Learn how to create a desktop application for Facebook, using their GraphAPI and Visual Basic.NET

Introduction

Hello again.  If you have read my previous article about creating an application for Facebook, you most probably have noticed that the application sample might not be working anymore. Why? Well, because that application was built on the REST API, which is being deprecated by Facebook and replaced by the GraphAPI framework.  Not to worry, this is the exact purpose of this article, and when Facebook changes their framework again, we'll cross that bridge when or if we get there.

GraphAPI

First, let me explain how the GraphAPI works, and what it is precisely. The GraphAPI is actually a lot less complicated than one would think.  It uses the very same principle programmers use every day, and that is: everything is connected, and everything has properties and / or methods. For example, each event in Facebook has certain properties, each friend has certain properties and methods. Everything is connected, but how? Very simple. Let us assume I Like a certain page. Then, somebody else also Likes that page. Right, now we have 2 people who share a common interest. Let us take it a step further. Because we have Liked the same page, we are now connected. We'll be able to see which friends each person has, we will see their Likes, and so on. So everything is connected, via a certain relationship that has been formed. Have a look at how Facebook explains their GraphAPI

FQL

Facebook Query Language uses a similar style to SQL to extract the correct information from the correct tables.  Anything you see on Facebook forms part of a database. It is broken down into several separate tables. For example: Friends is a table, Friend Request is a table, Messages is a table, Notifications is a table, Like is a table and so on. For a complete list of available tables, have a look here. The above tables I mentioned might have different names, as I was just using them to illustrate my example better. We will use FQL to extract the information we need in our sample application.

Sample

I was lucky enough to stumble upon CodePlex some time ago.  It is an excellent site and it gets better day by day. On CodePlex they provide an SDK for Facebook. An SDK is a software development kit, which provides samples and tutorials on a certain topic. The sad thing here is that the Facebook SDK they provide is strictly for C#. Sometimes I wonder if people do not realize how powerful VB.NET is, or if they just don't care. I love C# and VB equally, and I always try to make the same things in both languages, just to prove that it is possible. I had an extensive look at the sample they have provided and was quite happy with them. I then had the brainwave to make my own Notifier application with VB.NET.  I had two choices, use a C# / VB.NET converter, or convert it manually. I chose the hard option, which was to convert the codes manually. Now, do not get me wrong, this is not a verbatim copy of one of CodePlex's samples. Yes, I do things similar, because that is the only way, but I do make use of my own logic as well.

Because I chose to convert the code manually, I encountered a lot of issues, and had to improvise, and rewrite certain segments completely. With the sample that I am providing, I aim to first show you that Facebook applications can be done in VB.NET, and second to provide the ability for lazy people, such as myself, to check notifications from Facebook on my profile, thus eliminating the need to open my Internet browser and navigating to my Facebook profile page.

Setup

The first step is actually optional for this article, but I would really recommend it--that is if you really want to learn the complete ins and outs of creating a Facebook application.  The first step is to download the SDK from CodePlex.  This will give you access to all the needed DLL files inside their associated projects.  Once downloaded, the samples folder will be named something in the lines of facebooksdk_b3789011d8e2\Samples; inside there you will find all of the various samples provided. Have a look at a sample named CSWinFormsAuthTool. This is the base from which I will be working. What's important here is the fact that it gives you the Facebook.dll and the Newtonsoft.Json.dll, which we will use in our application.

The second step is to think of a proper name for your application, and then let Facebook know that you intend to make a program. Without setting your application up on Facebook, you will not get an AppID nor an App Secret. You will need these if you intend to develop your application further inside Visual Studio. We will be using Visual Studio 2010 for this example. Once you have a funky name, you will need to go to the Developers section of Facebook. At the bottom of your Facebook page, there will be a link entitled Developer. Go there. You may be asked to install the Developer Application as well.  Once you have done that, you will see that Facebook has given you access to Documentations, Samples, Forums and the Application Directory. Good, we're halfway there.

Choose to Create a New App. Once clicked, the screen will look like the following picture:

[NewApp.jpg]
Figure 1: New Facebook Application

It will pop up a Security Question screen once Continue is clicked. Fill in all the required information and Submit it. That's it for now. Once you have submitted the previous screen, you will be brought to your App Information page. You will notice that your AppID and APP Secret have been generated. Make note of these as you will need them inside your VB application. Our sample application ( Notifier )'s information looks like the following :

[AppInfo.jpg]
Figure 2: Facebook Application Info

Feel free to enter all the required information in this screen.  You can also always edit it afterwards, so do not worry too much about it now.

