Leniel Macaferi's blog

User Password Expired filter attribute in ASP.NET MVC

2012-05-24T00:32:00.001-03:00

A recent set of requirements I’ve been playing with deals with passwords. This one specifically handles password expiration.

Given that I’m working with ASP.NET MVC I know I can rest assured that there’s some great (read awesome) way of implementing a given requirement. This is exactly what happened and I want to show you how to have a clean and beautiful solution to this problem.

So my client’s requirement is the following:

Passwords should expire in 45 days.

I’m currently using the default ASP.NET membership provider. It gives you a database schema ready to manage users and roles. You just have to use ASP.NET Configuration Tool to create Roles and Users, decorate your Controllers/Actions with the Authorize attribute and you’re good to go most of the time. The default membership provider allows a fast project start – no doubt – but as always there’s something that must be done according to the infinitude of possible requirements that change project by project. One of these not contemplated things is a setting in the default provider for handling user’s password expiration. We have to roll our own code to manage this.

My friend Google told me that some folks have already done some work related to this and as always I borrow some of their code and adapt it to my specific case/technology.

First I created a PasswordExpiredAttribute that derives from/extends the AuthorizeAttribute. Here’s its code:

public class PasswordExpiredAttribute : AuthorizeAttribute
{
    private static readonly int PasswordExpiresInDays =
int.Parse(ConfigurationManager.AppSettings["PasswordExpiresInDays"]);

    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        IPrincipal user = filterContext.HttpContext.User;
           
        if(user != null && user.Identity.IsAuthenticated)
        {
            MembershipUser membershipUser = Membership.GetUser();

            TimeSpan ts = DateTime.Today - membershipUser.LastPasswordChangedDate;

            // If true, that means the user's password expired
            // Let's force him to change his password before using the application
            if (ts.TotalDays > PasswordExpiresInDays)
            {
                filterContext.HttpContext.Response.Redirect(
                    string.Format("~/{0}/{1}?{2}", MVC.Account.Name, MVC.Account.ActionNames.ChangePassword,
                    "reason=expired"));

            }
        }

        base.OnAuthorization(filterContext);
    }
}

As you see, the code goes inside the OnAuthorization overridable method. I get the PasswordExpiresInDays setting from the Web.config <appSettings> section. This gives an easy way to change the requirement in the future without the need of recompiling the whole app.

<appSettings>
    <add key="PasswordExpiresInDays" value="45" />
</appSettings>

The code explains itself but let’s go through it:

1 - If the User is authenticated, let’s get his membership data;
2 - A TimeSpan is useful for getting the difference in days between Today and the last time the user changed his password ( LastPasswordChangedDate )
3 - Check if the TimeSpan.TotalDays is greater than the PasswordExpiresInDays setting we got from the Web.config file. If true the user must change his password and we redirect him to the ChangePassword view.

Note 1: I’m using T4MVC to retrieve the Controller and Action names in the code above. You should take a look at it! Really…

Note 2: See that "reason=expired" in the response redirect URL? I’m using this querystring as a route parameter inside the ChangePassword action method to display a message to the user informing him that he’s being asked to change the password because it has expired.

/// <summary>
/// This allows the logged on user to change his password.
/// </summary>
public virtual ActionResult ChangePassword(string reason)
{
    var viewModel = new ChangePasswordViewModel();

    if (reason != null)
    {
        ShowMessage(Infrastructure.Notification.MessageType.Warning, Localization.PasswordExpired, true);
    }

    return View(viewModel);
}

By the way: I use MvcNotification infrastructure by Martijn Boland to display beautiful messages to the user.

OK, getting back to the main point… now it’s just a matter of applying the PasswordExpiredAttribute filter to every controller of the app but the AccountController. With ASP.NET MVC 3 it’s easy to apply a filter to every controller and action using GlobalFilters. Instead of going controller by controller to add this attribute we can just register it as a global filter in the Global.asax file:

public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
    filters.Add(new HandleErrorAttribute());
    filters.Add(new AuthorizeAttribute());
    filters.Add(new PasswordExpiredAttribute());
}

Doing so the PasswordExpiredAttribute will be executed for every controller and action but there’s a problem with the above approach. Since it’s a global filter, it’ll be executed even for the AccountController. Remember: we don’t want it to be executed for the AccontController… How can we exclude a global filter from a single controller or action? To achieve this, there’s an awesome thing we can do: create a ExcludeFilterAttribute and a ExcludeFilterProvider. WOW, ASP.NET MVC has a Filter Provider that gives us even more power when working with filters. Look here for the complete story: Exclude a Filter by Ori Calvo. I’ve uploaded the source code files here: ExcludeFilterAttribute.cs and ExcludeFilterProvider.cs

Now it’s just a matter of decorating the AccountController with the ExcludeFilter attribute like this:

[ExcludeFilter(typeof(PasswordExpiredAttribute))]
public partial class AccountController : BaseController
{
   ...
}

The ExcludeFilter attribute explicitly tells the ASP.NET MVC runtime to ignore the PasswordExpiredAttribute for the AccountController.

With this in place, once the logged in user tries to access any part of the site and his password is expired, he'll be redirected to the ChangePassword view and won't be allowed access to anywhere else in the site until he changes the password. This is great and the requirement is implemented.

Of course in software there are multiple ways of doing the same thing. If you know of any better option, please share you knowledge in the comments.

Hope it helps.

