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  • aftab 4:01 am on June 5, 2009 Permalink | Reply
    Tags: planix, planning poker, , software estimation, tagets   

    An Interesting Discussion on Software Estimation 

    Scott Hanselman has an interesting discussion on the ever elusive mirage of accurate software esitmation here.

    It also points to a number of software estimation techniques like Wideband Delphi, Proxy etc along with softwares that can help you with the estimation, like Planix, planningpoker, Steve McConnel’s Construx Estimate and SpreadsheetGear.

    The post is very accurately titled as Software Estimation: Remember that Targets are not Estimates.

    I liked the quote from Steve McConnel’s Book, Software Estimation: Demystifying the Black Art:

    Considering that optimism is a near-universal fact of human nature, software estimates are often undermined by what I think of as a Collusion of Optimists. Developers present estimates that are optimistic. Executives like the optimistic estimates because they imply that desirable business targets are achievable. Managers like the estimates because they imply that they can support upper management’s objectives. And so the software project is off and running with no one ever taking a critical look at whether the estimates were well founded in the first place.

    This post is a nice reminder that, Targets are not estimates.

    Happy Programming!

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  • aftab 11:58 pm on June 4, 2009 Permalink | Reply
    Tags: Agile Development, agile estimation, extreme programming,   

    A very quick guide to Agile Development 

    Here at RocketResearch.com you can find a very quick overview of agile development,

    It has everything to get a quick head start,  like a five minute guide to scrum, getting started with XP, agile estimation etc.

    Happy Programming!

     
  • aftab 5:50 pm on June 2, 2009 Permalink | Reply
    Tags: Ajax, asp.net, callback, clientside, ecmascript, ICallbackEventHandler, javascript   

    Client Callbacks in ASP.Net 

    By Default ASP.Net pages communicate with the server through a mechanism call “PostBack”. Postback is very useful and efficient, except for the cases, where 1) You have a huge page, with a lot of processing required at server, so doing all that processing on every postback is not only waste of resources on the server, but also hurts the user experience. 2) You have client side variable, which will be lost on page refresh(i.e. postback).

    You can avoid both these limitations by introducing Client Callbacks in your application. In a client callback a client side event makes a request to the server, at server the page is initiated, it members are created, however page runs a modified version of its life cycle and only method that is marked for invocation is called; that, then can return a value that can be read using another client side function.

    Through out this process, page is available to the user and results are quick in most of the cases as on a small amount of data is being exchanged between client and the server.

    To implement client callbacks you need to do some work both on server side as well as client side.

    On server side, you need to:

    1. Implement ICallBackEventHandler in the page, that you want to use callbacks in. It have two methods i.e. RaiseCallbackEvent and GetCallbackResults
    2. Provide implementation for RaiseCallBackEvent, this is the method is invoked by the client to perform callbacks. This method accepts string as an argument.
    3. Provide implementation for GetCallbackResults, this method is invoked by the server, to process the request and return the results to the client as a string
    4. Retrieve a reference of a client side function (Using ClientScript.GetCallbackEventReference method), this function will be invoked as the result of server side processing, and it can be used to process any results coming back from server
    5. Register a client side script, using Page.ClientScript.RegisterClientScriptBlock method, that will make a call to the server. 

    On ClientSide, you need to:

    1. Implement the function that you provided as an argument in step 4 above
    2. Call the function you registered in step 5 above, on a client side event.

    Lets look at the code that you will use to implement your client call backs. In our demo project, we have two comboboxes on our asp.net page. One contains a list of departments and other a list of employees in the selected department. What we want to do is, fill employee combobox with the respective department employees, whenever our user changes department in Department combobox, without doing a postback.

