Ravindra Kumar

A thinker, Analyzer and motivator.

[techravindra]

Virtual Reality - Is this world getting Unreal ?

There has been lot of buzz around the world for Virtual Reality in year 2015. Though VR related technology innovations are not new, but it all started to take shape when Oculus Rift showed their device prototype, couple of years back. It came more into lime-light after Facebook acquired it to foray into Virtual reality market segment. Oculus Rift is coming to the world in Q1 2016. Samsung has already launched Gear VR for its flagship GALAXY smartphone products.

So what is Virtual Reality:

It is something related to showing Virtual experience of real world things you have ever experienced. In simpler terms, it is all about experience of bridging the gap between your imagination and reality.

VR experience helps you in viewing 3-D effect of real world objects in panoramic views such as immersive view of indoor buildings, theatre views, gaming etc. By experiencing it you will feel like you are really their in action and involved in it. 

Who are in the Game: 

Apart from Oculus Rift and Samsung Gear VR, many other players and coming into Virtual Reality field. Sony Playstation VR headset is coming in mid of 2016, while HTC Vive powered by SteamVR is also all set for launch in april 2016. Zeiss VR one is another headset which is compatible on most of the Apple and Android devices. So, lot more is happening and coming in year 2016. This will be the ultimate year to see many technological advancements and entry of many new players in Virtual reality segment.

Role of Google Cardboard:

Wondering where Google is in this world of Virtual Reality? During Google I/O 2014 they came up with Google CardBoard(Video link), using which you can experience Virtual Reality in a Simple, fun and affordable way. And with no surprise they have their App ecosystem where we can get plenty of apps to immerse into Virtual reality.

Developers are getting into this by developing apps on SDK and updating to Google Play store. The Cardboard SDK for Unity allows you to easily bring your Unity3d projects to VR on Android and iOS.

Startups building on Virtual Reality ecosystem:

Technology startups are building on this and creative innovative solutions available for masses. Tantransha has launched its Google-inspired Cardboard which works for major smartphone models with ease. This brings the Virtual reality to everyone’s reach at fast pace and in affordable price. Get the Cardboard, install apps(Gaming, rollercoaster rides, youtube 360 etc) from Play store and jump into virtual world. 

Bringing your desktop content to Cardboard viewer is icing-on-the-cake to view your stuff closer and in three dimensional effect. Take the Remote control of your laptop/desktop and immerse into virtual possibilities. This is the way to start with your Virtual reality experience unless you have Oculus Rift and Samsung Gear VR in your gadgets list. And who knows, you may get more innovative ideas and convert them into reality via Virtual Reality. 

This is getting more popular and affordable because of smartphone penetrations worldwide. Possibilities and use-cases are endless, so whether you are a developer or Gaming lover, this is the right time to get started with Virtual Reality. 

Watch this blog space for all happenings around VR innovations in Year 2016. Do leave your comments or connect with us. Happy New Year!

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Building a Scalable Architecture for Web Apps

Speaker: Bhavin Turakhia This session covers a wide-array of topics and a plethora of lessons we have learnt (some the hard way) over the last 9 years in bui...

Nice video on Web Architecture

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Concurrency modes in WCF.

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Abstract Class vs Interface

An abstract class is a special kind of class that cannot be instantiated. An abstract class is only to be sub-classed (inherited from).

An interface is not a class. It is an entity that is defined by the word Interface. An interface has no implementation.

Multiple inheritance

Interface: A class may inherit several interfaces.

Abstract Class: A class may inherit only one abstract class.

Default implementation

Interface: An interface cannot provide any code, just the signature.

Abstract Class: An abstract class can provide complete, default code and/or just the details that have to be overridden.

Access Modifiers

Interface: An interface cannot have access modifiers for the subs, functions, properties etc everything is assumed as public

Abstract Class: An abstract class can contain access modifiers for the subs, functions, properties

Core VS Peripheral

Interface: Interfaces are used to define the peripheral abilities of a class. In other words both Human and Vehicle can inherit from a IMovable interface.

Abstract Class: An abstract class defines the core identity of a class and there it is used for objects of the same type.

Homogeneity

Interface: If various implementations only share method signatures then it is better to use Interfaces.

Abstract Class: If various implementations are of the same kind and use common behavior or status then abstract class is better to use.

Speed

Interface: Requires more time to find the actual method in the corresponding classes.

Abstract Class: Fast

Adding functionality (Versioning)

Interface: If we add a new method to an Interface then we have to track down all the implementations of the interface and define implementation for the new method.

Abstract Class: If we add a new method to an abstract class then we have the option of providing default implementation and therefore all the existing code might work properly.

