Bytes and Bites of Internet
ASP.NET
High Availability in ASP.NET application
Dec 2nd
From Wikipedia,
High availability is a system design approach and associated service implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period.
And it could include multiple database and application server connected in a clustered environment with redundant hardware. One of the method to make ASP.NET application available even if one server goes down it so make your application connect to secondary db server in the even of failure to connect to first server.
This post is to show this concept. (I am not very proud of my programming skills and I prepared this demo app in 15 mins, to please bare with me)
This simple app connects to one DB and if it fails (or gets timeout) it connects to second db. I am using SQL Authentication and this table is same on both Servers.
Crystal Reports in .NET
Nov 5th
Ok, after surviving 5 days without electricity I guess I am ready for new post. We had great storm last week and it caused state wide power outages. Some cities still don’t have electricity yet !! Anyways, this post is about creating basic report using Crystal Reports in ASP.NET
I think Crystal Report has been part of Visual Studio from beginning of time. And it has been very popular reporting tool due to its simplicity and flexibility (compared to SSRS). I personally think that it is more easy to work with compared to SSRS but it still misses features like report management and control. So I like to work with both of them 
.
With VS 2010, MSFT has changed it strategy. They still support CR, but they also has begun to promote SSRS. When you install VS 2010, it doesn’t install CR runtime components, so you will need to download it from SAP website (both Runtime and Controls).
Ok, so I begin with creating empty website project for ASP.NET. And then add web form using add new item. Then add report viewer control to page. Next step is strange but required in order to avoid error. Once control is added to page, close the project and open it again. With surprise you will be presented with upgrade wizard for your crystal report to upgrade to newer version !! If you look at CR, reference in page before upgrade is,
<%@ Register Assembly="CrystalDecisions.Web, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"
Namespace="CrystalDecisions.Web" TagPrefix="CR" %>
Developing ASP.NET Application in MONO under Linux
May 22nd
Today, I was playing with my new install of Linux. I installed Mono in it… (for those who don’t know what is MONO, is a cross platform IDE that can be used to develop .NET application in any environment) .. With my past encounters with Mono, I know that it is sort of complicated to make Mono work properly and you need to configure it specifically to work without glitch 🙂 … but with this newer Ubuntu 11.04, the process was way too simple.
During installation from "Ubuntu Software Center" I can select which add-on I want to install with Mono and everything will be configured automatically !! So only user intervention is just to select which add-on they want. Once you are done with installation you can fire up the application and start coding right away. Well, it is other case if you are way too much habituated with drag ‘n drop Visual Studio environment then you will find it a bit difficult to work with Mono since it doesn’t have VS like rich UI. But I say, it is way better then what you can get in Linux.
Sample Code:
<form id="form1" runat="server">
<asp:Button id="Button" runat="server" Text="MONO" OnClick="Button_Click"/>
<asp:Label id="Label" runat="server" Text=""/>
</form>
protected void Button_Click (object sender, EventArgs e)
{
Label.Text = "Hello Mono !!";
}
I guess this is one more reason to use Linux 🙂 …
That’s it for now ….
Sorting in GridView
Jan 15th
Sorting is kind of very useful information if we want to quickly analyze bunch of data based on columns. And being one of most used control to display data in ASP.NET, GridView can implement easily with few more line of codes (who doesn’t love to write more … right ?? 
)… And in today’s post I am showing how to add functionality to SORT data in GridView. Actually there are many ways to do it and use is kind of personal choice (I am not that deep into efficiency part, so not sure about it YET). Actually this method is kind of consolidation of different posts that I found on web world… so I don’t claim that it is an original invention… consider it as a bit amalgamation of different methods.
