This document summarizes the differences between RESTful and SOAP web services. It discusses how RESTful services use standard HTTP methods and URIs to manipulate resources, while SOAP uses XML and HTTP to define envelopes and encode requests and responses. The document also covers benefits of each approach, including RESTful services being simpler, having better performance and scalability, and being easier to implement in some languages and frameworks than SOAP.

1. Web Services
Chris McClelland
DevDays, Belfast April 2009
chris@ecliptic-design.com

2. About
Specialising in Mobile Strategy, Development,
Design and Usability.
New and rapidly developing company based in
Belfast, presently 4 people, but more to come!
Established Jan 2009.

3. Web Services?
WEB APP
“machine”
API iPhone
reques
t
data

4. Why?
WEB APP
API
Outsource - community
development
Growth
Novel Use of Data

5. Success Stories
Google Maps
Last.fm
Ebay
Facebook
Twitter

6. iPhone Developers Why?
free content
large existing user-base
mashups

7. @stroughtonsmith

8. REST vs SOAP

9. SOAP
Simple Object Access Protocol
XML
SOAP
XML to code and to decode data
SOAP to transport it

10. REST
REpresentational State Transfer
stateless
just HTTP + URIs
HTTP verbs:
GET: Retrieves a resource
POST: Sends data to create a resource
PUT: Sends data to update a resource
DELETE: Destroys a resource

11. SOAP
POST /InStock HTTP/1.1
Host: www.example.org
Content-Type: application/soap+xml; charset=utf-8
Content-Length: nnn
<?xml version=quot;1.0quot;?>
<soap:Envelope
xmlns:soap=quot;http://www.w3.org/2001/12/soap-envelopequot;
soap:encodingStyle=quot;http://www.w3.org/2001/12/soap-
encodingquot;>
<soap:Body xmlns:m=quot;http://www.example.org/stockquot;>
<m:GetStockPrice>
<m:StockName>IBM</m:StockName>
</m:GetStockPrice>
</soap:Body>
</soap:Envelope>
XML (Extensible Markup Language)

12. REST
GET www.example.org/user/2

13. methods URI
POST /user/create
GET /user/show/1
NOT RESTful
POST /user/update/1
POST/GET /user/delete/1
POST /user
GET /user/1
RESTful
PUT /user/1
DELETE /user/1

14. SOAP
HTTP/1.1 200 OK
Content-Type: application/soap+xml; charset=utf-8
Content-Length: nnn
<?xml version=quot;1.0quot;?>
<soap:Envelope
xmlns:soap=quot;http://www.w3.org/2001/12/soap-envelopequot;
soap:encodingStyle=quot;http://www.w3.org/2001/12/soap-
encodingquot;>
<soap:Body xmlns:m=quot;http://www.example.org/stockquot;>
<m:GetStockPriceResponse>
<m:Price>34.5</m:Price>
</m:GetStockPriceResponse>
</soap:Body>
</soap:Envelope>

15. REST
http://api.flickr.com/services/rest/?
request method=flickr.contacts.getList&api_key=XXX&api_sig=XXX
data <contacts page=quot;1quot; pages=quot;1quot; perpage=quot;1000quot; total=quot;3quot;>
<contact nsid=quot;12037949629@N01quot;
username=quot;Ericquot; iconserver=quot;1quot;
realname=quot;Eric Costelloquot;
friend=quot;1quot; family=quot;0quot; ignored=quot;1quot; />
<contact nsid=quot;12037949631@N01quot;
username=quot;nebquot; iconserver=quot;1quot;
realname=quot;Ben Cervenyquot;
friend=quot;0quot; family=quot;0quot; ignored=quot;0quot; />
<contact nsid=quot;41578656547@N01quot;
username=quot;cal_abcquot; iconserver=quot;1quot;
realname=quot;Cal Hendersonquot;
friend=quot;1quot; family=quot;1quot; ignored=quot;0quot; />
</contacts>

16. REST - data received
XML
JSON
RSS, Atom
RSS
PDF
Other e.g. PNG, Microformats

17. SOAP - benefits
WS-*
offers options for Privacy,
Transfer, Eventing, Addressing,
Notification, ReliableMessaging
Mature
Enterprise

18. REST Authentication
done via HTTPS
to avoid giving the application / developer your
username and password:
OAuth
“An open protocol to allow secure API
authorisation in a simple and standard method
from desktop and web applications.”

19. http://www.flickr.com/photos/factoryjoe/

20. http://www.flickr.com/photos/factoryjoe/

21. http://www.flickr.com/photos/factoryjoe/

22. REST - benefits
Simple
Popular, very Web 2.0
Better performance & scalability
Can be cached
Allows diverse formats e.g. JSON
Built into many web frameworks
Easier in Objective-C

23. iPhone Libraries
HTTP - ASIHTTPRequest
XML, Microformats, RSS, Atom -
NSXMLParser, libxml
JSON - json-framework
Rails - ObjectiveResource
SOAP - wsdl2objc
OAuth - MPOAuthConnection

24. RESTful APIs
All Yahoo: flickr
myspace, virb, facebook
delicious
Amazon Web Services, SimpleDB
vimeo, youtube
ebay
google

25. Thanks!
@chrismcclelland
chris@ecliptic-design.com
www.ecliptic-design.com