Web-APIs. Examples Consumer Technology Cross-Domain communication Provider Technology

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Carol Foster
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1 Web-APIs Examples Consumer Technology Cross-Domain communication Provider Technology

2 Applications Blogs and feeds OpenStreetMap Amazon, Ebay, Oxygen, Magento Flickr, YouTube 3 more on next pages

3 Facebook Open Graph Public Users/Pages: Profile pictures: Photos: Private (requires access-token) Friends Likes Music

$com/btaylor { } "id": "220439", "name": "Bret Taylor", "first_name": "Bret", "last_name": "Taylor", "link": "http://www.$

4 Response Facebook API { } "id": "220439", "name": "Bret Taylor", "first_name": "Bret", "last_name": "Taylor", "link": " "username": "btaylor", "gender": "male", "locale": "en_us"

5 Twitter Public User Info users/show... Location, Profile-Image, Description etc TimeLine screen_name=elaspix Followers Private Writing messages, delete Stuff follow new users Change background image & other properties

Response Twitter API http://api.twitter.

6 Response Twitter API

Google Search Most / all are Public Searches Image Search http://ajax.googleapis.

7 Google Search Most / all are Public Searches Image Search v=1.0&q=elaspix Web search Product search News search Blog search

8 Google API explorer

9 Example PageSpeed API Get speed improvement recommendations

10 Google Translation API Translations between languages

11 Response Goole Image Search API {"responsedata": {"results": [{"GsearchResultClass":"GimageSearch","width":"160","height":"120","imageId":"ANd9GcS_UgmJA DJiJfJzTyqwwRv2Rtzc8gjBAxi4P1jYol8MeQcEuDNmWxDvhg","tbWidth":"98","tbHeight":"74","unes capedurl":" et\u003dgjxfomblqnlt2lwoubhgcq\u0026nmid\u003d ","url":" surotz/image/3/photos/9/1200x120/1/ela-pix-005.jpg%3fet%3dgjxfomblqnlt2lwoubhgcq %26nmid%3D ","visibleUrl":"surotz.multiply.com","title":"darwin\u0026#39;s Site - darwin\u0026#39;s Photos","titleNoFormatting":"darwin\u0026#39;s Site - darwin\u0026#39;s Photos","originalContextUrl":" 5 Photos, 2 comments","contentnoformatting":"somepics 5 Photos, 2 comments","tburl":" q\u003dtbn:and9gcs_ugmjadjijfjztyqwwrv2rtzc8gjbaxi4p1jyol8meqceudnmwxdvhg:multipl y.com/mu/surotz/image/3/photos/9/1200x120/1/ela-pix-005.jpg%3fet %3DGjxFoMbLQNlt2LWoUBHGCQ%26nmid%3D "}, {"GsearchResultClass":"GimageSearch","width":"800","height":"600","imageId":"ANd9GcS3QZ8knIj viqi9o3xgc3k0npmmcfn7bs5e48lod06l_nzeak94ap71sg","tbwidth":"143","tbheight":"107","un escapedurl":" von der Preisverleihung 2/2008 Gründerwettbewerb - Mit \u003cb\u003e...\u003c/b\u003e","titlenoformatting":"fotos von der Preisverleihung 2/2008 Gründerwettbewerb - Mit...","originalContextUrl":"

12 Mash-ups Are web-services that combine several webapis to provide useful services to the user

13 Zeit API Access articles & authoris via API

14 ifttt if this, then that Combines dozens of webservices Uses triggers and actions that are connected with rules Create rules that react on user input (Likes, photo uploads, the actual temperature)

15 ifttt if this, then that Integrated development environment not required to program complex tasks

16 Web-API Document formats XML JSON

17 XML Extensible Markup language Many / most services respond in XML format Human readable Machine understandable due to semantic hierarchy

18 JSON Has a similar role as XML Responses are 30% shorter in characters Compared to XML Less human readable makes also use of hierachical semantics Further concept Array is a collections of subtrees with identical structure

