C# ASP.NET WEB API APPLICATION DEVELOPMENT

C#
1. ASP.NET WEB API INTRODUCTION
3/23/2016 © Syed Awase 2015-16 - ASP.Net MVC Ground Up 1
Section I
C#
WEB-API

C#
Process
Three Tier Architecture (Physical)
Assembly (.dll)
Data Business
Process
Assembly
(.exe/.dll)
Presentati
on

C#
InterProcess Communication
Data
Process
Assembly
(.dll)
Business Data
Process
Assembly
(.dll)
Business
END POINT/IP+PORT
END POINT/IP+PORT
Communication Protocol
TCP/IP/UDP/HTTP

C#
XML/JSON
SERIALIZED
? NEED FOR WEB API/WCF
Data
Process
Assembly
(.dll)
Business
WITHIN COMPANY OUTSIDE COMPANY
Request Access to Resources
ENDPOINT
/IP+PORT
Same Platform
.Net (Assembly
Reference .dll)
Same Platform
.Net (Assembly
Reference .dll)
Employee Access Outsiders
Same Platform
.Net (Assembly
Reference .dll)
JAVA/C++
PHP/RUBY
Platform
JAVA/C++
PHP/RUBY
Platform
XML/JSON
SERIALIZED
XML/JSON
SERIALIZED
JAVA/C++
PHP/RUBY
Platform
Firewall
Light weight WEB API
Light weight
WEB API
Same Platform
.Net (Assembly
Reference .dll)
WCF
XML+HTT
P
WCF
XML+HTTP
Same Platform
.Net (Assembly
Reference .dll) JAVA/C++
PHP/RUBY
Platform
WCF
XML+HTTP
WCF SERVICE
ASP.NET WEB API

C#
XML/JSON
SERIALIZED
? NEED FOR WEB API/WCF
Data
Process
Assembly
(.dll)
Business
WITHIN COMPANY OUTSIDE COMPANY
Request Access to Resources
ENDPOINT
/IP+PORT
Same Platform
.Net (Assembly
Reference .dll)
Same Platform
.Net (Assembly
Reference .dll)
Employee Access Outsiders
Same Platform
.Net (Assembly
Reference .dll)
JAVA/C++
PHP/RUBY
Platform
JAVA/C++
PHP/RUBY
Platform
XML/JSON
SERIALIZED
XML/JSON
SERIALIZED
Firewall
Light weight WEB API
Light weight
WEB API
WCF
XML+HTT
P
WCF
XML+HTTP
WCF
XML+HTTP
WCF SERVICE
ASP.NET WEB API

C#
ASP.NET WEB API
Web API is the great framework for
exposing your data and service to
different-different devices. it use the full
features of HTTP (like URIs,
request/response headers, caching,
versioning, various content formats)

C#
Web services
• A web service is a collection of protocols and
standards used for exchanging data between
applications or systems.
WebServices are published, described and located over Internet.

C#
Characteristics
1. A Web Service is accessible over the Web.
2. Web Services communicate using platform-independent
and language-neutral Web protocols.
3. A Web Service shares schemas and contracts/interface
that can be called from another program.
4. A Web Service is registered and can be located through
a Web Service Registry.
5. Web Services support loosely coupled connections
between systems.

C#
SOAP
• Simple Object Access
Protocol
• SOAP is an open protocol
specification defining a
uniform way of performing
RPCs using HTTP as the
underlying communications
protocol with XML for the
data serialization.
PORT 80 or HTP

C#
HTTP Body
SOAP-Packet
HTTP Header
HTTP Packet
TCP communication channel

C#
SOAP Messages
• SOAP provides a standard ‘envelope’ within which a message
can be delivered.
• SOAP is mechanism (protocol) for transferring information
(messages) between applications which may be widely
distributed.
• SOAP says nothing about the content of the message – the
sender and the receiver must understand the message for
themselves.
• SOAP is part of a communication stack.

C#
Web Services
WCF
SOAP

C#
SOAP STRUCTURE
• Each SOAP message will
have:
– An Envelope
– A Header (optional)
– A Body
– The Body may contain a
Fault element
SOAP BODY
SOAP ENVELOPE
FAULT
SOAP HEADER
Transport protocol
MIME header

C#
SOAP Structure(2)
• The envelope wraps the entire soap document
• The header allows additional information to be
passed as well as the body of the document – e.g.
Authentication
• The body element contains the core of the SOAP
document – this will contain either the RPC call or
the XML message itself
• The fault information will contain any exception
information

C#
Anatomy of a SOAP message
<?xml version=‘1.0’
encoding=‘UTF-8’?>
<SOAP-ENV:Envelope xmlns:SOAP_ENV=“http://schemas.xmlsoap.org/soap/envelope/”
xmlns:xsi=“http://www.w3c.org/1999/XMLSchema-instance”
xmlns:xsd=“http://www.w3c.org/1999/XMLSchema”>
</SOAP-ENV:Envelope>
<SOAP-ENV:Header>
</SOAP-ENV:Header
<SOAP_ENV:Body>
</SOAP-ENV:Body>