Bonus
While working on this requirement I posted a question at StackOverflow regarding the use of Web.config settings as magic strings. I’ve found a nice way to let the code a little bit cleaner. So, if you want a nice way to access your Web.config app settings as properties with compile time checking and nice error handling, you can do as described here: T4MVC for Web.config <appSettings>

This is a much better/cleaner code IMO (see the AppSettings class that was automatically generated with the T4 template):

public class PasswordExpiredAttribute : AuthorizeAttribute
{
    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        IPrincipal user = filterContext.HttpContext.User;

        if (user != null && user.Identity.IsAuthenticated)
        {
            MembershipUser membershipUser = Membership.GetUser();

            TimeSpan ts = DateTime.Today - membershipUser.LastPasswordChangedDate;

            // If true, that means the user's password expired
            // Let's force him to change his password before using the system
            if (ts.TotalDays > int.Parse(AppSettings.PasswordExpiresInDays))
            {
                filterContext.HttpContext.Response.Redirect(
                    string.Format("~/{0}/{1}?{2}", MVC.SGAccount.Name, MVC.SGAccount.ActionNames.ChangePassword,
                    "reason=expired"));

            }
        }

        base.OnAuthorization(filterContext);
    }
}

References:
ASP.NET MVC Authentication - Global Authentication and Allow Anonymous by Jon Galloway

ASP.NET MVC Authentication - Customizing Authentication and Authorization The Right Way by Jon Galloway

Exclude a Filter by Ori Calvo

Introducing System.Web.Providers - ASP.NET Universal Providers for Session, Membership, Roles and User Profile on SQL Compact and SQL Azure by Scott Hanselman

Conditional Filters in ASP.NET MVC 3 by Phil Haack

T4MVC by David Ebbo

Resize image on the fly with ASP.NET MVC

2012-04-26T01:26:00.001-03:00

I built a piece of code sometime ago and today I decided to optimize it.

My use case is this: a user can upload some photos of his house for example. Image dimensions (height x width) are not restricted. The user can upload any photo as long as its size is less than or equal to 750 KB.

Then, I have a listing page (Index.cshtml) that has a WebGrid. The grid shows realties available for sell, rent, etc. In this grid I want to display just a thumbnail of a given photo (the first one I grab as per code bellow) for each realty. I placed a constraint such that the thumbnail dimensions must be 100x100 pixels. Of course one shouldn’t load the full size version of a photo just to show it on the grid. The grid has 10 rows per page and if the images are on the range of 500 KB, the load put on the user connection to transmit all those photos from the server to the client would be high: 10 x 500 KB ≃ 5 MB. This would be an unresponsive page! No doubt…

Googling a little bit I stumbled upon something I didn’t know yet. It’s called WebImage and comes in System.Web.Helpers just as the WebGrid I discussed earlier. With this little kid on the block, one can have a controller “action” that does something like this:

public void GetPhotoThumbnail(int realtyId)
{
    // Loading photos’ info from database for specific Realty...
    var photos = DocumentSession.Query<File>().Where(f => f.RealtyId == realtyId);

    if (photos.Any())
    {
        var photo = photos.First();

        new WebImage(photo.Path)
            .Resize(101, 101, false, true) // Resizing the image to 100x100 px on the fly...
            .Crop(1, 1) // Cropping it to remove 1px border at top and left sides (bug in WebImage)
            .Write();
    }

    // Loading a default photo for realties that don't have a Photo
    new WebImage(HostingEnvironment.MapPath(@"~/Content/images/no-photo100x100.png")).Write();
}

Calling the .Write() method does the magic. As you can see, I’m not saving the thumbnail in the disk, that is, a new image is generated on the fly/dynamically and sent to the user’s browser. Amazing…

In a view using the Razor syntax one would have something like this to display the photo:

<img src="@Url.Action("GetPhotoThumbnail", new { realtyId = item.Id })" width="100" height="100"/>

Another useful variation/overload of the above action method is this one (even more dynamic):

public void GetPhotoThumbnail(int realtyId, int width, int height)
{
    // Loading photos’ info from database for specific Realty...
    var photos = DocumentSession.Query<File>().Where(f => f.RealtyId == realtyId);

    if (photos.Any())
    {
        var photo = photos.First();

        new WebImage(photo.Path)
            .Resize(width, height, false, true) // Resizing the image to 100x100 px on the fly...
            .Crop(1, 1) // Cropping it to remove 1px border at top and left sides (bug in WebImage)
            .Write();
    }

    // Loading a default photo for realties that don't have a Photo
        new WebImage(HostingEnvironment.MapPath(@"~/Content/images/no-photo100x100.png")).Write();
}

Then, in the view one would call the action passing the width and height variables as per requirement:

<img src="@Url.Action("GetPhotoThumbnail", new { realtyId = item.Id, width = 100, height = 100 })" />

There are a handful of available functions in a WebImage. You should really check them out.

You can find more insightful info about the WebImage class reading this post by Gunnar Peipman: ASP.NET MVC 3 Beta: Simple image manipulations using WebImage helper

Note: there really are better ways of handling this kind of situation (adding image caching, etc – see ImageResizer) but for the site I’m working on, the solution I show in this post is sufficient and pretty responsive right now.

Hope it helps.

Hide table column and colorize rows based on value with jQuery

2012-03-23T19:29:00.001-03:00

This is a handy piece of code that I used last year in one of my projects. I had scheduled to post it but it was just after I saw this question at StackOverflow that I decided to write about it. So here it is…

Let’s say you want a nice UI experience and to achieve that you wanna colorize/highlight a table row according to a given value present in a column of this row.
This is a simple task when we use jQuery.

I use the WebGrid that comes with ASP.NET MVC to display data on a web page using an HTML <table> element. It’s available in the namespace System.Web.Helpers. The approach described in this post is useful not only with the WebGrid but with any framework/language you use to output HTML code since the manipulation is done on the client side with jQuery.

Take this screen as an example:

Figure 1 - HTML table with last column Active to be hidden displaying values Yes and No

We want hide the last column “Active” and color the row which has a value Yes in this same column.

The above statement can be accomplished with the following code:

(function ($)
{
    hideColumnColorRow = function (column)
    {
        $('td:nth-child(' + column + '),th:nth-child( ' + column + ')').hide();

        $('tr').find('td:nth-child(' + column + '):contains(Yes)').parent().css('backgroundColor', 'LightGreen'); // Could be an hexadecimal value as #EE3B3B 
    };

})(jQuery);

The hideColumnColorRow function* takes the column number as a parameter. It hides the column <td> and its header <th> using jQuery’s supper useful nth-child selector. Then for each table row <tr> it traverses the row’s columns and looks at the value of each column using :contains selector. If it finds a value = ‘Yes’ it’ll assign a background color to the column’s parent, that in this case is the <tr> (the row) using its CSS backgroundColor property.

