As I was migrating my blogs on to wordpress,I just went through all my previous posts.It seems all my posts are just a brief overview ,very brief indeed,on various topics and promising detailed posts in due time.But nothing detailed ever turned up.I guess I have to stick on to the promises and start writing blogs in detail,explore things in detail.

    Not this post but…aaaahh….procrastination!!!!!

    No definitely not  (atleast to keep myself happy ;)).

    But definitely the next post.

    Ps: And it feels better to use wordpress :)

    Need not much of an explanation I guess. The title has it all…. ….a C# API for searching images from google. Works on Regex for matching the image URL from the HTML returned for the image tag search.This might stop working anytime google changes the formatting. Even the current regex is not returning all the images from a page.Working on that though..would be fixed in the next release. I started this to try the AsynEnumerator from PowerThreading Library by Wintellect. I guess i’ve not understood it fully and there is an overuse of it in this version..that too would be looked into the next release.

    Download VS2010 source code (right click and save link as and  rename to .rar) Download VS2008 source code (right click and save link as and  rename to .rar)

    PS: Since the search results format is changing often the code might not work sometimes.Doing my best to keep it updated and working.Do check the comments too to see if the regex match string is changed.Sometimes I might not get time to update the solution,but would just leave a comment.Latest comment should be the best to match with :)

    *Conditions Apply: might be there :)

    Quite often in the client-server model,the requirement of getting notified of certain changes in the server pops up.Say for example in the movie ticket booking system.When a person selects a seat for booking,the selected seat should become disabled for all the users currently logged in,so that you can avoid the message ‘Sorry the seat you were trying to book is already booked’.
    In such scenarios polling the server for changes might be one way to go about it.
    Another way might be the server calling back to all the clients when a seat selection happens.
    This post is about the second way and when the booking system is developed using WCF :)
    The WCF framework provides a easy way to achieve this…..Callbacks

    The whole concept is simple.The server keeps track of all the active clients and knows how to call them when the required change happens in the server.
    Again its all about certain interfaces that you have implement and some attributes that you have to specify.
    The ServiceContract that the client exposes also specifies the CallbackContract type.This is again another interface that the client needs to implement so that the server knows the type of client it is serving and can call back the functions on that interface.
    This is much more like the eventing model.All functions in the CallbackContract would be like your event handlers,which would be invoked by the server on a particular event happening in the server.
    You can go ahead and create a Publisher-Subscriber framework itself so that any future requirements of such nature would be easy to implement
    This article by Juval Lowy suggest a good way to implement a publisher-subscriber framework in WCF using callbacks.

    The code provided below shows a quick example of Callbacks.Run minimum of two clients,so you get to understand what it is all about :)

    Code Download

    Introduce Foreign Method(IFM) and Introduce Local Extension(ILE) are two refactoring techniques that comes handy when you need to add functionality to an exisiting class,source code of which is beyond your control. IFM is used when its just one or two functions that you need to add to the class.When the number of functions,that are to be added are more,then ILE is used.Not a rule though :) But now with Extension Methods the whole process is much more simpler. You need not do the subclassing or wrapper technique of ILE. This can be a third way of implementing ILE :).Thanks to the framework team for keeping it simple. The same date example using the ‘Extension Methods’ way of refactoring

    public static class MyExtensionMethods
       {
         public static DateTime NextDay(this DateTime date)
         {
          return new DateTime(date.Year, date.Month, date.Day+1);
         }
       }

    The function NextDay is now available on any DateTime object,just as if you have written if you had access to the source code. It’s the usage of ILE and IFM that has paved way for the inclusion of Extension Methods in the framework I guess.Thanks to Fowler for that. CodeProject

    Over the days I have been reading on Test Driven Development(TDD) and it seems really interesting methodology to go with as per development is concerned.
    Basic of TDD is that the development process relies on ‘tests’, that are written prior to code.
    Sounds astonishing!!!!
    It might to someone into the normal development mode,where tests are usually written after code, so as to match the code that is written.
    But TDD says just the opposite.
    Code to make the tests pass…Just pass..Nothing more and Nothing less.
    Thats where the catch is where most of we developers might find it difficult and needs getting used to.Not getting more into it as I would not be the best to comment on it :)
    So whats refactoring got to do here.
    Refactoring plays an integral part of TDD,so that the code is elegant and conveys just what it needs to,avoiding duplication.
    The TDD approach also assists in refactoring as you have tests readily available to assure that the functional behaviour is not affected while changing the code design.You are just click of a button away if you are having a automated test scripts (like nUnit) in veryfying refactoring.
    So both TDD and Refactoring goes hand in hand and helps in greatly improving the overall code quality.
    There are quite a lot resources out there on these.
    The best for refactoring would be of Refactoring: Improving the Design of Existing Code.
    For TDD Test-Driven Development in Microsoft .NET (Microsoft Professional) would be a good start and also the one by Kent Beck Test Driven Development: By Example

    It’s not uncommon to have problems in life, and so in the application/code that you write. I am not being too techie here. It’s just I am relating my thoughts to something technical. Being a software engineer, writing code is inevitable in my day-to-day life and so comes bugs :) I spend a lot of time sitting on to solve bugs(of late it’s been eating away my head) and so do I see people around me, at my workplace, doing the same.

