Client Perspective of Windows Azure Services Platform

Windows Azure was announced on PDC 2008 (Oct 27) and will hopefully be released mid next year. You probably already know about Azure by this time. If no, I would like to quote some from www.azure.com as intro: The Azure Services Platform is an internet-scale cloud computing and services platform hosted in Microsoft data centers. The Azure Services Platform provides a range of functionality to build applications that span from consumer web to enterprise scenarios and includes a cloud operating system and a set of developer services. Fully interoperable through the support of industry standards and web protocols such as REST and SOAP, you can use the Azure services individually or together, either to build new applications or to extend existing ones.

Let us have a quick overview of the clients we usually use in our daily life, then we will explore the potential of Azure and what is waiting for us down to the road:

Windows Client

• Full capabilities, power, rich UI, high performance
• Ability to utilize local resources e.g. audio, camera.
• Capable of blending different hardware and software resulting in amazing applications
• Private data, reliable and fastest
• Personal, trusted and full control

Web Client

• Data accessibility, availability
• Connect with devices, data services, friends
• Sociability, ability to share
• Interaction, collaboration, email, instant messaging
• Searchable
• Data security is questionable
• Open formats and standards for data exchange

Mobile Client

• Low capability compared to regular PC horsepower
• Portable: palm reach
• Smart device while powered by web. e.g. Search for restaurants nearby
• Your 24/7 companion

Smart Client

Did we forget about Smart Clients? These applications are usually Windows Forms application which take all the advantages of Windows Client including offline storage, utilization of local resources as well as the goodness of internet connectivity. The Smart Client was coined few years ago, but for .NET developers all Windows Client is pretty much generally considered as Smart Clients. The idea behind Smart Client was to utilize full local computing capabilities and exploit the web's accessibility, availability and nature of openness through XML Web Services to developers build great software.

Mesh

An important part of Live Services is Mesh, which enables developers to build application for consumer devices which are physically close to them. If you are at home you would be able to access through Windows Client, if you are on the go, you would be through Mobile Client, if you have Internet access only, you would be able to avail the service through Internet. Mesh allows us to get all those devices get connected, exchange data and stay synchronized. You can even add a Mac as device into Mesh to work with. Data communication among devices through Mesh is secured, since the data transferred between them are surely encrypted.

The following screenshots show how you can sync your local PC using Mesh and how your friends can share files or work on files you gave access them to:

Goodness of all Clients

Windows Azure Services Platform is actually an array of technologies, consists of set of tools, and extremely scalable on demand powered by Microsoft datacenters and their ingenious virtualization technology. The core of this platform is to provide user with best experience taking the goodies of each client platform we use in our daily life. Combining the power of HTTP, XML, REST and WebServices Azure lets developers to build cloud enabled applications. The basic advantage of using open and standard protocol for communicating between clients is decreased dependency on the tools, languages or platform of the client. Client could be made by Ruby, Python or it could be in iPhone.

Azure enables you to store your data in the cloud. No matter which client you used to work on your data, if you change your client, time-space, you will be able to get back to the same data once you worked on some other devices/OS.

Why hosting cloud application with Microsoft?

Microsoft has 460 millions Live users to date backed up by hundreds of thousands of servers in their datacenters. How many times have you seen Microsoft's sites down? I have not seen many times in life. So, their ability to host, manage super scalable and high traffic websites is not questionable at all. Who else can be a better host of your next big application other than Microsoft?

Cloudship: Membership Provider for the Cloud

Planning to move to the Azure Cloud, but already tied to the Membership API? I have recently written an article on Windows Azure which guides you to build a complete Membership provider library which can be leveraged by existing application to link to Microsoft’s cloud platform Windows Azure with no friction. Goals of this project were to be able to use regular ASP.NET Login controls, existing Membership code e.g. Membersip.UpadateUser(), MembershipUser.ChangePassword().