So, taking Figure 1 as an example, the above code can be used in an ASP.NET MVC view this way:

<script type="text/javascript">

    $(document).ready(function ()
    {
        hideColumnColorRow(5); // Hiding the 5th column and colorizing the row for which this column has a value = Yes
    });

</script>

* I’ve placed the jQuery/JavaScript function inside a file named custom.js. It resides inside the Scripts folder of the sample app available here. There’s no need to reference this script file in the view page because with the introduction of ASP.NET 4.5 we now have an all new Bundling and Minification Support for CSS and JavaScript files.

When the the app is run, this is the result:

Figure 2 - HTML table with column Active hidden and highlighted rows based on its value

This is a really interesting requirement that one can implement in no time thanks to the power of jQuery. jQuery is one of the most fascinating things when we talk about software development. Its creator “John Resig” should be awarded a Computer Science Nobel Prize if that existed. Well it could be the Turing Award.

Anyone should take a look at jQuery and start using it as early as possible. It’s a must have today. I simply love it!

Source code
I’ve put together a sample ASP.NET MVC 4 (uses NET Framework 4.5) so that you can try this out. You can run the app using the recently launched Visual Studio 11 Beta. You can download the free Visual Studio 11 Express Beta for Web here and the app code here.

Hope it helps.

Installing Brazilian Portuguese dict. in Sublime Text 2

2012-03-13T15:22:00.001-03:00

Today I downloaded one more dictionary to use with Sublime Text 2. Sublime Text is a multipurpose text and code editor. So far the best IMHO. I want to spell check my Portuguese texts of course. I followed the instructions described here to grab an additional dictionary.

From that page we have that:

Sublime Text uses Hunspell for its spell checking support. Additional dictionaries can be obtained from the OpenOffice.org Extension List

I then headed to OpenOffice.org to search for a pt-BR dictionary. I found it and then when I downloaded it from http://extensions.services.openoffice.org/en/project/Vero I got a file with a different extension (.oxt) of that used by Sublime Text 2. More on this bellow…

The file name is Vero_pt_BR_V208AOC.oxt.

Using Mac OS I tried to place this file inside this folder

/Users/leniel/Library/Application Support/Sublime Text 2/Packages/User

following the instructions given by Sublime Text 2 doc.

Closed Sublime Text 2 and reopened it. Went to the menu View > Dictionary and the new dictionary wasn’t there.

Well, something is plain wrong here. The already installed dictionaries that come with Sublime Text are present in this folder:

/Users/leniel/Library/Application Support/Sublime Text 2/Packages/Language - English/

Inside the above folder there are two English dictionaries with file extensions: .aff and .dic.

A little bit more thinking and I tried what could do the trick. I renamed the downloaded dictionary file from Vero_pt_BR_V208AOC.oxt to Vero_pt_BR_V208AOC.rar. Opened the compressed file and to my surprise there they were… extracted the files pt_BR.aff and pt_BR.dic. Easy as pie.

It turns out the .oxt file is just a wrapper…

I renamed the folder Language – English to just Languages and placed the files pt_BR.aff and pt_BR.dic in this folder. Closed Sublime Text 2 and reopened it. The new dictionary appeared:

Figure 1 - Sublime Text 2 Dictionary menu option listing the pt_BR dictionary just added

Hope it helps.

Export list of used NuGet packages for a given project

2012-03-12T01:23:00.001-03:00

This one is as simple as the title says… I just wanted to get a list of all NuGet packages I’m currently using in my ASP.NET MVC 4 project.

If you look at the NuGet Package Manager window that you can access by right clicking a project in Solution Explorer and then selecting Manage NuGet Packages… you’ll see that there’s an Installed packages option on the left vertical menu. This is good and all but the manager doesn’t have an option to export the list of installed packages to a simple .txt file.

Figure 1 - NuGet Package Manager listing Installed Packages for the project

One interesting thing is that NuGet uses a .XML file called packages.config that resides in the root folder of every project to actually fill the above window. Every time you add or delete a NuGet package this file is updated to reflect the changes.

This is the content of my packages.config file:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="AttributeRouting" version="1.5.4426" />
  <package id="DataAnnotationsExtensions" version="1.0.1" />
  <package id="DataAnnotationsExtensions.MVC3" version="1.0.1" />
  <package id="jQuery" version="1.7.1" />
  <package id="jQuery.Ajax.Unobtrusive" version="1.0" />
  <package id="jQuery.UI.Combined" version="1.8.17" />
  <package id="jQuery.Validation" version="1.8" />
  <package id="jQuery.Validation.Unobtrusive" version="1.0" />
  <package id="jquery-globalize" version="0.1.0" />
  <package id="knockoutjs" version="1.2.9.0" />
  <package id="log4net" version="1.2.10" />
  <package id="Microsoft.Web.Optimization" version="0.1" />
  <package id="microsoft-web-helpers" version="1.15" />
  <package id="Modernizr" version="2.0.6" />
  <package id="MvcSiteMapProvider" version="3.2.1.0" />
  <package id="Newtonsoft.Json" version="4.0.8" />
  <package id="NLog" version="2.0.0.2000" />
  <package id="RavenDB-Embedded" version="1.0.700" />
  <package id="System.Web.Providers" version="1.0.1" />
  <package id="T4MVC" version="2.7.0" />
  <package id="WebActivator" version="1.2.0.0" />
</packages>

This file serves the purpose of this post but it’d be a nice addition to the NuGet manager if it had a button to export the list of installed packages in a better formatted way. Just an idea.

Just let me take the opportunity to say “I Love You NuGet”. You let me explore the plethora of knowledge of fellow developers scattered all over the world in an easy way with the push of a button. I have no better words to describe you! You contribute enormously to the world development. Keep evolving!

Apple’s magic mouse & wireless keyboard battery life

2012-03-05T14:54:00.001-03:00

I’ve been collecting data regarding the battery life cycle of my Apple’s magic mouse and wireless keyboard. I thought it’d be good to post this data here so that you dear reader can draw your own conclusions about how long should the battery life last.

