Cameron Fletcher

File Transfer via Clipboard Text

I have recently been involved in some work that requires me to program on a Remote Desktop (via RDP over an SSL connection) so there is no development software installed locally. One of the downsides is that due to the restricted nature of the connection only text based copy and paste works, so it is not possible to transfer files onto the development environment. Not only this, but although the local machine has access to the internet, the development environment has none.

The solution? I wrote a console based application called MemCopy to copy files to and from the clipboard as text. It does this by either encoding the file as Base64 then saving it as text on the clipboard, or decoding it from the clipboard.

I'd only written this in one of the environments, so I had to decode it in the other before I could use it - a bit chicken and egg, if you ask me. Anyway, I have attached a link to the encoded text here (you didn't think I was going to give you the solution on a plate did you?)

The code below is all that was required to decode it. I placed the encoding into the resources as a file.

byte[] buffer = Convert.FromBase64String(Resources.Encoding);
FileStream stream = new FileStream("memcopy.zip", FileMode.Create,FileAccess.ReadWrite);
BinaryWriter writer = new BinaryWriter(stream);
writer.Write(buffer);
writer.Close();

For those of you without the technical acumen to decode the above source, I have attached a working copy MemCopy as a zip file here. Simply download and extract MemCopy to a folder of your choosing, copy the contents of the encoded text (above) into memory, then execute MemCopy from the extracted location using the following command:

MemCopy /decode MemCopy.zip

The result? Awesomeness.

Posted: Sep 24 2009, 18:27 by flet0496 | Comments (0) |

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Converting a CTE T-SQL statement into Linq2Sql

Below is the SQL statement including the common table expression that I need to re-write using Linq2Sql for an application I’m working on. The query identifies the subset of most up-to-date records using a group by query in a CTE. It then performs a join back to the booking table to return the full list of most up-to-date records.What is noticeable about this particular piece of code is the join between table and CTE making use of the isnull keyword.

with cte (RootBookingID, CreatedTime)
as
(
    select
        isnull(ParentBookingID, BookingID),
        max(CreatedTime) -- get the latset version
    from [system].Booking
    where Deleted = 0
    group by isnull(ParentBookingID, BookingID)
)
select b.*
from [system].Booking b inner join cte
on cte.RootBookingID = isnull(b.ParentBookingID, b.BookingID)
       and cte.CreatedTime = b.CreatedTime;

When rewriting this in C#, we first declare the query for the CTE as its own variable.

//define the cte to use as an anchor
var cte = from b in this.Model.Bookings
          where b.Deleted == false
          group b by b.ParentBookingID ?? b.ID into g
          select new
          {
              BookingID = g.Key,
              CreatedTime = g.Max(b => b.CreatedTime)
          };

We can then reuse this variable within our core query (below). Notice how the join on isnull is created by explicitly defining the name of the anonymous type.

//perform a join on the cte to get the results
var qry = from b in this.Model.Bookings
          join c in cte
                  on new
                  {
                      ID = (b.ParentBookingID ?? b.ID),
                      b.CreatedTime
                  } equals new
                  {
                      ID = c.BookingID,
                      c.CreatedTime
                  }
          order by b.PickUpTime
          select b;

The post here explains the stumbling blocks I encountered:

To join multi-valued keys you need to construct an anonymous type on both sides of the 'equals' that is the same type. The anonymous type initializer expression infers both type and name of members from the expressions that are supplied. Using the name = value syntax in the initializer you can specify the name the compiler uses when creating the type. If all members, types, and names are the same then the anonymous types are the same type.

Posted: Jul 21 2009, 13:03 by flet0496 | Comments (0) |

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An error was encountered. Please return to the previous page and try again.

If you are trying to use the ASP.NET website administration tool and are getting a web page stating "An error was encountered. Please return to the previous page and try again." it is possible that you have the same error as me (see below). Another symptom is clicking on the "How do I use this tool?" link and being presented with a message stating "Tool Has Timed Out". 

