Api web 2.0

1. Api web 2.0

2. Representational state transfer • REST is not a protocol or a format its a kind of architecture • A service is accessed with its URI through HTTP operation like GET, POST, PUT or DELETE. • Enough for most of web services • Example : http://www.inria.fr/add?var=1&var=2 3 ;)

3. HTTP Query with JAVA • Init the HTTP query: URL url = new URL("my_url"); HttpURLConnection UrlConn = (HttpURLConnection) url.openConnection(); urlConn.setRequestMethod("GET"); urlConn.setAllowUserInteraction(false); urlConn.setDoOutput(true); • Read the answer InputStream response = urlConn.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(response)); while ((String line = o_oBufReader.readLine()) != null){ //do whatever you want } • Diconnect urlConn.disconnect();

4. AJAX • Asynchronous javascript • HTTP query in javascript without reloading all the page • Richer interfaces • Example: mail notification and instant messaging in gmail.

5. AJAX : init the query Var xhr; if (window.XMLHttpRequest) { xhr = new XMLHttpRequest();     // Firefox, Safari, ... } else if (window.ActiveXObject) { xhr = new ActiveXObject("Microsoft.XMLHTTP"); // Internet Explorer } or try { xhr = new ActiveXObject("Microsoft.XMLHTTP"); //try Internet Explorer }catch(e) { xhr = new XMLHttpRequest() //firefox, safari ... }

6. AJAX : send and process query • Process function : request.onreadystatechange = function(){ // instructions }; • Send the query : xhr.open('GET', 'http://web2/api/method?param=value', true); xhr.send(null); • Important: Same Origin Policy So use a servlet as intermediary

7. JSON: JavaScript Object Notationhttp://www.json.org/ • JSON object: var person = { "name" : "John" "phone" : [ {"type" : "home", "num" : "1234"}, {"type" : "mobile", "num" : "5678"} ] }; • person.name; person.phone[0].num; • Eval function: var JSONString = "someVar = { 'color' : 'blue' }";    eval(JSONString); • Tutorial: http://www.hunlock.com/blogs/Mastering_JSON_(_JavaScript_Object_Notation_)

8. API flickrhttp://www.flickr.com/services/api/ • API_Key and secret: http://www.flickr.com/services/api/keys/apply/ Note : il faut un compte Yahoo pour y accèder. • URL API: http://api.flickr.com/services/rest/?method=method_name&param1=value1&param2=value2... • Paramètre souvent requis: api_key • On demande la clé en ligne, cf URL ci-dessus. • Recherche de photos par tags: http://api.flickr.com/services/rest/?method=flickr.photos.search&tags=a_tag&api_key=your_key

9. Example of XML Response • URL API: http://api.flickr.com/services/rest/?method_name&param1=value1&param2=value2... • Paramètre souvent requis: api_key • Recherche de photos par tags: http://api.flickr.com/services/rest/?method=flickr.photos.search&tags=a_tag&api_key=your_key

10. Don't worry: API JAVA ;) • Dom API: DocumentBuilderFactory fabrique = DocumentBuilderFactory.newInstance(); DocumentBuilder constructeur = fabrique.newDocumentBuilder(); Document document = constructeur.parse(rdfFile); Element racine = document.getDocumentElement(); NodeList photos = racine.getElementsByTagName("photo"); for(int i = 0; i < photos.getLength(); i++){ photos.item(i).getAttributes() … } • Or just forget to manipulate XML: http://sourceforge.net/projects/flickrj/

11. FlickrJ: API JAVAhttp://sourceforge.net/projects/flickrj/ • Init service: Flickr flickr = new Flickr(apiKey, secret, new REST()); • Different interfaces: • flickr.getPhotosInterface() • flickr.getPeopleInterface() • flickr.getContactsInterface() • flickr.getLicensesInterface() • flickr.getTagsInterface() • …

12. FlickrJ: examplehttp://sourceforge.net/projects/flickrj/ • Init service: Flickr flickr = new Flickr("47422029b3aabee4aca6a5853eca74b6", "ab7f2d30639a9828", new REST()); PhotosInterface pi = flickr.getPhotosInterface(); SearchParameters sp = new SearchParameters(); String []tabTag = {« cars »}; sp.setTags(tabTag); PhotoList photoList = pi.search(sp, 50, 1); Iterator it = photoList.iterator(); while (it.hasNext()) { Photo photo = (Photo) it.next(); out.println("<img src='" + photo.getThumbnailUrl() + "' />"); }

13. JSON and flickrhttp://api.flickr.com/services/rest/?method=method_name&format=json • URL API:Example: flickr.blogs.getList • XML response <blogs> <blog id="73" name="Bloxus" url="http://remote.bloxus.com/" /> <blog id="74" name="Manila" url="http://test1.userland.com/" /> </blogs> • JSON response rsp = { "stat": "ok", "blogs": { "blog": [{ "id" : "73", "name" : "Bloxus", "url" : "..." } { "id" : "74", "name" : "Manila", "url" : "..." } ] } } • URL API:Example for (var i=0; i<rsp.blogs.blog.length; i++){ var blog = rsp.blogs.blog[i] ... }

14. Youtubehttp://code.google.com/apis/youtube • API key and secret: http://code.google.com/apis/youtube/dashboard • REST interface: http://www.youtube.com/api2_rest • To request a response in JSON format, use the alt=json parameter. • Server side API: Java, .NET, PHP, python … • Widget and players API (client side): javascript, flash