Last, but not least one of the major goals was ease of use. No matter which suite of controls you use: ASP.NET AJAX or MVC, Cloudship can be leveraged as your Membership provider. To install it, into your existing application, simply:

1. Reference the DLL
2. Insert few lines inside web.config
3. You are good to go

In this article you will learn how to implement your own Membership API, thus you can start moving you application data to the Azure Cloud – the future of development and business with Microsoft. Here you go - Cloudship: Membership Provider for the Cloud.

Fixing DevelopmentStorage's database cannot be found problem on Windows Azure

This could be a common problem who are not using SQL Express. If you run an Azure application you may find it seeks for SQL Express instance in your machine if you do not have already. You may also find "An error occurred while processing this request." error due to this reason while you try creating tables from your models by StorageClient.TableStorage.CreateTablesFromModel. All you need to do is fire up Visual Studio and open the config file for DevelopmentStorage at C:\Program Files\Windows Azure SDK\v1.0\bin\DevelopmentStorage.exe.config. Now modify the connection string and the dbServer attribute of the service tag for Table, and save.

  <connectionStrings>
    <add name="DevelopmentStorageDbConnectionString"
         connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=DevelopmentStorageDb;Integrated Security=True"
         providerName="System.Data.SqlClient" />
  </connectionStrings>
  
  <appSettings>    
    <add key="ClientSettingsProvider.ServiceUri" value="" />
  </appSettings>
  
  <developmentStorageConfig>
    <services>
      <service name="Blob"
               url="http://127.0.0.1:10000/"/>
      <service name="Queue"
               url="http://127.0.0.1:10001/"/>
      <service name="Table"
               url="http://127.0.0.1:10002/"
               dbServer="localhost\SQLExpress"/>
    </services>
    ...

Restart Visual Studio and open up the Azure project again, now you should be able to run the DevelopmentStorage with the existing database installation of your PC.

jQuery intellisense in Visual Studio

Those who are excited like me about the news of jQuery integration into Visual Studio, started adopting jQuery replacing ASP.NET AJAX Client side API. Microsoft also declared there will be a patch for Visual Studio which will support jQuery as well as intellisene for that. For the enthusiasts who just can't for it, here is the way how we can start developing using jQuery with full intellisense support inside Visual Studio 2008:

1. Download jquery-1.2.6-vsdoc.js

2. Inside your JavaScript files, add a reference to it by placing the following line at the top of the JavaScript file:

/// <reference path="jquery-1.2.6-vsdoc.js" />

That's it. Enjoy!

Simple Form Validation - A Reflection based approach

Are you tired of placing multiple Validation controls on Form? If you are bored of following scenario like me, keep on reading the post:

A simple Email address validation can consist of whether

• The field is empty
• Longer than limit
• Email address format is invalid
• Already in use

Ordinary solution to this problem is placing multiple validation controls for a single TextBox. You can simply it by replacing all with a single Custom Validator. Our goal is to reduce amount of controls on the form to keep it simple. To do that, we would have to write code for Custom Validator that does it all. We also would like to write minimum code to validate the control without compromising manageability. Let us assume we would write the following code inside the ServerValidate of that control:

protected void cvEmailAddress_ServerValidate(object source, ServerValidateEventArgs args)
{
    ValidationController.ValidateControl<ProfileValidator>(cvEmailAddress, ProfileValidator.Fields.EmailAddress.ToString(), args);
}

Let us declare a ValidationErrorResult object that contains error messages and text to display in the UI:

public sealed class ValidationErrorResult
{
    public string ErrorMessage { get; set; }
    public string Text { get; set; }
}

And an Attribute which would be used to tag a specific method which would be responsible for validation of particular control:

[AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = true)]
public sealed class ValidationMethodAttribute : Attribute
{
    public ValidationMethodAttribute(string fieldName)
    {
        this.FieldName = fieldName;
    }

    public string FieldName { get; private set; }
}

If you are already familiar with Attirbute based programming, I hope you know the attribute of this piece of code is in fact ValidationMethod. We will soon see how to use this. The following is the method that checks the value and make a list of ValidationErrorResult that consists of which rules got failed. Notice that the ValidationMethod attribute contains the field name of the object which determines no matter whatever your method name is, that field name helps Validation controller to find this method out for validation.