This is interesting data to look at because I like statistics and it’s good to analyze data. It helps you predict what to expect… Obviously the batteries’ lifespan changes according to how much time you spend using these devices. In my case I tend to use the computer 8 hours/day on average.

Just now I decided to search for a neat app ( Finch for Mac ) so that I can track the time I pass working on the computer. This will for sure give me more accurate data in the near future. For now I’ll have to take this data for granted…

Take a look at the following Google spreadsheet:

As you see the keyboard has a great autonomy and there were periods in which I didn’t work as much as I’d like on the computer because the mouse charges used to last 3 weeks. This denotes periods of inactivity. Now that I’m doing more intensive work the mouse battery lasts only 1.5 weeks. This is half the time previously taken to drain the battery.

For the record: I also own an Apple’s battery charger. Recharging the batteries is an easy task. Once more I’m contributing to the environment.

All these Apple devices are great IMHO as it’s the case with everything made by Apple!

The only “complaint” is that I think the mouse should have a greater autonomy. Maybe this will be the case with more recent technology iterations.

Blogger dynamic views with Undocked Gadgets bar

2012-03-02T12:54:00.001-03:00

Blogger recently launched gadgets support for dynamic views. This is really cool and was a missing piece to go with dynamic views.

One of the things that I really didn’t like about the gadget bar is that it’s hidden (docked) in the right side of the window. It’s difficult to see and so I Googled about an undocked version but couldn’t find it.

Figure 1 - Blogger docked gadgets sidebar (barely visible) or could we say hidden?

Here I show you how to get an undocked version so that your visitors can enjoy the gadgets bar in its full glory. Follow these simple steps:

1 - Select the Template option at draft.blogger.com

2 - Click the Customize button

3 - In the Window that opens select Advanced

4 - Select Add CSS

5 - Copy & paste the following piece of code in the Add custom CSS field

#gadget-dock
{
    right: 0;
}

6 - Click Apply to blog button in the window top right corner

You won’t see the change applied immediately.

Now go and open your blog and you should see an undocked gadgets bar!

Figure 2 - Blogger undocked gadgets sidebar (now visible)

I hope blogger gives the option to customize this without the need for CSS code. It’ll be easier for its users and will provide a better experience for blog’s visitors…

EDIT

To answer Hannah’s question: if you also want to customize the background colors of the gadgets bar, you can apply these styles following the same procedure described above:

.gadget-icons
{
    background-color: red;
}

.gadget-title
{
    background-color: red;
}

.gadget-selected .gadget-icons
{
    background-color: yellow;
}

One thing to remember here is that as the gadgets’ icons are white you must choose a background color that’s not too much whitish.

Play with the colors and enjoy!

Listing compressed files within a .zip or .rar by file size

2012-02-03T15:20:00.001-02:00

I'd like to know any app that shows a list of the files that lie within a compressed file .zip or .rar. If the list could be ordered by file size it'd be great! It could be any software that runs on Windows or Mac OS since I use both OS using Parallels.

Why this is important to me?
The answer is that sometimes I need to send a compressed file to someone and this file generally contains lots of coding files that are part of a Visual Studio Solution/Project for example. I just want to send a subset of those files. There are some big files like DLLs and database files scattered everywhere in a lot of folders that don’t need to go with the compressed file.

So how can I avoid spending time going through all those folders/files, looking their size and deleting one by one to make the final compressed file to be uploaded smaller?

I thought about asking this question at SuperUser. To tell the truth I already had the question typed there but before I could post it and after a few tries by myself I got what I wanted using WinRAR with an easy play of menu commands. So how can you do this? Follow me…

1 - If you don’t know or don’t have WinRAR or use another file archiver, you can get it at:
http://www.rarlab.com/download.htm

I use WinRAR in its evaluation copy incarnation that once in while pops up a dialog asking you to purchase it. It works great even if you don’t want to purchase it… take it easy.

2 - At first compress the folders and files you want without getting bothered about the size of the resulting compressed file. After installing WinRAR it’s available in the context menu of any file or folder in Windows Explorer.

3 - Open the compressed file in WinRAR and play with the menu just a little bit. Go to the Options | File list and select Flat folders view and Details menu options.

Figure 1 - WinRAR listing the files of a compressed file (trunk.rar) by file size

Taking the above screenshot into consideration (it lists the content of a trunk project folder compressed), we can see that it has 1554 folders and 1624 files. This compressed file alone has 87 MB in disk when the actual uncompressed content has 193 MB in size but it’s still pretty big to send it over the wire… I have a lot of folders and files to go through if I want to delete the big and unnecessary files to try to decrease the final size! As you see, it also contains many duplicate files in different paths… it’s pretty daunting just to think about a manual scan. A visual scan in a single screen is much better. How do you get a big picture of this compressed file?

4 - Order all the files by size by clicking the size column header.

5 - Select all the files you want to remove/delete from the compressed file in just one go. One can do this in two different ways: clicking a file and holding the ctrl key and clicking another file to select not contiguous files OR selecting one file and pressing the shift key and clicking another file to select contiguous files. After this it’s just a matter of right clicking the file selection and executing the Delete files command.

Hope this useful tip helps you someday!

MP3 Scan+Repair tool for iTunes on Mac OS

2012-01-17T13:10:00.000-02:00

This is another post to add to my MP3 series…

Yesterday I tried to add/import a folder full of MP3 files to my iTunes library. Just after adding I opened iTunes and went check those MP3s. To my surprise the MP3s were not added to iTunes. I had a hard time trying to find those files since iTunes moved them from their initial location to a special folder called Not Added. My MP3s ended up here:

/Users/leniel/Music/iTunes/iTunes Media/Automatically Add to iTunes/Not Added/2012-01-16 14.34.38

Note that iTunes created a folder inside Not Added named with the date and time the import operation occurred. The folder Not Added also stores image files and whatever file iTunes doesn’t recognize as valid files to be imported.