C#
SOAP protocol binding
SOAPAction = “urn:soaphttpclient-action-uri”
Host = localhost
Content-Type = text/xml; charset=utf-8
Content-Length = 701
<SOAP-ENV:Envelope xmlns:SOAP_ENV=“http://schemas.xmlsoap.org/soap/envelope/”

C#
SOAP RPC
• SOAP RPC messages contain XML that
represents a method call or method response
• The SOAP XML will be converted into a
method call on the server and the response
will be encoded into SOAP XML to be returned
to the client

C#
SOAP Faults
• SOAP errors are handled using a specialised
envelope known as a Fault Envelope
• A SOAP Fault is a special element which must
appear as an immediate child of the body
element
• <faultcode> and <faultstring> are required.

C#
A SOAP fault
<?xml version=‘1.0’ encoding=‘UTF-8’?>
<SOAP-ENV:Envelope
xmlns:SOAP_ENV=“http://schemas.xmlsoap.org/soap/envelope/”
<SOAP_ENV:Body>
</SOAP-ENV:Body>
<SOAP-ENV:Fault>
<faultcode>SOAP-ENV:Server</faultcode>
<faultstring>Test fault</faultstring>
<faultactor>/soap/servlet/rpcrouter</faultactor>
<detail>
..
</detail>
</SOAP-ENV:Fault>

C#
SOAP Attachment
• Large quantities or binary data
may not fit well into a XML
SOAP message.
• In which case it can be sent ‘out
of band’ by attaching it to a
SOAP message
• Analogy : email attachments.
SOAP BODY
SOAP ENVELOPE
FAULT
SOAP HEADER
Transport protocol
MIME header
Attachment

C#
Attaching a file to a SOAP message
• To add a file to a SOAP message a tag is added
within the body of the message.
<?xml version=‘1.0’ encoding=‘UTF-8’?>
<SOAP-ENV:Envelope
xmlns:SOAP_ENV=“http://schemas.xmlsoap.org/soap/envelope/”
<SOAP_ENV:Body>
<attachment href=“{URL}”/>
</SOAP-ENV:Body>

C#
SOAP
• SOAP is an XML based
encoding of messages that
are typically sent over HTTP,
but could be sent over
SMTP or even FTP
• SOAP sites on top of HTTP
• Generally require a toolkit
and more processing power.
HTTP
• HTTP can serve any content
over HTTP such as HTML,
images, sound, video etc.
• HTTP is overTCP/IP
• HTTP based APIs refer to
APIs that are exposed as
one or more HTTP URIs and
typical responses are in XML
/ JSON. Response schemas
are custom per object

C#
URL
• Uniform resource locator
– http://www.google.com/
– https://www.google.com/username/logo.jpg
url scheme hostname urlpath
http://www.askapache.com/online-tools/http-headers-tool/

C#
Content Types
• Content type that a server specifies relies on
the Multi-purpose Internet Mail Extensions
(MIME)
Type/SubType Description
Application/atom+xml Atom feed
Application/json JSON data
Image/gif GIF image
Image/png PNG image
Video/mp4 Mp4 video
Text/xml Xml
Text/html Html
Text/plain Just text

C#
HTTP
• Ubiquitous (common)
• Interoperable
• Scalable
• Flexible
• Mature
• Simple

C#
Many Faces of HTTP Frameworks in
.NEt
• WCF Web
HTTP
• WCF Data
Services
• ASP.NET MVC
•ASP.NET
WEB API

C#
HTTP
• Stateless – Each
transaction between the
client and server is
independent and no state is
set based on a previous
transaction or condition.
• Uses requests from the
client to the server
and responses from the
server to the client for
sending and receiving data.
HTTP is designed
as a stateless
protocol meaning
each request
response
transaction is
independent

C#
HTTP is an application layer protocol
• The Web client and the Web server are application programs
• Application layer programs do useful work like retrieving Web
pages, sending and receiving email or transferring files
• Lower layers take care of the communication details
• The client and server send messages and data without knowing
anything about the communication network

C#
HTTP
HTTP: hypertext transfer protocol
•The rules governing the conversation between a Web client and a
Web server
•Request-response protocol
•It is a stateless (does not maintain a state of a session) and
asynchronous( an html document is loaded asynchronous by the
browser as soon as parts of it are available)
A network protocol is the set of rules governing a conversation between a
client and a server
Layer Function
Application Do useful work like Web browsing, email,
and file transfer
Lower layers Handle communication between the client
and server

C#
HTTP Message Types
Single HTTP Transaction
HTTP Request
HTTP Response

C#
• I would like to open a
connection
• GET <file location>
• Display response
• Close connection
• OK
• Send page or error message
• OK
Client Server
HTTP is the set of rules governing the format and content
of the conversation between a Web client and server
An HTTP conversation

