2. REST
(Representational State Transfer)
● REST is a Style of the Software architecture for
distributed system such as World wide web.
● It is nothing but using the current feature of web in
simple and effective way. some of the amazing feature
of web are :
o Widely accepted HTTP protocol.
o Standard and Unified method PUT, POST, GET and
DELETE.
o Stateless nature of HTTP protocol.
o Easy to use URI (Uniform resource identifier) format
to locate any resource.
It is a set of constraints not rules.
3. HTTP VERBS
● GET
● POST
● PUT
● DELETE
● HEAD
● OPTION
4. Principles of REST services
● Everything is a Resource.
● Every resource is identified by unique identifier.
● Use simple and uniform interfaces.
● Communication is done by representation.
● Be stateless.
6. Principles of REST services
● Every resource is identified by unique identifier
Example:
Customer Data URI
Get all Customer list GET http://www.custapp.com/employee/all
Get Customer by ID GET http://www.custapp.com/employee/101
8. Principles of REST services
● Use simple and Uniform interfaces.
eg : we exposed the customer and order data on the web,
Normal Method HTTP Method Uniform URI
AddCustomer PUT /customer/raj
InsertOrders PUT /order/001
SelectCustomer GET /customer/raj
getOrders GET /order/001
DeleteCustomer DELETE /customer/raj
RemoveOrder DELETE /order/001
9. Principles of REST services
● Communication is done by representation.
The client and server exchanging the representations.
10. Principles of REST services
● Communication is done by representation.
eg : we want to create a customer, we send some kind of
representation to the server using HTTP PUT,
<customer>
<name>raj</name>
<address>Vashi</address>
<customer>
and the server send some other representation to show that
the resource is created, and move towards the next step.
<customer>
<name>raj</name>
<next>http://www.custapp.com/customers/Orders</next>
</customer>
11. Principles of REST services
● Be Stateless.
Every request should be independent.
It means that once the request is processed, the next
request of the web visitor, does not have to come back to
same machine.
eg. VE.Box Restful services.
12. Play routes
Play routes consist of the HTTP method and URI and both
are associated with and Action generator ( controller's
static method)
routes are defined in "conf/routes" file.
Modules doesn't have the routes file, if we deploy the
routes in module, it will override the main application's
routes file.
route syntex :
HTTP Method URI Action
GET /customer/:id controller.Application.selectCustomer(id :
Long)
13. Play URI patterns
● Static path
GET /Customer/all controller.Customer.list()
● Dynamic parts
GET /Customer/:id controller.Customer.getCustomer(id: Long)
GET /Customer/:id/:name controller.Customer.getCustomer(id: Long,
name :String)
14. Play URI patterns
● Dynamic parts spanning several
dynamic part using the *id syntax
GET /files/*name
controllers.Application.download(name)
eg : GET http://www.custapp.com/files/image/001.gif
then the dynamic part will capture the " image/001.gif".
● Dynamic parts using regular expression.
regular expression for a dynamic part, using the $id<regex> syntax
GET /customer/$id< [0-9]+>
controller.customer.getCust(id: Long)
15. Action generator Methods
● The last part of the route definition.
● If the action method doesn't have any parameter name just give the fully
qualified name
GET / controller.CustApp.home()
● If the action method defines the parameter, the corresponding parameter
value will be searched in URI, either extracted from the URI path or from
the query String
Extract the page parameter from the path.
i.e. http://www.custapp.com/index
GET /:page controllers.CustApp.show(page)
Extract the page parameter from the query string.
i.e. http://www.custapp.com/?page=index
GET / controllers.Application.show(page)
16. Parameter Type
● Default parameter type is String
GET /:page controllers.CustApp.show(page)
page parameter is String here
● Parameter with fixed value.
GET /
controllers.CustApp.show(page = "home")
GET /:page controllers.CustApp.show(page)
● Parameter with default value
GET /
controllers.CustApp.show( page: Integer ?= 1)
17. Assets
● Serves the application’s static resources such as JavaScript, CSS and
images.
● The play 2.0 has a built-in controller Assets with the action "at(path:String,
file: String )" to serve the public data.
GET /assets/*file controllers.Assets.at(path="/public", file)
we can also get the static data using this
GET /jquery controllers.Assets.at("/public", "javascripts/jquery.js")
18. Assets
● Etag support
Etag is an identifier assigned by the server to a specific version of resource
found at the URL, if resource available at the URL change the new Etag is
assigned. Comparing ETags only makes sense with respect to one URL—
ETags for resources obtained from different URLs may or may not be equal.
● The Assets Controller automatically manage the ETag HTTP header, the
ETag value is generated through the resource name and file modification
date.
● when the browser makes a request specifying the ETag header the server
can respond with the "304 not modified"
19. Assets
● Gzip support
If a resource with the same name but using a .gz suffix is found, the Assets
controller will serve this one by adding the proper HTTP header:
Content-Encoding: gzip
● Cache-Control directive
Etag is enough for caching but if we want to add the custom cache-control for
any specific resource then in application.conf file we have to add the following
line :
"assets.cache./public/javascript/jquery.js" = "max-age=1000"
20. Assets
● By default the play compile all managed assets, the compilation process
clean and compile all the managed resources. This is the safest strategy
since tracking dependencies can be very tricky with front end technologies.
If you are dealing with a lot of managed assets this strategy can be very
slow. For this reason there is a way to recompile only the change file and
its supposed dependencies. You can turn on this experimental feature by
adding the following to your settings:
incrementalAssetsCompilation := true
in application.conf file.
21. Reverse Routing
in conf/routes file
Hello action
GET /error/:errorString controllers.CustApp.showError(errorString)
and we want to redirect our application control to the error page, then
public static Result index(Long id) {
if( id <= 0){
return redirect(controllers.routes.CustApp.showError("Invalid ID"));
}
return ok("OK");
}