Now I see that I have some folders like that one - that are being created since 2010-9-17 (when I bought my Mac mini) and some of those folders have MP3 files that I didn’t notice were missing in my library.

Then I realized that for some odd reason iTunes rejected those files. I googled about it with "iTunes won't import MP3" and to my delight I found a forum thread in which the user Afric Pepperbird recommended a fantastic tool called MP3 Scan+Repair by Christian Zuckschwerdt. Using this great piece of software I managed to add those MP3s to my iTunes library.

So as way to say thanks I decided to write a post to demonstrate how it works.

1 - Download MP3 Scan+Repair (it's in Beta and is free for the moment)

http://triq.net/articles/mp3-scan-repair-download

2 - Open the App and drag and drop the problematic folder (the one that lies within the Not Added folder) to the app screen:

Figure 1 - MP3 Scan+Repair main screen

3 - Select all the files using command+A and then click the hammer button (mouse button is over it) to repair the files:

Figure 2 - MP3 Scan+Repair listing the files and their respective problems

See the Messages column with the description of what’s wrong with each file… even warnings prevent iTunes from adding the MP3 file to its library.

When repairing MP3 Scan+Repair will try to recreate the MP3s moving the old ones to the trash and writing the new ones to the current folder.

After following these easy steps you should be good to go and add those MP3s files to your iTunes media library.

The app is straightforward and does what it advertises… I’m really satisfied!

Extract GPS coord from Google Maps to geotag photos

2011-12-29T21:08:00.001-02:00

This is a quick tip related to something that I just tried today and that worked.

My camera SONY DSC-HX100V has GPS capability built-in but it won't work everywhere and it needs some time to acquire the satellite signal. This way if you just want to take a quick snap you may end with photos that don’t have GPS location in their Exif metadata. GPS is a recent capability when we talk about cameras.

Figure 1 - SONY DSC-HX100V camera with built-in GPS

Taking that into consideration, let’s say you have some photos in iPhoto (Mac OS) or whatever program you use to manage your photos. I mention iPhoto here since it’s the app I use. Those photos don't have a location set due to no GPS signal available where the photos were taken. So how can one add that missing GPS location info/data on those photos? By the way, this process is called geotagging.

This is what I’ve tried and what worked perfectly in my case:

1 - Open Google Maps and find the place/point where you’ve taken the photos.

2 - Right click that place/point you want in the map and select Center Map here.

3 - Click the Link button. Black mouse pointer is over it in the screenshot bellow.

Figure 2 - Google Maps link popup box with URL that contains GPS coordinates

A popup box will open. Copy the text/URL and paste it in your preferred text editor app. The link will look something like this:

http://maps.google.com/maps/ms?msid=201266260819946046546.0004a0e1b939dec67f18e&msa=0&ll=-22.428568,-44.619633&spn=0.001983,0.004128

Pay attention to the highlighted part that correspond to the longitude and latitude data.

4 - Select the photos you want in iPhoto to apply Location information and press command+I to access the Assign a Place box. Copy the highlighted text above and paste it in the box. Press the enter key to finish the task.

Figure 3 - Adding GPS coordinates to iPhoto Assign a Place box

This procedure works great when you just want to add GPS coordinates in your photos no matter if your camera has a built-in GPS or not since any photo can be geotagged nowadays.

Hope it helps!

You can check my photos in this slideshow:

ResourceManager with External Localization Assembly

2011-12-01T17:33:00.000-02:00

As a software developer I like to work with everything that is related to software Localization known as L10n. Besides being a developer working defining the architecture that will be adopted in a given project and doing the hard “FUN” work writing the code, I’m also a translator if you don’t know it yet.

One thing I've been trying to do recently is to be able to use localized strings that are present in an external assembly [ DLL ] using the ResourceManager object.
I have localized strings in resource [ .resx ] files that are specific for each locale I support. I place these .resx files in a separate class library project to maintain things organized.

So, suppose the namespace of this class library is MyProject.L10n and the .resx file name is Localization.resx. This gives me access to a class named Localization within the code. I also have Localization.pt.resx. I support English and Portuguese locales in my project for now. This naming pattern allows me to have in the future a file called Localization.es-ES.resx for Castilian Spanish (as written and spoken in Spain) and another one called Localization.es-AR.resx for Argentine Spanish. During runtime the .NET framework will select the correct .resx file to extract the localized string from based on the current culture the user has set while browsing my website.

After adding a reference to this class library, I'm able to use this code in my ASP.NET MVC project in a Razor view:

MyProject.L10n.Localization.LocalizedString;

This works as expected, but it's not what I need, though. As you see the localized string key [ LocalizedString ] is hard coded. I want to be able to use the method GetString from the ResourceManager object so that I can write code like this:

ResourceManager.GetString(item.DynamicLocalizedStringValue);

The problem and the catchy here is that in order to use the resource manager the way I want, I have to point it to the external assembly this way:

grid.Column(
columnName: "Type",
header: Localization.Type,format: (item) => new ResourceManager("MyProject.L10n.Localization", typeof(Localization).Assembly).GetString(item.Type.ToString()))

This part does the tricky: typeof(Localization).Assembly

In the code block above I’m using WebGrid that is a new helper that comes with ASP.NET MVC 3. It simplifies the task of rendering tabular data. When I do item.Type.ToString() I’m actually getting different values for each row of my grid and I pass this dynamic value to ResourceManager that in return gives me the translated/localized version of a give string key.

Going even further I’ve implemented a Razor’s Helper method in a file called Helpers.cshtml and placed such file inside the App_Code folder. This is the helper’s code:

@using System.Resources
@using MyProject.L10n

@helper GetLocalizedString(string stringValue)
{
    ResourceManager rm = new ResourceManager("MyProject.L10n.Localization", typeof (Localization).Assembly);

    @rm.GetString(stringValue);
}

Now it’s just a matter of calling the helper this way in whatever place/view I need it:

grid.Column(
columnName: "Type",
header: Localization.Type,
format: (item) => @Helpers.GetLocalizedString(item.Type.ToString()))

The above code is way more clear than the one I showed your before…

Hope this post helps shed some light in this subject since the only thing that should be done is to get a reference to the assembly that holds the Localization class and pass it to the ResourceManger’s constructor.