C#
HTTP Status Codes

C#
HTTP Request
Request-Method is:
• GET – request whatever information is
identified by the Request-URL
• POST – request that server accepts the
entity enclosed in the request
• OPTIONS - request for information about
communication options
• PUT – request that the enclosed entity be
stored under the Request-URL
• DELETE – request that the server delete
the resource identified by Request-URL
• TRACE – invoke a remote, application-
layer loopback of the request message
• CONNECT – used by proxies in SSL
connections
• HEAD – identical to GET, but server must
not return a message body in response
• Request-header can have the
following fields (selection):
– Accept : MIME types of resources
accepted by browser
– Accept-Charset : charset accepted by
browser
– Accept-Encoding : encoding accepted
by browser
– Accept-Language : language accepted
by browser
– Authorization : user-agent wishes to
authenticate itself with a server
– Host : the host Request-URL points to
– Referer : the URL of document
refering this URL
– User-Agent : Firefox, Safari, IE

C#

C#
Safe vs Unsafe HTTP Request Methods
GET
HEAD
SAFE REQUEST METHOD
HTTP1.1
OPTIONS
POST
PUT
UNSAFE REQUEST METHOD
HTTP1.1
DELETE
http methods that do not modify resources http methods that modify resources
READ
WRITE

C#
HTTP vs HTTPS
HTTP
• It is hypertext transfer
protocol
• It is not secure and
unreliable
• HTTP urls begin with http://
• It uses port 80 by default
• It is subject to man-in-the-
middle and eavesdropping
attacks
HTTPS
• It is hypertext transfer
protocol with secure
• It is secure and reliable
• Https urls being with https
• It uses port 443 by default
• It is designed to withstand
such attacks and is
considered secure against
such attacks

C#
http://www.rexswain.com/httpview.html
http://headers.cloxy.net/

C#
Chrome add on tools for HTTP
Header viewing

C#
Request Messages
[method] [URL] [version]
[headers]
[body]
GET http://www.sycliq.com/articles/index.aspx
Host: google.com
Accept-Language : en-EN
Date: FRI, 19 Jan, 2016 10:10:26 GMT

C#
Common Request Headers
Header Description
Referer The URL of the referring page
User-Agent Information about the browser
Accept Preferred media types
Accept-Language Preferred Language
Cookie Cookie information
If-Modified-Since Date of last retrieval
Date Creation timestamp for the
message

C#
Full Request
Get/HTTP/1.1
Host: sycliq.com
Connection: keep-alive
User-Agent: Mozilla/5.0 (Windows 10; WOW64) Chrome/16.0.912.75
Accept: text/html, application/xhtml+xml, application/xml;q=0.9,*/*; q=0.8
Referer: http://www.google.com/url?&q=iot
Accept-Encoding: gzip, defalte, sdch
Accept-Language: en-Us, en; q=0.8
Accept-Charset: ISO-8859-1, utf-8;q=0.7,*q=0.3
http://www.askapache.com/online-tools/http-headers-tool/

C#
HTTP RESPONSE
[version] [status][reason]
[headers]
[body]
X-headers are reserved
for non-standard
headers
https://curlbuilder.com/

C#
HTTP Header
Response
Request

C#
Content Negotiation
• It is the process of selecting the
best representation for a given
response when there are multiple
representations available.
• Content negotiation (conneg) in
the ASP.NET Web API is an
intrinsic server-driven mechanism
used to determine, based on the
client's request, which media
type formatter (out of the box
there are 4 media type
formatters) to be used to return
an API response.
• In general a client sends the
Accept parameter in the Request
Header to determine the
response.
• In .NET, it really comes down to
deciding how to send down your
CLR object to the client, over
HTTP or from the ASP.NET Web
API perspective, serialization is
the process of translating a .NET
Common Language Runtime (CLR)
type into a format that can be
transmitted over HTTP. The
default formats are either JSON
or XML.

C#
Content Negotiation
• Core mechanism of
HTTP
• Client specific desired
formats using
AcceptHeader

C#
Summary
• We understood the evolution of web services
to support cross platform applications using
light weight http application protocol.

