator groupNames = keysObject.keys();
           List groupnameKeysList = new ArrayList();

           while (groupNames.hasNext()) {
               String key = (String);

           for (String group_name : groupnameKeysList) {
               groupObject = keysObject.getJSONObject(group_name);
               Iterator languageNames = groupObject.keys();
               List languagenamesKeysList = new ArrayList();

               while (languageNames.hasNext()) {
                   String key = (String);

               for (String language_name : languagenamesKeysList) {
                   languageObject = groupObject.getJSONObject(language_name);

If search parameter is passed, then search for a bot with the given name and add the bot to the botList if it exists. It will return all bots which have bot name as the searched name.

                   if (call.get("search", null) != null) {
                       String bot_name = call.get("search", null);
                           JSONObject botDetails = languageObject.getJSONObject(bot_name);
                           botDetails.put("name", bot_name);
                           botDetails.put("language", language_name);
                           botDetails.put("group", group_name);
                           botDetails.put("key", key_name);

If search parameter is not passed, then it will return all the bots created by the users.

                    else {
                       Iterator botNames = languageObject.keys();
                       List botnamesKeysList = new ArrayList();

                       while (botNames.hasNext()) {
                           String key = (String);

                       for (String bot_name : botnamesKeysList) {
                           JSONObject botDetails = languageObject.getJSONObject(bot_name);
                           botDetails.put("name", bot_name);
                           botDetails.put("language", language_name);
                           botDetails.put("group", group_name);
                           botDetails.put("key", key_name);

List of all bots, botList is return as server response.


For creating a list we need to iterate over each user and check whether the user has a draft bot. We get all the authorized clients from DAO.getAuthorizedClients(). We then iterate over each client and get their identity and authorization. We get the drafts of the client from DAO.readDrafts(userAuthorization.getIdentity()). We then iterate over each draft and add it to the drafts object. Each draft object consists of date created,date modified, object which contains draft bot information such as name,language,etc provided by the user while saving the draft, email Id and uuid of the user.

       JSONObject result = new JSONObject();
       List draftBotList = new ArrayList();
       Collection authorized = DAO.getAuthorizedClients();

       for (Client client : authorized) {
         String email = client.toString().substring(6);
         JSONObject json = client.toJSON();
         ClientIdentity identity = new ClientIdentity(, client.getName());
         Authorization userAuthorization = DAO.getAuthorization(identity);
         Map map = DAO.readDrafts(userAuthorization.getIdentity());
         JSONObject drafts = new JSONObject();

         for (Map.Entry entry: map.entrySet()) {
           JSONObject val = new JSONObject();
           val.put("object", entry.getValue().getObject());
           val.put("created", DateParser.iso8601Format.format(entry.getValue().getCreated()));
           val.put("modified", DateParser.iso8601Format.format(entry.getValue().getModified()));
           drafts.put(entry.getKey(), val);
         Iterator keys = drafts.keySet().iterator();
         while(keys.hasNext()) {
           String key = (String);
           if (drafts.get(key) instanceof JSONObject) {
             JSONObject draft = new JSONObject(drafts.get(key).toString());
             draft.put("id", key);
             draft.put("email", email);
       result.put("draftBots", draftBotList);

List of all drafts, draftBotList is returned as server response.

In conclusion, the admins can now see the bots and drafts created by the user and monitor where they are being used.


Continue ReadingDisplaying Private Skills and Drafts on SUSI.AI

Implementation of Role Invites in Open Event Organizer Android App

Open Event Organizer Android App consists of various features which can be used by event organizers to manage their events. Also, they can invite other people for various roles. After acceptance of the role invite, the particular user would have access to features like the event settings and functionalities like scanning of tickets and editing of event details, depending on the access level of the role.

There can be various roles which can be assigned to a user: Organizer, Co-Organizer, Track Organizer, Moderator, Attendee, Registrar.

Here we will go through the process of implementing the feature to invite a person for a particular role for an event using that person’s email address.

The ‘Add Role’ screen has an email field to enter the invitee’s email address and select the desired role for the person. Upon clicking the ‘Send Invite’ button, the person would be sent a mail containing a link to accept the role invite.