Blogger Posts Searcher using Google Data .NET/Java Client APIs

2011-11-21T18:38:00.002-02:00

It just happened today that I wanted to know if I had already published a post with a given title in one of the blogs I publish: http://jes4us.blogspot.com. During translation (I translate the posts from English to Portuguese) I had a feeling that I had already worked on a similar text… well, it turns out I was mistaken!

Instead of going through the extensive list of posts looking one by one I thought why not leverage the power of Google Data API? You may say: why not do a simple Google search instead? Good point. As I like to play with code I couldn’t resist.

So here it is. A simple and faster way of knowing if I have a post with a given title. Bellow you’ll find the codez to both the .NET client API and the Java one.

Blogger Data API for .NET
1 - Download the client library here: http://code.google.com/p/google-gdata/downloads/list

2 - Install the .msi package Google_Data_API_Setup_1.9.0.0.msi.

3 - Create a new Console project and reference the DLL Google.GData.Client that’s in this folder: C:\Google Data API SDK\Redist

using System;
using System.Linq;
using Google.GData.Client;

namespace BlogPostsSearcher
{
    class Program
    {
        static void Main(string[] args)
        {
            Service bloggeService = AcquireService();

            AtomFeed feed = AcquireAndSetupFeed(bloggeService);

            // Search posts that contain the word "StringToSearchFor" in their titles
            var query = feed.Entries.Where(p => p.Title.Text.Contains("StringToSearchFor");

            // Writes the Blog's Title
            Console.WriteLine(feed.Title.Text);

            // Prints each post found...
            foreach (AtomEntry entry in query)
            {
                Console.WriteLine(string.Format("Post Title: {0} - Date Published: {1}", entry.Title.Text, entry.Published.ToShortDateString()));
            }

        }

        private static AtomFeed AcquireAndSetupFeed(Service service)
        {
            FeedQuery blogFeedUri = new FeedQuery("http://www.blogger.com/feeds/" + YourBlogID + "/posts/default");

            // Setting the number of posts to retrieve
            blogFeedUri.NumberToRetrieve = 1000;

            AtomFeed feed = service.Query(blogFeedUri);
            
            return feed;
        }

        private static Service AcquireService()
        {
            Service service = new Service("blogger", "YourCompanyName-BloggerPostsSearcher");

            service.Credentials = new GDataCredentials("YourEmailAddress@gmail.com", "YourPassword");

            GDataGAuthRequestFactory factory = (GDataGAuthRequestFactory)service.RequestFactory;
            
            return service;
        }
    }
}

Blogger Data API for Java
1 - Download the client library here: http://code.google.com/p/gdata-java-client/downloads/list

2 - Unzip the file http://code.google.com/p/gdata-java-client/downloads/detail?name=gdata-src.java-1.46.0.zip

3 - Create a new Java Project and add references to:
- gdata-client-1.0.jar that’s in this path: gdata/java/lib/
- google-collect-1.0-rc1 that’s in this path: gdata/java/deps/

import java.io.IOException;
import java.net.URL;
import java.util.List;

import com.google.gdata.client.GoogleService;
import com.google.gdata.data.Entry;
import com.google.gdata.data.Feed;
import com.google.gdata.util.AuthenticationException;
import com.google.gdata.util.ServiceException;

/**
 * @author Leniel Macaferi
 * @date 11-21-2011
 */
public class BloggerClient
{
    public static void main(String[] args) throws IOException, ServiceException
    {
        try
        {
            GoogleService bloggerService = new GoogleService("blogger", "YourCompanyName-BloggerPostsSearcher");

            bloggerService.setUserCredentials("YourEmailAddress@gmail.com", "YourPassword");
            
            searchPosts(bloggerService, "YourBlogID", "StringToSearchFor");
        }
        catch (AuthenticationException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
    
    public static void searchPosts(GoogleService myService, String blogId, String search) throws ServiceException, IOException
    {
        // Request the feed
        URL feedUrl = new URL("http://www.blogger.com/feeds/" + blogId + "/posts/default");
            
        Feed resultFeed = myService.getFeed(feedUrl, Feed.class);

        // Setting the number of posts to retrieve...
        resultFeed.setTotalResults(1000);
        
        List<Entry> posts = resultFeed.getEntries();
        
        // Print the results
        System.out.println(resultFeed.getTitle().getPlainText());
        
        for (Entry post : posts)
        {
            if(post.getTitle().getPlainText().contains(search))
            {
                System.out.println("\t" + post.getTitle().getPlainText());
            }
        }
        
        System.out.println();
    }
}

In the code above you need to replace accordingly the following parts:

- YourEmailAddress
- YourPassword
- YourBlogID

References
Blogger Client Libraries and Sample Code

Blogger Developer's Guide: .NET

Blogger Developer's Guide: Java

RavenDB Embedded with Management Studio UI

2011-11-13T19:52:00.001-02:00

Go directly to solution with no bla bla bla…

I’ve been playing with RavenDB (a NoSQL document-oriented database) in an ASP.NET MVC 4 project for the past week. One thing I tried to do was to access RavenDB Management Studio UI so that I could see what’s actually present within the document store. This is important because one needs to check if docs are really being inserted, related docs are being deleted, etc…

Given that I’m running the embedded version of RavenDB (RavenDB-Embedded.1.0.499 package installed via NuGet in Visual Studio 2010), I was stuck trying to access the management studio since there isn’t much documentation on this subject when it comes to the EmbeddableDocumentStore. After struggling with it for about an hour of Googling and try and error, I decided to post a question at StackOverflow: Running RavenDB as an EmbeddableDocumentStore and accessing RavenDB Management Studio. Then I took a break to have launch and took a nap. After that I got back here to try a different approach and it really does work. Of course this is only a way to achieve what I want. This may not be the best approach but it’s enough. Just follow theses steps:

1 - Grab RavenDB latest build here:
http://builds.hibernatingrhinos.com/downloadlatest/ravendb

2 - Extract the files to C:\RavenDB-Build-499

3 - Edit the .config file in C:\RavenDB-Build-499\Server\Raven.Server.exe.config to point to your embedded database:

<appSettings> <add key="Raven/Port" value="8088"/> <add key="Raven/DataDir" value="C:\MyProject\trunk\MyProject\ App_Data\Database"/> <add key="Raven/AnonymousAccess" value="Get"/> </appSettings>

4 - Click the Start.cmd present in the root folder C:\RavenDB-Build-499\Start.cmd

The server status output window should appear while it starts:

Figure 1 - RavenDB server status window

When the server finishes its starting process, the Silverlight Management UI should be automatically opened in your preferred browser.