It would appear that Microsoft, in its wisdom, has developed a tool that cannot handle the path of the web application it is designed to administer containing non-standard characters. Or spaces. To fix, simply copy your solution to a path that doesn't contain any non-standard characters. Or spaces.

eg. Changing C:\Will (Not.) Work\see.sln to C:\WillWork\see.sln

It's an easy fix to a problem most likely created by a tool both from, and within, Microsoft. 

Posted: Jun 16 2009, 12:41 by flet0496 | Comments (1) |

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Sentence and Word Analysis #2

This as part two of my post on sentence and word analysis. In part one I discussed my motives for analysing the RSS feed in question. In this post I shall be building upon my initial findings and presenting the C# and SQL code that I used to do so.

I have continued to run the RSS reader periodically and now have 284 job descriptions to analyse. I have run through the initial results and identified the words and sentences that are irrelevant and placed these into a keywords table so that I may strip them from my results. This was quite a lengthy process as there were a significant number of these to exclude - nearly a thousand. Following that, I looked through the results and because of the different permutations of the keywords that I was looking for it was evident that I would need to look within the top 100 words/phrases to identify the ones that I was interested in. I made a decision to leave in keywords that related to job skills in addition to computer languages.

The top 100 keyword/skills results from analysis of 284 job descriptions. The analysis took 9.5 minutes to run.

A link to a backup of the database may be found here: jobs.zip (392.41 kb)
You will need to restore this into SQL Server before the .NET code (below) will work.

A link to the .NET code (C#) is here: RssReader.zip (3.48 kb)
You will need to modify the App.Config file to point to your RSS feed and database.

To run the analysis on the sentances in the database you'll need to execute the 'analyse' stored procedure. Once that has finished execuiting you'll need to perform a select from the 'analysis_results' view to view the results.

Posted: Jun 09 2009, 14:21 by flet0496 | Comments (1) |

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Sentence and Word Analysis #1

I was not put forward for a job recently because I had Windows Forms experience and not WinForms experience stated on my CV. The same agency also said I had not been singled out as they were looking for someone who had worked with MVC, unlike me as I had only worked with the Model View Controller framework.

I have come to understand that I have to not only write my CV to appeal to prospective employers who should know what I’m talking about but also for the multiple layers of incompetent individuals though which my CV must make its journey before arriving before someone who can actually read. I have come to refer to these individuals as the jam layer because whilst I am the icing on the cake (and most of the time, the cake itself - that is, after all, what I get paid for) they are the jam in-between because they have jam for brains.

So, I decided to analyse the results from a jobserve.com search for .NET roles based in the UK and identify the top used keywords and phrases so that I could litter my CV with them in the hope that someone with jam for brains would identify the correlation, even if they don't understand what that means.

To achieve this completed the following steps:

1. I wrote an RSS reader in C# that read my RSS feed (for .NET jobs based in UK) that I'd set up through jobserve.com.
2. The RSS reader then iterated through each posting and called a stored procedure in my SQL database that added the content of the job posting to a sentences table as a string.
3. I then had a stored procedure that split the string into words and added them to a words table along with details of the sentence they were in and their position within that sentence.
4. The more complex bit was looping through the words in each sentence concatenating from one to ten consecutive words together throughout the sentence and placing the resultant string into an analysis table.
5. I then performed a simple groupby query eliminating the conjunctives (and, or, as, etc.) to retrieve the results.

This took me a couple of hours and as jobserve.com only allows you to receive the last 24 hours worth of job postings via RSS I present you with the top 30 ranked words/phrases from 75 job postings (below). The rank column details the number of occurrences of that word within the 75 postings.

Annoyingly, these results are probably more use to anyone wishing to write an appealing CV profile about themselves. For my purposes I probably need a larger dataset to work on – I reckon about 500-600 job postings and more granular analysis of wordsets ie. group words into technical, competency based, business area, etc. – and also to look into maybe the top 100 from specific wordsets rather than just the top 30 generic words.

