Friday, May 16, 2014

What is NuGet and how to install it on Visual Studio 2013

NuGet is the package manager for the Microsoft development platform including .NET. The NuGet client tools provide the ability to produce and consume packages. The NuGet Gallery is the central package repository used by all package authors and consumers.

How to install NuGet using Visual Studio Extension Manager :
  • Open Visual Studio, Click Tools and then Extension Manager.
  • Navigate to Online, Find NuGet Manager Extension and click Download
  • In the Installer dialog box, click Install.
  • When installation is complete, close and re-open Visual Studio.

NuGet is now ready to use.

What is Entity Framework ?

Entity framework is an Object/Relational Mapping (O/RM) framework. It is an enhancement to ADO.NET that gives developers an automated mechanism for accessing & storing the data in the database and working with the results in addition to DataReader and DataSet. It eliminates the need for most of the data-access code that developers usually need to write.

It allows you to create a model by writing code or using boxes and lines in the EF Designer. Both of these approaches can be used to target an existing database or create a new database. It also provides services like change tracking, identity resolution, lazy loading, and query translation so that developers can focus on their application-specific business logic rather than the data access fundamentals.

Following figure shows the overall architecture of the Entity Framework (Source :

Application : Application which is going to use Entity Framework.

EDM (Entity Data Model): EDM consist three main parts- Conceptual model, Mapping and Storage model.
  • Conceptual Model: Defines model classes and their relationships.
  • Storage Model: It is your database design model which includes tables, views, stored procedures and their relationships and keys.
  • Mapping: Mapping consist information about how your conceptual model is mapped to storage model.
ADO.Net Provider: This layer communicates with database using standard ADO.Net.

Data Store : Type of database that you are going to use.

Below are the few Step-by-Step tutorials which will give you the better understanding of Entity Framework :

Tuesday, March 18, 2014

How to set permanent IP in Ubuntu ?

Steps :

*) Open the interfaces file :
          sudo vi /etc/network/interfaces

If you are using DHCP you will see the following lines :
          auth eth0
          iface eth0 inet dhcp 

*) To make it static, Change the line iface eth0 inet dhcp to iface eth0 inet static and add the following just below it:

address (IP address that you need to set)
netmask (Default mask which in this case is the default class c subnet)
gateway (Typically your router’s IP address)
network (The network that this machine is running on)

Here is a screenshot of how it should look below :

*) Once you save this file you need to restart your networking service.
       sudo /etc/init.d/networking restart
       sudo service networking restart

Note :
 /etc/init.d/networking restart command is deprecated on new debian and ubuntu, So in such case you can use :
            ifdown eth0 && ifup eth0

Friday, March 14, 2014

How to connect via SSH (putty) to your vmware machine (Ubuntu) ?

It was really a pain for me to work on Oracle VM, It won't allow you to use mouse or do copy-paste. So I decided to connect my local VM via SSH( Putty).

Steps :

1.  In your VM box, Goto Settings -> Network ->Adapter 1 and select "Bridged Adapter"

2. In your Ubuntu Machine, Install "openssh-server" 
          sudo apt-get install openssh-server

3. Reboot the VM and Run "ifconfig" command in terminal and get "inet addr" of "eth0".

4. Open putty, Enter the IP address(IP of your VM machine ) , Select port as "22" and connection type as "SSH" and click on open button.

5. Enter your credential and you are done :)

Friday, February 14, 2014

Working of WSO2 Identity Server

To enable OAuth support for your client application, First we need to register our application on WSO2 Identity Server.

Step to register Client App on WSO2 IS :

  1. Goto Management Console and Enter your username and password. By default its “admin”.
  2. Click Main button and then OAuth in Manage menu.
  3. Click on the Register New Application link on the OAuth Management page.

  1. Select OAuth 2.0 as the OAuth Version. Enter Application Name and your Callback Url. For this app to work use http://localhost:8080/playground/oauth2client.

   5. Click on Add button , you will see your application under the OAuth                Management Page.

  1. Click on the WSO2 application and copy the Client ID, Client Secret, Access Token URL and Authorize URL. We need these values for our web app.

You are done with the registration part..!!!

Sample App with WSO2 Identity Server :

Download the sample app from here and host it in Tomcat. You can see the app running at http://localhost:7070/playground.
  1. Click on Import Photos

  1. Select the Grant Type as “authorization code”. Enter Client Id , Authorize Endpoint that we got while registering our Application. Scope is Optional and click on Authorize.

3. WSO2 Identity Server requests access to noscope, After login click on Approve.

4. You will get authorization code, Now enter the value for the Access Token Endpoint and Client Secret and click Get Access Token.

5 . Once you get access token, Click on “Get Photo”.

Setup of WSO2 Identity Server on Windows 7

What is WSO2 Identity Server ?

WSO2 Identity Server is an enterprise-ready, fully-open source, lean, component-based solution for facilitating security and provides secure identity management for enterprise web applications, services, and APIs by managing identity and entitlements of the user securely and efficiently.
It helps improve customer experience by reducing identity provisioning time, guaranteeing secure online interactions, and delivering a reduced single sign-on environment. WSO2 Identity Server decreases identity management, entitlement management, and administration burden by including role-based access control (RBAC) convention, fine-grained policy-based access control, and SSO bridging.

