HTTP Client &

Web Service on Android

Mobile

Application Development

Web Services

HTTP Operation

Web Services

HTTP Operation

There are 2 types of common operation in HTTP

GET : Requests data from a specified resource

GET requests can be cached

GET requests remain in the browser history

GET requests can be bookmarked

GET requests should never be used when dealing with

sensitive data

GET requests have length restrictions

GET requests should be used only to retrieve data

Web Services

HTTP Operation

There are 2 types of common operation in HTTP

POST : Submits data to be processed to a specified resource

POST requests are never cached

POST requests do not remain in the browser history

POST requests cannot be bookmarked

POST requests have no restrictions on data length

Web ServicesIntrodution to

Web Service

Web Services

Today’s Web

Web designed for application to human interactions

Served very well its purpose :

Information sharing : a distributed content library

Enabled B2C e-commerce

Non-automated B2B interactions

How did it happens

Built on very few standards : http + html

Shallow interaction model : very few assumptions made about computing platforms

Result was ubiquity

Web Services

What’s Next ?

The Web is everywhere, there is a lot more we can do !

E-marketplaces

Open, automated B2B e-commerce

Business process integration on the Web

Resource sharing, distributed computing

Current approach is ad-hoc on top of existing standards.

e.g., application-to-application interactions with HTML forms

Goal :

Enabling systematic application-to-application interaction on the Web Web Service was born !

Web Services

What is Web Service ?

UDDI Consortium

Web services are self-contained, modular business applications that have open, Internet-oriented, standards-based interfaces

W3C

A web service is a software application identified by a URI, whose interfaces and bindings are capable of being defined,described and discovered as XML

A web service supports direct interactions with other software agents using XML-based messages exchanged via Internet-based protocols

So in short, we can said the web service is :

A software system designed to support interoperable machine-to-machine interaction over a network

Web Services

Why Web Service ?

Exposing the Existing Function on the network

Web services allows you to expose the functionality of your existing code over the network. Once it is exposed on the network, other application can use the functionality of your program.

Interoperability

Web services allow various applications to talk to each other and share data and services among themselves. For example, a VB or .NET application can talk to Java web services and vice versa

Standardized Protocol

Web services use standardized industry standard protocol for the communication.

Low Cost of Communication

Web services use SOAP over HTTP protocol, so you can use your existing low-cost internet for implementing web services.

Web ServicesWeb Service

Framework

Web Services

Web Service Architecture

In short, WS architecture can be described in terms of :

What goes “on the wire” :

Formats and protocols

What describes what goeson the wire :

Description languages

What allows us to find thesedescriptions :

Discovery of services

Web Services

WSA

Web Service Description Language

Describes the Web Service and defines the functions that are exposed in the Web Service

Universal Description, Discovery and Integration

UDDI is used to register and look up services with a central registry

Web Service Format

Format and protocol that used in web service communication

Web Services

WSA : WSDL

Provides functional description of network services

IDL description

Protocol and deployment details

Platform independent description

Extensible language

Structure :

portType

Abstract definition of a service(set of operations)

Multiple bindings per portType:

How to access it

SOAP, JMS, direct call

Ports

Where to access it

Service

Port(e.g. http://host/svc)

Binding(e.g. SOAP)

Abstract interface

portType

operation(s)

inMesage outMessage

Port

Binding

Web Services

WSA : UDDI

UDDI defines the operation of a service registry:

Data structures for registering

Businesses

Technical specifications : tModel is a keyed reference to a technical specification

Service and service endpoints: referencing the supported tModels

Rules for the operation of a global registry

“private” UDDI nodes are likely to appear, though

Web Services

WSA : UDDI

Web Service

Web Service

SIC CODENAICS

DUNS NumbersThomas Registry ID

Rosetta-NetBASDA

Simple.Buy

Schemas,

Interchange specification

businessEntitybusinessEntitybusinessEntity

businessServicebusinessService

bindingTemplatebindingTemplate

InstanceDetailsInstanceDetails

categoryBag

keyedReferencekeyedReference

identifierBag

keyedReferencekeyedReference

tModels

Web Services

WSA : Format & Protocol

There are some well-known WS formats & protocols that used in web service technology

SOAP

REST

BEEP

E-Business XML

Hessian

XINS

XLANG

The 2 most popular formats

Assignment• Find the definition and concept of

SOAP and REST !