The Role class is used for the different types of available roles.

public class Role {

    public Long id;

    public String name;
    public String titleName;

The RoleInvite class:

public class RoleInvite {

    public Long id;

    public Event event;

    public Role role;

    public String email;
    public String createdAt;
    public String status;
    public String roleName;

A POST request is required for sending the role invite using the email address of the recipient as well as the role name.

Observable<RoleInvite> postRoleInvite(@Body RoleInvite roleInvite);

On clicking the ‘Send Invite’ button, the email address would be validated and if it is valid, the invite would be sent.

binding.btnSubmit.setOnClickListener(v -> {
        if (!validateEmail({            
        roleId = binding.selectRole.getSelectedItemPosition() + 1;

createRoleInvite() method in RoleInviteViewModel:

public void createRoleInvite(long roleId) {

    long eventId = ContextManager.getSelectedEvent().getId();
    Event event = new Event();

            .doOnSubscribe(disposable -> progress.setValue(true))
            .doFinally(() -> progress.setValue(false))
            .subscribe(sentRoleInvite -> {
                success.setValue("Role Invite Sent");
            }, throwable -> error.setValue(ErrorUtils.getMessage(throwable).toString())));

It takes roleId as an argument which is used to set the desired role before sending the POST request.

We can notice the use of sendRoleInvite() method of RoleRepository. Let’s have a look at that:

public Observable<RoleInvite> sendRoleInvite(RoleInvite roleInvite) {
    if (!repository.isConnected()) {
        return Observable.error(new Throwable(Constants.NO_NETWORK));

    return roleApi
        .doOnNext(inviteSent -> Timber.d(String.valueOf(inviteSent)))


API Documentation: Roles, Role Invites

Pull Request: feat: Implement system of role invites

Open Event Organizer App: Project repo, Play Store, F-Droid

Continue ReadingImplementation of Role Invites in Open Event Organizer Android App

Implementation of Pagination in Open Event Organizer Android App

Pagination (Endless Scrolling or Infinite Scrolling) breaks down a list of content into smaller parts, loaded one at a time. It is important when the quantity of data to be loaded is huge and loading all the data at once can result in timeout.

Here, we will discuss about the implementation of pagination in the list of attendees in the Open Event Organizer App (Eventyay Organizer App).

It is an Android app used by event organizers to create and manage events on the Eventyay platform. Features include event creation, ticket management, attendee list with ticket details, scanning of participants etc.

In the Open Event Organizer App, the loading of attendees would result in timeout when the number of attendees would be large. The solution for fixing this was the implementation of pagination in the Attendees fragment.

First, the API call needs to be modified to include the page size as well as the addition of page number as a Query.

Observable<List<Attendee>> getAttendeesPageWise(@Path("id") long id, @Query("page[number]") long pageNumber);

Now, we need to modify the logic of fetching the list of attendees to include the page number. Whenever one page ends, the next page should be fetched automatically and added to the list.

The page number needs to be passed as an argument in the loadAttendeesPageWise() method in AttendeesViewModel.

public void loadAttendeesPageWise(long pageNumber, boolean forceReload) {


        getAttendeeSourcePageWise(pageNumber, forceReload)
            .doOnSubscribe(disposable -> progress.setValue(true))
            .doFinally(() -> progress.setValue(false))
            .subscribe(attendees -> {
            }, throwable -> error.setValue(ErrorUtils.getMessage(throwable).toString())));

Also in the getAttendeeSourcePageWise() method:

private Observable<Attendee> getAttendeeSourcePageWise(long pageNumber, boolean forceReload) {
    if (!forceReload && !attendeeList.isEmpty())
        return Observable.fromIterable(attendeeList);
        return attendeeRepository.getAttendeesPageWise(eventId, pageNumber, forceReload);

Now, in the AttendeesFragment, a check is needed to increase the current page number and load attendees for the next page when the user reaches the end of the list. 

if (!recyclerView.canScrollVertically(1)) {

    if (recyclerView.getAdapter().getItemCount() > currentPage * ITEMS_PER_PAGE) {
    } else {
        attendeesViewModel.loadAttendeesPageWise(currentPage, true);

When a new page is fetched, we need to update the existing list and add the elements from the new page.

public void showResults(List<Attendee> attendees) {
    binding.setVariable(BR.attendees, attendeeList);

Now, list of attendees would be fetched pagewise, thus improving the performance and preventing timeouts.