Figure 2 - RavenDB Management Studio UI (Web UI)

Now I can see my docs, indexes, etc… and I hope you can too! :D

Note to self
According to John Allers, one should be able to access the Management Studio without having to start the server manually. That’s fine and I had already tried that, but I could not get it working at first (some days ago). This has led me to try everything else today and my last resort was posting a question at StackOverflow. After trying once more the same procedure, that is, trying to access the management studio using the URL http://localhost:8080, I finally got it working! Go figure. One possibility is that I had another service running on port 8080 when I first attempted to access the UI. As Windows has restarted since then, that service (Hudson probably) that was running on port 8080 is stopped and now everything just works as expected.

Things to do:

1 - Instantiate your EmbeddableDocumentStore this way:

_documentStore = new EmbeddableDocumentStore
            {
                ConnectionStringName = "YourDbName",
                UseEmbeddedHttpServer = true
            };

2 - Copy Raven.Studio.xap present in C:\RavenDB-Build-499\Server\ folder to the root folder of your web project

3 - Run you your web app

4 - Access http://localhost:8080 and voila… everything SHOULD work out of the box.

5 - Select Default Database:

Figure 3 - RavenDB Management Studio accessed without running the server manually

Resources
Embedding RavenDB into an ASP.NET MVC 3 Application

Tree Graph Ordered Traversal Level by Level in C#

2011-11-05T21:09:00.001-02:00

Recently as part of a job interview process, I was asked to solve some programming problems. This post shows the solution for one of such problems.

Problem
The problem ( or could we call it an algorithm exercise? ) is this:

Consider a tree of integers. Knowing that its root node is 0, and given its adjacency list as a two dimensional array of integers, write a function that prints out the elements/nodes in order/level by level starting from the root. That is, the root is printed in the first line, elements that can be reached from the root by a path of distance 1 in the second line, elements reached by a path of distance 2 in the third line, and so forth. For example, given the following adjacency list (draw the tree for a better view):

0 => 1, 2, 3
1 => 0, 4
2 => 0
3 => 0, 5
4 => 1, 6
5 => 3
6 => 4

The program should print:

0
1 2 3
4 5
6

Little bit of theory
If you read about Tree in Graph theory, you’ll see that we can represent a tree using a graph because a tree is an undirected graph in which any two vertices are connected by exactly one simple path. In other words, any connected graph without cycles is a tree.

The tree in this problem isn’t a binary tree, it’s a n-ary tree.

Solution
With theory in mind, here goes my proposed solution…

I’m reusing some code from past posts. In special, the Graph, AdjacencyList, Node, NodeList and EdgeToNeighbor classes.

I use this method to fill a Graph with the Tree structure:

/// <summary>
/// Fills a graph with a given tree structure.
/// </summary>
/// <param name="graph"></param>
private static void FillGraphWithTreeStructure(Graph graph)
{
    // Vertexes
    graph.AddNode("0", null);
    graph.AddNode("1", null);
    graph.AddNode("2", null);
    graph.AddNode("3", null);
    graph.AddNode("4", null);
    graph.AddNode("5", null);
    graph.AddNode("6", null);

    // Edges
    graph.AddDirectedEdge("0", "1");
    graph.AddDirectedEdge("0", "2");
    graph.AddDirectedEdge("0", "3");

    graph.AddDirectedEdge("1", "4");

    graph.AddDirectedEdge("4", "6");

    graph.AddDirectedEdge("3", "5");

    /* This is the tree:
               
            0
          / | \
         1  2  3
        /       \
       4         5
      /
     6
             
        This is the expected output:
             
        Level 1 = 0
        Level 2 = 1 2 3
        Level 3 = 4 5
        Level 4 = 6

    */
}

This is the method that does the hard work:

/// <summary>
/// Performs an ordered level-by-level traversal in a n-ary tree from top-to-bottom and left-to-right.
/// Each tree level is written in a new line.
/// </summary> 
/// <param name="root">Tree's root node</param>
public static void LevelByLevelTraversal(Node root)
{
    // At any given time each queue will only have nodes that
    // belong to a level
    Queue<Node> queue1 = new Queue<Node>();
    Queue<Node> queue2 = new Queue<Node>();

    queue1.Enqueue(root);

    while (queue1.Count != 0 || queue2.Count != 0)
    {
        while (queue1.Count != 0)
        {
            Node u = queue1.Dequeue();

            Console.Write(u.Key);

            // Expanding u's neighbors in the queue
            foreach (EdgeToNeighbor edge in u.Neighbors)
            {
                queue2.Enqueue(edge.Neighbor);
            }
        }

        Console.WriteLine();

        while (queue2.Count != 0)
        {
            Node v = queue2.Dequeue();

            Console.Write(v.Key);

            // Expanding v's neighbors in the queue
            foreach (EdgeToNeighbor edge in v.Neighbors)
            {
                queue1.Enqueue(edge.Neighbor);
            }
        }

        Console.WriteLine();
    }
}

To spice things up I have implemented a Parallel version of the above method using a ConcurrentQueue:

