Charlie Calvert's Community Blog : Samples

CSharp “How Do I Videos (Podcasts)” for the Zune Software

Charlie Calvert — Sun, 01 Nov 2009 20:54:40 GMT

It can be handy to create custom RSS feeds for the Zune so that it is easy to download and watch selected videos. You can watch these videos either on your PC, or on the Zune itself. Here is a custom feed I created that contains all the new C# 4.0 language and IDE How Do I Videos, plus a selection of other How Do I videos. In total, at this time, there are 35 videos in the feed. The RSS I created uses a simple and quite minimal syntax tested only with Internet Explorer 8 and the software for Zune 4.0.740.0. The source for the C# program that generated the feed includes regular expressions, LINQ to Objects and LINQ to SQL. I discuss that program briefly at the bottom of this post.

Charlie’s Custom C# and Visual Studio Feed
The How Do I Video Home Page with over 500 Videos
How Do Videos for Visual Studio
How Do I Videos for C#
Download the source for this post from the LINQ farm.

You can use this custom feed from inside IE, as shown in Figure 0. However, I really created this feed to run on the Zune, so you should import the feed into the Zune software as a series of podcast. I explain this latter process in the next section of this post.

Figure 0: Viewing a simple RSS feed in IE 8. Click the image to expand it.

Using the Feed in the Zune Software

In this section I provide a quick tutorial for those who’ve never used Podcasts with a Zune. Open the custom RSS feed in IE and grab the URL from the address bar. Alternately, you can just right click on any of the links to the feed in this document and choose Copy Shortcut or whatever the equivalent command is in Firefox or other browsers. Open the Zune software and turn to the Collection | Podcasts page. Click the button on the bottom left of the page called Add a Podcast. The Subscribe dialog appears. Paste in the URL for the feed, as shown in Figure 1, and then click the Subscribe button. The various How Do I podcasts included in the feed should begin downloading to your system, as shown in Figure 2.

Figure 1: Subscribing to an RSS Podcast feed in Zune Software 4.0.740.0

Figure 2: Viewing a feed in the Zune Software.

You can then plug in your Zune and right click on the feed and choose to sync the videos to your device. I’ll confess, however, that many of these videos look best on a PC, since you need a certain amount of screen real estate to adequately view the code typed in by the presenters.

Creating the RSS Feed by Screen Scrapping

I created this feed by the time honored hack of screen scraping. I first copied the URL for the home page of each video and passed it to C# code designed to download the HTML associated with the URL. The program parsed the HTML looking for the elements I needed in my feed. LINQ to XML provided a handy tool for creating my simple RSS feed. I simply passed in the data retrieved from the HTML file to a set of LINQ routines designed to produce the XML for an RSS feed.

This technique is simple to implement. Screen scraping is nevertheless a very brittle practice, as my code will last only so long as the basic structure of the HTML pages that I’m parsing remains static. How long such conditions will prevail one can only suppose.

I called my quick and dirty program CreateRssFeed, and its source is available for download. The program is based on two custom classes, one for generating the RSS feed, the other for using Regular Expressions to parse the HTML file. I store the URLs for the 35 HDI video pages in a file called UrlsToProcess.txt. I won’t bore you with the complete listings for this code, but I show the main body in Listing 1, and a short excerpt from the RSS feed is shown in Listing 2.

When you download the source, you will find versions for both VS 2008 and VS 2010, Beta 2. The latter solution contains both a console and a windows forms app. They each have their advantages, but I tend to prefer the former.

Listing 1: The main body of the program.

Code Snippet
 using System;
using System.Collections.Generic;
using System.IO;
using CreateRssVideo.Code;
 
namespace CreateRssVideo
{
    class ProgramConsole
    {
        static void Main(string[] args)
        {
            string[] urls = File.ReadAllLines("UrlsToProcess.txt");
            List<string> items = new List<string>();
 
            ParseHdiVideoPages parser = new ParseHdiVideoPages(items);            
            foreach (var url in urls)
            {
                parser.ProcessUrl(url);
                Console.WriteLine(items[items.Count-1]);
            }
 
            File.WriteAllText(@"..\..\CSharpZuneReadyHowDoIVideos.rss", parser.RetrieveXml());
        }
    }
}
 

Listing 1: An abbreviated version of the RSS Feed created by the code for the CreateRssVideo program.