C#
ASP.NET WEB API
3/23/2016
© Syed Awase 2015-16 - ASP.Net MVC Ground
Up
47

C#
ASP.NET

C#
ASP.NET WEB API
A Framework for creating
HTTP Services that can
reach a broad range of
clients including browsers
and mobile devices

C#
ASP.NET WEB API TIMELINE
April 2010
WCF
WebHttp
Binding(.N
et4)
October20
10 WCF
Web API
on
CodePlex
Feb 2012
ASP.Net
Web API
(Beta)
March
2012
ASP.Net
OpenSou
rce
Aug 2012
ASP.Net
Web API
4
Release
Sep
2013
ASP.Net
Web
API 2
RC

C#
HTTP & ASP.NET WEB API
• HTTP Fundamentals via Web API
– HTTP Messages
– URIs
– Verbs
– Controllers and Actions
– Status Code
– HttpRequestMessage
– HttpResponseMessage
– Error Handling
– Content Negotiation
– MediaType Formatters
– OData
– Validations
– Dependency Resolver
• Hosting
– HTTP.SYS
– IIS 101
– HTTP Compression
– Persisted Connections
– Web API Self Hosting
• More HTTP and Web API
– Caching
– Concurrency
– Security
– Streaming
– WebSockets and SignalR

C#
What?
• A fully supported and extensible framework for
building HTTP based endpoints
• Built on the top of ASP.NET
– Mostly ASP.NET Routing
• Released with ASP.NET MVC4
– Not linked to MVC – you can use alone, with MVC4 or you
can use with ASP.NET web forms
– Available via NuGET
• Also includes a new HTTP Client

C#
Why?
• First-class modern HTTP programming model
• Easily map resources to URIs and implement the uniform
interface of HTTP
• Rich support for formats and HTTP content negotiation
• Request validation
• Enable hypermedia with link generations
• Separate out cross cutting concerns (like authorization,
caching)
• Help Page generation
• Flexible hosting
• Light-weight testable, scales

C#
Why?
• You are building
– An HTML5 application that needs a services layer
– A mobile application that needs a services layer
– A client-server desktop application that needs a
services layer
– Reach more clients (Native Mobile Applications,
Cross platform applications)
– Scale with the cloud
– Embrace HTTP as an Application protocol

C#
Why to choose Web API?
• If we need a Web Service and don’t need SOAP, then ASP.Net Web API is
best choice.
• It is used to build simple, non-SOAP-based HTTP Services on top of existing
WCF message pipeline.
• It doesn't have tedious and extensive configuration like WCF REST service.
• Simple service creation with Web API. With WCF REST Services, service
creation is difficult.
• It is only based on HTTP and easy to define, expose and consume in a
REST-ful way.
• It is light weight architecture and good for devices which have limited
bandwidth like smart phones.
• It is open source.

C#
HTTP & ASP.NET WEB API
• HTTP Fundamentals via Web API
– HTTP Messages
– URIs
– Verbs
– Controllers and Actions
– Status Code
– HttpRequestMessage
– HttpResponseMessage
– Error Handling
– Content Negotiation
– MediaType Formatters
– OData
– Validations
– Dependency Resolver
• Hosting
– HTTP.SYS
– IIS 101
– HTTP Compression
– Persisted Connections
– Web API Self Hosting
• More HTTP and Web API
– Caching
– Concurrency
– Security
– Streaming
– WebSockets and SignalR

C#
What’s new?
ASP.NET Web API 2
• Attribute Routing
• Improved testability
(IHTTPActionResult,
HttpRequestContext)
• Odata: $select, $expand,
$value,$batch
• Request batching
• OWIN (Open Web Interface for
.NET) Integration
• Portable Web API Clients
• Web API Security
(CORS,OAuth2.0, Authentication
filters, filter overrides)
ASP.NET Web 2.1
• Attribute Routing
improvements
• Global error handling
• Help page improvements
• IgnoreRoute support
• BSON formatter
• Better async filter
• Portable query building and
parsing

C#
WEB API Features
• It supports convention-based CRUD Actions since it works with HTTP verbs
GET,POST,PUT and DELETE.
• Responses have an Accept header and HTTP status code.
• Responses are formatted by Web API’s MediaTypeFormatter into JSON,
XML or whatever format you want to add as a MediaTypeFormatter.
• It may accepts and generates the content which may not be object
oriented like images, PDF files etc.
• It has automatic support for OData. Hence by placing the new [Queryable]
attribute on a controller method that returns IQueryable, clients can use
the method for OData query composition.
• It can be hosted with in the application or on IIS.
• It also supports the MVC features such as routing, controllers, action
results, filter, model binders, IOC container or dependency injection that
makes it more simple and robust.

C#
ASP.NET WEB API TOOLS
• ASP.NET WEB API 2
Ships with Visual Studio
2013
• Requires .NET 4.5 or
later
• http://www.asp.net/we
b-api
• Fiddler
• Getpostman (chrome
addon)
• XHR POSTER (chrome
addon)
• HTTPHeaders (chrome
addon)
https://curlbuilder.com/ http://jflasher.github.io/spark-helper/
https://www.hurl.it/

C#
Is this REST?
• The ASP.NET Web API doesn’t dictate an
architectural style
• However you can build a RESTful service on
top of it
– It does not get in your way if you want to design
using the REST architectural style