19 Provider-Technology REST SOAP Java Server Pages

20 Restful Services Is an web-service architecture Rest = Representational State Transfer REST is an architectural style for distributed hypermedia systems, describing the software engineering principles guiding REST and the interaction constraints (Fielding, R. T.) to rest A client is either computing something or is waiting for user input (in rest mode) During rest mode the client does not produce net-load The state of a client changes if it calls a function from the server

21 Restful Services Constraints of the Rest-Architecture Client versus Server separate entities on their own Stateless no client stuff is stored on the server, everything is passed in the header of the message scalability, isolation from internal server changes Cachable cache response for further use Layered dont know how many hops in between mediate the request (e.g. tunnels, firewalls, proxies etc.) Uniform interface

22 URIs An uri should read like a self documenting interface And consits of (Roccia, Y., 2014) Each entitiy / ressource is addressed by a unique ID

23 RESTful web services Supported methods provided by htt-protocol GET Clients sends only URL and header to server and retrieve something from the server (should not change anything on the server, is therefore called safe ) POST Clients use an additional body to submit data (file, form) to the server, Change the state of the server (that processes the data) [PUT] very rare Replaces the state of /update a ressource on the server [DELETE] very rare Removes a ressource on the server

24 Rest Header Using a Get/Post Header, the quality of services are managed Navigation purpose (the network of ressources is called hypermedia) Caching purpose Grants for cross domain access Media type of the response Requested representation of the resource (document format)

25 Short summary on REST Key concepts Give every thing an ID Link things together Use standard methods Resources with multiple representations Communicate statelessly To make your apps part of the web, design it RESTfully REST is an architecture, not an implementation

26 SOAP Simple object access protocoll Used for remote procedure calls Used mostly for intra-enterprise applications (Offers more security) Supports type safety Offers specification on interfaces

27 SOAP compartments xml as message format Http as transimission protocoll (to pass firewalls) WSDL (web services description language) to describe what the service requires and offers RPC (Remote Procedure Call) access to methods on remote objects

28 Task setup SOAP-Server extract the soapsamples.zip Interface Service Starter ( Server) Inspect web service description language Inspect xml-schema Client Examples by

29 SOAP versus HTTP RESTful SOAP HTTP RESTful More difficult to start Rigid type checking exactly defined interfaces Methods exposed simply with Java annotations Most often stateful XML wrapper makes messages lengthy Always body requ. Supports binary params Lightweight, loose coupling, Interoperability through web-standards Directly human readable Callable by either client supporting html Easy to build Short XML messages

Architecture of Web Applications Model-View-Controller Controller Receives user interactions to updates the model View http://www.

30 Architecture of Web Applications Model-View-Controller Controller Receives user interactions to updates the model View Shows a data representation to the user Model Is the business logic in combination with persistent data bases

31 Java-Server Pages SUN's answer to PHP, CGI and ASP (Microsoft) Serve dynamic content to the user's browser Make a Java Class respond to HTML request Statefulness through URL-rewriting (Serve pages with individual URLs) HTTP-Cookies

32 Java Servlet Webcontainer Servlet receives a request and generates response Can be combined with html Manages lifecycle of the service Mapping URL to a servlet Access right management

33 Apache Tomcat Open Source Servlet Container Not to be confused with apache web server Directory structure below webapps WEB-INF classes Packages and compiled class files (usually from Eclipse's bin directory) lib (all required libs as JAR's) Web.xml (configuration, mapping)

34 Tomcat's web xml Maps URLs to Java-Klasses Maps from to MyServlet.class

Session 8. Reading and Reference. en.wikipedia.org/wiki/list_of_http_headers. en.wikipedia.org/wiki/http_status_codes

Session 8. Reading and Reference. en.wikipedia.org/wiki/list_of_http_headers. en.wikipedia.org/wiki/http_status_codes Session 8 Deployment Descriptor 1 Reading Reading and Reference en.wikipedia.org/wiki/http Reference http headers en.wikipedia.org/wiki/list_of_http_headers http status codes en.wikipedia.org/wiki/_status_codes