Further reading:

Open Event Organizer App: Project repo, Play Store, F-Droid

Continue ReadingImplementation of Pagination in Open Event Organizer Android App

CRUD operations on Config Keys in Admin Panel of SUSI.AI

SUSI.AI Admin Panel now allows the Admin to create, read, update and delete config keys present in system settings. Config keys are API keys which are used to link the application to third party services like Google Maps, Google ReCaptcha, Google Analytics, Matomo, etc. The API key is a unique identifier that is used to authenticate requests associated with the project for usage and billing purposes.

CRUD Operations

Create Config Key

To create a config key click on “Add Config Key” Button, a dialog opens up which has two field Key Name and Key Value. this.props.actions.openModal opens up the shared Dialog Modal. On clicking on “Create”, the createApiKey is called which takes in the two parameters.

handleCreate = () => {
     modalType: 'createSystemSettings',
     type: 'Create',
     handleConfirm: this.confirmUpdate,
     keyName: this.state.keyName,
     keyValue: this.state.keyValue,
     handleClose: this.props.actions.closeModal,
 handleSave = () => {
   const { keyName, keyValue } = this.state;
   const { handleConfirm } = this.props;
   createApiKey({ keyName, keyValue })
     .then(() => handleConfirm())
     .catch(error => {

Read Config Key

API endpoint fetchApiKeys is called on componentDidMount and when Config Key is created, updated or deleted.

 fetchApiKeys = () => {
     .then(payload => {
       let apiKeys = [];
       let i = 1;
       let keys = Object.keys(payload.keys);
       keys.forEach(j => {
         const apiKey = {
           serialNum: i,
           keyName: j,
           value: payload.keys[j],
         apiKeys: apiKeys,
         loading: false,
     .catch(error => {

Update Config Key

To Update a config key click on edit from the actions column, Update Config Key dialog opens up which allows you to edit the key value. On clicking on update, the createApiKey API is called.

 handleUpdate = row => {
     modalType: 'updateSystemSettings',
     type: 'Update',
     keyName: row.keyName,
     keyValue: row.value,
     handleConfirm: this.confirmUpdate,
     handleClose: this.props.actions.closeModal,

Delete Config Key

To delete a config key click on delete from actions column, delete config key confirmation dialog opens up. On clicking on Delete, the deleteApiKey is called which takes in key name as parameter.

 handleDelete = row => {
   this.setState({ keyName: row.keyName });
     modalType: 'deleteSystemSettings',
     keyName: row.keyName,
     handleConfirm: this.confirmDelete,
     handleClose: this.props.actions.closeModal,
 confirmDelete = () => {
   const { keyName } = this.state;
   deleteApiKey({ keyName })
     .catch(error => {

In conclusion, CRUD operations of Config Keys help admins to manage third party services. With these operations the admin can manage the API keys of various services without having to look for them in the backend.


Continue ReadingCRUD operations on Config Keys in Admin Panel of SUSI.AI

Migration to Model-View-ViewModel Architecture and LiveData in Open Event Organizer App

Open Event Organizer App (Eventyay Organizer App) is the Android app used by event organizers to create and manage events on the Eventyay platform as well as check-in and check-out attendees along with other functionalities. The app used the MVP (Model-View-Presenter) architecture and is being ported to MVVM (Model-View-ViewModel). This article will explain the procedure of migrating MVP to MVVM architecture and implementing LiveData. 

Why migrate to MVVM?

The MVVM architecture is designed to store and manage UI-related data in a lifecycle conscious way. Configuration changes such as screen rotations are handled properly by ViewModels.

Tight Coupling:

The issue of tight coupling is resolved since only the View holds the reference to ViewModel and not vice versa. A single View can hold references to multiple ViewModels.


Since Presenters are hard bound to Views, writing unit tests becomes slightly difficult as there is a dependency of a View.

ViewModels are more unit test friendly as they can be independently tested. There is no dependency of the View.

Here, the implementation is being described with the example of About Event module in the Open Event Organizer App.