C#
Versus the WCF Web Framework
• WCF also has a framework for building HTTP
based services
– Based on WCF attributed programming and
configuration models
• When would you choose WCF over ASP.NET
Web API
– You are limited to .NET 3.5
– You also are exposing a SOAP based services

C#
WCF Challenges
• It is also based on SOAP and return
data in XML form.
• It is the evolution of the web
service(ASMX) and support various
protocols like TCP, HTTP, HTTPS,
Named Pipes, MSMQ.
• The main issue with WCF is, its
tedious and extensive configuration.
• It is not open source but can be
consumed by any client that
understands xml.
• It can be hosted with in the
applicaion or on IIS or using window
service.
• To use WCF as WCF Rest service you
have to enable webHttpBindings.
• It support HTTP GET and POST verbs
by [WebGet] and [WebInvoke]
attributes respectively.
• To enable other HTTP verbs you have
to do some configuration in IIS to
accept request of that particular verb
on .svc files
• Passing data through parameters
using a WebGet needs configuration.
The UriTemplate must be specified
• It support XML, JSON and ATOM data
format.

C#
Choosing between WCF or WEB API
• Choose WCF when you want to create a service that should support
special scenarios such as one way messaging, message queues, duplex
communication etc.
• Choose WCF when you want to create a service that can use fast transport
channels when available, such as TCP, Named Pipes, or maybe even UDP
(in WCF 4.5), and you also want to support HTTP when all other transport
channels are unavailable.
• Choose Web API when you want to create a resource-oriented services
over HTTP that we can use the full features of HTTP (like URIs,
request/response headers, caching, versioning, various content formats).
• Choose Web API when you want to expose your service to a broad range
of clients including browsers, mobiles, iphone and tablets.

C#
MVC
• Used to create web applications
that comply with MVC design
patterns generating both views
and data
• MVC has provision to return data
in JSON format using JsonResult
• Requests are mapped on to the
action name.
• Model binding, filter, router and
other MVC features are different
from ASP.NET and extends from
system.web.mvc
Web API
• Used to create full blown HTTP
services with easy and simple way
that returns only data
• Helps to build REST-ful services
over the .NET framework and it
also supports content-negotiation
( deciding the best response
format data that could be
acceptable by the client ex: JSON,
XML, etc.), Self hosting
• Requests are mapped to the
actions based on HTTP verbs
• Web API can be used with
ASP.NET and as a stand alone
service layer and extends from
system.web.http assembly
• A light weight architecture

C#
INTRODUCTION, ROUTING,
ATTRIBUTE ROUTING
3/23/2016
Up
65

C#
Getting Started
• Create a WebAPI
Project
• Create an ASP.NET
Project and add a Web
API Project
• Create any project!
– Install-package
Microsoft.AspNet.WebApi.SelfHost
– Using NuGet

C#
WEB API SCAFFOLDING PROJECT
WebAPI
ASP.NET MVC5
Project
Global.asaxGlobal.asax
WebApiConfig.cs

C#
Conventional Routing
• Convention-based routing, you
define one or more route
templates, which are basically
parameterized strings.
• ASP.NET Hosting Layer Maps URIs
and Verbs to controller
– Must derive from APIController
• New Extension Method for
Routing
– MapHttpRoute
– Registers a differentHandler to
the routing Infrastructure
• HttpControllerHandler
• Advantage being that
templates are defined in a
single place and routing
rules are applied
consistently across
controllers
• ASP.NET Routing is the most
common way to map URIs
and Verbs to your methods
– Not the only way however
– Self Hosting can use this
system or replace it with your
own.

C#

C#
WebAPI Configuration Services
And WebAPI Routes

C#
Attribute Routing
• Convention-based routing
makes it hard to support
certain URI patterns that
are common in RESTful
APIs.
• E.g. Customers have orders,
movies have actors, books
have authors
• It’s natural to create URIs
that reflect these relations
– /customers/1/orders
• Attribute routing, is
trivial to define a route
for this URL.
• Simply by adding an
[attribute] to the
controller action

C#
Attribute routing
Enabling Attribute Routing
WebAPI
Configuration
Services
And WebAPI
Routes
set a common prefix for an entire controller
by using the [RoutePrefix] attribute:

C#
Override the route prefix
Use a tilde (~) on the method attribute to
override the route prefix:

C#
Route prefix parameters
route prefix can include parameters:

C#
Route constraints
Route constraints let you restrict how the parameters
in the route template are matched. The general syntax
is "{parameter:constraint}"

C#
Supported constraints
Constraint Description Example
alpha
Matches uppercase or lowercase
Latin alphabet characters (a-z, A-Z)
{x:alpha}
bool Matches a Boolean value. {x:bool}
datetime Matches a DateTime value. {x:datetime}
decimal Matches a decimal value. {x:decimal}
double
Matches a 64-bit floating-point
value.
{x:double}
float
Matches a 32-bit floating-point
value.
{x:float}
guid Matches a GUID value. {x:guid}

