The Internet as Web Services: introduction to ReST

The Internet as Web Services: introduction to ReST

The Internet
as Web Services:
introduction to ReST

Oscar Zambotti is a student of Information Technology at the Faculty of Science, University of Trento.He attended the 9-months course "ICT secure programming expert" in Bozen offered by the European Social Fund.Now he's in FBK for his stage period in the SoNet Group and following the Presentation or die motto is giving this presentation in the very beginning of his stage.Oscar is very interested in social networking and programming applications about it. He is also a speaker and DJ in a local radio station.http://[email protected]

Bio

The Internet as Web Services: introduction to ReST Oscar Zambotti, 2009

What is a Web Service?

Different ways: SOAP and ReST

Examples: Twitter and Flickr

How am I going to use ReST?

What am I going to talk about?


1. What is a Web Service?


The challenge now is to join forces to research on Software & Services Technologies, to bring advances to the market and to ensure European leadership in the new Internet economy: The Internet of Services.Internet of Services, Software and Virtualisation - Objective ICT 2009.1.2, Call 5 of the Seventh Framework Programme (2007-2013)
European Commission - Information Society and Media

The Internet has shown remarkable resilience and flexibility in the face of ever increasing numbers of users, data volume, and changing usage patterns, but faces growing challenges in meetings the needs of our knowledge society. This is the moment to start designing the Internet of the Future.Future Internet - Research programs of the CIT (Center for Innovation Technology)
Fondazione Bruno Kessler

The vision of the Future Internet

A Web Service (WS) is a software system designed to support interoperable machine-to-machine interaction over a network. - W3C GlossaryUsually a WS provides the API (Application Programming Interface).

Hardware limitations?

Languages limitations?

Access limitations?

What is a web service?


Use of web services? E.g. Flickrvision


Flickr photos with Google Maps

A mashup is a Web application that combines data or functionality from one or more sources into a single integrated application.http://www.programmableweb.com


Web services for mashups


ProgrammableWeb statistics

1308 APIs3957 Mashups(12 May 2009)

The trend...

2. Different ways:
SOAP and ReST

SOAP (Simple Object Access Protocol) uses XML and RPC or HTTP.Businesses can register their WS on UDDI
(Universal Description, Discovery
and Integration) and provide
documentation with WSDL
(Web Services
Description Language)


image: WikipediaHow to use a web service: SOAP

image: Wikipedia

classifieds


How to use a web service: SOAP /2

Sample:
Request...

http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous

http://localhost:8080/axis2/services/MyService

ECE5B3F187F29D28BC11433905662036

classifieds


How to use a web service: SOAP /3

...Response

ReST (Representational State Transfer) is an architectural style for distributed hypermedia systems, it is not just a method for building web services.Introduced by Roy Thomas Fielding in his dissertation to become Ph.D. in 2000.Resource URI
Interaction RepresentationAn application can interact with a resource by knowing the identifier of the resource (URI), and the action required (HTTP methods). ReST is stateless.

How to use a web service: ReST


HTTP consists in URIs, methods, status codes...The most important HTTP methods compose the basic functions in computer science: CRUD

How to use a web service: ReST /2


HTTPCRUDSQL

POSTCreateINSERT

GETReadSELECT

PUTUpdateUPDATE

DELETEDeleteDELETE

http://example.com/losties



POST
- Create -GET
- Read -PUT
- Update -DELETE
- Delete -

Create a new passengerList

http://example.com/losties/4815162342

Response format: HTML, XML (RSS, Atom, custom), JSON, ...

Suggested reading: How I explained ReST to my wife (Ryan Tomayko)

POST
- Create -GET
- Read -PUT
- Update -DELETE
- Delete -

Passenger dataUpdate passenger dataDelete passenger

An application is ReSTful when has resources accessible by representations.http://example.com/losties/4815162342

Some services are ReST-like: you use HTTP methods but using APIs methods as parameters (Flickr).http://example.com/losties/getLostie?id=4815162342

Nouns vs Verbs



A large number of developers
chooses ReST instead of SOAP.


SOAP vs. ReST on ProgrammableWeb

3. ReST examples
(Python code)

What is Twitter?

