Creating a RESTful API for increasing a mobile app performance is as normal spot as having oat at breakfast in the cutting edge technology evolution. The Android library at present does not have an exquisite solution to address this upfront task.

There are two key assignments that you need to extract. There are systems and applications specifically designed using this style of to aim for faster performance speed, improving reliability, and enabling scalability with the support of additional users.

retrofit with rxjava1

To accomplish these objectives, programmers integrate returnable components that can be overseen and upgraded without influencing the framework in general while it is running.

The standard systems are exorbitantly pricey as far as code significance and practicality is concerned. You either need to compose AsyncTask or twist up a Thread/Runnable to enable async handling. Furthermore, you have to manage Java data stream to parse information from HttpClient. Obviously, this demands one to compose a page of attempt/catch for capturing all the conceivable errors.

Understanding the functioning of RxJava

RxJava describes itself as an API for asynchronous programming with observable streams.

RxJava is the open-source implementation of ReactiveX in Java. The two main classes are Observable and Subscriber. In RxJava, an Observable is a class that emits a stream of data or events, and a Subscriber is a class that acts upon the emitted items.

RxJava makes the provision for open-source application of ReactiveX within the Java. The two principle classes are Observable and Subscriber. In RxJava, an Observable class is responsible for disseminating flood lot of information, events. While on the other hand, Subscriber defines a class that follows up on the transmitted data.

Understanding RxJava

An occasion ofSubscription speaks of the association between an observer and observable. In you callunsubscribe() on this example to expel the association. This is for instance valuable to evade overhauls to gadgets after they have been arranged.

understanding-rxjava

Understanding the use of Observable.just()

Observable.just() creates an Observable such that when an Observer subscribes, theonNext() of the Observer is immediately called with the argument provided toObservable.just().


import java.util.Arrays;
import java.util.List;

import rx.Observable;

public class RxJavaExample {
        public static void main(String[] args) {
                List list = Arrays.asList("Android", "Ubuntu", "Mac OS"); 
                Observable> listObservable = Observable.just(list);  
                listObservable.subscribe(new Observer>() {                          

            @Override
            public void onCompleted() {}

            @Override
            public void onError(Throwable e) {}

            @Override
            public void onNext(List list) {
                                System.out.println(list);
            }
        });
        }
}

Creates a list

Creates the Observable

Registers the Observer

Also, it is important to note that passing a null value to JUST shall return an Observable emitting null as an item.

The standard workflow for an Observable is to radiate one or more things, and afterward execute the task either successfully or may lead to an error. An Observable can have different Subscribers, and for everything discharged by the Observable, the thing will be sent to the Subscriber.onNext() strategy to be taken care of.

Once an Observable has got done with transmitting data, it will fetch the output with Subscriber.onCompleted() technique, or if there is a blunder the Observable will call the Subscriber.onError() process.

Retrofit Model to make it work with RxJava

Retrofit is a sort of safe REST Android client created by Square. The library gives a potential framework for confirming and interfacing with APIs and sending parsing system requests in alignment with OkHttp.

Retrofit serves as one of the most influential HTTP clients Library for Android simply because it is easy to incorporate in comparison to the incredible performance it gives compared to rest of the others.

This library makes downloading JSON or XML data from a web API relatively straightforward. Once the data is downloaded, then it is parsed into a Plain Old Java Object (POJO) which must be defined for each "resource" in the response.

This HTTP client library makes downloading JSON or XML information from a web API genuinely easy. Once data downloading is completed, the library then parsed into a Plain Old Java Object (POJO) which is to be defined for each respective ‘resource’ in response.

Here is the generic factory class to do the implementation (excluding the RestAdapter implementation)


static  T createRetrofitService(final Class class, final String endPoint) {  
    final RestAdapter restAdapter = new RestAdapter.Builder()
            .setEndpoint(endPoint)
            .build();
    T service = restAdapter.create(clazz);

    return service;
}

The Github REST API gives you back the accompanying JSON. You can attempt it yourself!

Curl https://api.github.com/users/linkedin


{
  "login": "LinkedIn",
  "blog": "http://engineering.linkedin.com",
  "public_repos":   73,
  //...truncated JSON
}

We will define the model in a Java file. The field variables in the model are automatically parsed from the JSON response. So you don't need to worry about writing the parsing code. Make sure that the variable names are the same as API definition:

We shall now characterize the model in a distinctive Java record. The field variables as implemented in the model are naturally parsed after the JSON reaction. So you don't have to stress over composing the parsing code. It important to ensure that the variable names are precisely the same as API definition:


public class Github {  
    private String login;
    private String blog;
    private int public_repos;

    public String getLogin() {
        return login;
    }

    public String getBlog() {
        return blog;
    }

   public int getPublicRepos() {
        return public_repos;
    }
}

And you are done! Other than Java's boilerplate stuff (boo), the code is very concise and readable. If you have more than one endpoint you want to access, simply add it to your service interface at little additional cost!

Comparing Retrofit with Google Volley

Retrofit and Volley are both comprehensive networking libraries for present day Android applications, yet each has its set of merits depending on the project scope.

Retrofit Volley
It is ideal to move ahead with Retrofit if it is to be utilized for standard REST API with JSON. It is important to make sure that there are not numerous custom necessities with regards to caching, request access, retries, and so on. Volley is useful when you are running high on fine-grained necessities. Also, it works well when you require a large amount of flexibility from your systems administration layer later on at the expense of extra code.
Retrofit is ideal to use in case you need to communicate directly with the Web Service. Programmers tend to use peer library Picasso for downloading the images. Also, utilizing OkHTTP for performing HTTP operations is a good option id that lies out of Retrofit or Picasso. Volley is assumed to compete with unified Retrofit and Picasso. The add-on of using volley is that you just need to use a single set of library unlike what one does with Retrofit. The downside is that is undocumented and unsupported.
Retrofit is easy enough to use. The biggest advantage is that it lets you make API calls as simply as you make Java method calls. It gives luxury in the hands of developers in defining URLs to hit and the defining the request/response type parameters as Java classes. Volley involves a lot of complexities in general. The biggest disadvantage of using Volley it only supports String, Image, JSONArray, and JSONObject as its response type. To make it worst, for avoiding the problem of emptying JSONObjects all by yourself and utilizing it like Retrofit, one need to incorporate this GsonRequest class, representing a request whose response is renewed to type T by Gson automatically.


More than saving the time and resources, RxJava helps in minimizing the efforts that are required for smooth functioning of mobile applications. Also, calling the REST APIs are relatively easy with a retrofit that with Volley.

For the efficient operation of our mobile applications, our programmers move ahead to work with JSON in JavaScript because it offers a lightweight platform along with the fine-grained control over request and responses.