/// <summary>
/// Performs an ordered level-by-level traversal in a n-ary tree from top-to-bottom and left-to-right in Parallel using a ConcurrentQueue.
/// Each tree level is written in a new line.
/// </summary> 
/// <param name="root">Tree's root node</param>
public static void LevelByLevelTraversalInParallel(Node root)
{
    // At any given time each queue will only have nodes that
    // belong to a level
    ConcurrentQueue<Node> queue1 = new ConcurrentQueue<Node>();
    ConcurrentQueue<Node> queue2 = new ConcurrentQueue<Node>();

    queue1.Enqueue(root);

    while (queue1.Count != 0 || queue2.Count != 0)
    {
        while (queue1.Count != 0)
        {
            Node u;
                    
            queue1.TryDequeue(out u);

            Console.Write(u.Key);

            // Expanding u's neighbors in the queue
            foreach (EdgeToNeighbor edge in u.Neighbors)
            {
                queue2.Enqueue(edge.Neighbor);
            }
        }

        Console.WriteLine();

        while (queue2.Count != 0)
        {
            Node v;
                    
            queue2.TryDequeue(out v);

            Console.Write(v.Key);

            // Expanding v's neighbors in the queue
            foreach (EdgeToNeighbor edge in v.Neighbors)
            {
                queue1.Enqueue(edge.Neighbor);
            }
        }

        Console.WriteLine();
    }
}

Now it’s time to measure the execution time using a StopWatch:

private static void Main(string[] args)
{
    Graph graph = new Graph();

    FillGraphWithTreeStructure(graph);

    Stopwatch stopWatch = new Stopwatch();

    stopWatch.Start();

    LevelByLevelTraversal(graph.Nodes["0"]);

    stopWatch.Stop();

    // Write time elapsed
    Console.WriteLine("Time elapsed: {0}", stopWatch.Elapsed);

    //Resetting the watch...
    stopWatch.Reset();

    stopWatch.Start();

    LevelByLevelTraversalInParallel(graph.Nodes["0"]);

    stopWatch.Stop();

    // Write time elapsed
    Console.WriteLine("Time elapsed: {0}", stopWatch.Elapsed);

    Console.ReadKey();
}

Now the results:

Sequential
0
1 2 3
4 5
6
Time elapsed: 00:00:00.0040340

Parallel
0
1 2 3
4 5
6
Time elapsed: 00:00:00.0020186

As you see, time is cut by a factor of 2. I currently have a Core 2 Duo processor in my Mac mini.

Hope you enjoy it and feel free to add your 2 cents to improve this code! Of course there are other ways of solving this very problem and I would like to see those other ways. Do you have any other better idea?

Download
You can get the Microsoft Visual Studio Console Application Project at:

https://sites.google.com/site/leniel/blog/TreeLevelTraversal.rar

To try out the code you can use the free Microsoft Visual C# 2010 Express Edition that you can get at: http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-csharp-express

SVN, Hudson & MSBuild - Building code on post commit

2011-10-25T18:49:00.001-02:00

SVN, Hudson and MSBuild - Revision control repository
SVN, Hudson and MSBuild - Continuous Integration

This is the third and last installment in the series I’m writing about SVN, Hudson and MSBuild.

Today I’m going to show you the last piece that actually makes the whole thing work. We could call this the plumbing. The piece lies within a specific SVN folder related to your project. It’s called hooks. The path to the hooks folder is this:

Figure 1 - Project’s hooks folder before the setup

As you can see there are some template files ( .tmpl ). The one we’re going to use to inform Hudson that it’s time to build the code just committed to the repository is the file post.commit.tmpl. Make a copy of this file and change its extension to .bat since it’ll be used by SVN to execute some commands. The file should be named post-commit.bat.

Open the .bat file and add this code at the end:

SET REPOS=%1
SET REV=%2
SET CSCRIPT=C:\WINDOWS\system32\cscript.exe
SET VBSCRIPT=C:\svn\post-commit-hook-hudson.vbs
SET SVNLOOK=C:\Program Files\VisualSVN Server\bin\svnlook.exe
SET HUDSON=http://leniel-pc:8080/
"%CSCRIPT%" "%VBSCRIPT%" "%REPOS%" %REV% "%SVNLOOK%" %HUDSON%

Note above that we’re setting some vars and pointing to some specific files:

- CSCRIPT points to cscript.exe file that should be present in your Windows system32 folder.

- VBSCRIPT points to to the post-commit-hook-hudson.vbs file and its code is as follows:

repos = WScript.Arguments.Item(0)
rev = WScript.Arguments.Item(1)
svnlook = WScript.Arguments.Item(2)
hudson = WScript.Arguments.Item(3)

Set shell = WScript.CreateObject("WScript.Shell")

Set uuidExec = shell.Exec(svnlook & " uuid " & repos)
Do Until uuidExec.StdOut.AtEndOfStream
uuid = uuidExec.StdOut.ReadLine()
Loop
Wscript.Echo "uuid=" & uuid

Set changedExec = shell.Exec(svnlook & " changed --revision " & rev & " " & repos)
Do Until changedExec.StdOut.AtEndOfStream
changed = changed + changedExec.StdOut.ReadLine() + Chr(10)
Loop
Wscript.Echo "changed=" & changed

url = hudson + "subversion/" + uuid + "/notifyCommit?rev=" + rev
Wscript.Echo url

Set http = CreateObject("Microsoft.XMLHTTP")
http.open "POST", url, False
http.setRequestHeader "Content-Type", "text/plain;charset=UTF-8"
http.send changed

- SVNLOOK points to svnlook.exe file that comes with VisualSVN Server (see part 1 of this series for more details about it).

- HUDSON points to your Hudson server address. Change it accordingly.

With it all configured we should be ready to get an automatic build when code is committed to the repository.

To test your environment, change any file already versioned and commit it. Open Hudson in your browser and watch a new build start automatically.

If you look in Hudson’s build Console Output you’ll see that the build was initiated by an SCM change.

That’s all!

This is how your SVN project hooks folder should look like now:

Figure 2 - Project’s hooks folder after the setup

Can you spot another .bat file in the folder? It’s the pre-revprop-change.bat. I’ve been using it so that I can modify the commit’s log message/comment when I forget to mention something or to correct spelling. More info about this file can be seen in this StackOverflow question: What is a pre-revprop-change hook in SVN and how do I create it?