Working with Webservices (Cloud Services)

Transcription

1 Working with Webservices (Cloud Services) Nilanjan Banerjee University of Maryland, Baltimore County Baltimore, MD Intro to Mobile Computing 1

2 Some of the simple web based services you would use! Writing data to a database Querying data from a database Map queries (already learned about it) (extracting maps, geocoding, reverse geocoding)

3 Other advanced webservices (Hawaii Webservice from Microsoft) Optical Character Recognition System (OCR) Relay services and Rendezvous Services Speech to Text Service Traslator Service (Microsoft Transalator) Path prediction

4 Other webservices we will learn about places API Street View API google messaging service

5 Usually two ways of accessing webservices over Http/Https HttpGet HttpPost What are the differences?

6 Formats in which data is sent back to you json (JSONObject) { "glossary": { "title": "example glossary", "GlossDiv": { "title": "S", GlossList": { "GlossEntry": { "ID": "SGML", "SortAs": "SGML", "GlossTerm": "Standard Generalized Markup Language", "Acronym": "SGML", "Abbrev": "ISO 8879:1986", "GlossDef": { "para": "A meta-markup language, used to create markup", "GlossSeeAlso": ["GML", "XML"] }, "GlossSee": "markup" } } } } }!

7 Formats in which data is sent back to you xml (XmlPullParser) <!DOCTYPE glossary PUBLIC "-//OASIS//DTD DocBook V3.1//EN"> <glossary><title>example glossary</title> <GlossDiv><title>S</title> <GlossList> <GlossEntry ID="SGML" SortAs="SGML"> <GlossTerm>Standard Generalized Markup Language</GlossTerm> <Acronym>SGML</Acronym> <Abbrev>ISO 8879:1986</Abbrev> <GlossDef> <para>a meta-markup language,</para> <GlossSeeAlso OtherTerm="GML"> <GlossSeeAlso OtherTerm="XML"> </GlossDef> <GlossSee OtherTerm="markup"> </GlossEntry> </GlossList> </GlossDiv> </glossary>!

8 General architecture for accessing databases Intermediary Script (php, perl etc) Backend database Mobile Phone

9 Sending simple text data from a Mobile phone (Server side) Adding userinfo --- username and password $firstname = $_REQUEST["firstname"];! $lastname = $_REQUEST["lastname"];! $username = $_REQUEST["username"];! $fpassword = $_REQUEST["fpassword"];! require_once('db.inc.php');! $insertquery="insert INTO table_name (first_name, last_name, user_name, fpassword) VALUES ('$firstname', '$lastname', '$username', '$fpassword )";! $result = mysql_query($insertquery);! mysql_close();! - db.inc.php <?! $user= XXX";! $password= YYY";! $database="weedidapp";! $host="mpss.csce.uark.edu";! or die( "Unable to select database");!?>!

10 Authenticating userinfo (server side) Check that the username password is present in the database Note that this is all in plaintext. Ideally you would create a MD5 hash of the password and store the hash <?php! foreach ($_GET as $key => $value) { eval("\$". $key. " = \"". $value. "\";");}! $username = $_REQUEST["username"];! $fpassword = $_REQUEST["fpassword"];! require_once('db.inc.php');! $query="select * from table where user_name='$username' AND fpassword='$fpassword'";! $result = mysql_query($query);! if($result && mysql_numrows($result)>0)! echo "y ;! else! echo "n ;! mysql_close();!?>!

11 Adding text to a mysql database Send the data encoded in the url For e.g., latitude= ;longitude= The url is parsed by the php script and a hashtable with <key, value> pairs are extraced _REQUEST[ latitude ] = _REQUEST[ longitude ] = $latitude = $_REQUEST[ latitude"];! $longitude = $_REQUEST[ longitude"];! require_once('db.inc.php');! $insertquery="insert INTO table_name (latitude, longitude) VALUES ( $latitude', '$longitude )";! $result = mysql_query($insertquery);! mysql_close();!

