Develop Reference

NodeMCU server bad response, when sending GET request from Android app

I've made little server based on NodeMCU. All works good, when I'm conneting from browser, but problem starts, when I'm trying to connect from Android app uisng OkHttp or Volley, I'm receiving exceptions.
java.io.IOException: unexpected end of stream on Connection using OkHttp,
EOFException using Volley.
Problem is very similar for this
EOFException after server responds, but answer didn't found.
ESP server code
srv:listen(80, function(conn)
conn:on("receive", function(conn,payload)
print(payload)
conn:send("<h1> Hello, NodeMCU.</h1>")
end)
conn:on("sent", function(conn) conn:close() end)
end)
Android code
final RequestQueue queue = Volley.newRequestQueue(this);
final String url = "http://10.42.0.17:80";
final StringRequest request = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
mTemperatureTextView.setText(response.substring(0, 20));
System.out.println(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
System.out.println("Error + " + error.toString());
mTemperatureTextView.setText("That didn't work!");
}
}
);
mUpdateButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
queue.add(request);
}
});

What you're sending back is not HTTP. It's nothing but a protocol-agnostic HTML fragment. Furthermore, there's a memory leak lingering.
Try this instead:
srv:listen(80, function(conn)
conn:on("receive", function(sck,payload)
print(payload)
sck:send("HTTP/1.0 200 OK\r\nServer: NodeMCU on ESP8266\r\nContent-Type: text/html\r\n\r\n<h1> Hello, NodeMCU.</h1>")
end)
conn:on("sent", function(sck) sck:close() end)
end)
you need to send back some HTTP headers, HTTP/1.0 200 OK and the newlines are mandatory
each function needs to use it's own copy of the passed socket instance, see how I renamed conn to sck in the two callback functions, see https://stackoverflow.com/a/37379426/131929 for details
For a more complete send example look at net.socket:send() in the docs. That becomes relevant once you start sending more than just a couple of bytes.

Android - Retrofit 2 - Authenticator Result

I'm trying to use Retrofit (2.0.0-beta3), but when using an Authenticator to add a token, I can't seem to get the data from the synchronous call. Our logging on the back-end just shows a lot of login attempts, but I can't get the data from the body to actually add to the header.
public static class TokenAuthenticator implements Authenticator {
#Override
public Request authenticate(Route route, Response response) throws IOException {
// Refresh your access_token using a synchronous api request
UserService userService = createService(UserService.class);
Call<Session> call = userService.emailLogin(new Credentials("handle", "pass"));
// This call is made correctly, as it shows up on the back-end.
Session body = call.execute().body();
// This line is never hit.
Logger.d("Session token: " + body.token);
// Add new header to rejected request and retry it
return response.request().newBuilder()
.header("Auth-Token", body.token)
.build();
}
}
I'm not exactly too sure on why it's not even printing anything out. Any tips on how to solve this issue would be greatly appreciated, thanks for taking the time to help.
These are the sources I've been reading on how to implement Retrofit.
Using Authenticator:
https://stackoverflow.com/a/31624433/3106174
https://github.com/square/okhttp/wiki/Recipes#handling-authentication
Making synchronous calls with Retrofit 2:
https://futurestud.io/blog/retrofit-synchronous-and-asynchronous-requests

I managed to get a decent solution using the TokenAuthenticator and an Interceptor and thought I'd share the idea as it may help some others.
Adding the 'TokenInterceptor' class that handles adding the token to the header is the token exists, and the 'TokenAuthenticator' class handles the case when there is no token, and we need to generate one.
I'm sure there are some better ways to implement this, but it's a good starting point I think.
public static class TokenAuthenticator implements Authenticator {
#Override
public Request authenticate( Route route, Response response) throws IOException {
...
Session body = call.execute().body();
Logger.d("Session token: " + body.token);
// Storing the token somewhere.
session.token = body.token;
...
}
private static class TokenInterceptor implements Interceptor {
#Override
public Response intercept( Chain chain ) throws IOException {
Request originalRequest = chain.request();
// Nothing to add to intercepted request if:
// a) Authorization value is empty because user is not logged in yet
// b) There is already a header with updated Authorization value
if (authorizationTokenIsEmpty() || alreadyHasAuthorizationHeader(originalRequest)) {
return chain.proceed(originalRequest);
}
// Add authorization header with updated authorization value to intercepted request
Request authorisedRequest = originalRequest.newBuilder()
.header("Auth-Token", session.token )
.build();
return chain.proceed(authorisedRequest);
}
}
Source:
http://lgvalle.xyz/2015/07/27/okhttp-authentication/

I have similar authenticator and it works with 2.0.0-beta2.
If you get lots of login attempts from you Authenticator, I suggest make sure that when you make the synchronous call, you are not using Authenticator with that call.
That could end up in loop, if also your "emailLogin" fails.
Also I would recommend adding loggingInterceptor to see all trafic to server: Logging with Retrofit 2