Now, we have set up our application, and Facebook knows about it.  Let's now design our application in Visual Studio 2010.

Design

Create a new VB.NET Windows Forms application in Visual Studio 2010, and give it a name such as Notifier.

Notifier consists of 4 Forms; add the forms along with their associated controls and properties:

Object	Property	Setting
Form	Name	frmIntro
	FormBorderStyle	FixedToolWindow
	ShowInTaskbar	False
	Size	170, 84
	StartPosition	CenterScreen
	Text	Notifier
Button	Name	btnFacebookLogin
	Location	20, 16
	Size	125, 28
	Text	Login
Form	Name	frmInfo
	Size	702, 482
	StartPosition	CenterScreen
	Text	Notifier is loading info, Please be patient
Panel	Name	Panel1
	Dock	Bottom
	Location	0, 390
	Size	694, 58
Panel	Name	Panel2
	Dock	Top
	Location	0, 0
	Size	694, 36
Panel	Name	Panel3
	Dock	Fill
	Location	0, 36
	Size	694, 354
Panel	Name	Panel4
	Dock	Top
	Location	0, 0
	Size	694, 100
Panel	Name	Panel5
	Dock	Fill
	Location	0, 100
	Size	694, 254
Label	Name	lblName
	Autosize	True
	Font	Microsoft Sans Serif, 9.75pt, style=Bold
	Location	3, 9 Inside Panel1
	Size	45, 16
	Text	Hello
PictureBox	Name	picProfilePic
	Location	3, 6 Inside Panel4
	Size	70, 67
Label	Name	Label1
	AutoSize	True
	Location	79, 6 Inside Panel4
	Text	Post a Message:
TextBox	Name	txtMessage
	Location	82, 21 Inside Panel4
	Multiline	True
	Size	327, 76
Button	Name	btnPostToWall
	Location	415, 21 Inside Panel4
	Text	Post to Wall
WebBrowser	Name	wbNotifier
	Dock	Fill
	Location	0,0 Inside Panel3
	Size	694, 254
LinkLabel	Name	lklNotif
	AutoSize	True
	Location	8, 33 Inside Panel1
	Size	113, 13
	TabStop	True
	Text	No New &Notification(s)
LinkLabel	Name	lklMess
	AutoSize	True
	Location	188, 33 Inside Panel1
	Size	103, 13
	TabStop	True
	Text	No New &Message(s)
LinkLabel	Name	lklFriend
	AutoSize	True
	Location	358, 33 Inside Panel1
	Size	89, 13
	TabStop	True
	Text	No New &Friend(s)
Button	Name	btnExit
	Anchor	Bottom, Right
	Location	607, 23 Inside Panel1
	Size	75, 23
	Text	E&xit
Timer	Name	tmrNotifier
	Enabled	True
	Interval	20000
Timer	Name	tmrError
	Interval	5000
Form	Name	frmFBLogin
	FormBorderStyle	FixedDialog
	MaximizeBox	False
	MinimizeBox	False
	ShowInTaskbar	False
	Size	438, 376
	StartPosition	CenterScreen
	Text	Notifier is logging into Facebook
WebBrowser	Name	webBrowser
	Dock	Fill
Timer	Name	tmrError
	Enabled	True
	Interval	1000
Timer	Name	tmrError2
	Interval	5000
Form	Name	frmError
	FormBorderStyle	FixedToolWindow
	ShowInTaskbar	False
	Size	388, 120
	StartPosition	CenterScreen
	Text	There has been an error.

Once finished and run, your Forms should look more or less like the following:

[frmIntro.jpg]
Figure 3: frmIntro

[frmFBLogin.jpg]
Figure 4: frmFBLogin

[frmInfo.jpg]
Figure 5: frmInfo

[frmError.jpg]
Figure 6: frmError

Code & Explanations

OK, you can wipe the sweat from your forehead now :). This was indeed a mission. The funny thing here is, the code will get quite lengthy, so after you have taken a break, continue with the coding. As I've said, the whole purpose, which you can probably figure out by looking at the designs, is to get specific notifications from your Facebook profile - that will be the easy part, the tough part is getting access to Facebook.

frmIntro

Open frmIntro's Code Window. Recall earlier that I spoke about a DLL file named facebook.dll, well, we will need to add it as a Reference now. Click Project, Add Reference. Select the Browse tab, and navigate to that DLL.

