Notes to self

I have a process that is using MSDTC (Microsoft Distributed Transaction Co-ordinator) to manage the transaction.

The transaction is controlled inside a c# .Net windows form executable that manages the transaction by the TransactionScope() object.

The transaction is maintained across 2 SQL server and an Oracle server and it all works… most of the time.

All transactions are opened inside a using statement, as follows

using (TransactionScope scope = new TransactionScope())

Or similar.

The overview of the .exe is it monitors a queue of jobs to process. It processes the work inside the transaction successfully commits, and then after that updates the status on the job queue to success or failure.

When there is an application error, the program throws an exception which means it ends the main transaction and in an outer transaction updates the status to failure.

Intermittently when the core logic was throwing errors on many jobs the entire process would fail with the following error:

Connection currently has transaction enlisted.  Finish current transaction and retry.

But it was intermitted. I had the same 12 jobs throwing errors on every run and sometimes it would crash with the above error after 2 jobs, 8 jobs, 4 jobs or it would actually not crash at all. On my development box I could not replicate it at all?

So I figured I had a race condition.

The fix

After the main transaction block of code and before opening the next TransactionScope object to update the status, I put a 100ms sleep.

    // Stop race condition
    System.Threading.Thread.Sleep(100);

    item.Success = false; // <-- this is my object for updating the success or failure
    using (TransactionScope scope = new TransactionScope())
    {
        context.SubmitChanges();
        scope.Complete();
    }

The problem has disappeared. I think the re-opening of a new TransactionScope() object did not allow enough time for MSDTC to close the previous transaction and it was crashing.

Cheers
John

I have recently moved my free wordpress.com blog (the one that you are reading) to my own domain.

If you read the contents on this site I hope you think I am reasonalby technically savy, but the feat of moving my site and redirecting the wordpress.com links was problematic and it took me a few days and many wrong turns to get it done.

I found that most instructions are based on apache/linux hosted solutions and I had issues using my IIS/Windows based host. My windows based host uses Plesk 10 (@ the time of writing).

Before you even begin to touch a computer there are a few things you have to think of first!

1. Root site or sub-domain?

Is this the only thing that you will have on your domain or are you going to have something else hosted on http://www.yourdomain.com? You need to answer this now as when you go to buy your domain mapping from wordpress.com you can only map a whole domain. So you would be better off hosting it @ http://blog.yourdomain.com, leaving the www for other things.

I started by creating my wordpress site with a click once install under a sub-directory in my httpdocs folder (main root web folder on my host), so I had my wordpress site setup @ http://www.homedev.com.au/ntsblog but as you can’t register a sub directory I had to start again.

So in my case I went and created a new sub-domain, http://ntsblog.homedev.com.au, and now I could register the sub-domain with my wordpress.com site.

2. Permalinks!!!!

Before you go any further you need to consider permalinks.

The issue

WordPress.com by default uses links that are styled as “Pretty Links” and default to a format of /%year%/%monthnum%/%day%/%postname%/” which means a posts will appear as http://blog.yourdomain.com/2011/11/31/post_title

The problem is that with version 3.2.1 of wordpress on a Windows host the “Pretty Link” is not supported by default and most “Permalinks” contain “index.php” in the path. see image..

Why is this a problem? Consider the link to your wordpress.com article that gets returned in a google search. When you try and do the domain mapping from wordpress.com to your domain, google will pass through a URL that your hosted wordpress site cannot handle.

This article discusses the various ways of mapping pretty links, and the section you are taken to is specifically for IIS/Windows systems.

http://codex.wordpress.org/Using_Permalinks#Permalinks_without_mod_rewrite

My hosting provider already had a copy of Microsoft “URL Rewrite Module”, so I created a web.config file as per the suggestion in this article and applied it to my site but it would not work.

