Networking

a.    Implement the HTTP Client object

b.    Retrieve data in various formats from network services

c.    Upload and download files across the network

d.    Post JSON-formatted data to a web service; receive and process JSON data from a network endpoint

e.    Receive and process XML data from a network endpoint

f.     Handle network and data errors

  Exercise - 1

   Implement the HTTP Client object and analyse XML HTTP Request Life Cycle

Solution

function xhrlifecycle(){

var xhr = Ti.Network.createHTTPClient({

    onload: function(e) {

// function called in readyState DONE (4)

Ti.API.info('onload called, readyState = '+this.readyState);

    },

    onerror: function(e) {

// function called in readyState DONE (4)

Ti.API.info('onerror called, readyState = '+this.readyState);

    },

    ondatastream: function(e) {

// function called as data is downloaded

Ti.API.info('ondatastream called, readyState = '+this.readyState);

    },

    onsendstream: function(e) {

// function called as data is uploaded

Ti.API.info('onsendstream called, readyState = '+this.readyState);

    },

onreadystatechange: function(e) {

switch(this.readyState) {

case 0:

// after HTTPClient declared, prior to open()

// though Ti won't actually report on this readyState

Ti.API.info('case 0, readyState = '+this.readyState);

break;

case 1:

// open() has been called, now is the time to set headers

Ti.API.info('case 1, readyState = '+this.readyState);

break;

case 2:

// headers received, xhr.status should be available now

Ti.API.info('case 2, readyState = '+this.readyState);

break;

case 3:

// data is being received, onsendstream/ondatastream being called now

Ti.API.info('case 3, readyState = '+this.readyState);

break;

case 4:

// done, onload or onerror should be called now

Ti.API.info('case 4, readyState = '+this.readyState);

break;

}

},

    timeout:5000  /* in milliseconds */

});

xhr.open("GET", 'http://api.sba.gov/rec_sites/keywords/domain/irs.json');

xhr.send();  // request is actually sent with this statement

}

  Exercise - 2

Retrieve data in various formats from network services

Solution

function httpnetwork(){

var url = "http://api.sba.gov/rec_sites/keywords/domain/irs.xml";

var xhr = Ti.Network.createHTTPClient({

    onload: function(e) {

// this function is called when data is returned from the server and available for use

        // this.responseData holds any returned binary data

        Ti.API.info(this.responseXML);   // this.responseXML holds any returned XML (including SOAP)

               

    },

    onerror: function(e) {

// this function is called when an error occurs, including a timeout

         Ti.API.info('Error from network');

        Ti.API.info(e.error);

        //alert('error');

    },

    timeout:5000  /* in milliseconds */

});

xhr.open("GET", url);

xhr.send();  // request is actually sent with this statement

}

  Exercise - 3

 download files across the network

Solution

function downloadfile(){

var file ;

var xhr = Titanium.Network.createHTTPClient({

onload: function() {

// first, grab a "handle" to the file where you'll store the downloaded data

file = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory,'myaudio.mp3');

file.write(this.responseData); // write to the file

Ti.App.fireEvent('audio_downloaded', {filepath:file.nativePath});

},

timeout: 10000

});

xhr.open('GET','http://www.freesound.org/data/previews/2/2686_5150-lq.mp3');

xhr.send();

Ti.App.addEventListener('audio_downloaded', function(e) {

//image.image = e.filepath;

Ti.API.info(file.nativePath);

var audio = Titanium.Media.createSound({

url:file.nativePath,

preload: true

});

audio.play();

});

};

  Exercise - 4

Post JSON data from a network endpoint

Solution

function postJSONData(){

   var xhr = Ti.Network.createHTTPClient({

    onload: function onLoad() {

        alert("Loaded: " + this.status + ": " + this.responseText);

    },

    onerror: function onError() {

        alert("Errored: " + this.status + ": " + this.responseText);

    }

});

xhr.open("POST","https://c0ceb560ef3c83761ce4c21a93b2ce718311fa76.cloudapp-enterprise.appcelerator.com/api/newtest");

var authstr = 'Basic ' + Ti.Utils.base64encode('WqrIxir6bD9oHoV07seH4T8vrrnc0rQA:');

xhr.setRequestHeader("Authorization", authstr);

xhr.setRequestHeader("Content-Type","application/json");

xhr.send(JSON.stringify({

    "first_name": "Mohan",

    "last_name": "Singh",

}));

   } 

  Exercise - 5

Receive and process JSON data from a network endpoint

Solution

var funcToExecute=function () { //function called when GET URL is loaded from HTTP

console.log("inside first cal back");

if(this.status == '200'){

    if(this.readyState == 4)

JSONObj=JSON.parse(this.responseText);

var data = [];

for (var i = 0; i < JSONObj.length ; i++) { //Loop through

//for (var i = 0; i < 10 ; i++) {

 var listItem = JSONObj[i];

data.push({

title :listItem["name"]

});

}

//Create table and set values

var table = Titanium.UI.createTableView({}); 

table.setData(data);

$.tableContainer.add(table);

console.log("Table Set");

}

};

//HTTP request call

var xhr=Titanium.Network.createHTTPClient();    

xhr.onerror = function(e){ 

 Ti.API.error('Bad Sever =>'+e.error);

};

xhr.open("GET","http://api.sba.gov/geodata/all_links_for_county_of/orange county/ca.json");//ADD your URL

xhr.onload=funcToExecute;

  Exercise - 6

Detect Network Change

Solution

Titanium.Network.addEventListener('change', function(e) {

    Ti.API.info('network changed: ' + e.networkTypeName);

    Ti.API.info('Reason: ' + e.reason);

    if (e.online) {

        Ti.API.info('device is online');

    } else {

        Ti.API.info('device is offline');

    }

});