Once the reference has been added, we need to add its Imports Statement as well:

Imports Facebook

The next step is creating an AppId variable inside our application.  We will need to supply the ID Facebook gave us.  Without giving the AppID, we will not be able to log in. Then, we need to specify the Permissions for our program. We need to do this because each permission setting allows us to access different information. For example, to read messages we need a certain permission, to read our wall on Facebook, we need a specific permission setting, and so on.

    Private _appId As String = "211959065496840" 'Notifier App ID on FaceBook
    'Add Permissions for our app
    Private _extendedPermissions As String() = {"user_about_me", "publish_stream", "offline_access", "read_requests", "read_stream", "read_mailbox"}

For a complete list of available Permissions, and what they give access to, have a look here. The next two variables I have created works with our Error Window. Instead of showing MessageBoxes, I opted to display this window, which is much more customizable than a MessageBox.

    Private blnMessShown As Boolean 'Was the Error shown?

    Private NFE As New frmError 'Error Screen

The sub procedure that makes everything happen, in this case, all the authentication and authorization, is called DisplayAppropriateMessage, and looks like :

    ''' Ensures That we Have Successfully Logged into our Facebook account
    
    Private Sub DisplayAppropriateMessage(ByVal facebookOAuthResult As FacebookOAuthResult)

        If facebookOAuthResult Is Nothing Then

            'User most likely closed the FacebookLoginDialog, so do nothing
            Return

        End If

        If facebookOAuthResult.IsSuccess Then

            'We got the access token, Continue
            Dim infoDialog = New frmInfo(facebookOAuthResult.AccessToken)
            infoDialog.ShowDialog() 'Show Main Screen

        Else

            'We failed to get the access token. Most likely the user clicked don't allow
            'Inform user that there was an Error

            If Not blnMessShown Then 'If Error Screen hasn't been shown yet

                NFE.Show() 'Show
                NFE.lblMess.Text = facebookOAuthResult.ErrorDescription 'Display Error Information
                blnMessShown = True 'Set Message Shown to true, so that we don't show it again
                tmrError.Enabled = True 'Enable Error Timer

            End If

        End If

    End Sub

What happens here is, it checks for a successful return from the Facebook authorization object.  Successful would mean that the correct AppId and Login credentials were supplied. In the event that IsSuccessful is False, it will mean that either the user didn't supply his correct details, or he / she chose not to 'Allow' Notifier to get access to his / her settings. Then, the error screen would appear and disappear 5 seconds later.

The following two events show how the frmFBLogin form, which provides the capability to give Notifier access to your Facebook profile, and to exit in the event of an error.

    Private Sub btnFacebookLogin_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFacebookLogin.Click

        Dim facebookLoginDialog = New frmFBLogin(_appId, _extendedPermissions) 'frmFBLogin Object
        facebookLoginDialog.ShowDialog() 'Show form with appropriate permissions

        DisplayAppropriateMessage(facebookLoginDialog.FacebookOAuthResult) 'Get Result

    End Sub


    Private Sub tmrError_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrError.Tick

        If Me IsNot Nothing Then

            NFE.Close() 'Close Error Form

        Else

            Application.Exit() 'Exit

        End If

    End Sub

That's it for frmIntro.

frmFBLogin

Add the same Imports Statement to frmFBLogin:

Imports Facebook

Declare the following variables:

    Private _navigateUri As Uri 'URI object, easy access to parts of a URL
    Private blnMessShown As Boolean 'Error Message Shown?

    Private NFE As New frmError 'Error Form

_navigateUri is an URI object.  This makes it easier for us to access certain parts of a URL. We will use this object to get the url of the authorized object. The other two objects are again used for our error form.

Now, before we continue, remember how we created the frmFBLogin object on frmIntro? In case you have forgotten, we did this :

Dim facebookLoginDialog = New frmFBLogin(_appId, _extendedPermissions) 'frmFBLogin Object

Notice something strange here? OK, the something strange that I am referring to is how we have used New. Usually with Form objects there are no parameters inside its constructor, ie, New. We needed to do this because the authorization and permissions needed to be there, first. If it had been placed inside the Form Load event, it would not have worked, as the authorization process already ( by that time ), returned unsuccessful.