[ValidationMethod("Email")]
public static List<ValidationErrorResult> ValidateEmail(object value)
{
    var email = value as string;
    var results = new List<ValidationErrorResult>();

    // Blank
    if (string.IsNullOrEmpty(email))
        results.Add(new ValidationErrorResult()
        {
            ErrorMessage = "You did not provide an Email Address.",
            Text = "Cannot be left blank"
        });

    // Length 128
    if (email.Length > 128)
        results.Add(new ValidationErrorResult()
        {
            ErrorMessage = "You exceeded length limit.",
            Text = "Keep it less than 129 characters"
        });

    // Valid Email Address
    if (!Regex.IsMatch(email, "^[\\w\\.\\-]+@[a-zA-Z0-9\\-]+(\\.[a-zA-Z0-9\\-]{1,})*(\\.[a-zA-Z]{2,3}){1,2}$"))
        results.Add(new ValidationErrorResult()
        {
            ErrorMessage = "You provided an invalid Email Address.",
            Text = "Invalid Email Address"
        });

    // Is Already In Use
    if (IsAlreadyInUse(email))
        results.Add(new ValidationErrorResult()
        {
            ErrorMessage = "You provided an invalid Email Address.",
            Text = "Invalid Email Address"
        });

    return results;
}

Here is the ValidationController which goes through the Validation class and looks for the method that has the attribute which validates the control's value.

public class ValidationController
{
    public static List<ValidationErrorResult> Validate<T>(string fieldName, object value)
    {
        var results = new List<ValidationErrorResult>();
        var type = typeof(T);
        var methods = type.GetMethods(BindingFlags.Static | BindingFlags.Public);

        var method = methods.Single<MethodInfo>(delegate(MethodInfo m)
        {
            return ((ValidationMethodAttribute[])m.GetCustomAttributes(typeof(ValidationMethodAttribute), false))[0].FieldName == fieldName;
        });

        return (List<ValidationErrorResult>)method.Invoke(null, new object[] { value });
    }

    public static void ValidateControl<T>(CustomValidator validator, string fieldName, ServerValidateEventArgs args)
    {
        var results = Validate<T>(fieldName, args.Value);

        if (!(args.IsValid = !(results.Count > 0)))
        {
            validator.ErrorMessage = results[0].ErrorMessage;
            validator.Text = results[0].Text;
        }
    }
}

Use your personal blog with Windows Live Writer

I'm very glad to tell you that your ".NET Research" personal blog is compatible with Windows Live Writer. You can compose, format, insert photos inside your posts offline and publish when you become online totally from this client without even opening the ".NET Research" site. Let us the steps to do this assuming you have properly installed Windows Live Writer.

Step 1. Run Windows Live Writer and Weblog > Add Weblog account..

Step 2. Choose another weblog service like the following screen and click Next:

Step 3. Now type http://dotnetbd.org as your Weblog Homepage URL, enter your credential like here I used as admin:

Now Windows Live Writer will download some necessary files to work offline and will appear with a white blank screen for you to write your first post! That's it. These simple two steps will enable you to use this powerful tool to work with your ".NET Research" personal blog. Happy blogging!

LINQ to Flickr

One of my colleagues Mehfuz Hossain developed a wonderful open source project which allows you to query Flickr photos by LINQ, also lets you insert, delete photos directly to/from Flickr. You wonder how to extend LINQ in such an amazing way? It’s easy by writing your own custom LINQ provider, which was not-so-easy until he came up with another handy open source project named LINQ Extender. He did all the expression parsing stuff to ease our pain. Now you can make your own LINQ to Anything using this so easily.

For your heads up on LINQ extenders, here he wrote an article and LINQ to Flickr, open source project is hosted at Codeplex.