C#
int Matches a 32-bit integer value. {x:int}
length
Matches a string with the specified length
or within a specified range of lengths.
{x:length(6)}
{x:length(1,20)}
long Matches a 64-bit integer value. {x:long}
max
Matches an integer with a maximum
value.
{x:max(10)}
maxlength Matches a string with a maximum length. {x:maxlength(10)}
min Matches an integer with a minimum value. {x:min(10)}
minlength Matches a string with a minimum length. {x:minlength(10)}
range
Matches an integer within a range of
values.
{x:range(10,50)}
regex Matches a regular expression.
{x:regex(^d{3}-d{3}-
d{4}$)}

C#
Custom Route Constraints
custom route constraints by implementing the IHttpRouteConstraint interface.
constraint restricts a parameter to a non-zero integer value.

C#
Custom Route Constraint

C#
Optional URI Parameters and
Default Values
make a URI parameter optional by adding a question mark to the route
parameter. If a route parameter is optional, you must define a default value for
the method parameter.
[OR]

C#
Route Name
In Web API, every route has a name. Route names are useful for generating links,
so that you can include a link in an HTTP response.
set the Name property on the attribute.

C#
Route Order
When the framework tries to match a URI with a route, it evaluates the routes in a
particular order. To specify the order, set the RouteOrder property on the route
attribute. Lower values are evaluated first. The default order value is zero.
How is the total ordering is determined ?
1. Compare the RouteOrder property of the route attribute.
2. Look at each URI segment in the route template. For each
segment, order as follows:
i. Literal segments.
ii. Route parameters with constraints.
iii. Route parameters without constraints.
iv. Wildcard parameter segments with constraints.
v. Wildcard parameter segments without constraints.
3. In the case of a tie, routes are ordered by a case-insensitive ordinal
string comparison (OrdinalIgnoreCase) of the route template.

C#
Route Order
1. orders/details
2. orders/{id}
3. orders/{customerName}
4. orders/{*date}
5. orders/pending

C#
• Define one or more
templates, which are
basically parameterized
strings.
• Templates are defined in a
single place and routing
rules are applied
consistently across all
controllers
Attribute Routing
• Convention based routing
makes it hard to support
certain URI patterns that are
common in RESTful APIs.
• Applied to Controller Action
Methods or at the Controller
level.
• Ability to define constraints
and custom route constraints
• Route names are useful for
generating links, so that they
can include a link in an HTTP
response

C#
SUMMARY
• Approaches for creating web api 2
applications
• Conventional routing using MapHttpRoute
• Attribute Routing approaches
• In fact, you can combine both techniques in
the same project.

C#
ACTION RESULTS IN WEB API
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ACTION RESULTS
• Converting the return value from a controller action into an HTTP
response message.
• WEB API 1 : two ways of creating response from an API action
– Either return a specific object instance (or void) and let the Web API pipeline
convert that to an HttpResponseMessage for you
– Return a raw HttpResponseMessage, where the user has to construct it
manually and bypass all of the internal Web API mechanisms (formatters,
content negotiation).
• WEB API 2: IHTTPACTIONRESULT is a kind of wrap of
HTTPRESPONSEMESSAGE. It contains ExecuteAsync method to create an
HttpResponseMessage, further simplifies unit testing of your controller.
The return type are kind of strongly typed classes serialized by Web API
using media formatter into the response body.
– Drawbacks being one cannot directly return an error code, such as 404. Instead you
can only throw and HttpResponseException error.

C#
WEB API Controller Action
• Web API uses different mechanisms to create
the HTTP response
Return type How Web API create the response
Void Return empty 204 (No Content)
HttpResponseMessage Convert directly to an HTTP response message
IHTTPActionResult Call ExecuteAsync to create an
HTTPResponseMessage, then convert to an HTTP
response message
Other type Write the serialized return value into the response
body; return 200(OK)

C#
VOID
• If the return type is
void, Web API simply
returns an empty HTTP
response with status
code 204 (NO
CONTENT)

C#
HttpResponseMessage
• HttpResponseMessage
return type, converts the
return value directly into
an HTTP response
message using the
properties of the
HttpResponseMessage
object to populate the
response.
• The option gives you a lot
of control over the
response message

C#
HttpResponseMessage

C#
Content
Negotiation in
ASP.NET WEB API
“the process of selecting
the best representation
for a given response
when there are multiple
representations
available”
RFC 2616

C#
Primary
Mechanism for
Content
Negotiation in
HTTP are using
these request
headers
1. Accept : which media types are
acceptable for the response, such as
“application/json”, “application/xml” or a
custom media type such as
“application/vnc.example+xml”
2. Accept-Charset: which character sets
are acceptable such as UTF-8 or ISO
8859-1
3. Accept-Encoding: which content
encoding are acceptable, such as gzip.
4. Accept-Language: preferred natural
language, such as “en-us”
5. Other Option – if the request contains
an X-Requested-With header,
indicating an AJAX request, the server
might default to JSON if there is no
Accept header