First step is the creation of a new class AboutEventViewModel which extends ViewModel.

public abstract ViewModel bindAboutEventViewModel(AboutEventViewModel aboutEventViewModel);

The new ViewModel has to be added to the ViewModelModule:

Constructor for the ViewModel:

public AboutEventViewModel(EventRepository eventRepository,  CopyrightRepository copyrightRepository,
DatabaseChangeListener<Copyright> copyrightChangeListener) {
    this.eventRepository = eventRepository;
    this.copyrightRepository = copyrightRepository;
    this.copyrightChangeListener = copyrightChangeListener;

    eventId = ContextManager.getSelectedEvent().getId();

We are using Dagger2 for dependency injection. 


LiveData is a lifecycle-aware data holder with the observer pattern.

When we have a LiveData object (e.g. list of attendees), we can add some LifecycleOwner (it can be Activity or Fragment) as an observer. Using this:

The Activity or Fragment will remain updated with the data changes.

Observers are only notified if they are in the STARTED or RESUMED state which is also known as the active state. This prevents memory leaks and NullPointerExceptions because inactive observers are not notified about changes.

Now, let’s discuss about the implementation of LiveData. We will create objects of SingleEventLiveData<> class.

private final SingleEventLiveData<Boolean> progress = new SingleEventLiveData<>();
private final SingleEventLiveData<String> error = new SingleEventLiveData<>();
private final SingleEventLiveData<Event> success = new SingleEventLiveData<>();
private final SingleEventLiveData<Copyright> showCopyright = new SingleEventLiveData<>();
private final SingleEventLiveData<Boolean> changeCopyrightMenuItem = new SingleEventLiveData<>();
private final SingleEventLiveData<String> showCopyrightDeleted = new SingleEventLiveData<>();

The functions to get the LiveData objects:

public LiveData<Boolean> getProgress() {
    return progress;

public LiveData<Event> getSuccess() {
    return success;

public LiveData<String> getError() {
    return error;

public LiveData<Copyright> getShowCopyright() {
    return showCopyright;

public LiveData<Boolean> getChangeCopyrightMenuItem() {
    return changeCopyrightMenuItem;

public LiveData<String> getShowCopyrightDeleted() {
    return showCopyrightDeleted;

Now, we can remove getView() methods and instead, these objects will be used to call various methods defined in the fragment.

Let’s discuss the changes required in the AboutEventFragment now.

The Fragment will have ViewModelProvider.Factory injected.

ViewModelProvider.Factory viewModelFactory;

Declare an object of the ViewModel.

private AboutEventViewModel aboutEventViewModel;

Then, in onCreateView(), viewModelFactory will be passed to the ViewModelProviders.of() method as the factory, which is the second parameter.

aboutEventViewModel = ViewModelProviders.of(this, viewModelFactory).get(AboutEventViewModel.class);

Replace all references to the Presenter with references to the ViewModel.

Add the Fragment as an observer to the changes by adding the following in the onStart() method:

aboutEventViewModel.getProgress().observe(this, this::showProgress);
aboutEventViewModel.getSuccess().observe(this, this::showResult);
aboutEventViewModel.getError().observe(this, this::showError);
aboutEventViewModel.getShowCopyright().observe(this, this::showCopyright);
aboutEventViewModel.getChangeCopyrightMenuItem().observe(this, this::changeCopyrightMenuItem);
aboutEventViewModel.getShowCopyrightDeleted().observe(this, this::showCopyrightDeleted);

Two parameters are passed to the observe() method  –  first one is LifecycleOwner, which is our Fragment in this case. The second one is a callback along with a parameter and is used to call the required method.

With this, the implementation of MVVM and LiveData is brought to completion.


Documentation: ViewModel, LiveData

Further reading:

Open Event Organizer App: Project repo, Play Store, F-Droid

Continue ReadingMigration to Model-View-ViewModel Architecture and LiveData in Open Event Organizer App

Tracking location on Android – using GPS to record data in Neurolab

In the Neurolab-Android app, we have a feature for recording data. It uses data incoming from the hardware device and stores it in a data table format with various parameters. Two of these parameters happened to be the latitude and longitude (location) of the user using the app. For that, we needed to implement a location tracking feature which can be used while recording the data in the data table.

Let’s start off with adding the required permission uses in the Android Manifest file.

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

These will be used to ask permissions from the user to access the devices’ internet and location/GPS.

Now, we will be making our Location Tracker class that will be used in tracking the location and getting the corresponding latitude and longitude. 