I know it's a late answer but for anyone still wondering how to Add / Refresh token with Retrofit 2 Authenticator, here is a working solution:
Note: preferenceHelper is your Preference Manager class where you set/get your shared preferences.
public class AuthenticationHelper implements Authenticator {
private static final String HEADER_AUTHORIZATION = "Authorization";
private static final int REFRESH_TOKEN_FAIL = 403;
private Context context;
AuthenticationHelper(#ApplicationContext Context context) {
this.context = context;
}
#Override
public Request authenticate(#NonNull Route route, #NonNull Response response) throws IOException {
// We need to have a token in order to refresh it.
String token = preferencesHelper.getAccessToken();
if (token == null)
return null;
synchronized (this) {
String newToken = preferencesHelper.getAccessToken();
if (newToken == null)
return null;
// Check if the request made was previously made as an authenticated request.
if (response.request().header(HEADER_AUTHORIZATION) != null) {
// If the token has changed since the request was made, use the new token.
if (!newToken.equals(token)) {
return response.request()
.newBuilder()
.removeHeader(HEADER_AUTHORIZATION)
.addHeader(HEADER_AUTHORIZATION, "Bearer " + newToken)
.build();
}
JsonObject refreshObject = new JsonObject();
refreshObject.addProperty("refreshToken", preferencesHelper.getRefreshToken());
retrofit2.Response<UserToken> tokenResponse = apiService.refreshToken(refreshObject).execute();
if (tokenResponse.isSuccessful()) {
UserToken userToken = tokenResponse.body();
if (userToken == null)
return null;
preferencesHelper.saveAccessToken(userToken.getToken());
preferencesHelper.saveRefreshToken(userToken.getRefreshToken());
// Retry the request with the new token.
return response.request()
.newBuilder()
.removeHeader(HEADER_AUTHORIZATION)
.addHeader(HEADER_AUTHORIZATION, "Bearer " + userToken.getToken())
.build();
} else {
if (tokenResponse.code() == REFRESH_TOKEN_FAIL) {
logoutUser();
}
}
}
}
return null;
}
private void logoutUser() {
// logout user
}
}
Also note:
preferenceHelper and apiService needs to be provided in some way.
This is not an example that will work for all systems and api's but an example in how adding and refreshing the token should be done using Retrofit 2 Authenticator

Using Retrofit with Restfull Post WebServices

I'm trying to use Retrofit with Restful WebService. Everything seems alright, but somehow when I run this code this will always returns this
Method not found. Retrofit 404 Error
Here is my WebServices Code
public function processApi() {
$func = strtolower(trim(str_replace("/","",$_POST['request'])));
if ((int)method_exists($this,$func) > 0) {
$this->$func();
} else {
// If the method not exist with in this class, response would be "Page not found".
$this->response('Method not found',404);
}
}
private function login() {
// Cross validation if the request method is POST else it will return "Not Acceptable" status
if ($this->get_request_method() != "POST") {
// If invalid inputs "Bad Request" status message and reason
$error = array('status' => "0", "msg" => "Bad Request");
$this->response($this->json($error), 406);
}
// Input validations
if (empty($email) and empty($password)) {
$error = array('status' => "0", "msg" => "Invalid Email address or Password");
$this->response($this->json($error), 400);
}
}
public class ObjectPost {
#SerializedName("request")
String request;
#SerializedName("email")
String event_id;
public void setRequest(String request) {
this.request = request;
}
public void setEvent_id(String event_id) {
this.event_id = event_id;
}
}
And here is my Android Request Code
public class RestClient {
public interface ClientInterface {
#POST(Config.LOGIN_URL)
void login(#Body ObjectPost mObject,
Callback<LoginBeans> callback);
}
public static ClientInterface initRestAdapter() {
OkHttpClient client = new OkHttpClient();
return (ClientInterface) new RestAdapter.Builder()
.setLogLevel(RestAdapter.LogLevel.FULL)
.setClient(new OkClient(client))
.setEndpoint(Config.SERVER_URL)
.build()
.create(ClientInterface.class);
}
}

The value in the
Config.LOGIN_URL
Is most likely incorrect. Please remember that
Config.SERVER_URL
Must contain the base URL address. e.g. http://www.server.com/ (also please note the slashes are important)
Next, what is in your attribute must be only the remainder of the specific method that would be appended on that base url. e.g. if the method you want to call is login, it should be
#POST("/login")
Once again, I am not kidding about the slashes.
Also remember that if a query parameter is sent through as null, retrofit ignores it (you may face this problem later).
If you need any further help, you already have your loglevel set to full, please add the logcat to your question so we can see what is happening.

Your code looks alright.
Basically you need to make sure your backend. Ensure that the controller or whatever is actually right.
Maybe this will be quite applicable to you https://github.com/square/retrofit/issues/789
So, instead of looking at your Android code, it's a good reason to look somewhere else I would say.

How to wait for RequestQueue job to finish?

