Introduction to JSON

What is JSON

Json Stands JavaScript Object Notation.

JSON is a lightweight text-based open standard data-interchange format.

JSON files are saved with .json extension. Internet media type of JSON is "application/json".

JSON is derived from a subset of JavaScript programming language (Standard ECMA-262 3rd Edition—December 1999).

It is entirely language independent and can be used with most of the modern programming

Similaries between XML & JSON

No end tag like XML

Shorter than XML

Quicker to read and write when compare to XML

Can be parsed using built-in JavaScript functions like eval() and parse()

Uses arrays – Efficient for handling huge data

No reserved words

Data Types in JSON

JSON supports following datatypes:

Number

String

Boolean

Array

Object

JSON Syntax

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How to - Solve SQL Server 2012 Identity Problem. Identity increased from 6 to 1000 ............

During application development, we often input dummy data into our database for testing purposes. But then we we want all records of the table to be deleted and also want to start the identity column values from 0. For this, we delete the truncate command. This will delete data from table and also reset the identity column value to 0.

Example

truncate table [table_name]

truncate table product

But truncate command fails to delete the data if there is a relationship given to the table and the identity column is not reset.

So, in this case, first you need to delete data from the child. 

After deleting data, fire this command and it will reset 

your identity column to 0.

DBCC CHECKIDENT('[table_name]', RESEED, [new_reseed_value])

-- for example

DBCC CHECKIDENT('product', RESEED, 0)

Question

Say I have a table which uses an int auto identity as a primary key it is sporadically skipping increments, for example:

1, 2, 3, 4, 5, 1004, 1005

You can use below two choices

Use trace flag 272 , this will cause a log record to be generated for each generated identity value. The performance of identity generation may be impacted by turning on this trace flag.

Solution 1:

     1. Open "SQL Server Configuration Manager"

      2.                Click "SQL Server Services" on the left     pane

     3.                Right-click on your SQL Server instance name on the right pane ->Default: SQL Server(MSSQLSERVER)

    4.               Click "Properties"

    5.                Click "Startup Parameters"

    6.               On the "specify a startup parameter" textbox type "-T272"

   7.               Click "Add"

8.Confirm the changes 

CLICK ON aDD bUTTON

And then restart your sql server.

Use a sequence generator with the NO CACHE setting

solution 2

CREATE SEQUENCE MySeq AS int

  START WITH 1

  INCREMENT BY 1

  NO CACHE;

Installation of SQL SERVER 2012 ( In Windows 8 operating System)

In windows 8 operating system

first install windows 7 service pack1  and then install sql server .

Otherwise u might get an error as sql server cluster fail over

Select New SQL SERVER STAND ALONE INSTALLATION .

Click on Ok

Click on Next

Click on Next

Click on Next Button

Click on Install Button

Click on Next

Click on Next Button

SELECT ALL (Click on SELECT ALL BUTTON) and click on Next Button.



Click on Next Button

Click on Next Button



Server Configuration:

Click on Next Button

select Mixed Mode and enter password.

Click on Add Current User and Click on Next Button



Click on Add Current User and Click on Next



Click on Next Button



Click on Add Current User and Click on Next

Controller Name: leave empty
Click on Next

Click on Next Button
the following screen appears and click on Install.

REST BASED SERVICES USING WCF

REST stands for Representational state transfer

Very popular for services

Principle: is if there is any resource then everyone has to access that resource. Rest also defines that URL should be friendly.

http://sitename/service/getjobs

http://sitename/service/Add/Job/1/Programmer/10

REST URL should be as must as plane URL

REST is the term coined by Ray Fielding in PH.D to describe an architecture style of networking systems.

There are Rest services & Rest –Like services which uses XML and HTTP.

Rest outlines the philosophy of mapping.

HTTP Verbs to Create, retrieval, update, delete

Rest is not only for services, it is the for Html 5.

Rest architecture says everything should be a resources.

Rest say we will develop a program and give the URL to everyone.

REST is not approved by W3 till now.

Note:

When we talk about the Database as a resource we usually talk in terms of CRUD operations. I.e. Create, Retrieve, Update and Delete. Now, What REST says is that for a remote resource all these operations should be possible and they should be possible using simple HTTP protocols

Actually only the difference is how clients access our SERVICE .Normally, a WCF service will use SOAP, but if you build a REST service, clients will be accessing your service with a different architectural style (calls, serialization like JSON, etc.)

We have to prepare help File for Rest for the client, saying that what are the methods somewhat we have to give the reply to client.

Now the basic CRUD operations are mapped to the HTTP protocols in the following manner:

·         GET: This maps to the R (Retrieve) part of the CRUD operation. This will be used to retrieve the required data (representation of data) from the remote resource.

·         PUT: This maps to the U (Update) part of the CRUD operation. This protocol will update the current representation of the data on the remote server.

·         POST: This maps to the C (Create) part of the CRUD operation. This will create a new entry for the current data that is being sent to the server.

·         DELETE: This maps to the D (Delete) part of the CRUD operation. This will delete the specified data from the remote server.

Now, the list of Employee Details can be retrieved as

www.WebsiteName.com/Employees

To retrieve specific employee details from the Employee Table we have an Id Column in the database. To access the details of particular employee

www.WebsiteName.com/Employees/1

Since these are GET requests, data can only be retrieved from the server. To perform other operations, if we use the similar URI structure with PUT, POST or DELETE operation, we should be able to create, update and delete the resource from the server. 

WCF Rest supports for REST

        Programming Model

        WebGetAttribute

WebInvokeAttribute

WebServiceHost

Channels & Dispatcher Infrastructure.

WebHttpBinding

WebHttpBehaviour

Utility Classes & Extensibility Points

        Uri Template

       Uri Template Table

        Query String Converter

        WebHttpDispatchOperationSelector

WebGet:

Is the attribute which make our [Operation Contract] as web method enabled to consume as Rest Style & Binding is WebHttpBinding

[WebGet]

[Operation Contract]

Void Add ();

Web InvokeAttribute:àWeb Get +All Others

Now, How to Call this Method

http://sitename/servicename.svc/Add

Here Add is the method name

If it returns string, we will get result also as string.

WebServiceHostFactory

To make Rest Enabled all the following things are required

System.ServiceModel.dll

System.ServiceModel.Web.dll

To make URL as Friendly we use uri Template

Example

http://site/service/Add?a=10&b=20

It is not friendly URL

So friendly URL is

http://site/service/Add/10/20

To make URL as friendly:

[WebGet(UriTemplate=”Add/{a}/{b}”)]

[operationContract]

Void Add(int a, int b)

Note: Webhttpbinding does not support SOAP format. what format is Json,pox

In visual studio 2010 we have two ways to create Restful Services:

Start a WCF Service as usual and add Operation Contract as required

Additionally add Rest attribute that is web get /web invoke

System. Service model namespace & system. Service model. Web namespaces to be added.

Go to web.config and add End Points with WebHttpBinding only. 

This binding is enough for consuming and also hosting.

Go to service directive .svc file and add factory=”webservicehostfactory” attribute to this directive.

Difference between Web Services, WCF, WCF Rest

Web Service:
 It is based on SOAP and return data in XML form.

    It support only HTTP protocol.

   It is not open source but can be consumed by any client that understands XML.

It can be hosted only on IIS

WCF

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 application or on IIS or               using WINDOWS SERVICE. 

WCF REST

  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