1. Web Services
The SOAP
&
The REST
Edison Lascano

2. Web Services
Web Services: Method of communication for
web applications (Internet, intranet, extranet,
desktop, mobile) .
Application layer :
Mainly the HTTP protocol and port 80.
Port and protocol may change, e.g.
SMTP
Message Formats:
XML, JSON, RSS, longer than binary.
MIME types match resource
representations.

3. JSON / XML
{"Table": {"httpStatus":"200","primary_key": "val1","key1":
"value1","key2": "value2"}}
<tables>
<httpStatus value="200"/>
<table primary_key="val1" key1="value1" key2="value2" />
</tables>
{"Student": {"httpStatus":"200","student_id": "005802615","name":
"Edison Lascano","address": "2199 McLaughlin Ave"}}
<students>
<httpStatus value="200"/>
<student student_id="005802615" name="Edison Lascano"
address="McLaughlin" />
</students>

4. Web Services
• The basis of web 2.0 and many distributed
applications currently
• Public APIs are published by web 2.0
providers in SOAP, REST, XML-RPC, js.
Private APIs are used internally.
REST http://weather.yahooapis.com/forecastrss?w=2502265
SOAP http://www.programmableweb.com/api/bing
• MASHUPS (main users of Web APIs)
– Public APIs + local APIs + My Application
– Don't develop what is done, use others'
resources. Low coupling. But, APIs may
disappear at any moment, Yahoo search.

5. API´s

6. Technology

7. Web Services in Web 2.0
• http://www.programmableweb.com .
Cloud Services providers publish their
Web APIs: AWS, Google App Engine...
• Technology:
-Tools, Languages, Platforms: Java, .Net,
Python, php, Ruby, …
-Distributed Objects: JEE-EJBs, .Net Remoting;
ORMs: Persistent Units, JPAs: Linq,
Hibernate, Eclipse Link
-Clients: desktop, gadgets, widgets, mobiles,
web, Ajax, Flex, JavaFX, Spring... Client-

8. SOAP Web Services
• Simple Object Access Protocol,
acronym dropped after 2003, it is a
service oriented protocol
• Microsoft begins in 1998, currently
supported by the World Wide
Consortium W3C
• Usually Service verb form: URLs
Uniform Resource Locator “getItem”

9. Ser UDDI
vice
Reg
istry
SOAP Web Services
L
W
W SD
SD
L
SOAP Messages
Ser Ser
vice vice
• SOAP: protocol Pro
vide
r
Con
sum
er
– SOAP envelope: SOAP Header+SOAP Body
– It uses XML
• WSDL: IDL
– Description of the methods, parameters, types
– XML
• UDDI: Universal Description Discovery
and Integration
– The service broker
– Besides the Web Server

10. What is a SOAP Web Service?
• Distributed Objects?
• Is it RMI?
• Is it RPC?
– Every Web Service has a set of
operations,
– Two libraries in Java to program ws
are JAX-WS and JAX-RPC.

11. REST
Representation State Transfer
• Architectural style
• Resource Oriented
• Spread from 2000, It looks like they
always existed, but became to be
noticed and well organized/architected
after Roy Fielding Dissertation.
http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm
• Fielding is one of the authors of HTTP.

12. REST
• A representation of the resource is
returned
– Resource: Noun form: URI, Uniform
Resource Identifier
• HTTP Methods: GET, PUT, POST,
DELETE
• WADL: Web Application Def Lang
– Unlike Soap, WADL is not mandatory to
discover the resource, the providers supply
development documentation: URI´s lists.

