Introduction to Web APIs and Protocols

1. Introduction to Web APIs and Protocols By J. H. Wang Dec. 12, 2011

2. Outline • Popular Web APIs • Google APIs • Yahoo! APIs • Bing API • Others • Protocols in Web APIs • HTTP • HTML • JSON • XML

3. Google APIs • Google APIs (http://code.google.com/intl/zh-TW/more/ ) • AJAX APIs (deprecated) • AJAX Search: Blog, Book, News, Web, Image, Video • Custom Search API • Maps API • Google Code Playground • http://code.google.com/apis/ajax/playground/

4. Others: • Google Chart API (Visualization API), Desktop API, Calendar API, Contacts API, Picasa API, Social Graph API, Earth API, GeoCoding API, Prediction API, URL Shortener API, YouTube API • Google Data API • Book Data, Calendar Data, Contacts Data, Web Albums Data, Spreadsheets Data, YouTube Data, … • University Research Program for Google Search and Translate (not accepting new applications) • Google API consoles: translate API, prediction API, custom search API • Check more at: Google Code and Google Labs (more information in English version)

5. Yahoo! APIs • Yahoo! APIs (http://developer.yahoo.com/) • Search • BOSS (Build your Own Search Service) (not free!) • Web, image, news, blogs (beta) • SearchMonkey: to enhance search results (shut down in Oct. 2010) • Search Marketing • Location • Local, Maps • PlaceFinder, PlaceMaker • Traffic, Weather

6. Others • Yahoo Social APIs: social directory, contacts, user status, updates • Media: Flickr API, music, media player • GeoPlanet, Network Time, Term Extraction, Yahoo! Answers • Taiwan ONLY: 生活+, 地圖, 知識+, 斷章取義, 無名小站, 奇摩拍賣 • Check more at: Yahoo! Developer Network (YDN) (http://developer.yahoo.com/ )

7. Bing APIs • Bing API 2.0: (http://www.bing.com/toolbox/bingdeveloper/ ) • Web, image, news, video search • Translation, spell, relatedsearch • Bing Maps • AJAX control, iOS control, SOAP services, REST services • Others • More information at: Bing Developer Center

8. Others • Facebook API (https://developers.facebook.com/ ) • micro-blogging • Twitter API (https://dev.twitter.com/ ) • plurk API (http://www.plurk.com/API ) • Digg API (http://developers.digg.com/ ) • Technorati API: blog search (terminated in Oct. 2009!) • MySpace API (http://developer.myspace.com/ ) • Del.icio.us API (http://delicious.com/help/api ) • social bookmarks

9. New York Times API (http://developer.nytimes.com ) • Article search • Movie reviews • TimesTags • … • Scopus API (http://searchapi.scopus.com/ ) • search for papers, authors, affiliation, citations • MediaWiki API • Ebay API

10. Mashups (Web Application Hybrid) • Using and combing data, presentation, or functionality from two or more sources to create new services • Using open APIs and data sources to produce enriched results

11. Some Example Mashups • HousingMaps • http://www.housingmaps.com/ • ChicagoCrime • http://www.chicagocrime.org/

12. Example: Tourist Blog Information Integration System

13. System Architecture Resultpresentation Tourist blogs Google Maps location Wordsegmentation query Wikipedia blogs YouTube others Panoramio

14. Some Factors in Integrating Web APIs • What service are you going to provide? • Location-based services: Geo & Local APIs • Data sources: Web, news, blog, or personal data? • Social relationships? • Visualization? • Which platform? • Mobile devices • PCs • Data quality?