    First things First; Implement ICallbackEventHandler interface

    public partial class _Default : System.Web.UI.Page,ICallbackEventHandler

    Implement two methods of ICallbackEventHandler

    #region ICallbackEventHandler Members
        /// <summary>
        /// this method Returns the results of a callback event.
        /// </summary>
        /// <returns></returns>
        public string
    GetCallbackResult()
        {
            //as only strings can be sent back to the client, we are will iterate through the list of
            //employees and convert it into comma delimited string
            string employeelist="";

            foreach (Department dept in departmetList)
            {
                if (dept.Name == deptArg)
                {
                    foreach (Employee emp in dept.Employeelist)
                    {
                        employeelist += emp.Name;
                        employeelist += ",";
                    }
                }
            }

            return employeelist;
        }

        /// <summary>
        /// This method is invoked by the client, this will be used to receive parameter values from the client
        /// </summary>
        /// <param name="eventArgument"></param>
        public void
    RaiseCallbackEvent(string eventArgument)
        {
            //right now all we are doing is to set the class level variable to eventArgument
            //that was sent by the client, recall that it is departments name.
            deptArg = eventArgument;
        }

    In your page_load event handler, first retrieve the reference of client function that will be invoked as the result of call back using ClientScriptManager.GetCallbackEventReference,

    string callbackEventReference = Page.ClientScript.GetCallbackEventReference(this, "arg", "GetResults", "");

    this method has several overloads, the one we have used takes target (in this case “page”), the “argument” that was passed by the client, name of the client side event handler that received the result of callback event and context as arguments. Context is any client script that will be evaluated prior to making a callback request. In this case we have passed an empty string.

    Then you need to build and register a client side script, that will call this CallBackEventReference, this is the script that will make the call to the server.

    string callbackScript;

    callbackScript = "function CallServer(arg){" + callbackEventReference + ";}";

    //register callbackScript with the client using ClientScriptManager.RegisterClientScriptBlock
            Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "CallServer", callbackScript, true);

    So this was all that you need to do in our server side code, and now we will look at the client side code that we need to write to complete our client Callback.

    First we will write the function (using ECMAScript) in script block of our aspx file, GetResults; that we have been referencing in our code above,

        function GetResults(result)
        {
            if(result!="")
            {
            var array=result.split(",");
            for (var i=0;i<array.length;i++) {
            option = new Option(array[i],array[i]);
            var slc_target = document.getElementById("ddlEmployee");
            slc_target.options[i] = option;
            }       

            }
            else
            {
            //do something
            }
        }

    This function is accepting results; which is a string and it is splitting it into an array. Then all it does is, bind “ddlEmployee” a combobox on the page, with this array.

    and finally on a client side event of another combobox, “ddlDept”, we will invoke “CallServer” client side function that we registered using our serverside code and we will pass department as an argument.

    <asp:DropDownList Width="100" ID="ddlDept" runat="server" OnChange="CallServer(ddlDept.value)">

    I have attached the demo VS 2008 sollution here, when you run the project, you can see that, whenever you change any value in the Department Combo box, values in Employees combobox are refereshed without making a postback to the server.

    Download demo project here

    And Happy Programming!

     
    • RRaveen 10:36 am on July 2, 2009 Permalink | Reply

      Dear Friends,

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      Thank you
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      Founder CodeGain.com

  • aftab 4:47 am on June 2, 2009 Permalink | Reply
    Tags: developer, great, skills,   

    15 Tips to be great software developer 

    I just bumped into a great article by Miguel Angel Carrasco of http://www.realsoftwaredevelopment.com. It put forwards 15 tips, that if followed help you become not just good software developer but Great Software Developer, here is a summary and you can check the whole article here.

    1. Great quality code at lightening speed
    2. “100%” Correct interpretation of problem
    3. Look at the solution(s) from all possible angles before you start coding.
    4. How much confidence your manager has in your code
    5. How much confidence others have in your solution
    6. Always meet users requirements
    7. Staying up to date
    8. Contributions towards the team
    9. Make great meeting minutes
    10. Be teachable and take criticism well
    11. Be always available when needed
    12. Dress professionally everyday
    13. Communication abilities
    14. Goal Settings skills
    15. Organizational skills

    Great list, Good job Miguel Angel Carrasco

     
    • davidlongstreet 7:08 pm on October 1, 2009 Permalink | Reply

      I find it interesting that knowing something about the business problem or business domain did not make it on the top 15 list towards being a great software developer.

      Those software developers who know the business domains are treated as partners towards a business solution instead of just a coder.

      David Longstreet
      http://www.RebootRethink.com
      davidlongstreet.wordpress.com

    • aftab 11:35 am on October 3, 2009 Permalink | Reply

      You have an interesting point and i agree with you, however if we go back to the Carrasco’s list, #2 and #6 are not possible until you have good knowledge of business domain.

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