Assume the URL was
http://ntsblog.homedev.com.au/2011/11/09/how-to-move-wordpress-com-site/

The URL re-writer would try to go to:

http://ntsblog.homedev.com.au/2011/11/09/how-to-move-wordpress-com-site/index.php/2011/11/09/how-to-move-wordpress-com-site/

In the end I did a little bit of tweaking and came up with the following solution…

web.config

Put this is the root directory of your wordpress site.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
  <rewrite>
    <rules>
      <rule name="Main Rule" stopProcessing="true">
        <match url=".*" />
        <conditions logicalGrouping="MatchAll">
          <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
          <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
        </conditions>
        <action type="Rewrite" url="redirect.php?path={R:0}" />
      </rule>      
    </rules>
  </rewrite>
  </system.webServer>
</configuration>

If you look at the “Action Type” link this is re-writing the url to go to a page called “redirect.php” passing in a parameter of the relative path. So we now need to create the “redirect.php” page.

redirect.php

Again, create this file in the root of you wordpress site.

<?php

  $relative_url = $_GET['path'];
  $new_relative_url = 'index.php/'. $relative_url;
  $hostname = $_SERVER['SERVER_NAME'];
  $new_url = 'http://' . $hostname . '/' . $new_relative_url;
  
  header("Location: " . $new_url)

?>

So what is this doing?
The URL re-writer matches the invalid URL and re-writes the url to “redirect.php”. This page then takes in the parameter, and rebuilds the full url to the site based upon inserting “index.php” in the chain. This works and also the “referrer” and “search engine” stats are not affected by the extra redirect.

To test this take an existing post on your new site, remove the index.php and paste that into a new browser window. The site should redirect to the index.php version. This means any link to your wordpress.com site will redirect to your new domain and be successfully passed along to the index.php page.

The only problem with this is that I don’t see how you could reverse the process and return to your wordpress.com site. The new articles will be found with index.php and if you try to go back to worpress.com as the primary domain the links with index.php will all break. Solution don’t go back. I will follow this up with wordpress and see if I can find a better solution.

Buy a domain from wordpress.com

Before you buy a domain read these wordpress articles about mapping domains or mapping sub-domains

Now seeing as I had created a sub-domain I went down the route of creating a CNAME entry. In plesk this means going to your DNSSettings and adding in a new CNAME. But being new to plesk I did not notice that when you make a DNS setting the settings shows with a warning like this
and right up on the top of the page you need to confirm the change by clicking Update.

So failing to notice that I handn’t saved the CNAME entry I gave up in frustration. So even though it told me not to I bought a domain and followed the full domain mapping instructions and it worked.

The instructions are fully mapped out in the mapping domains article but here are some extra tips.

1. Go to your domain name provider site and find your name server settings, copy and paste them into a .txt document so you don’t forget them.
2. With my name server provider, my names servers had a “Registrar Lock” on them. To update the ns1.wordpress.com, ns2.wordpress.com, ns3.wordpress.com, I had to
   1. Un-tick the checkbox and click save to clear the registrar lock.
   2. add the wordpress name servers and click save.
3. now go to your wordress.com site and go to Store –> Domains.
4. enter your domain, blog.yourdomain.com and click Add, follow the process to purchase the domain mapping
5. Once registered, select your domain as the “Primary Domain” and click “Update Primary domain”
6. Return to your name server and enter in the previous name server settings that you backed up to the text file.
7. Re-enable the “Registrar Lock” if you have one.

Your wordpress site should now all be working.

What Plugins?

Now you’ve been using wordpress.com for a while and you probably have it configured how you like it, so how do you make your new site just like wordpress.com.
Most of the plugins on wordpress.com are special to wordpress.com, so I found it difficult to find and install the plugins to get the functionality I am used to.
So here is a mapping between functionality and the plugin you can freely download and install:

#	wordpress.com	Plugin Equivalent
1.	Site Statistics	Jetpack
2.	Importer	WordPress Imported
3.	Ratings	GD Star Rating

Other plugins I have found of interest;

• Easy AdSense Lite
• Google Analytics for WordPress
• Preserve Code Formatting – keeps spaces and formatting when posting code snippets into your post.