Web ServicesWeb Service

Format &

Protocol

Web Service Format & Protocol

There are 2 most popular web service formats that often used service-based application development

SOAP (Simple Object Access Protocol (SOAP)

REST (REpresentational State Transfer)

SOAP

SOAP (Simple Object Access Protocol)

SOAP is a protocol specification for exchanging structured information in the implementation of web services in computer networks

It uses XML Information Set for its message format, and relies on other application layer protocols, most notably Hypertext Transfer Protocol (HTTP) or Simple Mail Transfer Protocol (SMTP), for message negotiation and transmission

SOAP

SOAP (Simple Object Access Protocol)

SOAP basically using XML formatted message to perform data communication

XML message structure

Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format which is both human-readable and machine-readable

It is defined by the W3C

http://www.w3schools.com/xml/

https://en.wikipedia.org/wiki/XML_Schema_(W3C)

SOAP Example

OpenWeatherMapAPI : XML mode

http://openweathermap.org/

Try type or click and open this address in your web browser !

http://api.openweathermap.org/data/2.5/weather?q=Malang&mode=xml&appid=2de143494c0b295cca9337e1e96b00e0

REST

REST (REpresentational State Transfer)

Representational State Transfer (REST) is an architectural style that specifies constraints, such as the uniform interface, that if applied to a web service induce desirable properties, such as performance, scalability, and modifiability, that enable services to work best on the Web

In the REST architectural style, data and functionality are considered resources and are accessed using Uniform Resource Identifiers (URIs), typically links on the Web

In the REST architectural style you can use XML or JSON message to perform data communication, but usually we prefer to use JSON because it’s more lightweight than XML

REST Example

OpenWeatherMapAPI : JSON mode

http://openweathermap.org/

Try type or click and open this address in your web browser !

http://api.openweathermap.org/data/2.5/weather?q=Malang&mode=json&appid=2de143494c0b295cca9337e1e96b00e0

XML vs JSON

Web Services

Incorporating

Web Services in

Android Mobile

Applications

Web Services

Web Services in Mobile Apps

Many Web Services and APIs were originally developed with server to server or server to browser in mind, not mobile applications

Mobile platforms have their own set of challenges given :

Bandwidth

Memory and CPU Availability

Storage Capacity

Connectivity Options and Issues

Security

User Interaction and Display

REST + JSONis better !

Web Services

Web Services in Android

Android has ability to consume HTTP web service response using some methods

Using HTTPClient from Apache package Deprecated since API Ver. 14

HttpURLConnection from Java Net package

Another HTTP API

After HTTPClient deprecated, Google suggest to use HttpUrlConnection instead (Android Documentation)

Web ServicesAndroid HTTP

Consume

Example

Basic Example : Grabbing Image from Web

Web Services

Grabbing Image from Web

Activity_get_image.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<ImageView

android:id="@+id/img"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center" />

<Button

android:text="Download Content"

android:id="@+id/Button01"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

</LinearLayout>

Web Services

Grabbing Image from Web

HTTPConnection.java

public class HTTPConnection {

public InputStream OpenHttpConnection(String urlString) throws IOException {

InputStream in = null;

int response = -1;

URL url = new URL(urlString);

URLConnection conn = url.openConnection();

if (!(conn instanceof HttpURLConnection))

throw new IOException("Not an HTTP connection");

try {

HttpURLConnection httpConn = (HttpURLConnection) conn;

httpConn.setAllowUserInteraction(false);

httpConn.setInstanceFollowRedirects(true);

httpConn.setRequestMethod("GET");

httpConn.connect();

response = httpConn.getResponseCode();

if (response == HttpURLConnection.HTTP_OK) {

in = httpConn.getInputStream();

}

} catch (Exception ex) {

throw new IOException("Error connecting");

}

return in;}}

Web Services

Grabbing Image from Web

GetImageActivity.java

public class GetImageActivity extends Activity {

HTTPConnection conn = new HTTPConnection();

String imageURL = "http://file.filkom.ub.ac.id/fileupload/assets/

upload/file/PTIIK/konten/2014-10/pimpinan.jpg";

private class BackgroundTask extends AsyncTask<String, Void, Bitmap> {

protected Bitmap doInBackground(String... url) {

// ---download an image---

Bitmap bitmap = DownloadImage(url[0]);

try {

Thread.sleep(3000);

} catch (InterruptedException e) {

e.printStackTrace();

}

return bitmap;

}

protected void onPostExecute(Bitmap bitmap) {

ImageView img = (ImageView) findViewById(R.id.img);

img.setImageBitmap(bitmap);

}

}

Web Services

Grabbing Image from Web

GetImageActivity.java (continued)

private Bitmap DownloadImage(String URL) {

Bitmap bitmap = null;

InputStream in = null;

try {

in = conn.OpenHttpConnection(URL);

bitmap = BitmapFactory.decodeStream(in);

in.close();

} catch (IOException e1) {

e1.printStackTrace();

}

return bitmap;

}

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_get_image);

Button btnOpen = (Button) findViewById(R.id.Button01);

btnOpen.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {

new BackgroundTask().execute(imageURL);

}

});}

Web Services

Grabbing Image from Web

GetImageActivity.java (continued)

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.menu_get_image, menu);

return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

// Handle action bar item clicks here. The action bar will

// automatically handle clicks on the Home/Up button, so long

// as you specify a parent activity in AndroidManifest.xml.

int id = item.getItemId();

//noinspection SimplifiableIfStatement

if (id == R.id.action_settings) {

return true;

}

return super.onOptionsItemSelected(item);

}

}