Firstly, we are going to define some variables – an array of manifest permissions for enabling GPS, some constant values for requesting specific permissions, a provider for the GPS provider.

private String[] mapPermissions = new String[]{
    public static final int GPS_PERMISSION = 103;
    private static final int UPDATE_INTERVAL_IN_MILLISECONDS = 400;
    private static final int MIN_DISTANCE_CHANGE_FOR_UPDATES = 1;
    private String provider = LocationManager.GPS_PROVIDER;

We also need to initialize and have a location manager ready to request location updates from time to time. Defining a locationManager need to get the system service for location. We define it in the following way:

LocationManager locationManager = (LocationManager)getContext().getSystemService(Context.LOCATION_SERVICE)

Next, we set up a location listener which listens to location changes of the device. We define that in the following way:

private LocationListener locationListener = new LocationListener() {
        public void onLocationChanged(Location location) {
            bestLocation = location;

Now, that we have our variables, permissions, location manager and listener set up, we can start capturing the location.

    public void startCaptureLocation() {
        if (PermissionUtils.checkRuntimePermissions(context, mapPermissions)) {
            locationManager.requestLocationUpdates(provider, UPDATE_INTERVAL_IN_MILLISECONDS, MIN_DISTANCE_CHANGE_FOR_UPDATES,
        } else {
            PermissionUtils.requestRuntimePermissions(context, mapPermissions, GPS_PERMISSION);

Firstly, we need to check for the runtime permissions required for our task. We achieve this with the function ‘checkRuntimePermissions’ which we have created in a utility class named ‘PermissionUtils’. The code of this utility class can be found here: It basically self checks individual permissions from the array passed in the arguments with the Android system.

We then use the location manager instance to request current location updates using the constants and the location listener we defined earlier.

So now, that we have started capturing the user device location, we can get the device Location object values (latitude and longitude). 

    public Location getDeviceLocation() {
        if (bestLocation == null) {
            if (PermissionUtils.checkRuntimePermissions(context, mapPermissions)) {
                return locationManager.getLastKnownLocation(provider);
            } else {
                return defaultLocation();
        } else {
            return bestLocation;

This method requests the location and returns a Location object. If there is an internet connection problem or the device location is disabled from the device settings, it returns a default location object. Here in the Neurolab project, we had set the default location latitude and longitude to 0.0.

Now we can use this location while creating the recorded file in our app directory which can be used after importing that recorded file in the app. We will be storing the location in two columns in the recorded file which is in a table format.

We write the latitude and longitude of the device in the file using a PrintWriter object and get the latitude and longitude of the device in the following way:

long latitude = locationTracker.getDeviceLocation().getLatitude()
long longitude = locationTracker.getDeviceLocation().getLongitude()

Then, using the PrintWriter object we can write the data into the file in the following way:

PrintWriter out = new PrintWriter(new BufferedWriter(new                        FileWriter(csvFile, true)));
out.write(data + "\n");

Here, the ‘data’ contains the latitude and longitude converted to String type.

That’s it! Now you can use the LocationTracker object to capture the location and get the current device location using it in your own app as well.

Hope this blog, adds value to your Android development skills.



Tags: FOSSASIA, Android, GPS, GSOC 19, Neurolab, Location

Continue ReadingTracking location on Android – using GPS to record data in Neurolab

Neurolab data transfer – Establishing serial communication between Arduino and Android

In the development process of the Neurolab Android, we needed an Arduino-Android connection for transfer of data from datasets which included String and float data type values. In this blog post, I will show you how to establish a serial communication channel between

Android and Arduino through USB cable through which we can transmit data bidirectionally.



  1. Android Phone
  2. Arduino (theoretically from any type, but I’ll be using Arduino Uno)
  3. USB 2.0 Cable Type A/B (for Arduino)
  4. OTG Cable (On The Go)
  5. Normal USB Cable (for transferring the data from Android Studio to your phone)


  1. Android Studio
  2. Arduino IDE

Wiring and Setup

Wiring must be established in the following way:

                                                                                 Figure: Android-Arduino Setup

Working on the Android Side

We would be using the UsbSerial Library by felHR85 for establishing serial


1. Adding the dependency:

a) Add the following line of code to your app level build.gradle file.

implementation "com.github.felHR85:UsbSerial:$rootProject.usbSerialLibraryVersion"