Open the Designer file for frmFBLogin, and edit the New constructor to look like the following:

    Public Sub New(ByVal appId As String, ByVal extendedPermissions As String(), ByVal logout As Boolean)
        Dim loginParameters As IDictionary(Of String, Object) = New Dictionary(Of String, Object)() From { _
         {"response_type", "token"}, _
         {"display", "popup"} _
        } 'Login with correct parameters 

        _navigateUri = FacebookOAuthClient.GetLoginUrl(appId, Nothing, extendedPermissions, logout, loginParameters) 'Get Result

        InitializeComponent()
    End Sub

    Public Sub New(ByVal appId As String, ByVal extendedPermissions As String())
        Me.New(appId, extendedPermissions, False) 'Supply AppID & Permissions to get authorized
    End Sub

Yes, you see two New Subs.  The first one, makes sure that we are allowed to login, and determines how it should return its result. Inside there we also obtain the result from the Authorization client. The second New procedure uses our AppId and Permissions to login to our account. You can find more information on how Facebook authorizes users here.

Let us now go back to frmFBLogin.vb.  The next thing we add in here is a Property:

    ''' Facebook authorization result
    
    Public Property FacebookOAuthResult() As FacebookOAuthResult

        Get

            Return m_FacebookOAuthResult 'IsSuccessful / Not

        End Get

        Private Set(ByVal value As FacebookOAuthResult)

            m_FacebookOAuthResult = value

        End Set

    End Property

    Private m_FacebookOAuthResult As FacebookOAuthResult 'Authorization Object

This makes it easier for us to determine what the Authorization object will return, and easier to manage. So now, we can just check the status of m_FacebookOAuthResult. The rest of frmFBLogin's events looks like:

    Private Sub FacebookLoginDialog_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load

        webBrowser.Navigate(_navigateUri.AbsoluteUri) 'Navigate to appropriate URL, to authorize Notifier

    End Sub

    Private Sub webBrowser_Navigated(ByVal sender As Object, ByVal e As WebBrowserNavigatedEventArgs) Handles webBrowser.Navigated

        Dim oauthResult As FacebookOAuthResult 'Result of Authorization

        If FacebookOAuthResult.TryParse(e.Url, oauthResult) Then

            Me.FacebookOAuthResult = oauthResult
            Me.DialogResult = If(oauthResult.IsSuccess, DialogResult.OK, DialogResult.No) 'Successful Yes, or No

        Else

            Me.FacebookOAuthResult = Nothing 'If Nothing, then problems with Internet connection etc.

        End If

    End Sub

    Private Sub tmrError_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrError.Tick

        Static i As Integer

        If Me.Visible Then 'If This form is Visible for more than 10 seconds, something is wrong, it cannot log in

            i += 1

            If i >= 10 Then

                Me.Hide() 'Hide

                If Not blnMessShown Then 'Show error form

                    NFE.Show()
                    NFE.lblMess.Text = "Cannot Log In, Possibly Due To Bad Internet Connection"
                    blnMessShown = True
                    tmrError2.Enabled = True

                End If

            End If

        End If

    End Sub

    Private Sub tmrError2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrError2.Tick

        Application.Exit() 'Exit

    End Sub

Inside Load we navigate to whichever URI was returned. The WebBrowser_Navigated event is the most important here. It checks if everything is OK, ie, authorized properly. If it is, it will allow further access to our Facebook profile. Think of this form as a bridge. This bridge starts at the Login button on frmIntro, and stops at displaying the information on frmInfo. Without this bridge, nothing will happen. We need to authenticate the application's ID; we need to see if it has the correct permissions, we need to see if the person has a valid Facebook account and is logged on; this is what happens with this form. The two Timer events are there to determine any errors. In the first timer event, we make use of a static counter that counts to ten. If it reaches ten, there was an error. It should not take longer than 10 seconds to complete the bridging process, if it does, your internet is giving problems. This I had to put in, because I live in South Africa, and our Internet service is very bad on occasion.