C#
IHttpActionResult
• Introduced in Web API2
• IHttpActionResult Interface defines an
HttpResponseMessage factory
• Advantages of using IHttpActionResult
– Simplifies unit testing webapi controllers
– Moves common logic for creating HTTP responses into
separate classes
– Makes the intent of the controller action clearer, by hiding
the low-level details of constructing the response

C#
IHttpActionResult
Contains a single method, ExecuteAsync,
which asynchronously creates an
HttpResponseMessage instance

C#
Other Return Types
• Web API uses a media
formatter to serialize the
return value. Web API
writes the serialized value
into the response body.
• A disadvantage of this
approach is that you
cannot directly return an
error code e.g. 404.
• You can only throw an
HttpResponseException
for error codes.

C#
Assemblies
• Client and raw messaging typesSystem.Net.Http
• Model Binding and media type formatterSystem.Net.Http.Formatting
• Basic Hosting InfrastructureSystem.Web.Http
• Common APIsSystem.Web.Http.Common
• ASP.NET hostingSystem.Web.Http.WebHost
• Self hostingSystem.Web.Http.SelfHost
• DataController is an APIController that handles “CRUD” type operationsSystem.Web.Http.Data
• Specific implementations of DataControllerSystem.Web.Http.Data.EntityFramework
• Common code for data apiSystem.Web.Http.Data.Helpers

C#
UNIFORM INTERFACE
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C#
• The Uniform interface of REST
• ASP.NET Web API and the uniform interface
• Content Negotiation
• Model binding and formatting
• HTTP-deep diving

C#
REST
• Representational State Transfer
• Architecture for building systems ( by Roy Fielding)
• Based on the advantages of the Web
– URIs
– Uniform Interface
– Stateless
– Hypermedia-driven(i.e links)
– Cache-ability

C#
It’s all about URIs
• A RESTful service models its resources as URIs
– Builds on the success of the web
• Everything is addressable via a URI
• You interact with a resource by using the
Uniform Interface
– Start with URI, add well-known HTTP verbs

C#
Uniform interface
• No Side-effects (Safe)
• Idempotent(calling a million times has the same effect as one request)
• Retrieves resource
• Cacheable
GET
• Creates a new resource
• Same as SOAP – still unsafePOST
• Updates an existing resource
• Also idempotentPUT
• Removes a resource
• Also idempotentDELETE

C#
Implementing using Conventions
• The route determines which Controller should
be invoked based on the request URI
• Controller derives from APIController
• Method invoked is picked based upon the
verb of the incoming HTTP request
– GET
– POST
– PUT
– DELETE

C#
Verbs to Attributes
• If you don’t want to name your methods with the Convention,
you can add attributes to your methods
– Name method whatever you’d like
– Routing still picks Controller
• AcceptVerbs
– Can specify multiple verbs to one method
• Specific attributes
– HttpGet
– HttpPost
– HttpPut
– HttpDelete

C#
Content Negotiation
• Dynamically determining the media type of a
resource based on client request
– Client sends Accept header with 1...N media types
(XML/JSON)
– Server sends back appropriate response with Content-Type
header
– Client also sends Content-Type header when sending a
body
• Web API provides automatic content negotiation
• Implemented using MediaTypeFormatter base class
– More on this in extensibility Module

C#
Parameter Binding in ASP.NET WEB API
• When a WEB API calls a
method on a controller,
it must set values for
the parameters, a
process called binding.
Rules of binding
• Simple types – include .NET
primitive types (int, bool, double
..+ TimeSpan, DateTime, Guid,
decimal and String)
• Complex types –Web API tries to
read the value from the message
body, using a media-type
formatter
Simple type Complex Type

C#
Simple type Complex Type
id – parameter is of simple type and gets the value from the request URI
Item-parameter is a complex type, so WEB API uses a media-type
formatter to read the value from the request body
For complex types, however, consider using media-type formatters
whenever possible.A key principle of HTTP is that resources are sent in the
message body, using content negotiation to specify the representation of the
resource. Media-type formatters were designed for exactly this purpose.

