I recently posted about using CAPTCHA on my blog in an attempt to reduce the amount of comment spam. The implementation I posted about has worked well for me but I decided I would like to switch to reCAPTCHA. Not only is this free CAPTCHA service robust and well tested, it also helps to digitize books, newspapers and old time radio shows. Taking the thousands of hours people spend entering CAPTCHA information each day and utilizing them for an additional purpose is a brilliant idea.

As with the previous solution I was sure that someone would have already done the work to integrate reCAPTCHA with BlogEngine.NET. My assumption was correct and I quickly found a solution in the form of an extension written by Filip Stanek. I followed the simple installation process and had the control appearing in the comment form straight away. After a short period of testing I quickly found a couple of problems. Once the first comment was added all subsequent comments entered resulting in an error that was reported via the callback. The log viewer added to the administration area was also throwing an exception and failing to load.

I tracked both of these problems down to the extension expecting the return value from BlogService.LoadFromDataStore to be a Stream. This method returns an object instance and delegates its work to the currently configured BlogProvider. The BlogProvider.LoadFromDataStore method also returns object, and it turns out that the type of the object returned will be different depending on the provider being used. My data store is a VistaDB.NET database so I am using the DbBlogProvider instead of the default XmlBlogProvider. Unfortunately the DbBlogProvider returns a string and the XmlBlogProvider returns a Stream. There is nothing stopping the next provider that is written from returning yet another type. This no doubt makes life difficult for those writing BlogEngine.NET extensions.

To get the extension working with the DbBlogProvider you will need to make a couple of small changes. In the Recaptcha.cs file, find the code below in the UpdateLog method.

Stream s = (Stream)BlogService.LoadFromDataStore(BlogEngine.Core.DataStore.ExtensionType.Extension, "RecaptchaLog");
List<RecaptchaLogItem> log = new List<RecaptchaLogItem>();
if (s != null)
{
    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(List<RecaptchaLogItem>));
    log = (List<RecaptchaLogItem>)serializer.Deserialize(s);
    s.Close();
}
log.Add(logItem);

Replace it with the following code.

string data = (string)BlogService.LoadFromDataStore(BlogEngine.Core.DataStore.ExtensionType.Extension, "RecaptchaLog");
List<RecaptchaLogItem> log = new List<RecaptchaLogItem>();
if (!string.IsNullOrEmpty(data))
{
    using (MemoryStream stream = new MemoryStream(Encoding.Unicode.GetBytes(data)))
    {
        System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(List<RecaptchaLogItem>));
        log = (List<RecaptchaLogItem>)serializer.Deserialize(stream);
    }
}
log.Add(logItem);

In the RecaptchaLogViewer.aspx.cs file, find the code below in the BindGrid method.

Stream s = (Stream)BlogService.LoadFromDataStore(BlogEngine.Core.DataStore.ExtensionType.Extension, "RecaptchaLog");
List<RecaptchaLogItem> log = new List<RecaptchaLogItem>();
if (s != null)
{
    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(List<RecaptchaLogItem>));
    log = (List<RecaptchaLogItem>)serializer.Deserialize(s);
    s.Close();
}

Replace it with the following code.

string data = (string)BlogService.LoadFromDataStore(BlogEngine.Core.DataStore.ExtensionType.Extension, "RecaptchaLog");
List<RecaptchaLogItem> log = new List<RecaptchaLogItem>();
if (!string.IsNullOrEmpty(data))
{
    using (MemoryStream stream = new MemoryStream(Encoding.Unicode.GetBytes(data)))
    {
        System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(List<RecaptchaLogItem>));
        log = (List<RecaptchaLogItem>)serializer.Deserialize(stream);
    }
}

You should now be able to use the extension with the DbBlogProvider without any problems. The rest of the extension seems to work without any problems and appears to be well written overall. It is definitely worth checking out if you are looking for a reCAPTCHA solution for BlogEngine.NET.

Santosh Benjamin recently announced that a Release Candidate of MockBird v2.0 is now available for download on CodePlex. In case you are not yet familiar with MockingBird, it is a tool that allows you to mock web services through configurable message interception. Below is a high level overview of the system.

If this sounds like something you would be interested in, be sure to test it out and provide some feedback.

It is not uncommon to have databases with a Compatibility Level that does not match the version of SQL Server they are running on. When you upgrade a SQL Server installation the databases retain a Compatibility Level that matches the version you upgraded from. The same applies to restoring or attaching databases from an earlier version.

I wrote the script below to set the Compatibility Level of a database to match the version of SQL Server. It is designed to work only on SQL Server 2005 and SQL Server 2008 instances. It uses the sys.databases view that does not exist in SQL Server 2000. I decided to use this view because I knew the script would not be executed on a SQL Server 2000 instance.

DECLARE @database nvarchar(128)
SET @database = 'Foo'

DECLARE @databaseLevel tinyint
SELECT @databaseLevel = compatibility_level FROM sys.databases WHERE name = @database
IF @databaseLevel IS NULL
    BEGIN
        PRINT N'The database ''' + @database + ''' does not exist.'
        RETURN
    END

PRINT N'Database Compatibility Level: ' + CONVERT(nvarchar, @databaseLevel)

DECLARE @productVersion nvarchar(128)
SELECT @productVersion = CONVERT(nvarchar(128), SERVERPROPERTY('ProductVersion'))
PRINT N'Server Product Version: ' + @productVersion

DECLARE @majorVersion tinyint
SELECT @majorVersion = CONVERT(tinyint, SUBSTRING(@productVersion, 0, CHARINDEX('.' , @productVersion)))
PRINT N'Server Major Version: ' + CONVERT(nvarchar, @majorVersion)

DECLARE @serverLevel tinyint
SET @serverLevel = @majorVersion * 10
PRINT N'Server Compatibility Level: ' + CONVERT(nvarchar, @serverLevel)

IF @databaseLevel = @serverLevel
    BEGIN
        PRINT N'The Compatibility Level for ''' + @database + ''' already matches the SQL Server version.'     
        RETURN
    END

DECLARE @query nvarchar(max)
SET @query = N'ALTER DATABASE [' + @database + '] SET SINGLE_USER'
EXEC sp_executesql @query

EXEC sp_dbcmptlevel @database, @serverLevel
PRINT N'The Compatibility Level for ''' + @database + ''' has been updated.'

SET @query = N'ALTER DATABASE [' + @database + '] SET MULTI_USER'
EXEC sp_executesql @query