papadi Development Blog - .NET and Software Development by Dimitris Papadimitriou

February 23, 2010

Creating a Skype add-on using .NET - Part 1

Skype provides pretty rich API for us developers to create add-ons that can customize it's behaviour. There are a number of ways to use this API and access Skype functionality programmatically. Skype4COM is one of these ways and is the recommended one if you want to create your add-on using .NET. Skype4COM is a wrapper dll that provides Skype functionality into the COM world, therefore also to the .NET world, since .NET can use COM dll libraries.

Skype4COM.dll is located into the Program Files\Common\Skype folder (or Program Files (x86)\Common\Skype in case of x64 version of Windows). It is installed (and registered) there if you install Skype with Extras enabled (this is an option of one of the steps of Skype installation). Once done, you can add a reference to it from your .NET project. Simply right click on your project in the Visual Studio solution explorer, select Add Reference and then click on the COM tab. Skype4COM should be in the list populated there.

Example

Here is a simple (self descriptive) example of accessing Skype functionality from your C# code:

SkypeClass skype = new SkypeClass();

Debug.WriteLine(skype.Friends.Count);

Note that once new SkypeClass() is executed, Skype will warn the end-user that some process is trying to access it. End-user must allow your process to access Skype, else you will get an exception.

x64 operating systems!

Here is something you should take care of! I missed this step and in the beginning and spend quite some time figuring out why SkypeClass fails to be initialized! Since Skype4COM is a x86 (a.k.a. 32 bit) library, your add-in should also be x86 in order to be able to use it. In order to configure your project to produce a x86 executable you need to use the configuration manager of Visual Studio. Click on Build menu and then Configuration Manager. In Active solution platform drop down list, select <New>... and on the dialog that opens select x86 as platform. If you miss performing this steps you will notice the problem only on machines with x64 operating system. If operating system is x86, your .NET executable will run as x86 process anyway so it will succeed in instantiating Skype4COM dll.

Resources

Skype4COM Reference (all things you can do with Skype4COM)

Examples (a number of useful examples in many languages)

Forums (unfortunately you will not find prompt help there. most of the threads remain unanswered for days)

Filed under // .NET Remote Collaboration Skype Tools

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February 19, 2010

Comparison of issue tracking systems

Couple of years ago Sotiris Fillippidis - friend of mine and author of famous Zaharias Dentoftiahno tales - initiated a table of existing issue tracking systems to compare their features. Here is his blog post.

Today I came accross something similar in Wikipedia. It's a list of about 40 or more issue tracking systems. Take a look...

Filed under // Tools

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February 18, 2010

Overriding a small problem with Net.Tcp Port Sharing service and Visual Studio 2010 RC

I installed Visual Studio 2010 RC a couple of days after it became available, after uninstalling the previous installed beta 2. Today I discovered a small problem with Net.Tcp Port Sharing service. The status of the Windows Services console was the one show in the attached screen shot. It appears that the installation didn't update the service and it was still registered with executable that was in the previous version of .NET 4 (beta 2). So when trying to start the service I was getting a File not found error in Windows Event log.

I'm not sure if this was a problem of installation of RC or uninstallation of beta 2. Anyway, fixing the problem was easy. I downloaded .NET Framework 4 RC and executed it with the Repair option selected.

Filed under // .NET Visual Studio

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February 16, 2010

Windows Authentication in WCF Services

Click here to download:

WindowsAuthenticationTest.zip (17 KB)

There aren't may things one has to do to enable windows authentication in a WCF service. Actually Windows Authentication is by default enabled when using most of the standard bindings of WCF.

Configuration

The following configuration ensures this anyway (use this configuration both on server and on client side):

<system.serviceModel>

</security>

</binding>

</wsHttpBinding>

</bindings>

...

Server

To get the credentials of the user on server side using the following (password in never included):

var identity = OperationContext.Current.ServiceSecurityContext.PrimaryIdentity;

Client

On client you have two options:

a) Do not ask credentials from the user (Integrated Authentication): The credentials of the current logged on user will be used. This requires that the user is logged on to a Windows Domain that is trusted or is the same with the Domain of the server. There is no special code to write here. Simple instantiate the client proxy and use it.

b) Ask for Windows Credentials from the user: This is useful when you expect that your application will be used by users using machines not registered to known Windows Domains. In this case you have to create a typical log in dialog and ask for user name and password. Username must contain the domain name (Eg. MYDOMAIN\myUserName). Also this requires that the username and password the user will use belong to a domain that is trusted or is the same with the Domain of the server. In this case you also need to write the following line after instantiating your client proxy, and use the credentials you collected from the log in dialog:

clientProxy.ClientCredentials.Windows.ClientCredential = new NetworkCredential("MYDOMAIN\\myUsername", "myPassword");

Important

Patterns and Practices team created an excellent pdf document called 'WCF Security Guidance'. This is a quite big document that describes perhaps all the security scenarios that you might consider. It is organized in such a way that you can find what you are looking for quickly. Check it out!