Thats it for now.

Cheers
John

I’ve been trying to do the MVCMusicStore v3.0b tutorial, and I wanted to use SQLExpress rather than SqlServerCe.4.0.

When trying to do this I ran into a number of problems but I finally figured it out.

This guide assumes you already have a working copy of SQL Server Express and that your user account is a System Administrator for the database.

This is the link to the PDF document for the v3.0b tutorial. MvcMusicStore v3.0

(*all page numbers quoted as on the document, page 45 is actually Page 46 when listed in Acrobat)

Below is what I did and the 2 solutions that I found..

1. As on page 45* I created the AppData Folder.
2. I downloaded the MVC assets and extracted the files from the zip file.
3. Right click on AppData and add an existing file, and add in the MvcMusicStore.mdf.
4. Edit the web.config and added the following connection string:
   

   
   <connectionStrings>
     <add name="MusicStoreDb"
       connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|MvcMusicStore.mdf;Integrated Security=True;"
       providerName="System.Data.SqlClient" />
   </connectionStrings>
     

5. Added the MusicStoreEntities.cs as on page 47.

At this point Debug the site and I was getting errors. First I was getting errors about meta data failures.
I managed to play a bit more and somehow fixed the meta data issues so that it was no longer erroring, but the queries were not returning any data.

Then I noticed the following 2 issues:

1. Write some code like the following
   
   

   
         MusicStoreEntities db = new MusicStoreEntities();
         string connection = db.Database.Connection.ConnectionString;
       

   
   
   Run up in debug and check the value stored in the connection string.
   
   Note that the database name is related to the application MvcMusicStore, “MvcMusicStore.Models.MusicStoreEntities”? WTF?
2. Put a watch on the db.Database.Genres object and note the sql statement is is going to execute. The table name is “dbo.Genres”.
   The issue? Your datbase doesn’t have a “Genres” table it has a “Genre” table (minus the ‘s’).

Solution 1

So to fix these issues I have done the following:

1. Create a default constructor in the MvcMusicStoreEntities class like follows:
   

   
   public MusicStoreEntities()
   {
       this.Database.Connection.ConnectionString = 
              ConfigurationManager.ConnectionStrings["MusicStoreDb"].ConnectionString;
   }
   

   
   This over-rides the connection string with the one that we have specified in the web.config.
   
   
2. Pluralise your database.

   If your hosting your database on SQL Server you can use the SQL Management studio, or if you are hosting it in AppData then use the server explorer.
   Right click on each table and select “Open Table Definition”. Press F4 to view the properties window, Edit the “Name” property and change the name of the table and add an ‘s’ to the end, Genre -> Genres, Album -> Albums, Artist -> Artists etc. Save the file to apply the name change.

3. Edit: A bit more digging and I also found this solution to the Pluralised problem, this removes the pluralised table names. Probably a bit easier than the above solution
   In your MusicStoreEntities class add the following
   

   
           using System.Data.Entity.ModelConfiguration.Conventions;
   
           protected override void OnModelCreating(DbModelBuilder modelBuilder)
           {
               modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
           }
   

Debug your site and it should all work now.

Solution 2

In attempting to work out the above solution I also found a second solution.

1. Ensure the constructor is removed from the MusicStoreEntities class.
2. Edit the web.config file and add the following connection string
   

   
       <connectionStrings>
         <add name="MusicStoreDb"
           connectionString="Data Source=.\SQLEXPRESS;Integrated Security=True;"
           providerName="System.Data.SqlClient" />
       </connectionStrings>
       

3. Add the Sample Data as on page 47 & 48 of the PDF guide.

Debug your site and it should work.

Launch SQL Mangement Studio and refresh the list of databases, you will see you new database [MvcMusicStore.Models.MusicStoreEntities] and look at the tables and they have pluralised names.

Hope this works for you as it did for me. Happy MVC’ing.