C#
[FromURI]
• To force WEB API
to read a complex
type from the URI
• Add the [FromUri]
attribute to the
parameter.
http://localhost/api/geopoint/?Latitude=47.678558&Longitude=-
122.130989
The client can put the Latitude and Longitude values in the query string and Web API
will use them to construct a GeoPoint

C#
[FromBody]
• To force WEB API to
read a simple type
from the request
body, add the
[FromBody] attribute
to the parameter
• At most one
parameter is allowed
to read from the
message body.
The reason for this rule is that the request body might be stored in a non-
buffered stream that can only be read once.
Content-Type: application/json

C#
ModelBinding and Formatting
• The Web API will automatically bind URI and HTTP
Body data to your methods
– Body data can be passed to MediaTypeFormatter based
on Content-Type
– Model Binding (same as ASP.NET MVC) is used on Query
String (URI) data
• Rule-body can only be read once
• [FromBody] and [FromUri] attributes used to control
• ModelBinding attribute can specify a custom
ModelBinding for a parameter

C#
HTTP-Diving Deeper
• Routing and controllers take care of the basics of HTTP
– URI + Verb
• What if you want to reach down further into the HTTP stack?
– Send back particular return methods
– Interrogate additional HTTP headers
• HttpRequestMessage/HttpResponseMessage are the answer
in the Web API
– HttpRequestMessage can replace body parameter
– HttpResponseMessage can replace return parameter

C#
Enable all http methods to come through
Current http methods supported are
Enable for/change/ Add “Put”, “DELETE”

C#
ASP.NET WEB API PROCESSING
ARCHITECTURE

C#
BASEBALL STATS 3-TIER WEB API
APPLICATION DB FIRST APPROACH
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C#

C#
Create WEB API Project

C#
Data Layer Project

C#
Service Layer Project

C#
Install Entity Framework with NuGet to
Data and Service Layer Projects

C#
Create DB, TABLES
Populate data through Insert Statements in SQL Query

C#
ADD REFERENCE FOR WEB API LAYER

C#
ADD REFERENCE FOR SERVICE LAYER

C#
DATA LAYER EF

C#
EF DB FIRST

C#
DB Connection Settings

C#
Service Layer

C#
Add WebAPI Controller

C#
ApiController

C#
Add Connection String
<connectionStrings>
<add name="PlayerContext"
connectionString="metadata=res://*/PlayerModel.csdl|res://*/PlayerModel.ss
dl|res://*/PlayerModel.msl;provider=System.Data.SqlClient;provider
connection string="data source=DESKTOP-
I57JOS9SQLEXPRESS2014;initial catalog=DEVENVIRONMENT;integrated
security=True;MultipleActiveResultSets=True;App=EntityFramework""
providerName="System.Data.EntityClient" />
</connectionStrings>
WebAPI -> Web.config

C#

C#
MOVIE REVIEW WEB API
APPLICATION WITH CODE FIRST
APPROACH
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C#
Movie and Review Classes

C#
Connection String
<connectionStrings>
<add name="DefaultConnection" connectionString="Data Source=DESKTOP-
I57JOS9SQLEXPRESS2014;Initial Catalog=Work;Integrated Security = SSPI"
providerName="System.Data.SqlClient" />
</connectionStrings>
Web.config

C#

C#
Package Manager Console
Enable-Migrations
Add-Migration Initial
Update-Database

C#
Migrations -> Configuration.cs

C#
Relationship FixUP
• Navigation properties are not loaded explicitly
• Cyclic Reference
.
https://msdn.microsoft.com/en-in/data/jj713564.aspx

C#
Run the Application

C#
MEDIATYPEFORMATTERS IN WEB
API
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C#
SERIALIZATION
The process of translating a .NET
Common Language Runtime (CLR) type
into format that can be transmitted over
HTTP. The default format can be either
JSON or XML.
A media type formatter that is
an object of type
MediaTypeFormatter performs the
serialization in the ASP.NET Web API
pipeline.

C#
MediaTypeFormatter
• To seamlessly convert HTTP data to/from .NET types.
• media type: refers to the value of the content-type
header within an HTTP request and response.
– Media types allow agent (client) and server to define the
type of the data sent in the HTTP body (payload).
– It is also used within the accept header in the request to
allow content negotiation, i.e. client notifies the server of
the media types it accepts/prefers.
Media type formatter is the bridge between the HTTP world
of URI fragments, headers and body on one side, and the
controller world of actions, parameters and return types.

C#
Using MediaTypeFormatters
• Global formatters sitting in
the formatters property of
HttpConfiguration.
• If you are using ASP.NET
hosting (IIS, Cassini, etc)
then you can use
GlobalConfiguration.Configuration
to access the instance
of HttpConfiguration
containing formatters.
• For Self-Hosting
– Create a
HttpSelfHostConfiguration
object which has
formatters property.
App_Start-> WebApiConfig.cs
Result in Output window

C#
MediaTypeFormatters

C#
Order of handling a request from a
MediaType Formatter
• System.Net.Http.Formatting.JsonMediaTypeFormatter, based
on JSON.NET
• System.Net.Http.Formatting.XmlMediaTypeFormatter, based
on DataContractSerializer
• System.Net.Http.Formatting.FormUrlEncodedMediaTypeForm
atter, for handling HTML form URL-encoded data
• System.Web.Http.ModelBinding.JQueryMvcFormUrlEncodedF
ormatter, for handling model-bound HTML form URL-encoded
data

C# ASP.NET WEB API APPLICATION DEVELOPMENT

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