Note: The ‘usbSerialLibraryVersion’ may change from time to time. Please keep your project with the latest library version. Updates can be found here.

b) Add jitpack to your file.

allprojects {
   repositories {
       maven { url "" }

2. Working with Arduino:

We need to program the Arduino to send and receive data. We achieve that with the help of Arduino IDE as mentioned above. Verify, compile and upload a sketch to the Arduino for sending and receiving data. If you are a complete beginner in Arduino programming, there are example sketches for this same purpose. Load an example sketch from under the communication segment and choose the serial communication sketch. Here, we will be working with a simple sketch for the Arduino such that it simply echoes whatever it receives on the serial port. Here is sketch code:

// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:

// the loop routine runs over and over again forever:
void loop() {
  char incomingByte;
   // If there is a data stored in the serial receive buffer, read it and print it to the serial port as human-readable ASCII text.
    incomingByte =;

Feel free to compile and upload it to your own Arduino.

2. Working with Android:

  1. Firstly, we need an USBManager instance initialized with the system service – ‘USB_SERVICE’. This needs to be done in an Activity (preferably main) so that this instance can be passed to the Communication Handler class, which we are going to create next.
  2. Now, we will be working with a class for handling the serial communications with our Android device and the Arduino board. We would pass the USBManager instance to this class wherein work will be done with that to find the USBDevice and USBDeviceConnection

Starting with, we need to search for any attached Arduino devices to the Android device. We create a method for this and use the ‘getDevicesList’ callback to achieve this in the following way:

public void searchForArduinoDevice(Context context) {
        HashMap usbDevices = usbManager.getDeviceList();

        if (!usbDevices.isEmpty()) {
            boolean keep = true;
            for (Object object : usbDevices.entrySet()) {
                Map.Entry<String, UsbDevice> entry = (Map.Entry<String, UsbDevice>) object;
                device = entry.getValue();

                int deviceVID = device.getVendorId();
                if (deviceVID == ARDUINO_DEVICE_ID) { //Arduino Vendor ID = 0x2341
                    PendingIntent pi = PendingIntent.getBroadcast(context, 0,
                            new Intent(ACTION_USB_PERMISSION), 0);
                    usbManager.requestPermission(device, pi);
                    keep = false;
                } else {
                    connection = null;
                    device = null;
                if (!keep)

c. Now, in the Activity where we will be testing or intend to work with the serial connection, we check for the usb permission in a broadcast receiver which is registered in the onCreate method of the activity along with an Intent Filter. The Intent filter has the usp permission as an action added to it.

usbCommunicationHandler = USBCommunicationHandler.getInstance(this, NeuroLab.getUsbManager());

        deviceConnector = new DeviceConnector(NeuroLab.getUsbManager());

        IntentFilter intentFilter = new IntentFilter();
        registerReceiver(broadcastReceiver, intentFilter);

d. In the onReceive callback of the broadcast receiver, if the usb permission is granted, we initialize the serial connection with a baud rate for our Arduino device. In this initialization method, we get the connection and serial port of the connected Arduino to the Android device with which we can work. The method is implemented in the following way:

public boolean initializeSerialConnection(int baudRate) {
        connection = usbManager.openDevice(device);
        serialPort = UsbSerialDevice.createUsbSerialDevice(device, connection);
        if (serialPort != null) {
            if ( { 
            } else {
                Log.d("SERIAL", "PORT NOT OPEN");
                return false;
        } else {
            Log.d("SERIAL", "PORT IS NULL");
            return false;
        return true;

e. Now, with this ‘serialPort’ we can read data from the Arduino in the UsbReadCallback callback from the USBSerialInterface. The data is read in the form of array of bytes. This read data can be used to carry out the various functionalities we want to achieve.

With the above steps we can establish a serial connection between Android and Arduino, transmit data from Arduino to Android device for processing.

The whole working source code of the Neurolab Android project can be found here:

Thanks for taking the time to read this blog. Hope it was able to make some good contributions to your knowledge base.



Tags: FOSSASIA, Neurolab, GSOC19, Open-source, Arduino, Serial terminal

Continue ReadingNeurolab data transfer – Establishing serial communication between Arduino and Android

Implementing pagination with Retrofit in Eventyay Attendee

Pagination (Paging) is a common and powerful technique in Android Development when making HTTP requests or fetching data from the database. Eventyay Attendee has found many situations where data binding comes in as a great solution for our network calls with Retrofit. Let’s take a look at this technique.

