Read and update json file data every second - android

I am reading a JSON file from a web server and want to update my data every second. I am changing my style sheet with the data of JSON file.
I apply this course in ionic 3.
public level;
public sensor;
constructor(public navCtrl: NavController , public peopleData:PeopleDataProvider) {
peopleData.getPeople().subscribe(waterlevel => {
this.level = (waterlevel.val/1000)*100;
this.levelStyles = {height: (waterlevel.val/1000)*100+'%' };
Can anyone tell me how to update this code every second?

It all depends on the web API that you are using. If it supports websockets, then your life will be much easier as you do not need to poll data every second. Just do a google search "How to get real-time updates from a web end point supporting websockets in android?".
If your web APi is an http, then you will have to poll every second (which is not recommended and is a bad practice). In this situation you can use a third-party service like streamdata.io to convert your http web api in to something that pushes update to your JSON file using Server Sent Events (SSE).
Here's in an example on their website how to use it in android projects:
android-server-sent-events

Related

Create a middle BackEnd for a Mobile app

I am developing a mobile app on Android.
I download a lot of information from the backend via REST API.
For example for obtain the information about a contract I use the api the following request:
GET /contracts/01212314.json
It return a json with many fields
{
"conto_contrattuale": "01212314",
"intestatario": "Dennis D'Amico",
"utilizzo": "COTTURA + PROD. ACQUA 7 GG",
"codice_settore_merceologico": "E1",
"settore_merceologico": "ELETTRICITA",
"codice_societa_vendita": "Z016",
"societa_vendita": "Estra Energie S.r.l.",
"fornitura_indirizzo": "Via Palermo",
"fornitura_civico": "20",
"fornitura_precisazione": "Rosso",
"fornitura_cap": "59100",
"fornitura_comune": "Prato"
"rid": false,
"fatt_elettronica": true,
"fatt_email": "andrea.bettarini#devise.it",
"fatture_scadute": 1,
}
But I am only interested to the field : "fornitura_indirizzo"
I can't modify the backend and the API.
So I think to create a new middle backend that fetch the info from the actual backend and exposes a call only for the field "fornitura_indirizzo".
How can I do?
Is it possible on google cloud platform? and is it free?
Thank you for your consideration.
You can put a file on your server that fetches the data en then recreates a partial array and echo that in json.
Example:
$contract = Json_decode("/contracts/xxxx.json", true);
$needed_info = $contract["fornitura_indirizzo"];
Echo json_encode($needed_info);
I can't access to the server and modify. I can only send request.
I apologise if I misunderstand your goals here, but why bother with creating this new back end for your app. You could simply call the existing back end and ignore the unneeded information. Either way, that existing back end has to send all that info somewhere for every request your mobile app performs. You're also adding more latency to the request since it has to go through your back end first.
I can see this being worth it though if your goal is to minimize the data downloaded by the mobile app when it does a request.

WebExtensions: How to send a message to content script? (Android)

I just noticed that the tabs API is only available for the desktop not for Android. In the past I have used this code to send messages to my content scripts:
sendMsgToTabs(msg) {
return browser.tabs.query({}).then(tabs => {
let msgPromises = []
for (let tab of tabs) {
let msgPromise = browser.tabs.sendMessage(tab.id, msg)
msgPromises.push(msgPromise)
}
return Promise.all(msgPromises)
})
}
But how am I supposed to do that when the tabs API is not available?
I mean the only thing I can think of is to constantly send empty messages from the content scripts to the background script and whenever the background script has new information then it can send a direct response to one of these messages. But that sounds horribly inefficient. There must be a better way, right?
As of Firefox 54, use .tabs.sendMessage()
As of Firefox 54, the tabs API is supported on Firefox for Android.
Alternative for versions of Firefox prior to Firefox 54.
The storage API is stated as supported in Firefox for Android. Thus, while I have not tested it, a method you could use to send data to content script would be to save a value using chrome.storage.local.set(). By listening to the chrome.storage.onChanged event in your content script(s), you can then be notified of that data being stored/changed. This will provide an event driven way to send a message (i.e. stored data) to the content script.
In order to differentiate between receiving the data in different tabs, you will need to establish a protocol for what the data you save means. This could be as simple as just a particular saved key/value meaning that all content scripts should send a message to the background script to get more information, or more complex where you send/store something like:
{
contentScriptMessage: {
tab: 14,
frame: 1234,
message: 'Some data'
}
}
In each content script's chrome.storage.onChanged listener, it can then ignore any changes that are not to the tab/frame in which it is running.
This methodology will require fleshing out as you try to implement it. Hopefully, at least part of the chrome.tabs API will be implemented for Android in the near future.