13. URIs / URLs
http://ajax.googleapis.com/ajax/services/language/translate?q=be%20happy?&v=1.0&langpair=en |ko
http://www.youtube.com/embed/u1zgFlCw8Aw?autoplay=1&origin=http://example.com
http://api.search.yahoo.com/ImageSearchService/V1/imageSearch?appid=YahooDemo&query=Quito&results=2
http://api.search.yahoo.com/ImageSearchService/V1/imageSearch?appid=YahooDemo&query=Quito&results=
http://weather.yahooapis.com/forecastrss?w=2502265
http://developer.yahoo.com/weather/
https://www.dropbox.com/developers/start
https://api.dropbox.com/1/oauth/request_token

14. RESTful Web services
“If an application complies with the 6 REST
constraints, then it is RESTful” Roy Fielding
• Three Client Constraints:
• C/S, for separation of concerns
• Stateless, Client holds the session state
• Cacheable,To improve scalability and
performance, but be careful of getting outdated
information
• Three Coding Constraints:
• Layered Systems, they do not know about
each other implementations, the URI is enough
• Code on Demand, Javascript, any or “none”
• Uniform Interface, for all WSs.

15. RESTful Uniform Interface
• HTTP Request/Response Codes:
• 200 OK; 300 Redirect; 400 Error, e.g. 404
• Noun form URIs
. http://www.example.com/resources/
. http://www.example.com/resources/item1
. http://www.example.com/resources/item1/json
. http://www.example.com/resources/item1?format=json
• HTTP Methods
• GET /items/{id} # read an Item
• POST /items/{id} # create an Item
• PUT /items/{id} # update an Item
• DELETE /items/{id} # delete an Item

16. Some REST advice
• Use the standard HTTP methods, not
as in SOAP, that you must create new
methods for every requirement.
• Opportunities  Improve your REST
design
– Provide one URI for every resource
– Minimize the use of QUERY_STRING,
prefer items/1 over items?id=1
– Logical over physical URIs, items/1 over
items/1.html
– No verbs in the URI, they are resources

17. More REST advice
• Use hyperlinks in the Response when need
to communicate an executed action ack/nack.
• Use / to represent parent/child relationships.
e.g. stock/items1 doctor1/patients/1
• Use GET to allow the client retrieving a
resource representation, not POST
• Use POST to update a big object, so the URI
will not be long and your data can not be
seen in the URI.
• Use GET, PUT, POST, DELETE properly.

18. The REST way of
implementing the Web
Services
HTTP GET request URI1
Items List
Response
(HTML/XML/JSON...) HTTP response
HTTP GET request URI
Web Server Item
Response
(HTML/XML/JSON...) HTTP response
PO
HTTP POST (HTML/XML/JSON...) URI
PO
URL to submitted PO HTTP response
Adapted from: Roger L. Costello, “REST (Representational State Transfer), XML Technology Course”

19. Web app architecture designs
• Client ↔ REST ↔ EJB ↔ DB (EIS)
• Client ↔ SOAP ↔ EJB ↔ DB (EIS)
Client ↔ REST ↔ JPA ↔ DB (EIS)
Client ↔ REST ↔ DB (EIS), SOAP can be
interchanged with REST in any case
• Client ↔ REST ↔ .NET ↔ ORM ↔ DB(EIS)
Client ↔ SOAP ↔ .NET ↔ ORM ↔ DB(EIS)
.NET can be replaced by any other
Distributed Objects technology.

20. SOAP web service lab
• Netbeans 7.2 full version
• Create a new Web Application, then a
create a new “Web service”
• Implement a new operation using the
wizards, finally test the Web Service
and take a look of the generated WSDL
file.

21. REST Web Service Lab
• Create a new Web Application
• Create new RESTful web services
– From patterns, simple root resource
– New RESTful web services from database,
finally test the RESTful web services, read
the WADL file and then try some URIs to
read the XML/JSON data returned.

22. Web Services (Java)
SOAP REST
JAX-WS JAX-RS
annotations: annotations:
@WebService @Path
@WebMethod @GET, @PUT, …
@WebParam @PathParam,
@QueryParam

23. Web Services clients
SOAP REST
JAX-WS stub Consume through
generation from simple HTTP
WSDL import calls from Java, js
WADL is not
needed

24. Motivation for REST
"The motivation for developing REST was to create an architectural model for
how the Web should work, such that it could serve as the guiding framework
for the Web protocol standards.
REST has been applied to describe the desired Web architecture, help identify
existing problems, compare alternative solutions, and ensure that protocol
extensions would not violate the core constraints that make the Web successful."
- Roy Fielding