Example: Twitter


Twitter REST API Method: statuses/show
Returns a single status, specified by the id parameter below. The status's author will be returned inline.URL:
http://twitter.com/statuses/show/id.formatFormats: xml, json, rss, atomHTTP Method(s): GETRequires Authentication:
false, unless the author of the status is protected

Example: Twitter /2


Twitter REST API Method: statuses/update
Updates the authenticating user's status. Requires the status parameter specified below. Request must be a POST. A status update with text identical to the authenticating user's current status will be ignored to prevent duplicates.URL:
http://twitter.com/statuses/update.formatFormats: xml, json, rss, atomHTTP Method(s): POSTRequires Authentication: true

http://apiwiki.twitter.com/Twitter-API-DocumentationSome methods require authentication (OAuth)

import httplib
# some code...def fetch_following(self):
conn = httplib.HTTPConnection("twitter.com")
conn.request("GET","/friends/ids/"+self.screen_name+".json")
r1 = conn.getresponse()
print r1.read()
conn.close()

Example: Twitter /3


Output (sample!): user IDs[5428712,31528501,6603122,30304051,30303627,5159271,
17572031,15147484]

Obj: fetch the list of the user IDs that a user is following

What is Flickr?Screenshot

Example: Flickr


Developers need a couple of keys to use the APIs.Some methods require authentication.

Example: Flickr /2


REST Request FormatREST is the simplest request format to use - it's a simple HTTP GET or POST action.The REST Endpoint URL is http://api.flickr.com/services/rest/To request the flickr.test.echo service, invoke like this:
http://api.flickr.com/services/rest/?method=flickr.test.echo&name=valueBy default, REST requests will send a REST response.

Example: Flickr /3


http://www.flickr.com/services/api/

Some methods require authentication.

import urllib, urllib2, jsonFRI = "http://api.flickr.com/services/rest/?"
KEY = "d00fa386476950f75555555555555555"
SECRET = "cac879e555555555"
FORMAT = "json"# some code...def people_find_by_username(username):
# some code...def contacts_get_public_list(username):

nsid = people_find_by_username(username) req = {'method': CONTACTS_GETPUBLICLIST, 'api_key': KEY,
'user_id': nsid, 'format': FORMAT, 'nojsoncallback': 1}
params = urllib.urlencode(req)
contacts_public_list =
urllib2.urlopen(FRI,params).read()
print contacts_public_list

Example: Flickr /4


HTTP POST (implicit)

Obj: fetch the list of the friends a user

Example: Flickr /5


Output (sample!): collection (dictionaries, lists){"contacts":
{"page":1, "pages":1, "per_page":1000, "perpage":1000,
"total":39, "contact":
[{"nsid":"81107858@N00", "username":"Jack",
"iconserver":"207", "iconfarm":1, "ignored":0},
{"nsid":"23578585@N00", "username":"Locke",
{"nsid":"81158128@N00", "username":"Sawyer",
{"nsid":"29563291@N00", "username":"Hurley",
{"nsid":"20347812@N00", "username":"Kate",
"iconserver":"113", "iconfarm":1, "ignored":0}]}, "stat":"ok"}

4. How am I going to use ReST?

Web-based tool, with prepopulation using Web APIs, that displays the network of a user and its evolution over some social networks before and after a defined event.

What am I going to do? Socialdash


Questions?Ideas?Suggestions?

Thanks


http://sonet.fbk.eu

European Commission: Seventh Framework Programme
http://cordis.europa.eu/fp7
http://cordis.europa.eu/fp7/ict/programme/challenge1_en.html

Strategic guidelines in FBK: the Future Internethttp://cit.fbk.eu/future_internet

W3C Glossary
http://www.w3.org/TR/ws-gloss/

Representational State Transfer (ReST) by Roy Thomas Fielding
http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htmhttp://www.ics.uci.edu/~fielding/

Suggested readings:
http://tomayko.com/writings/rest-to-my-wife

Bibliography


Muokkaa otsikon tekstimuotoa napsauttamalla

Muokkaa jsennyksen tekstimuotoa napsauttamallaToinen jsennystasoKolmas jsennystasoNeljs jsennystasoViides jsennystasoKuudes jsennystasoSeitsems jsennystasoKahdeksas jsennystasoYhdekss jsennystaso

The Internet as Web Services: introduction to ReST

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