  • Problems without Pagination in Android Development
  • Implementing Pagination with Kotlin with Retrofit
  • Results and GIF
  • Conclusions


Making HTTP requests to fetch data from the API is a basic work in any kind of application. With the mobile application, network data usage management is an important factor that affects the loading performance of the app. Without paging, all of the data are fetched even though most of them are not displayed on the screen. Pagination is a technique to load all the data in pages of limited items, which is much more efficient


Step 1:  Set up dependency in build.gradle

// Paging
implementation "androidx.paging:paging-runtime:$paging_version"
implementation "androidx.paging:paging-rxjava2:$paging_version"

Step 2:  Set up retrofit to fetch events from the API

fun searchEventsPaged(
   @Query("sort") sort: String,
   @Query("filter") eventName: String,
   @Query("page[number]") page: Int,
   @Query("page[size]") pageSize: Int = 5
): Single<List<Event>>

Step 3: Set up the DataSource

DataSource is a base class for loading data in the paging library from Android. In Eventyay, we use PageKeyedDataSource. It will fetch the data based on the number of pages and items per page with our default parameters. With PageKeyedDataSource, three main functions loadInitial(), loadBefore(), loadAfter() are used to to load each chunks of data.

class EventsDataSource(
   private val eventService: EventService,
   private val compositeDisposable: CompositeDisposable,
   private val query: String?,
   private val mutableProgress: MutableLiveData<Boolean>

) : PageKeyedDataSource<Int, Event>() {
   override fun loadInitial(
       params: LoadInitialParams<Int>,
       callback: LoadInitialCallback<Int, Event>
   ) {
       createObservable(1, 2, callback, null)

   override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, Event>) {
       val page = params.key
       createObservable(page, page + 1, null, callback)

   override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, Event>) {
       val page = params.key
       createObservable(page, page - 1, null, callback)

   private fun createObservable(
       requestedPage: Int,
       adjacentPage: Int,
       initialCallback: LoadInitialCallback<Int, Event>?,
       callback: LoadCallback<Int, Event>?
   ) {
       compositeDisposable +=
           eventService.getEventsByLocationPaged(query, requestedPage)
               .subscribe({ response ->
                   if (response.isEmpty()) mutableProgress.value = false
                   initialCallback?.onResult(response, null, adjacentPage)
                   callback?.onResult(response, adjacentPage)
               }, { error ->
                   Timber.e(error, "Fail on fetching page of events")

Step 4: Set up the Data Source Factory

DataSourceFactory is the class responsible for creating DataSource object so that we can create PagedList (A type of List used for paging) for events.

class EventsDataSourceFactory(
   private val compositeDisposable: CompositeDisposable,
   private val eventService: EventService,
   private val query: String?,
   private val mutableProgress: MutableLiveData<Boolean>
) : DataSource.Factory<Int, Event>() {
   override fun create(): DataSource<Int, Event> {
       return EventsDataSource(eventService, compositeDisposable, query, mutableProgress)

Step 5: Adapt the current change to the ViewModel. 

Previously, events fetched in List<Event> Object are now should be turned into PagedList<Event>.

sourceFactory = EventsDataSourceFactory(
val eventPagedList = RxPagedListBuilder(sourceFactory, config)

compositeDisposable += eventPagedList
   .doOnSubscribe {
       mutableProgress.value = true
       val currentPagedEvents = mutablePagedEvents.value
       if (currentPagedEvents == null) {
           mutablePagedEvents.value = it
       } else {
           mutablePagedEvents.value = currentPagedEvents
   }, {
       Timber.e(it, "Error fetching events")
       mutableMessage.value = resource.getString(R.string.error_fetching_events_message)

Step 6: Turn ListAdapter into PagedListAdapter

PageListAdapter is basically the same ListAdapter to update the UI of the events item but specifically used for Pagination. In here, List objects can also be null.

