Basics of Working With Windows Azure Table Storage

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.WindowsAzure.Storage.Table;

namespace AzureTableStorage
{
    public class EmployeeEntity : TableEntity
    {
        public EmployeeEntity()
        {
        }

        public EmployeeEntity(int id, string name, double sal)
        {
            Id = id;
            Name = name;
            Salary = sal;
            PartitionKey = id.ToString();
            RowKey = name;
        }

        public int Id { get; set; }
        public string Name { get; set; }
        public double Salary { get; set; }
    }
}

Let's now have a look at how objects of the type EmployeeEntity can be stored in an Azure table. Open up program.cs and the following using statements at the top of the file.

using System.Configuration;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Table;

Inside the main method, copy and paste the following code.

string connStr = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connStr);
CloudTableClient client = storageAccount.CreateCloudTableClient();
CloudTable table = client.GetTableReference("employee");
table.CreateIfNotExists();

var emp = new EmployeeEntity(1, "BillG", 123456.33);
TableOperation insertOp = TableOperation.Insert(emp);
table.Execute(insertOp);

The preceding code is pretty simple and self-explanatory. For the code above to read the Azure table connection string, you need to put the right connection string in the app.config file.

<connectionStrings>
    <add 
        name="ConnString" 
        connectionString="DefaultEndpointsProtocol=http;AccountName=XXXXX;AccountKey=XXXX">
    </add>
</connectionStrings>

You can get the values for the AccountName and AccountKey keys from the Storage section of the Azure management portal. Log into your Azure account, go to the Storage section and click the "Manage Keys" link at the bottom. Clicking on "Manage Keys" will open up a popup with all the details that you need to construct the connection string.

Upon executing the program, it will create a table called employee and add an employee entity. You can check whether the employee entity is stored in the table or not by going to the Server Explorer and connecting to your storage account as shown below.

Retrieving an entity from a table

Let's now retrieve the entity that we just stored. Add the following method after the main() method inside your program.cs file. Once added, invoke the method from main() to see if the employee we added to the table can be retrieved or not.

private static EmployeeEntity RetrieveEmployee()
{
    string connStr = ConfigurationManager.ConnectionStrings["ConnString"].ConnectionString;
    CloudStorageAccount storageAccount = CloudStorageAccount.Parse(connStr);
    CloudTableClient client = storageAccount.CreateCloudTableClient();
    CloudTable table = client.GetTableReference("employee");
    table.CreateIfNotExists();
    
    TableOperation retOp = TableOperation.Retrieve<EmployeeEntity>("1", "BillG");
    TableResult tr = table.Execute(retOp);
    
    return tr.Result as EmployeeEntity;
}

Simulating Azure Table Storage on the local machine

First, you need to run a program called DSInit to set up SQL Server or LocalDB as the table storage. When you run the program, it creates a database in the specified SQL Server instance with quite a few tables. To run the program, run the Windows Azure command prompt from the Windows Azure start menu as an administrator. At the prompt, run the following command

DSInit /sqlInstance:<SqlServerInstanceName>

In my case, "SQL Express" is the name of my local SQL Server name. I ran the command as follows.

DSInit /sqlInstance:sqlexpress

The next step is to start the storage emulator from the Start menu. The storage emulator sits quietly in the system tray, but when you open it from the system tray, it is as in the following.

You now need to change the connection string to point to your local Azure table storage setup. The following connection string should work for you.

<connectionStrings>
    <add 
        name="ConnString" 
        connectionString="UseDevelopmentStorage=true;DevelopmentStorageProxyUri=http://ipv4.fiddler">
    </add>
</connectionStrings>

When testing in the local environment, clients are forced to use a web proxy. So, you must run Fiddler (www.fiddler2.com) before you run the program in the local environment. I read somewhere on the internet that this wasn't a requirement in the previous versions of the SDK and is considered a bug by some people. So you may not be forced to use a web proxy when the next version is released.