Fields and Constants

Interface: No fields can be defined in interfaces

Abstract Class: An abstract class can have fields and constrants defined

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Instancing Modes in WCF. (PerCall, PerSession, Single)

[ServiceBehaviour(InstanceContextMode= InstanceContextMode.ParCall)] public class SimpleService : ISimpleService {        public void DoWork() { } }

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If you try, you risk failure. If you don’t, you ensure it.

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Message Exchange Patterns in WCF

MEP describes how client and the wcf service communicate and exchange messages.

Request-Reply(default)

One-Way

Duplex

Request-Reply:-

This is the default message exchange pattern.

Client sends a message to wcf and waits for the message reply.

The client waits for the service call to complete even if it returns void type.

Faults and exceptions gets reported to clients immediately if any.

IsOneWay parameter of OperationContract specifies the message exchange pattern.

[ServiceContract] public interface ISampleService

{

     [OperationContract]      string RequestReplyOperation();      [OperationContract(IsOneWay = false)]     string GetServiceInfo();

}

One-Way:-

In case of One-Way operation only one message is exchanged between client and wcf service. Client sends a call to the service method and doesn’t wait for the reply.

To make an operation to one way set IsOneWay equal to true. As messages are exchanged one way, faults are not getting reported.

Clients are unaware of server channel fault until the subsequent calls.

One-way calls are not asynchronous in nature, they looks like this. 

Calls gets queued if service is busy and client is blocked until then.

Exception is thrown if operation marked with one-way has a return type, reference type or output parameters.

[techravindra]

WCF Fundamentals

Hosting WCF Service:

Self Hosting:

Hosting a WCF service in any managed .net application is called self hosting.

Using Console application - We can host WCF service in console application. it is very simple and fast to do.

Advantages:-

Very easy to setup. specify the configuration in app.config and with a few lines of code we have service up and running.

Easy to debug as we don’t have to attach separate process which hosts wcf service.

Supports all bindings and transport protocols.

very flexible to control the lifetime of service using open() and close() methods of service host.

Disadvantages:-

The service is available to the clients only when host is running.

Self hosting does not support automatic message based activation that we get when hosting in IIS.

Custom code is required.

Self hosting is only used during development and demo phase and not in real time situations(for live WCF services).

Using windows application - Hosting in windows application is similar to console application except the UI control we can have in case of windows. We can have start and stop control through user interface. All the advantages and disadvantages remains same.

Using Windows Service -

Windows service is similar to any other program running on windows machine. they differ in below points:

Service runs on the background.

They can be configured to start automatically on windows start.

They don’t have any user interface.

Windows service provides core operating features such as:- Event logging, providing security and error reporting. We can use windows service to host WCF service.

Installing windows service - if we have added project installer in service project then through visual studio command line we can install and uninstall the service.

install -i “service executable path”

install -u “service executable path”

Advantages:-

Windows service can be configured to start automatically. with this the WCF service hosted in this is also started automatically.

Service can be automatically restart and recover from failures.

Supports all bindings and transport protocols.

Disadvantages:

Involves writing custom code in creating windows service.

Service must be deployed on the production server.

Difficult to debug, need to attach the process within which wcf service is running.

Hosting WCF service in IIS:

To host a WCF service in IIS we need to create a file with .svc extension. This file contain ServiceHost directive. The service attribute of ServiceHost directive specifies which service it points to. The service code can reside in any of following:-

The .svc file

In separate assembly

A file in App_code folder

The configuration of web service goes into web.config file. There is no need to instantiate the service host and start the service, as required in Self Hosting.

Advantages:-

No code required to host and  instantiate the ServiceHost.

Automatic message based activation.

Automatic process recycling.

Hosting WCF service in IIS 5.1 and 6.0 is limited to HTTP communication protocol.

Hosting WCF service in IIS using WAS support:

To support NON-HTTP protocol in IIS we need to install the following:

Install Windows Process Activation Service

Install Windows Communication Foundation Non-HTTP Activation component.

Enable Non-HTTP protocol support for your application in IIS.

Advantages:-

No code required to host the service

Automatic process recycling, Automatic message based activation and idle time management etc.

Support for non-http protocols.

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If you can not find a new path, don't kick yourself.

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Best Portal for Algorithm Lovers

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Inspirational lines on Society.

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All the video related to Algorithms taught to MIT students.

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DESCRIPTIONS HERE

Here are the most difficult puzzles which are usually being asked to the interview candidates for top companies recruitment.

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Data & Object Factory helps developers succeed with .NET Design Patterns through training, products, and a .NET Design Pattern and Practices community

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.NET Design Pattern Framework for developers and architects

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The only time human brain does multi tasking is when they are listening to others.