Secure android application made by ionic framework

I'm working on an android apps. I am using ionic framework. In some pages I need to get data from a web server and the result is an object json.
My problem is if some one arrives to GET the pages where I get the json data, one can fetch all my database data by changing the http request.
Is there any way that can improve security of my apps?
You should make some kind of authentication mechanism, for example, a token in the header, that way you know wether the user has access to that resource or not.
So when you make your request you can generate a configuration for that particular request.
Example:
var url = "http://yourserver.com/api/your/path";
var config = {
"headers": {
"Authorization": "Bearer someBearerFromTheServer"
}
};
$http.get(url, config);
The backend implementation for this to work depends on the language you use. Here google is your best friend.
A more advanced way to do this, is to use interceptors in the $http service and attach the token to the header in every request, but be careful, you should secure this so you won't send your credentials to every request you make (sometimes your app might need to request data from another server).
You can read more about $http services and its configurations in the $http service documentation.
Regards

What is an easy way to stub / dummy a restful web service?

I want to create an android application, this application will make RESTful calls to a web service to obtain some data.
I know what the RESTful interface will be, but I don't want the hassle of creating my own implementation. Is there an easy way to create a stub RESTful web service that will return some static data without having to write a full blown WS application to do this?
Mocky.io allows you to create stub endpoints and specify the data they return via public URLs.
Runscope (disclaimer, I'm a founder) allows you to capture a real request once, then replay back the response as needed via Response Playback URLs.
I've found using Sinatra really useful for this sort of thing if you want to test the actual HTTP calling code. You can have a endpoint returning data in seconds. Very little Ruby knowledge required.
require 'sinatra'
require 'json'
get '/Person' do
content_type :json
{ :id => 345, :key2 => 'John Doe' }.to_json
end
Is all you would need to return a simple json object.
One of the approaches (similar to Vinnie's) is to make a local implementation of your webservice. For example, your webservice allows you to log a user in and to get a list of users online.
The webservice interface looks like this:
public interface WebService {
public LoginResponse login(String user, String pass) throws Exception;
public UsersOnlineResponse getOnlineUsers() throws Exception;
}
Then, we implement this interface for remote webservice which will be used in production. Remote implementation makes HTTP calls with help of HTTP client, retrieves response and parses it to an appropriate response object. Here is a fragment of it:
public class RemoteWebService implements WebService {
private AndroidHttpClient client = AndroidHttpClient.newInstance(USER_AGENT);
#Override
public LoginResponse login(String user, String pass) throws Exception {
LoginResponse response = client.execute(
createPostRequest(METHOD_LOGIN, user, pass),
new JsonResponseHandler(LoginResponse.class));
handleResponse(response); // verify response, throw exceptions if needed
return response;
}
}
For testing purposes, when webservice is not available or is being developed, we implement local webservice. Local implementation takes predefined JSON responses from assets folder and parses it to an appropriate response object. It's up to you how to implement webservice behaviour: it can be simple static responses or some random/validation-dependent responses. Here is the part of it:
public class LocalWebService implements WebService {
private Context context;
public LocalWebService(Context context) {
this.context = context;
}
#Override
public LoginResponse login(String user, String pass) throws Exception {
Thread.sleep(DELAY); //emulate network delay
if (validateParams(user, pass)) {
return parseAssetsJson("ws/login.json", LoginResponse.class);
} else {
Response response = parseAssetsJson("ws/status_bad_request.json", Response.class);
throw new WebServiceException(response);
}
}
public <T> T parseAssetsJson(String filename, Class<T> klass) throws IOException {
InputStream is = context.getAssets().open(filename);
return JsonParser.getInstance().fromJson(new InputStreamReader(is), klass);
}
}
Next, we want to switch between implementations painlessly. The usage of both implementations of the webservice is transparent, because we use WebService interface. So, we'll configure the WebService instance on app launch. Application class suits our needs:
public class App extends Application {
public static final boolean USE_LOCAL_WS = false;
private static WebService webService;
public static getWebService() {
return webService;
}
#Override
public void onCreate() {
super.onCreate();
webService = USE_LOCAL_WS ? new LocalWebService(this) : new RemoteWebService();
}
}
I'd suggest checking out WireMock (disclaimer - I wrote it):
http://wiremock.org/
You can run it standalone on your laptop, configure stubbed responses and verify that your app send the requests you expected it.
It's configurable via a fluent Java API or JSON (files or over HTTP).
I ended up writing a mock service tool for a similar purpose: https://github.com/clafonta/Mockey/wiki
A mock service is a great tool for quickly building UIs and validating your client code, but it can become a rabbit hole, so I recommend you use something that is already out there before building your own. Github has plenty of results when you search for 'mock'. Regardless of what you do, here are a few key stumbling blocks that you may encounter.
You end up working with the wrong data/JSON format. For example, your app works great with the mock service, but breaks when hitting the real service because your app consumes a JSON object but the real service returns an Array of JSON objects. To avoid this, you could try using JSON Schema to help highlight invalid JSON models in your mock service.
Your app doesn't make a valid request. Your mock service will typically not care about the incoming request. For example, the real service needs a "customerID" and your app never passes it in. To avoid this, you could build some "required request parameter" validation logic in your mock service.
Testing challenges. Your automated functional testing approach needs to interact with your mock service tool if you want to test things beyond the simple "happy path". For example, you run your test "user A logs-in and sees 0 messages" vs. "user B logs-in and sees 20 messages".
You can try Jadler (http://jadler.net). It's an http stubbing/mocking library I've been working on for some time. It should meet all your requirements I believe.
Just in case someone is still looking at this thread at year >= 2017. There's free tool out there now that let's you create mock soap and rest web services in seconds without the need to install or deploy anything on your box.
amock.io
You can select your http method, response code, response message body, content-type, specify custom endpoint, etc.
It's very useful for returning mock data from remote web services to you app, any kind of app.
Disclaimer, I developed this service, out of necessity and I made it free so others can benefit from the solution.
Beeceptor (disclaimer, I'm the author) shall help you for the exact use-case here. Create an API endpoint, define a mock path and response. Use it in hackathons to build mock APIs in seconds.
Beeceptor is more than a mocking service. It is an HTTP proxy for APIs. For example, if you have a real API, use the real API as ultimate target. Beecetor intercepts traffic and using rules,
when rules are matched, APIs are mocked
when no rule matches, your target endpoint is hit as usual.
With Mocky.io, you shall have different API paths, with Beeceptor your base URL is going to be same all the time.
There's pretty new mock API solution called QuickMocker that allows not only stubbing static data, but also generate fake (faker), random and contextual data using shortcodes. Supports multiple HTTP methods and RegExp URL path which allows to create even one single dummy endpoint that can intercept anything you need. And yeah, it allows to debug any request made to your fake API domain.
Probably the best thing to do is create a mock for the REST web service service while you're developing your application code and then replace it with code to call the actual web service returning "real" data, once your application is written.
I'm currently writing a very similar application to yours which (like you) obtains data from a RESTful web application. In my application, I'm following the MVP pattern recommended by GWT and is also documented by Martin Fowler as the PassiveView pattern.
What you want to do is abstract away the code to make the REST web service call into an interface (the Model). The responsibility of this model class is to provide data to the Presenter/Controller. The Presenter will handle all of your business logic and then pass data up to the view (the view should be pretty dumb as well allowing it to also be mocked out). During testing, you will create a MockModel to implement the model interface and pass test data to the Presenter - without making an actual web service call at all! Then, when you're ready, you will replace this class with the actual web service and start your integration testing.
This approach has the added benefit in that it will be easy to create specific (and repeatable) test cases in your mock model. If you don't have control of the actual web service (and I'm assuming you don't), this can be difficult (or even to impossible) to achieve. The result should be a more robust, better tested application without to need to create any test XML or JSON or creating the web services yourself.
Create some files with dummy responses and put into a folder. Now go to command-line and execute the following:
python -m SimpleHTTPServer
You can now access these files and dummy responses at
http://:8000
I suggest taking a look at FakeRest (https://github.com/marmelab/FakeRest), a client-side only Fake Server using XMLHTTPRequest monkey patching.
Disclaimer: I wrote it.
Atmo could be useful.
Disclaimer: I'm the author of atmo.
You can make use of http://maqueapp.com/ to create the mock web service. Its quick and easy. I heard about it on theflexshow episode 157 (not flexshow!)