Filed under // .NET Security WCF

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February 8, 2010

5 simple (non state of the art) features that make Skype so easy to use

I have been using Skype intensively for some months now, to make both personal and professional voice and video calls. Put aside the superb quality of voice and video (which I've seen also in other solutions like Live Messenger), I noticed some very simple, yet extremely useful features that differentiate it from the competition:

Incoming call notification on all speakers: This means that you can have your headphones pluged in so that you can use them to communicate, but still hear the incoming call notifications when you are not wearing them! (see 1st picture)
Order of preference for sound devices: This is very useful if you are using a laptop and your sound equipement changes frequently. You can specify which device (speakers/microphone) will be used for communication. If not found the next available will be used etc. So if you want to use the microphone of your external camera at work but the integrated microphone of your laptop when you are on the move, you don't have to get into the options page every time. You specify this once and you are done (see 2nd picture).
Mute is canceled when you answer or start a call: Often when you are about to make or answer a call you may forget that you muted your speakers just a while ago. This can also happen to the other participant, especially if he/she is not very comfortable with this way of communication. Skype takes initiative and enables your speakers when a call is started. It's obvious that since you started or answered a call you want to use them! When call is completed speakers are muted again.
Auto answer call: Enable this feature and Skype can be used as a remote surveilance system (see 3rd picture).
Echo / Sound Test Service: A very simple idea that helps you identify microphone, speakers and bandwidth problems. Echo user is a virtual user always present in your contact list. Call this user and see if and how other users hear you.

It seems that web conferencing and remote collaboration will become daily activity of mine in the near future. So stay tuned for more details about this experience.

Click here to download:

5_simple_non_state_of_the_art_.zip (201 KB)

Filed under // Remote Collaboration Skype Tools

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January 22, 2010

Resharper and RIA Services

(The following are applicable to current Resharper and RIA Services releases (see post date). I'm sure it will be fixed in the future)

Watch it RIA Service users that use Resharper!

RIA Services has a strange way (personal opinion) of doing code generation for references services, instead of using the traditional Service Reference approach. Actually, regardless of Resharper and the problem I'm describing underneath, when I first saw a RIA Services application I was really wondering how this works.

And it seems that Resharper is "wondering" also! That's why if you are using Resharper code inspection and/or intellisense you will notice that the classes that are supposed to be generated by RIA Services are not "visible" in your project. Actually if you do nothing, but just create a new 'Silverlight Business Application' using the Visual Studio template and open then App.xaml.cs you will see the picture bellow.

To fix this you have two options:

Disable Resharper completely (Tools>Add-in Manager in Visual Studio)
Disable Code Inspection and Intellisense of Resharper and let the Visual Studio do it:
1. Resharper>Options in Visual Studio...
2. Environment>Intellisense>General
3. and Code Inspection>Settings

Filed under // .net silverlight

Comments [3]

October 21, 2009

Finally! Create Project, Add New Item and Add Reference dialogs are fast!

I just installed Visual Studio 2010 Beta 2 on my machine. I only had little time to play with it so far but I'm so excited! Finally dialog boxes are fast! I never understood so far why 'Create New Project' and 'Add New Item' were so slow in previous versions! Any why 'Add Reference' was opening .NET Assembly tab by default and not Project tab.

Guess what! Huge improvement in VS 2010! Dialogs open extremely fast and Add Reference shows Project tab by default now. And even if you press COM or .NET tabs they are rendered in a few milliseconds!

Startup time of Visual Studio itself seems also improved!

Filed under // .NET Visual Studio

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October 15, 2009

CNET TechTracker - Scan your computers for new software versions

CNET TechTracker (www.download.com) can help you get notifications when a new version of software installed on your machine is released! It really works! You can configure to automatically run on windows tray and check for new software daily, weekly, monthly or manually. I suppose that this is possible only for software being distributed over download.com, but this is fairly big software database!

The results are reported to you with a tray notification or on the web. I've seen other applications like this one in the past, but none from such an important vendor like CNET. I suggest you try it out! See part of the results for my PC...

Click here to download:

CNET_TechTracker_-_Scan_your_c.zip (240 KB)

Filed under // Tools Windows

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October 13, 2009

E-commerce modules for DotNetNuke

Some time ago I was involved in a project of creating an online store for a Greek firm. The store was to be implemented using dotnetnuke. I made a research back then to find what was the most appropriate dotnetnuke module for that particular case. I run into a blog post which was presenting some, but the most interesting part was the comments under it. If you search you will find a couple of mine also there.

Its been several months now that I keep getting notifications about new comments on that post. The discussion goes on and on... Its quite interesting, have a look...

Filed under // .net dotnetnuke web

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October 10, 2009

Use REST and let others do the caching for you

I run into an (one year) old article of Udi Dahan today. He explains how REST can be used to scale up an application, of course without the need to add additional hardware.

The idea is simple. If you have a SOAP web service that thousants of clients call, then a common practice would be to add caching behind it, in order to avoid hitting your database (or other resources) for each request. Common and cheap practice that works up to some extend.

However, If you use REST instead of SOAP for your service, then your responses are simple HTTP responses. Therefor you can add some HTTP headers in them, forcing the intermediates of the communication (proxy servers for example) to cache the response themselves. The result would be that when the client tries to hit your server, intermediate servers will return the cached response instead of hitting your server. Nice!!!

Read the article...

Filed under // Web

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