class EventsListAdapter : PagedListAdapter<Event, EventViewHolder>(EventsDiffCallback()) {

   var onEventClick: EventClickListener? = null
   var onFavFabClick: FavoriteFabClickListener? = null
   var onHashtagClick: EventHashTagClickListener? = null

   override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): EventViewHolder {
       val binding = ItemCardEventsBinding.inflate(LayoutInflater.from(parent.context), parent, false)
       return EventViewHolder(binding)

   override fun onBindViewHolder(holder: EventViewHolder, position: Int) {
       val event = getItem(position)
       if (event != null)
           holder.apply {
               bind(event, position)
               eventClickListener = onEventClick
               favFabClickListener = onFavFabClick
               hashTagClickListAdapter = onHashtagClick

    * The function to call when the adapter has to be cleared of items
   fun clear() {



Databinding is the way to go when working with a complex UI in Android Development. This helps reducing boilerplate code and to increase the readability of the code and the performance of the UI. One problem with data-binding is that sometimes, it is pretty hard to debug with unhelpful log messages. Hopefully, you can empower your UI in your project now with data-binding. 

Pagination is the way to go for fetching items from the API and making infinite scrolling. This helps reduce network usage and improve the performance of Android applications. And that’s it. I hope you can make your application more powerful with pagination. 


Open Event Codebase:


Google Codelab:

Continue ReadingImplementing pagination with Retrofit in Eventyay Attendee

Dialog Component in SUSI.AI

Dialog Component in SUSI.AI is rendered in App.js to remove code redundancy. Redux is integrated in the Dialog component which allows us to open/close the dialog from any component by altering the modal states. This implementation allows us to get rid of the need of having dialog component in different components.

Redux Code

There are two actions and reducers which control the dialog component. Default state of isModalOpen is false and modalType is an empty string. To open a dialog modal the action openModal is dispatched, which sets isModalOpen to true and the modalType. To close a dialog modal the action closeModal is dispatched, which sets isModalOpen to default state i.e. false.

import { handleActions } from 'redux-actions';
import actionTypes from '../actionTypes';

const defaultState = {
 modalProps: {
   isModalOpen: false,
   modalType: '',

export default handleActions(
   [actionTypes.UI_OPEN_MODAL](state, { payload }) {
     return {
       modalProps: {
         isModalOpen: true,
   [actionTypes.UI_CLOSE_MODAL](state) {
     return {
       modalProps: defaultState.modalProps,

Shared Dialog Component

Dialog Modal can be opened from any component by dispatching an action. 

To open a Dialog Modal: this.props.actions.openModal({modalType: [modal name]});

To close a Dialog Modal: this.props.actions.closeModal();

Shared Dialog Component has a DialogData object which contains objects with two main properties : Dialog component and Dialog size. Other props can also be passed along with these two properties such as fullScreen. Dialog Content of different Dialogs are present in their respective folders. Each Dialog Content has a Title, Content and Actions.Different Dialog types present are:

  1. Confirm Delete with Input: This dialog modal is used when a user deletes account, device and skill. 
  2. Confirm Dialog: This dialog modal is used where confirmation is required from the user/admin such as on changing skill status, on password reset,etc.
  3. Share Dialog: This dialog modal opens up when the share icon is clicked in the chat.
  4. Standard Action Dialog: This dialog modal opens up on restore skill, delete feedback, system settings and bot.
  5. Tour Dialog: This dialog modal opens up SUSI.AI tour.

To add a new Dialog to DialogSection, the steps are:

  1. Import the Dialog Content Component
  2. Add the Dialog Component to DialogData object in the following manner:
const DialogData = {
[dialog componet name]: { Component : [imported dialog component name], size : [size of the Dialog Component]},

Code (Reduced)

const DialogData = {
  login: { Component: Login, size: 'sm' },
const DialogSection = props => {
 const {
   modalProps: { isModalOpen, modalType, ...otherProps },
 } = props;

 const getDialog = () => {
   if (isModalOpen) {
     return DialogData[modalType];
   return DialogData.noComponent;

 const { size, Component, fullScreen = false } = getDialog();

return (
      open={isModalOpen || !visited}
      onClose={isModalOpen ? actions.closeModal : actions.setVisited}
       {Component ? <Component {...otherProps} /> : null}

In conclusion, having a shared dialog component reduces redundant code and allows to have a similar Dialog UI across the repo. Also having one component managing all the dialogs removes the possibility of  two dialogs being fired up at once.


Continue ReadingDialog Component in SUSI.AI