12 Retrieving text from a mysql server and sending it back mysql_select_db("locationgame",$con);! $list = mysql_list_tables("locationgame");! $i = 0;! $idarray = array();! $latarray = array();! $longarray = array();! $count = 0;! while($i < mysql_num_rows($list))! {! $tb_names[$i] = mysql_tablename($list,$i);! $sql = "SELECT * FROM $tb_names[$i] order by Date desc limit 1";! $result = mysql_query($sql, $con);! $num = mysql_numrows($result);! $j = 0;! while($j < $num)! {! $fielddate=mysql_result($result,$j,"date");! $fieldlatitude = mysql_result($result, $j, "Latitude");! $fieldlongitude = mysql_result($result, $j, "Longitude");! $phpdate = strtotime($fielddate);! $dist = distance($fieldlatitude, $fieldlongitude, $latitude, $longitude);! $idarray[] = $tb_names[$i];! $latarray[] = $fieldlatitude;! $longarray[] = $fieldlongitude;! $count ++;! $j++;! }! $i++;! }! for ($i = 0; $i < $count; $i++)! {print "$idarray[$i] ; print "$latarray[$i] ; print "$longarray[$i] ; print "\n ;}! mysql_close($con);!

13 Code on the phone httpclient = new DefaultHttpClient(); 91 httppost = new HttpPost(php_script); 92 // Add your data 93 namevaluepairs = new ArrayList<NameValuePair>(2); 94 namevaluepairs.add(new BasicNameValuePair("User ", name.trim())); 95 namevaluepairs.add(new BasicNameValuePair("Password", pass.trim())); 96 httppost.setentity(new UrlEncodedFormEntity(nameValuePairs)); // Execute HTTP Post Request 99 response = httpclient.execute(httppost); 100 inputstream = response.getentity().getcontent(); data = new byte[256]; buffer = new StringBuffer(); 105 int len = 0; 106 while (-1!= (len = inputstream.read(data)) ) 107 { 108 buffer.append(new String(data, 0, len)); 109 } inputstream.close();

14 Uploading images to a mysql server php script enter where image is stored and its Characteristics (size etc) store Image in a folder database Name of image and attributes Send actual images folder Phone

15 Schematic for upload of images String (Base64 encoded) String byte ByteArray OutputStream Bitmap binary (Base64 decoded) image Image Android Server

16 Uploading images to the server <?php $base=$_request['image']; echo $base;// base64 encoded utf-8 string $binary=base64_decode($base);// binary, utf-8 bytes header('content-type: bitmap; charset=utf-8 ); $file = fopen('test.jpg', 'wb'); fwrite($file, $binary);fclose($file); echo '<img src=test.jpg>';?>

17 Sending images from the phone 29 byte [] byte_arr = stream.tobytearray(); 30 String image_str = Base64.encodeBytes(byte_arr); 31 ArrayList<NameValuePair> namevaluepairs = new ArrayList<NameValuePair>(); namevaluepairs.add(new BasicNameValuePair("image",image_str)); try{ 36 HttpClient httpclient = new DefaultHttpClient(); 37 HttpPost httppost = new HttpPost(php_script); 38 httppost.setentity(new UrlEncodedFormEntity(nameValuePairs)); 39 HttpResponse response = httpclient.execute(httppost); 40 String the_string_response = convertresponsetostring(response); 43 }catch(exception e){ }

18 Sending images from the phone (Response) String res = ""; StringBuffer buffer = new StringBuffer(); inputstream = response.getentity().getcontent(); 53 int contentlength = (int) response.getentity().getcontentlength(); 55 if (contentlength < 0){ 56 } 57 else{ 58 byte[] data = new byte[512]; 59 int len = 0; 60 try 61 { 62 while (-1!= (len = inputstream.read(data)) ) 63 { 64 buffer.append(new String(data, 0, len)); 65 } 66 } 67 catch (IOException e) 68 {} 71 try 72 { 73 inputstream.close(); 74 } 75 catch (IOException e) 76 {} 80 res = buffer.tostring();. 83 } 84 return res; 85 }

19 More Sophisticated Service (Relay and Rendezvous Service) Cloud service Relay point in the cloud Mobile device 1 <device name, identifier> Mobile device 2 <device name, identifier>

20 More Sophisticated Service (Path Prediction ) Path prediction service: given a set of location, the service predicts what you destination is. OCR: takes a jpeg image with text and returns the text embedded in the image Text-to-speech: takes upto 10second of speech and converts it to text and returns the text Translate: take text in some other language and uses Microsoft translate to convert it to English and returns the english text back.