This is how it works (I have included the Code file in the end, also just to note I have used Visual Studio 2010 and AdventureWorks sample database which are free to use )…
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" AllowSorting="true" onsorting="GridView1_Sorting"> <Columns> <asp:BoundField DataField="Name" HeaderText="Name" ReadOnly="True" SortExpression="Name" /> <asp:BoundField DataField="City" HeaderText="City" SortExpression="City" /> <asp:BoundField DataField="BirthDate" HeaderText="BirthDate" SortExpression="BirthDate" DataFormatString="{0:d}" /> </Columns> </asp:GridView>
Here, I have set AutoGenerateColumns=”False” … which will allow me to write my own setting of Columns which is kind of more flexible for example, I can set the way DATE column to only include date .. not the time, Or header of columns ! Also I have set AllowSorting=”true”, which will enable sorting. Now even though I have enabled sorting it will not sort data automatically !! we need to add some kind of event handler which will deal will SORT event which is ONSORTING.
Custom error pages in ASP.NET …
Jan 9th
If you have designed even a single application, then you know that it is very difficult if not impossible to code an application that will not generate any sort of exceptions. No matter how hard a developer can try to cover all holes, users will always find way to crash your application and ASP.NET is not an exception to this (I guess that is why testing is crucial component of SDLC.)
In ASP.NET if you get any kind of error you will get really weird message displayed in your web browser. Something like in the screenshot below (Yesss .. I know its IE 9 
). And with just once glance at it you can imagine how great security risk this type of message can be. If you have some kind of database connection string (for which hopefully I assume that password is not hardcoded 
), users might be able to see what’s behind door no. 2. Or at least it wont look “good” either.
And as until your application thoroughly tested by real user, you might never find any weird errors in you app. So, I think it is always good idea to have some kind of mechanism to catch all error that might have missed by your try – catch block !!. In ASP.NET, actually you can design your own error pages called “CUSTOM ERROR PAGES” which kind of provides protection against general errors as well as specific errors (e.g. 400, 401, 403, 500 few to name ). This feature can be really handy if you have really giant application and it may possible that you might have missed some specific scenarios…
How to get user IP address in ASP.NET
Dec 9th
There can be number of ways security and auditing can be implemented in any application. It can be done at Application Level, or at Application Server level or at Database Server Level. And I think best practice is to take advantage of all 3 based on user requirement, as we all know that having little “extra” security always generates burden on system as a whole. Actually it really depends on user requirement, for example some simple quote request form will not have that security features as any bank transaction form will have. (you got the point, right ??)
One way to track user is by IP address. IP stands for Internet Protocol which is basically used to relay (send/receive) information (in form of packets) to network (or internet). It lives at Internet Layer in Protocol Stack. And when any machine is connected in network (here I will use network and internet terms interchangeably for sake of simplicity) it is assigned a unique IP address based on which that machine can be identified. For example 74.125.226.144 will take us to www.Google.com which is more human readable name which is actually an address of a computer that is running Google search engine. (in reality they never use static IP for security, I think it is some sort of proxy server that route requests to main server, this technology has changed very much since the invention of internet) … oki, back to main topic. In short if we get IP address of user, we can always identify user from that because in enterprise network usually each machine is assigned to that person only.
Ajax Control Toolkit and IE 9 Runtime Error
Nov 29th
You guys may be thinking that what the hell is wrong with this guy. First he doesn’t write much and even if he write he always cries about errors he get while working on his things !!! Its always he , he and he … with error error and errors only … but fact is no matter how much I try to code well, I frequently get really really weird errors and being my log, I like to keep track of these errors in this blog.
Oki, so another error today. As you might know, I like to taste things before they release. Actually, I like that because it keeps me updated with new stuffs in technology of present time. So keeping that tradition alive, I had installed IE 9 Beta in my machine from few months now. Just today I was working / playing with my code as usual. actually it was an old program that I was rewriting to do some improvement in functionality. So, after making some changes I tried to run the program, but I got something like this as error Microsoft JScript runtime error: Invalid set operation on read-only property.
I tried to f9 the code and at one point it was showing some that it need some files from my AJAX Control toolkit (I was using many controls from AJAX Control toolkit). But I was not getting any idea what it is really missing. It was showing me error that we see when we are using component of AJAX Control Toolkit but not including Toolkit Script manager. But I have already included Toolkit Script manager into program, and that actually made me confused about error.