That's it for frmFBLogin. We have all the correct info, in order to read your profile's information. Let us now go to the meat of the program, frmInfo, where we will display our new Notification messages.

frmInfo

This form will be our main interface, which the users will work on.  This is also where we will see all our notifications, etc. Add the following two Imports statements

Imports Facebook
Imports System.Threading 'Dealing with multiple Threads

Add the following variables:

    Private ReadOnly _accessToken As String 'Access Token

    'Font Setup
    Private strFont As String = "Microsoft Sans Serif"
    Private fSize As Single = 8.5F
    Private fStyle1 As FontStyle = FontStyle.Regular
    Private fStyle2 As FontStyle = FontStyle.Bold

    Private blnFriends As Boolean 'Have Friends
    Private blnMess As Boolean 'Have Messages
    Private blnNotif As Boolean 'Have Notifications

    Private WithEvents fb As FacebookClient 'FaceBook Client

    'My Facebook details, for example: Name + Picture
    Private strMyDetails1() As String
    Private strMyDetails2() As String

    Private strFriend1() As String 'Friends FQL Result

    'Messages FQL Result(s)
    Private strMess1() As String
    Private strMess2() As String
    Private strMess3() As String

    'Notifications FQL Result(s)
    Private strNotif1() As String
    Private strNotif2() As String

    'Error Form
    Private blnMessShown As Boolean

    Private NFE As New frmError

We will do a lot of string manipulation with these objects, but more on that later. If your string handling capabilities are a bit rusty, or limited, have a look at this FAQ. I will be doing the Subs and events as they are displayed in the program's code. Here's an easy one to start off with:

    Private Sub frmInfo_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing

        btnExit.PerformClick() 'Exit

    End Sub

Hmm, do I really need to explain that? OK, just in case, this exits the application properly. Now a tricky one:

    ''' Load Profile Pic and Call GetInfo

    Private Sub GraphApiExample()

        Try
            fb = New FacebookClient(_accessToken) 'Get Facebook Details

            Dim result1 As Object = fb.[Get]("/me") 'get MY Details

            lblName.Text = "Hello " 'Initialise Name Label

            'Get Profile Picture
            picProfilePic.LoadAsync(String.Format("https://graph.facebook.com/{0}/picture?type={1}", result1.id, "square"))

            GetInfo(_accessToken) 'Retrieve Notifications
     
        Catch ex As FacebookApiException 'Show Error Form

            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        End Try


    End Sub

This sub, (You will notice I've kept the same name as in the C# example), is where the whole data retrieval process starts. The result1 object will get all my details. Then, we retrieve and display the profile picture, and call the GetInfo sub, which collects all the information we want. The rest of the code concentrates on the error form, in the event of an error. Add this next sub.

    ''' Use FQL to Retrieve Notifications from associated tables

    Public Sub GetInfo(ByVal accessToken As String)
        Try

            fb = New FacebookClient(accessToken) 'Get Details

            'Use a Batch Request, instead of 4 different queries
            fb.BatchAsync({
                New FacebookBatchParameter().Query("SELECT first_name FROM user WHERE uid=me()"),
                New FacebookBatchParameter().Query("SELECT uid_from, uid_to FROM friend_request WHERE uid_to=me()"),
                New FacebookBatchParameter().Query("SELECT unread_count FROM mailbox_folder WHERE viewer_id=me()"),
                New FacebookBatchParameter().Query("SELECT notification_id FROM notification WHERE is_unread = 1 AND recipient_id=me()")})

        Catch ex As Exception 'Error

            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        End Try

    End Sub

In this sub, we use FQL to get all the appropriate information. We are making use of the FaceBookBatchParameter object to group all 4 queries into one. This makes retrieval faster. There are four queries, each getting information from separate tables, namely: user, friend_request, mailbox_folder and notifcation. Remember I said that everything is stored in separate tables, at the beginning of this article? Well, here you can see that, and you can also see which fields we need to query for.