Part two of this post may be found here.

Posted: May 30 2009, 11:59 by flet0496 | Comments (2) |

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Internal Interfaces

Occasionally there is the need to expose, for the purposes of an API or such like, a property of a class that has different external and internal implementations. Consider the code below: a person class with an Id property that is set to -1 by default with an external get property and an internal set property.

public class Person
{
    private int _id = -1; // default value
 
    public int Id
    {
        get { return this._id; }
        internal set { this._id = value; }
    }
}

If there are several classes that implement the Id property in this manner and there is a need to reference them through a common interface externally then implementing the following on each of the classes should be sufficient:

public interface IIdentifiable
{
    int Id { get; }
}

However, to reference these classes internally using the same common interface may be insufficient as it does not allow a call to the internal set property. Clearly it would not be efficient, or necessarily easy, to cast the classes to their individual types prior to making the call. One solution is to use a separate interface for internal operations; an interface with internal scope:

internal interface IIdentifiableInternal : IIdentifiable
{
    new int Id { get; set; }
}

Here, we implement the IIdentifiable interface and declare the Id property as new, effectively hiding its IIdentifiable implementation. We don’t reflect this in quite the same manner in our implementation of the IIdentifiableInternal interface on our class though. Instead, we explicitly implement the IIdentifiableInternal interface:

public class Person : IIdentifiableInternal
{
    private int _id = -1; // default value
 
    public int Id
    {
        get { return this._id; }
    }
 
    int IIdentifiableInternal.Id
    {
        get { return this._id; }
        set { this._id = value; }
    }
}

The external members of the class now include the public get method of the Id property, as does the public IIdentifiable interface. However, internally the class can be referenced using the IIdentifiableInternal interface which allows access to both the get and set methods of the property.

What has been demonstrated is how to take a number of classes with common members that have both public and internal scope and provide a means to reference them through a common interface, both internally and externally.

As a final point, if you have a linked library which you want to have access to the internal interfaces then you can use the following assembly attribute to expose internal to the specified assembly:

[assembly: InternalsVisibleTo("MyLibrary.InterfaceExample")]

Posted: May 09 2009, 18:51 by flet0496 | Comments (3) |

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Overridden method OnMeasureItem is not being invoked

I just ran into an issue when subclassing the ComboBox class whereby the OnMeasureItem method that I was overriding was not being called. I had set the DrawMode to OwnerDrawFixed in the constructor for my ComboBox which had in turn filtered through to the designer (non-default value). When I amended the value in the constructor to OwnerDrawVariable the change did not then filter through to the designer (no surprises there). The result being that my constructor had the following code:

this.DrawMode = DrawMode.OwnerDrawVariable;

However, this was clearly at odds with the designer as illustrated in the figure below:

In order to stop this occurring again, and to stop any modification of the DrawMode via the designer, I changed the line in the constructor of my ComboBox to reference the base like so:

base.DrawMode = DrawMode.OwnerDrawVariable;

I then added the DrawMode property with the new keyword to replace the base version (see below). You need to include the property setter as the designer will still try to assign a value to DrawMode.

[Browsable(false)]
public new DrawMode DrawMode
{
    get { return base.DrawMode; }
    set { }
}

After tidying up the designer code everything works like a dream.

Posted: May 04 2009, 18:21 by flet0496 | Comments (1) |

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Welcome to my Blog

Having decided it was time to get myself on the blogging bandwagon I started to look for a blogging engine that would suit my needs. I was initally taken by some of the MSDN blogs provided by Community Server that use the paperclip theme but further investigating led me to BlogEngine.NET, an open source project built on .NET which can only be described as awesome. My choice to go with this piece of software was confirmed when I found a paperclip theme for it provided by Caio Proiete who had taken the time to port it from the orignial. And this is the result. Welcome to my blog.

Posted: Apr 11 2009, 14:06 by flet0496 | Comments (0) |

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