Code Snippet
 <?xml version="1.0" encoding="utf-8" standalone="yes"?>
<!--Charlie's RSS Feed for Videos-->
<rss version="2.0">
  <channel>
    <title>CSharp How Do I Video Custom Feed for Zune Software</title>
    <description>VS 2010 Related Videos</description>
    <link>http://blogs.msdn.com/charlie</link>
 
    <item>
      <title>Add Tool Windows to the Visual Studio IDE?</title>
      <description>This video demonstrates how to</description>
      <link>http://msdn.microsoft.com/en-us/vstudio/dd250814.aspx</link>
      <enclosure url="http://download.microsoft.com/CreatingToolWindows.wmv" type="video/x-ms-wmv" />
    </item>
 
  </channel>
</rss>
 

The C# code for the CreateRssVideo program uses the build-in WebClient object to download the HTML for the video home page as a string:

private static string RetrieveHtmlFromSite(string urlName)
{
    WebClient objWebClient = new WebClient();
    byte[] requestedUrl = objWebClient.DownloadData(urlName);
    UTF8Encoding utf8 = new UTF8Encoding();
    string htmlAsString = utf8.GetString(requestedUrl);
    return htmlAsString;
}

It then uses bits of Regular Expression code to parse the HTML and extract the title, description and video URL from it:

private string FindStringInHtmlFile(string htmlAsString, string regEx)
{
    Regex r = new Regex(regEx, RegexOptions.IgnoreCase);

    MatchCollection matchCollection = r.Matches(htmlAsString);
    string groupItem = "";

    if (matchCollection.Count > 0)
    {
        foreach (Group groupItemFound in matchCollection[0].Groups)
        {
            groupItem = groupItemFound.Value;
        }
    }
    return groupItem;
}

Below is a sample of one of the simple regular expressions that I pass into the FindStringInHtmlFile method. This particular bit of code is used to retrieve the description of the video from the HTML file:

private static string regExDescriptionText = @"([A-Z\s0-9#\.,\(\)\-]+)";
private string regExDescription = @"<p><strong>About this Video</strong></p><p>" + regExDescriptionText;

While we are parsing the HTML, the program works step by step to create the RSS document using LINQ to XML. The first stage in the RSS creation is to new-up an outline or shell that will hold the meat of the document:

public void Start()
{
    string link = "http://blogs.msdn.com/charlie";
    string title = "CSharp How Do I Video Custom Feed for Zune Software";
    string description = "VS 2010 Related Videos";

    theDocument = new XDocument(new XDeclaration("1.0", "utf-8", "yes"),
        new XComment("Charlie's RSS Feed for Videos"),
        GetChannel(link, title, description));
}        

private static XElement GetChannel(string link, string title, string description)
{
    return new XElement("rss", new XAttribute("version", "2.0"),
        new XElement("channel",
                        new XElement("title", title),
                        new XElement("description", description),
                        new XElement("link", link)));
}

The Start method creates the document itself, including an XML declaration and a comment. The GetChannel method adds a few simple fields to the document that describes its purpose and which list the URL for my home page. Compare this code with the first few lines from Listing 1 to be sure you understand its purpose.