The next event:

    ''' Fires once all details have been retrieved, we must now use it

    Private Sub fb_PostCompleted(ByVal sender As Object, ByVal e As FacebookApiEventArgs) Handles fb.PostCompleted
        Try

            Dim ResultObject As Object = New Generic.Dictionary(Of String, Object) 'Contains ALL Info asked in GetInfo

            ResultObject = e.GetResultData 'Get Results and store all of it

            'Original string looks like : [{"first_name":"Ockert"}]
            strMyDetails1 = ResultObject(0).ToString.Split(":")
            strMyDetails2 = strMyDetails1(1).Split("""")

            strFriend1 = ResultObject(1).ToString.Split(":")

            'Original string looks like :[{"unread_count":5},{"unread_count":0},{"unread_count":26}]
            strMess1 = ResultObject(2).ToString.Split(":")
            strMess2 = strMess1(2).Split("""")
            strMess3 = strMess2(0).Split("}")

            strNotif1 = ResultObject(3).ToString.Split(":")
            If strNotif1.Length > 1 Then
                strNotif2 = strNotif1(1).Split("""")
            End If

        Catch ex As Exception 'Error

            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        End Try

    End Sub

Is where we format the information correctly. All objects queried are stored in one dictionary object. How it stores it will require us to do string manipulation; in other words, split the arrays of information continuously until we get the result we are looking for. Some of the array objects were quite difficult, especially the Messages. That one took me a while. But, this is precisely why there are Debugging tools such as Breakpoints, and the Console.WriteLine methods, which writes information to the Immediate Window. Those are just two very powerful, yet simple tools to use, to see if you get the correct data. Many people don't make use of Breakpoints, or, they just conveniently forget about them.

    ''' 

    ''' Interval set so high, to give enough time for all info to be read and threads to complete
    ''' Use manipulated strings and update display
    ''' 
    ''' 
    ''' 
    ''' 
    Private Sub tmrNotifier_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrNotifier.Tick
        Try
            lblName.Text = "Hello " & strMyDetails2(1) 'Name

            'if new friend(s)
            If strFriend1(0) <> "[]" AndAlso strFriend1(0) <> "" Then
                lklFriend.Font = New Font("Microsoft Sans Serif", 8.5, FontStyle.Bold)
                lklFriend.Text = "New &Friend(s)"
            End If

            'If Unread message count is higher than 0
            If Val(strMess3(1)) > 0 Then
                lklMess.Font = New Font("Microsoft Sans Serif", 8.5, FontStyle.Bold)
                lklMess.Text = "New &Messages(s)"
            End If

            'If new notifications
            If strNotif1.Length > 1 Then
                If Val(strNotif2(1)) > "0" Then
                    lklNotif.Font = New Font("Microsoft Sans Serif", 8.5, FontStyle.Bold)
                    lklNotif.Text = "New &Notification(s)"
                End If
            End If

            tmrNotifier.Enabled = False 'Disable timer

            Me.Text = "Notifier"

        Catch ex As FacebookApiException 'Error(s)

            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        Catch ex2 As Exception

            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex2.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        End Try
    End Sub

The above event will be fired only once, as the Timer is disabled after it has done its work. What work? Well, it updates the display, meaning it changes the LinkLabels' texts and fonts, and displays my name. The Timer's interval was set to 20000, because it has to wait until all the data has been retrieved successfully form the previous subs.

    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click

        Application.Exit() 'Exit

    End Sub

    Private Sub lklMess_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles lklMess.LinkClicked

        wbNotifier.Navigate("http://www.facebook.com/?sk=inbox") 'Go to inbox

        lklMess.Font = New Font("Microsoft Sans Serif", 8.25, FontStyle.Regular) 'Reset Font
        lklMess.Text = "No New &Message(s)"

    End Sub

    Private Sub lklFriend_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles lklFriend.LinkClicked

        wbNotifier.Navigate("http://www.facebook.com/friends/edit/?sk=requests") 'Go to Requests page

        lklFriend.Font = New Font("Microsoft Sans Serif", 8.25, FontStyle.Regular)
        lklFriend.Text = "No New &Friend(s)"

    End Sub

    Private Sub lklNotif_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles lklNotif.LinkClicked

        wbNotifier.Navigate("http://www.facebook.com/notifications.php") 'Go to Notifactions page

        lklNotif.Font = New Font("Microsoft Sans Serif", 8.25, FontStyle.Regular)
        lklNotif.Text = "No New &Notification(s)"

    End Sub

    Private Sub tmrError_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrError.Tick

        If Me IsNot Nothing Then 'Close Error screen if displayed

            NFE.Close()

        Else

            Application.Exit() 'Exit

        End If

    End Sub

Almost done, we only have to do two more things. The first would be to edit the btnPostToWall button, to actually post a message on your profile's wall:

    ''' Post Message to wall

    Private Sub btnPostToWall_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPostToWall.Click
        fb = New FacebookClient(_accessToken) 'Get access

        Try

            fb.Post("/me/feed", New Dictionary(Of String, Object)() From { _
             {"message", txtMessage.Text} _
            }) 'Use Post to post the message

            MessageBox.Show("Message posted successfully")

            Exit Sub

        Catch ex As Exception 'Error
            If Not blnMessShown Then
                NFE.Show()
                NFE.lblMess.Text = ex.Message
                blnMessShown = True
                tmrError.Enabled = True
            End If
        End Try


    End Sub

Here we made use of the Facebook's object's Post method to physically post a message.

The very last thing we have to do is to open frmInfo's Designer window and edit it's constructor:

    Public Sub New(ByVal accessToken As String)
        _accessToken = accessToken

        InitializeComponent()

        GraphApiExample()

    End Sub

If you are still awake, or didn't fall asleep when I covered frmIntro, you will have noticed we created a frmInfo object like this:

            Dim infoDialog = New frmInfo(facebookOAuthResult.AccessToken)

Inside the DisplayAppropriateMessage sub. We had to do this, because once we have a valid access token, we can access the information through the querying methods I have shown. Also, if you have noticed, I never called the GraphApiExample anywhere inside frmInfo. We call it inside the constructor, so that it can fire immediately, and not only after the form has been loaded.

Setup Application

Our application is now 99.99% complete. Yes, it works and you can use it already, no problem. But, what if you are indeed writing an application for Facebook? What is the next step? What are the following steps? If you're interested, let me tell you. We need to create a decent Setup project. The reason for this is, once your application is approved, people have to download your application and install it. The installer will bundle all the DLLs into the Installer, and will also inform the users that .NET Framework 4.0 is needed, if they do not have it already.

Add a Setup project to your existing project, and choose whichever settings you want, like shortcuts on the Desktop, or Programs menu, etc. Once complete, you'll have an installer that will install everything where the user wants it.

Managing your Facebook Application

OK, all of the real programming work is complete. What we have to do now is to submit our application, Notifier.exe to the Application Directory on Facebook. We have to do this so that they can see that it is valid and uses the correct APIs. They do not store your application, it is only necessary for the reason I mentioned. Now Facebook has a clue as to what your application looks like, or what its function is. Approval takes about 3 days. Communication from Facebook is not very good, you may receive an email notifying you that your application has been approved, or not - as in my case. Help from their side is also almost completely non-existent. Luckily they have the Developers Forum, which you can search through, and then there is Google... Once approved, your Application's profile should be updated, and it will show you the following screen.

[NotifierSettings.jpg]
Figure 7: Notifier Settings

You can edit all of your settings as you like. Now, this may come as a surprise to you. It doesn't automatically give you the Download App button. You have to do some modifications to your settings first. This I battled with, because there were no indications on what to do next. As I mentioned, Facebook really needs to make their Application Submission process better. This is what you should do. First, you should upload your Installer to a webserver. If you already have a website, and have FTP access, you could just upload it to wherever you want on your domain. Remember that address, as you will need to provide that URL as the Download link inside the App Settings section. Here's a screenhot of what mine looks like :

[AppSettings.jpg]
Figure 8: App Settings Download URL

That is not all. What I figured out myself, (Again, Facebook really needs to give developers more guidelines and tips), was that you have to make your application a Native App. Do this by clicking Edit underneath App Information. Select Mobile and Devices, and then select the Native App radio button. As displayed in the following picture:

[NativeApp.jpg]
Figure 9: Native App

When we go back to the Application's Profile page, we will now have the Download button.

[Download.jpg]
Figure 10: Download, Finally!

I also find that getting Information such as total monthly users and so on is quite difficult. It is not very easy to manage your application, or maybe I'm just a bit thick. Eventually I figured out that if you go to My Apps, it will show you how many people like your app, and how many are using it. In my case, the count is still growing :)

[Statisctics.jpg]
Figure 11: Statistics

Conclusion

That is it. I sincerely hope you have enjoyed this article, and learned something valuable. Until next time...

About the Author

Hannes du Preez is a Microsoft MVP for Visual Basic. He is a trainer at a South African-based company. He is the co-founder of hmsmp.co.za, a community for South African developers.