15. Some Protocols in Web Services • RESTful (REpresentational State Transfer) • SOAP (Simple Object Access Protocol) • The standard, version 1.2 • HTTP • JSON (JavaScript Object Notation) • XML

16. SOAP vs. REST • SOAP • Pros: • Language, platform, and transport agnostic • Designed to handle distributed computing environments • The standard for Web services, and has better support from other standards (WSDL, WS-*) • Built-in error-handling • Extensibility • Cons: • Conceptually more difficult, more heavy-weight • More verbose • Harder to develop, requires tools

17. REST • Pros: • Language and platform agnostic • Much simpler to develop than SOAP • Small learning curve • Concise, no need for additional messaging layer • Closer in design and philosophy to the Web • Cons: • Assumes a point-to-point communication model • Lack of standards support for security, policy, reliable messaging • Tied to the HTTP transport

18. HTTP • HyperText Transfer Protocol • The protocol standard for the World Wide Web • Defined by IETF, W3C • RFC 2616, HTTP 1.1 • Overview • Web browser (the HTTP client) submits an HTTP request to the HTTP server, which provides resources (such as HTML files) and returns a response

19. HTTP Request Message • Request line: • GET /images/logo.png HTTP/1.1 • Headers • Accept-Language: en • Empty line • (Each line must end with <CR><LF>) • Optional message body

20. Request Methods • 9 methods indicating the action to be performed on the identified resource • GET • POST • PUT • DELETE • HEAD, TRACE, OPTIONS, CONNECT, PATCH

21. Some HTTP Header Fields • Requests • Accept-Charset • Connection • Content-Type • Content-Length • Date • From • Host • Responses • Connection • Content-Type • Content-Length • Date

22. Response Message • Status line • Status codes • 404 • Reason phrase • Not found • Types of status codes • 1xx informational • 2xx success • 3xx redirection • 4xx client error • 5xx server error

23. Example HTTP Session • Client request • GET /index.html HTTP/1.1<CR><LF> • Host: www.example.com<CR><LF> • <CR><LF> • Server response • HTTP/1.1 200 OK • Date: Mon, 23 May 2005 22:38:34 GMT • Server: Apache/1.3.3.7 (Unix) (Red-Hat/Linux) • Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT • Etag: “3f80f-1b6-3e1cb03b” • Accept-Ranges: bytes • Content-Length: 438 • Connection: close • Content-Type: text/html; charset=UTF-8

24. HTML • HyperText Markup Language: the language for Web pages • HTML 4.01 (W3C recommendation, 1999) • HTML 5 (W3C working draft, May 2011) • Elements • Tags: <xxx> … </xxx> • Attributes • Ex: headings, paragraphs, tables, forms, comments, …

25. An Example HTML File • <html> <head> <title>Hello HTML</title> </head> <body> <p>Hello World!</p> </body> </html>

26. JSON • JavaScript Object Notation (JSON): a lightweight data-interchange format (http://www.json.org/ ) • Easy for humans to read and write • Easy for machines to parse and generate • Based on a subset of JavaScript Programming Language, but it’s completely language independent • JSON is built on two structures • Name/value pairs: objects • Ordered list of values: arrays • More details in RFC 4627

27. JSON Examples • { "Image": { "Width": 800, "Height": 600, "Title": "View from 15th Floor", "Thumbnail": {"Url":"http://www.example.com/image/481989943", "Height": 125, "Width": "100" }, "IDs": [116, 943, 234, 38793] } }

28. JSON Examples • [ { "precision": "zip", "Latitude": 37.7668, "Longitude": -122.3959, "Address": "", "City": "SAN FRANCISCO", "State": "CA", "Zip": "94107", "Country": "US" }, { "precision": "zip", "Latitude": 37.371991, "Longitude": -122.026020, "Address": "", "City": "SUNNYVALE", "State": "CA", "Zip": "94085", "Country": "US" } ]

29. XML • eXtensible Markup Language: a set of rules for encoding documents in machine-readable form • XML 1.0 (W3C Recommendation) • An application profile of SGML (ISO 8879)

30. An Example XML File • <?xml version="1.0"?><note>    <to>Tove</to>    <from>Jani</from>    <heading>Reminder</heading>    <body>Don't forget me this weekend!</body></note>

31. Thanks for Your Attention!