As the information for each HDI video is discovered, a new <item> node is created for the RSS feed. This node lists the title for the video, describes the video, and references the URL for the HTML page where the video is stored. Finally, and most importantly, the code includes the <enclosure> node which stores the URL of the actual video. It is the <enclosure> node that the Zune software uses to locate the video which it downloads to your system:

private static XElement GetItem(string itemTitle, string description, string linkUrl, string videoUrl)
{
    XElement item = new XElement("item",
                new XElement("title", itemTitle),
                new XElement("description", description),
                new XElement("link", linkUrl),
                new XElement("enclosure",
                    new XAttribute("url", videoUrl), new XAttribute("type", "video/x-ms-wmv")));
    return item;
}

Once the <item> node has been created, it is added to the XML document itself:

public void AddItem(string itemTitle, string description, string linkUrl, string videoUrl)
{            
    XElement item = GetItem(itemTitle, description, linkUrl, videoUrl);            

    var linkNode = from x in theDocument.Descendants("link")
                   select x;
    
    linkNode.First().AddAfterSelf(item);            
}

Note that this code includes a simple LINQ query used to discover the proper insertion point in the XML document, and then employs the LINQ to XML AddAfterSelf operator to insert the new <item> XML node into the code for the RSS feed. The program enters and loop and repeats the process of creating and inserting <item> nodes into our RSS feed multiple times. Once all the URLs in our UrlsToProcess.txt document have been examined the program exits.

Summary

The primary purpose of this post is to provide an RSS feed that you can use to download videos for viewing in the Zune software or in the Zune itself. I also showed a simple, and very brittle, screen scraping program that I used to create the feed. I wrote this program for my own use, and pass it on to you with only minimal claims of its value. If nothing else, it provides some examples of how to have fun writing Regular Expressions, and demonstrates how easy it is to use LINQ to Objects and LINQ to XML to create XML documents.

The video feed.
The source from the LINQ farm.

Sample Code for Games, P2P Apps, Vista Tools, Web Services for Flickr, MySpace, Digg and YouTube

Charlie Calvert — Wed, 19 Mar 2008 08:45:29 GMT

A number of interesting sample applications have been released for C#, VB and C++ developers over the last few months. These include

C# Sample code for building Peer 2 Peer applications on Vista
A C# toolkit for developing Facebook applications
C# interfaces for web services from Digg, YouTube, Amazon, Flickr and other popular sites
C# WPF tools
C++ Sample Games

Here are links to some of the most important of these toolkits:

Below you can see a WPF application for Peer to Peer Network programming.

FIgure 2: An easy to build Peer to Peer application that allows you to chat, send file or share pictures over a network.

The Coding for Fun Developer Kit

This developer kit has code for controlling many powerful technologies that are built into Vista:

Bluetooth
Vista Contacts
Vista Calendar
Telephony
Desktop Search
Power Management

There are also a series of Web Services that you can use to interact with popular Internet destinations

Yahoo Traffic
Flickr
MySpace
Amazon.com
Craig's List
Delicious
Digg
YouTube

Below you can see one of the sample applications that comes with the Coding 4 Fun Developer Kit. I entered in the string "LINQ", and the application retrieved related links to books about LINQ found on Amazon.com.

Figure 1: Clicking on the links in this demo application causes a browser to be launched that shows books on Amazon.com related to LINQ.

Vista Peer 2 Peer ToolKit

Build Peer to Peer Applications using drag and drop WinForms and WPF controls.
Build applications that stream video and music

Orcas Beta 2 VPC's to Expire November 1, 2007

Charlie Calvert — Fri, 26 Oct 2007 22:50:24 GMT

I use one of the Beta 2 VPC's regularly, and so I was interested to learn that it will expire prematurely on November 1, 2007. This is not Orcas itself that will expire, but the entire OS. If you have any projects or data that you are keeping on one of these virtual machines, you should move it right away. A new Beta 2 VPC will be made available for those who want to keep testing. More details are available here:

http://blogs.msdn.com/jeffbe/archive/2007/10/25/vs2008-beta2-vpcs-expiring-prematurely.aspx

Looking for Input on Visual Studio Content

Charlie Calvert — Sun, 14 Oct 2007 02:19:46 GMT

Kathleen McGrath and the folks who create the documentation for Visual Studio are running a survey to get feedback from users. Here is your chance to comment on the various types of online documentation provided by Visual Studio. Several different types of content are covered in the survey, including the content of the help files, online videos, samples, IntelliSense, books, third party web sites and search engines, the experience you have when you press F1, or the experience you have when you use the index to search through the docs. Don't miss this chance to tell us what you think about the content you encounter when you use C#, VB, C++, VSTO, VSTA, VS SDK or other technologies in Visual Studio.