    I always go in seek of the problem that caused the bug, rather than to find a solution for the bug. Certain others go in seek of the solution for the bug, rather than the problem that caused the bug. So am I not saying the same thing in two different ways….solving the bug!!!! But they are not…at least for me :)

    Seeking for the problem gives you the solution for the bug and also a better understanding of the code that you have written. You seek for the problem because you feel the mistake is at your part, maybe a implementation one or a logical one. Seeking for the solution too solves the bug but does not give you a better understanding of that you have done. Mostly the solution might be a workaround to cover up some of your own mistakes, which went unnoticed, as you were too concerned of the solution for the bug and not the problem for the bug. This might really not solve the bug too, it might just be a temporary fix or a specific scenario fix.

    This is just an example. Same goes in the day to day life. Whenever you go in seek for solutions you are actually creating more problems for yourself. Maybe a real life example(non technical :)) would do good. Say you are a spendthrift and you keep spending away all what you get. Need money urgently?? Solution is to borrow from your friend. Does it really solve the problem?? Nope !! The problem here is that you are spendthrift. So try to change that and not keep borrowing :).

    Don’t be happy with the solution, hunt down the problem. Happy hunting :)

    suarez_world_cup_2010 Luis Suárez….that name would be said few more times, at least till Uruguay’s fate is decided in FIFA WC 2010.Early Saturday morning(IST),witnessed some dramatic moments of WC 2010.With the game about to be pushed into the shootout,which it did end up eventually,Ghana was to score a goal of substitute Dominic Adiyiah’s header which was denied by Suárez with his ‘hands’.The drama ended as Asamoah Gyan struck the crossbar for the penalty awarded and the match moved on to shootout,which saw Uruguay through to the best 4….shattering the African hopes.
    Is he a Hero or a Cheat????
    Wasn’t it something anyone would have done?
    Wasn’t that a reaction rather than a response to a situation?
    Ghana could have scored in the penalty awarded.But is just a penalty enough instead of a sure shot goal?

    Would it be the next ‘Hand Of God’??

    Hero Or Cheat,fouls are committed knowingly and unknowingly in any game,as in football,as in this dramatic game.

    So the play goes on says referee and so does Uruguay without him into the final 4

    edit: Not too far says Netherlands,putting an end to the Uruguay’s tale of WC 2010

    Database Synchronization Updating an old database, with newly created/modified database objects(mostly stored procedures,views,functions and table value parameters), from a new database was a very common,tedious,error prone task that was performed at my workplace for the past few months.This came up with the client requesting to retain their existing data and just make updates to their old database from our development database(which of course is the new/latest one), whenever a deliverable was made.
    When the very work I do is to automate peoples work,I felt perturbed seeing this being done manually.So decided on to automate it :)
    Writing SQL scripts would be db expert way I guess.But I am no expert in that so decided to do it in my way.
    The .Net way :)
    Thanks to the whole concept of .Net and Microsoft for having exposed such complex functionalities in the most elegant way ….. SMO(SQL Server Management Objects).
    You have to add a reference to Microsoft.SqlServer.Smo and a few other assemblies(Check the source code for more details).
    Rest everything the API provides.

    Code quality might not be that good.Just did it in an hour :)
    A help is there within the app.

    Thanks to .Net once more :)

    RBAC(Role Based Access Control) is something that is very common in the day-to-day world.
    So what is this all about.It is just about a authorization check on whether you have the access to a particular resource or not.
    When faced with scenarios like this when developing applications, where you have to implement Role based access for the different users that are to use the system you might be confused on how to implement this.
    Say you have a WCF service exposing a set of services.You have a WPF thick client consuming this service.Say for example you are exposing a service to Add/Delete/View Employees.Based on the various roles you need to allow/disallow the access to the functionality.The easiest way would be enable/disable the controls that would be used invoke the corresponding functionality,based on the user role.
    So am I done?
    What if tomorrow you are exposing this service to some other client of yours,who is to develop his on User Interface(UI) for the service.
    Do I have a problem here?
    Yes of course!!!
    What if he does not make the same check on the UI to enable/disable the controls that would act as his inputs.So here exactly is where you have a access break.Any user will be able to perform all functions irrespective of the access specified for him.
    So how do I go about?
    Make this check at the service level itself.Check for access and throw a NoAccess exception if not authorized.What exactly happens when you try to enter a no-access area in your office :)
    UI synchronization is an added level to this,so that you can stop unnecessary service calls.

    Will soon post a implementation sample :)

    visual studio debug not working Quite a few days back,I faced a peculiar problem :).Visual Studio was not having the green play button(the one for Start Debugging) enabled.No way was I able to start debugging.
    Google gave many suggestions,none was of help.
    I soon found out that,in Startup Projects(From the menu Project -> Properties),the option multiple was selected and all the projects were set to an action None)(Setting this to Start Without debugging also creates this same problem) :)

    Yet to find out how this happened automatically but still setting up the startup project,made the green button glow :)

    Be sure to check this the next time if the green button doesn’t glow :)