How to use a server to store/receive data?

I am wondering what is required to setup a server so that you can store data on it, and then have an application send requests to it to store and receive data. More specifically, I am working on an Android application where a user will generate data and then that should be stored on a server so other users can access it. But I do not know how setting up a server to be capable of this works. I have worked on Android applications in the past that sends requests (put, post, get, etc) to a server, but that back end was already set up for me. Any info or resources about setting this up would be great.
There are many, many different ways to accomplish this.
Since you're already working with a Google technology, Android - you could start by creating a Google App Engine project. Following the tutorials you can get started setting up a simple back end solution that will store data for you and you can make requests to it for that data.
Another advantage to this for you is that you don't have to learn how to install software on a server and all the dependencies that arise from that, etc. Simply set up a new account and push-button deploy through Eclipse or command line.
And since you've used Java in Android, you can use JAva for Google App Engine (GAE) too!
Getting started: http://code.google.com/appengine/docs/java/gettingstarted/introduction.html
You can try ready to use BAAS/PAAS services to store your data, e.g. QuickBlox for Android http://quickblox.com/developers/Android, where you can manipulate with your data with few strings
QBLocation location = new QBLocation();
location.setLatitude(35.0);
location.setLongitude(53.0);
location.setStatus("I'm at this place");
String someImportantString = "Dr. Henry Walton Indiana Jones";
QBLocations.createLocation(location, new QBCallbackImpl() {
#Override
public void onComplete(Result result, Object context) {
// retrieve context object inside callback
String passedContextObject = (String) context;
System.out.println(passedContextObject);
// do stuff with result
}
}, someImportantString);
All logic of data exchange with server is encapsulated in framework.

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