Access the survey: http://go.microsoft.com/fwlink/?LinkId=102169. Click here to read more about the survey.

101 LINQ Samples Code Updated

Charlie Calvert — Mon, 12 Mar 2007 09:10:08 GMT

Just a quick note to let you know that the LINQ Samples code has been updated. The only change is to add the LINQ to Entities code back into the SampleQueries example. If you open up SampleQueries, you will see a new item called 101 LINQ to Entities samples.

SampleQueries has six sections, each with approximately 101 sample methods in it. Each section demonstrates a different LINQ technology:

LINQ to Objects
LINQ to SQL
LINQ to XML
LINQ to XML Part II
LINQ to DataSet
LINQ to Entities

Get the updated samples here.

March CTP Samples Overview Video

Charlie Calvert — Mon, 05 Mar 2007 12:15:48 GMT

Here is a short 7 minute video to serve as an introduction to the Samples that are included with the Visual Studio Orcas March CTP. The samples that shipped with the CTP needed to be updated. As a result, its best if you don't pull them from the CTP help file, instead, download them from my blog.

This video gives you a brief introduction to the samples, and explains about the support directories, called Data, and ObjectDumper. These directories contain files that some of the other projects rely upon. The video also shows you key samples such as SampleQueries, DynamicQuery, ExpressionTreeVisualizer and WinFormsDataBinding.

I recorded the video on my Vista laptop, and ran the samples in the Virtual PC version of the March CTP. Especially if you are running Vista, you also might enjoy using the VPC version of the CTP.

LINQ Samples Update

Charlie Calvert — Mon, 05 Mar 2007 09:12:57 GMT

Here are a set of updated samples for the Visual Studio Orcas March CTP. These samples replace all the LINQ and LINQ to XML samples that shipped with the March CTP.

This is a first cut on updating the samples. More updates may follow. Please report any problems you have with these samples by posting comments to this blog entry.

History

March 5, 2007: Removed LINQ to Entities code, changed connection string (Version 02).
March 11, 2007: Updated and Restored LINQ to Entities code in SampleQueries (Version 03).
March 23, 2007: Structure of main project updated. (Version 04)

Downloads

Download updated samples.

February/March Orcas CTP Now Available

Charlie Calvert — Thu, 01 Mar 2007 11:44:14 GMT

The February CTP (aka as the March CTP) is now available for download as a regular install and as a virtual PC. Here is a video that serves as an introduction to the CTP.

FebCtp Video: Stream it
FebCtp Video: Download Video
Text overview from the install page.
Please check out the samples Update page, as some of the samples that shipped with the CTP had issues. Get the latest updates, and watch the samples video.

This CTP is a pre-release version of Visual Studio Orcas. This release features support for LINQ to SQL, which means you can use LINQ to query relational databases.

There were a few issues with this CTP when running on Vista, and when running side by side with Visual Studio 2005. As a result, if you have VS 2005 installed, or if you are running on Vista, then I would suggest using the VPC version of this download. When downloading the VPC version of Orcas, don't forget to get the base image.

Here is a link to various LINQ related articles and posts, and be sure also to see this post which details many of the changes since the May CTP. Here is a link to videos and articles that I have written on LINQ.

Here are some Anders videos from Tech Ed Barcelona:

Here are few other LINQ related videos to help you get started:

Here are some specs to review:

CSharp Samples

Charlie Calvert — Wed, 14 Feb 2007 03:38:44 GMT

I've become the default manager for the samples that ship with the various Orcas CTP's and upcoming betas. As a result, I'm going to start a new category here on my blog where I can share information about these samples. It is quite likely that we will need to post updates to the Orcas samples during the CTP and Beta cycles. If that happens, the updates or links to the updates will appear here on my blog. To keep informed about the Orcas samples simply subscribe to the Samples RSS feed by using the links on the edges of this blog, or else come back here regularly and look for updates.