I'm trying to create a login page for my app. I check the credentials by doing a get request to a web server which is tied in to my user database.
public boolean checkCredentials(String email, String password) throws JSONException {
// Make a get request to the server
String url = MyUtils.createLoginUrl(email, password);
JsonObjectRequest jsObjRequest = new JsonObjectRequest
(Request.Method.GET, url, requestParam, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
successLogin = response.length() > 0;
jsonResponse = response.length() > 0 ? response : null;
//requestPending -= 1;
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
MyUtils.showToast(getBaseContext(), error.getMessage().toString());
//requestPending -= 1;
}
});
SingletonRequestQueue.getInstance(this).addToRequestQueue(jsObjRequest);
//requestPending += 1;
// I WANT THE JOB TO FINISH BEFORE RETURNING FROM THIS FUNCTION
return successLogin;
}
Is there a non-blocking way to do this using the Volley library? Google wasn't giving me much info.

You can't with Volley and you shoudn't with other tools. Long running operations like going to database or to network block the UI thread which is a bad practice since the user can't interact to the UI.
Talking about volley, it does all this job asynchronous in three thread levels:
UI
Cache
Network
See here the schema.
All three levels allows the system to cache the responses and use a pool thread to dispatch all the requests at the same time if enough space and memory.
Some time ago people recommended you to do:
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
This avoided the NetworkOnMainThreadException, but as I told you before it is a really bad practice because you will be skipping a bunch of frames by waiting.
I know listeners are a pain, but all we have to live with them in Android Dev.

Mock Api Responses in Android Testing

I'm looking for a way to mock api responses in android tests.
I have read the roboelectric could be used for this but I would really appreciate any advice on this.

After a small bit of looking around on the web I have found MockWebServer to be what I was looking for.
A scriptable web server for testing HTTP clients. This library makes it easy to test that your app Does The Right Thing when it makes HTTP and HTTPS calls. It lets you specify which responses to return and then verify that requests were made as expected.
To get setup just add the following to your build.gradle file.
androidTestCompile 'com.google.mockwebserver:mockwebserver:20130706'
Here is a simple example taking from their GitHub page.
public void test() throws Exception {
// Create a MockWebServer. These are lean enough that you can create a new
// instance for every unit test.
MockWebServer server = new MockWebServer();
// Schedule some responses.
server.enqueue(new MockResponse().setBody("hello, world!"));
// Start the server.
server.play();
// Ask the server for its URL. You'll need this to make HTTP requests.
URL baseUrl = server.getUrl("/v1/chat/");
// Exercise your application code, which should make those HTTP requests.
// Responses are returned in the same order that they are enqueued.
Chat chat = new Chat(baseUrl);
chat.loadMore();
assertEquals("hello, world!", chat.messages());
// Shut down the server. Instances cannot be reused.
server.shutdown();
}
Hope this helps.

MockWebServer didn't work for me with AndroidTestCase. For instance, ECONNREFUSED error happened quite randomly (described in https://github.com/square/okhttp/issues/1069). I didn't try Robolectric.
As of OkHttp 2.2.0, I found an alternative way which worked well for me: Interceptors. I placed the whole mock response inside a json file stored on androidTest/assets/, say, 'mock_response.json'. When I instanced an OkHttp for testing, I exposed an Interceptor which I would rewrite the incoming response. Basically, body() would instead stream the data in 'mock_response.json'.
public class FooApiTest extends AndroidTestCase {
public void testFetchData() throws InterruptedException, IOException {
// mock_response.json is placed on 'androidTest/assets/'
final InputStream stream = getContext().getAssets().open("mock_response.json");
OkHttpClient httpClient = new OkHttpClient();
httpClient.interceptors().add(new Interceptor() {
#Override
public Response intercept(Chain chain) throws IOException {
return new Response.Builder()
.protocol(Protocol.HTTP_2)
// This is essential as it makes response.isSuccessful() returning true.
.code(200)
.request(chain.request())
.body(new ResponseBody() {
#Override
public MediaType contentType() {
return null;
}
#Override
public long contentLength() {
// Means we don't know the length beforehand.
return -1;
}
#Override
public BufferedSource source() {
try {
return new Buffer().readFrom(stream);
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
})
.build();
}
});
FooApi api = new FooApi(httpClient);
api.fetchData();
// TODO: Let's assert the data here.
}
}

This is now even easier with Mockinizer which makes working with MockWebServer easier:
val mocks: Map<RequestFilter, MockResponse> = mapOf(
RequestFilter("/mocked") to MockResponse().apply {
setResponseCode(200)
setBody("""{"title": "Banana Mock"}""")
},
RequestFilter("/mockedError") to MockResponse().apply {
setResponseCode(400)
}
)
Just create a map of RequestFilter and MockResponses and then plug it into your OkHttpClient builder chain:
OkHttpClient.Builder()
.addInterceptor(loggingInterceptor)
.mockinize(mocks) // <-- just plug in your custom mocks here
.build()