Downloading the product :

  • In your Web browser, go to
  • If you are a new user downloading WSO2 products for the first time, register and log in.
  • Once you are logged in, click the Binary button in the upper right corner of the page.

The binary distribution contains the Carbon binary files for both Windows and Linux operating systems, compressed into a single ZIP file.

Installing the Identity Server :

Before installing, You must set your JAVA_HOME environment variable.
  • Download the latest version of the Identity Server as described above
  • Extract the archive file to a dedicated directory for the Identity Server, which will hereafter be referred to as <WSO2_HOME>.

Starting the Server :

To start the server, you need to run the script “wso2server.bat” which is under $WSO2_HOME/bin folder.
Once the server has started, you can see the Management Console by opening a Web browser and typing in the management console's URL. You can check the URL as the last line in the start script's console. Check the screenshot below :

Use “admin” as username and password to sign in to the Management Console.
By default, The session-timeout value is 15 minutes but you can change this in the $WSO2_HOME/repository/conf/tomcat/carbon/WEB-INF/web.xml file as follows:


Stopping the Server :

To stop the server, press Ctrl+C in the command window or click the Shutdown/Restart link in the navigation pane in the Management Console.

Resources :

How to retrieve Facebook profile using Apache Oltu

This tutorial shows you the basic of OAuth using Apache Oltu (Formely known as Apache Amber). We have created a Java Web Application that authenticates the user to Facebook via OAuth 2.0 and retreive the protected resources from Facebook.

Setup :
  • SSL enabled Tomcat Server as we have deployed our Web Application on tomcat. Click here for instruction on How to enable SSL on Apache Tomcat 7.0
  • Registered Facebook Application. Check here for instruction on How to register App on Facebook.
  • Download the OltuClientFB Application from the GIT repository.
  • If you are using Maven then add below dependency or download Apache Oltu client jars :

Run the Project :

Check out the project from the above URL, import into the eclipse and Run as a Server.

Navigate your browser to https://localhost:<port>/OltuClientFB. You will see the following page:

Click on the link and it will take you the Facebook page for Authentication :

Once you are login into Facebook, It will ask you to allow the Oauth application to access your private data:

Once you click on “Okay” button. It will display your profile detail like UserId, Name etc.

Code Description :


In the Servlet initParams, We have defined the clientId, clinetSecret and the redirectUri, You can change it as per your Apps.
// clientId is 'App ID '
@WebInitParam(name = "clientId", value = "YOUR_CLIENT_ID"),
// clientSecret is 'App Secret'
@WebInitParam(name = "YOUR_CLIENT_SECRET", value = "70ba69525274876dce9697ad183a9051"),
// This must be identical to 'Valid OAuth Redirect URI's'
@WebInitParam(name = "redirectUri", value = "https://localhost:7443/OltuClientFB/OAuthServlet/callback"),})

The Java Web Application act as a third-party website or termed as “client” which operate on behalf of a user. It first sends the request to Facebook which authenticates the user, obtain the user's authorization(i,e Approve/Deny page) and issues an access token which client can use while interacting with the resource server i,e Facebook to access public profile of the user.

End user Authorization request :

Created the End User Authorization Request by providing end-user authorization URI at the Authorization Server (e.g. Facebook), application's client id and a redirect URI in order to receive the authorization code. Apache Oltu has an enum OAuthProviderType for authorization and token endpoints of common OAuth 2 providers like Facebook.

OauthClientRequest authClientRequest = OAuthClientRequest

The above code will produce an OAuth request where all the parameters are encoded in the URL query.


Get Authorization Code from redirect URI :

Once the user grants permission for your client application, then the Facebook will redirects the user to redirectUri with the code in the request parameter.

OAuthAuthzResponse oar = OauthAuthzResponse.oauthCodeAuthzResponse(request); code = oar.getCode();

Exchange OAuth code for an access token :

Apache Oltu has two different classes to parse the access token response. Facebook’s response is not fully compliant with the final version of the OAuth 2 specification, but it can be parsed using the class GitHubTokenResponse.

OauthClientRequest authClientRequest = OAuthClientRequest.tokenProvider(OAuthProviderType.FACEBOOK)
//create OAuth client that uses custom http client under the hood
oAuthClient = new OAuthClient(new URLConnectionClient());
GitHubTokenResponse oAuthResponse = oAuthClient.accessToken(authClientRequest,
String accessToken = oauthResponse.getAccessToken();

Get Facebook profile data :

OAuthClientRequest bearerClientRequest = new OAuthBearerClientRequest("").setAccessToken(accessToken).buildQueryMessage();
OAuthResourceResponse resourceResponse oAuthClient.resource(bearerClientRequest, OAuth.HttpMethod.GET,

This class will display the user profile on the UI.

Summary :

This application demonstrates the basic of OAuth 2.0 using Apache Oltu i,e how to authenticates the user and retreive the protected resources from Facebook.

Resources :

Code download link:

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