15. API JAVA Youtubehttp://code.google.com/p/gdata-java-client/downloads/list • Import import com.google.gdata.client.youtube.YouTubeService; import com.google.gdata.util.ServiceException; • Init service YouTubeService myService = new YouTubeService("the name of my app"); • Init search query: YouTubeQuery query = new YouTubeQuery(new URL(URL_VIDEOS_FEED)); • Appel au service: VideoFeed videoFeed = service.query(query, VideoFeed.class); for (VideoEntry ve : videoFeed.getEntries()) { ... }

16. API Youtube • Parametrize query: • search terms: query.setVideoQuery(searchTerms); • Order:RELEVANCE, VIEW_COUNT, PUBLISHED, RATING : query.setOrderBy(YouTubeQuery.OrderBy.RELEVANCE); • Number of results: query.setMaxResults(count); • Pagination: query.setStartIndex(start); • include restricted content (excluded by default):query.setIncludeRacy(true); • Code example

17. Google search: AJAX APIhttp://code.google.com/apis/ajaxsearch/documentation/ • Basis: // create a search controlvar searchControl = new google.search.SearchControl(null);// add in a full set of searcherssearchControl.addSearcher(new google.search.LocalSearch());searchControl.addSearcher(new google.search.WebSearch());searchControl.addSearcher(new google.search.VideoSearch());searchControl.addSearcher(new google.search.BlogSearch());searchControl.addSearcher(new google.search.NewsSearch());searchControl.addSearcher(new google.search.ImageSearch());searchControl.addSearcher(new google.search.BookSearch());searchControl.addSearcher(new google.search.PatentSearch());// tell the searcher to draw itself and tell it where to attach// Note that an element must exist within the HTML document with id "search_control"searchControl.draw(document.getElementById("search_control"));

18. Google search: AJAX APIhttp://code.google.com/apis/ajaxsearch/documentation/ • SearcherControl Draw Modes: • create a drawOptions object var drawOptions = new google.search.DrawOptions(); • tell the searcher to draw itself in linear mode drawOptions.setDrawMode(google.search.SearchControl.DRAW_MODE_LINEAR); • tell the searcher to draw itself in linear mode drawOptions.setDrawMode(google.search.SearchControl.DRAW_MODE_TABBED); • decouple the "search form" from the set of search results drawOptions.setSearchFormRoot(document.getElementById("id_dom_elem")); • Display results : searchControl.draw(element, drawOptions);

19. Google search: AJAX APIhttp://code.google.com/apis/ajaxsearch/documentation/ • Keeping a Search Result: // establish a keep callback searchControl.setOnKeepCallback(this, MyKeepHandler); function MyKeepHandler(result) { // clone the result html nodevar node = result.html.cloneNode(true); // attach itvar savedResults = document.getElementById("saved_results");savedResults.appendChild(node); }

20. Google maphttp://code.google.com/apis/ajaxsearch/ http://gmaps-samples.googlecode.com/svn/trunk/demogallery.html

21. API Facebook • Install facebook "Developper" application to get API_Key and secret. • Interface restful: http://api.facebook.com/restserver.php?v=1.0&api_key=YOUR_API_KEY&method=METHOD_NAME&sig=METHOD_OPTIONS • FacebookML: A meta language to develop facebook apps (interpreted on facebook servers) • FQL: Facebook Query Language • Server API: Php, java, .NET, etc;

22. API java pour Facebook • Plus maintenue par facebook: Alternatives: http://code.google.com/p/facebook-java-api • Authentification de l'application: Facebook fb = new Facebook(request, response, FB_API_KEY, FB_SECRET_KEY); fb.requireLogin("") if(!face.isLogin()) return null; //can't access application FacebookRestClient fbrclient = fb.getFacebookRestClient(); • Id utilisateur: fbrclient.users_getLoggedInUser();

23. API java pour Facebook • Récupérer le nom et status de l'utilisateur courant (un peu compliqué, mais bon…): //fill the list of users ArrayList<Long> user = new ArrayList<Long>(); //set of information required on users EnumSet<ProfileField> fields = EnumSet.of(com.facebook.api.ProfileField.NAME, com.facebook.api.ProfileField.STATUS); users.add(fbrclient.users_getLoggedInUser()); Document d = fbrclient.users_getInfo(users, fields); String userName = d.getElementsByTagName(com.facebook.api.ProfileField.NAME.fieldName) .item(0).getTextContent(); String userName = d.getElementsByTagName(com.facebook.api.ProfileField.NAME.fieldName) .item(0).getTextContent();

24. API java pour Facebook • Informations sur les amis: Document d = fbrclient.friends_get(); NodeList userIDNodes = d.getElementsByTagName("uid"); Collection<Integer> friends = new ArrayList<Integer>(); for (int i = 0; i < userIDNodes.getLength(); i++) {Node node = userIDNodes.item(i);Integer id = Integer.valueOf(node.getTextContent());friends.add(id); } Document infos = fbrclient.users_getInfo(users, fields); //then we can iterate on the list of friends id and get the information for(Integer id : friends){ String fieldName = infos.getElementsByTagName(...).item(i).getTextContent(); //etc. }

25. And more… • All google apps: http://code.google.com/more • Open social http://code.google.com/apis/opensocial/ • Maps: http://code.google.com/apis/maps/ • Etc. • Delicious: http://delicious.com/help/api • Digg: http://apidoc.digg.com/ • Technorati: http://technorati.com/developers/api/ • And most of web 2.0 platforms propose access to their data through APIs!!!

26. It's your turn now !!! Build a search engine that search on different web 2.0 services and propose differents médias: • Photos with flickr • Video with youtube • People and social features with facebook • And whatever you want with web 2.0 APIs.