I’m not sure how this happened, but it looks like it may have something to do with this… App_Offline.htm – ScottGu’s Blog.

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Cleaning the solution, closing Visual Studio and reopening it seemed to fix it for me.  Hope this helps!

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I’ve been doing a fair amount of work over the years for a limited company formation agent and unfortunately, this has meant dealing with Companies House.  I’ve not really had much other work where I’ve had to interact with government systems, but I think that, to put it politely, working with Companies House on a technical level has its own unique challenges.

Before I go into too much detail, why am I posting this?  I guess mostly it is because this is my blog and it seems like a good place to vent frustration, but there is also an element that I hope it may help some other people, whether working on similar systems that integrate with Companies House, other government agencies or just other systems that might have similar issues.

If you don’t feel that it is useful then by all means, please feel free to ignore this series of posts – no one is forcing you to read it!

As a bit of background, Companies House is the government agency responsible for forming and maintaining the records for companies, including (and mostly) limited companies in various different forms.  My client is a company formation agent, which means that they deal with forming companies, providing suitable documents for the constitution of the company called memorandum and articles or M&As for short (there are standard ones, but they have all sorts of legal problems) and providing advice about forming companies.  They also have a list of “off the shelf”/”pre-made” company names – companies that they have already set up and are ready for someone to buy and trade with immediately.

As well as all this, they provide a number of other services, mostly targeted towards accountants.  I’m not really going to go into much detail about these, because they don’t involve working with Companies House and that is the topic of this series of posts.

From a technical point of view, it all started quite a number of years back (I forget when exactly), when Companies House started accepting incorporations electronically.  This was done via a rather bizarre system of us sending and receiving emails with numbered tags in to pass the data back and forwards.  This was subject to all sorts of problems and was not very human readable (when the problems happened to try to debug them), so Companies House eventually decided to replace their quirky tag-by-email system with a more modern system of POSTing XML data to a gateway using HTTPS.  They even elected to use the government standard GovTalk encapsulating envelope system to standardise the communications.

Anyway, that’s the brief background – I’ll post some more detail in future posts.

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Retrieving the COM class factory for component with CLSID {0006F03A-0000-0000-C000-000000000046} failed due to the following error: 80080005.

I tried it on my development machine (also Windows 7), and found that it worked fine.  Then I noticed that if I didn’t have Outlook loaded before trying to send the email, it seemed to work.  I realised that I was running my program as Administrator to temporarily work around some permissions problems, and that when Outlook was loaded normally, it was running as the normal logged in user.  I tried loading Outlook as Administrator and it worked fine, so I sorted out the permissions problem and turned off “run as Administrator” in the compatibility section of the program’s shortcut properties.  It still worked fine.  It looks like COM can’t operate between different users, which I suppose makes sense.

There may be other problems that can cause this same exception though – a quick search gave me a few other possible problems and solutions.

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Just a bit of background first in case you aren’t clear on the SQL Server terminology.  A login consists of a username and some means of authenticating (usually a password or Windows authentication, but it could be a certificate or key).  It also has a default database and language.  It is stored at the server level and can have server wide roles.  This doesn’t affect the rights within a specific database though.

A user has a name and is connected to a login.  It is stored at the database level and it has particular roles for that specific database that affect the permissions for that user.  A login can have multiple users, but a user can only have one login.  When you log in as a specific login and try to access a database, SQL server looks to find a user in that database that maps to the login and applies permissions appropriately.

When you move databases from one server to another, reinstall SQL server as a new instance or similar situations, the user and the login become disconnected and you can’t login any more.  In principle, you could just delete the user and recreate it from the login, but that isn’t always practical, either because you have lots of them to do, or commonly because the user owns certain objects in the database and it isn’t in a state where it can be deleted.  In practice, therefore, it is necessary to have a way to reconnect a user and login.

My previous post was about how to reconnect these using sp_change_users_login with the ‘auto_fix’ parameter, but as I have said, Microsoft are removing that and we are supposed to use ALTER USER instead.

So what else can sp_change_users_login do apart from reconnecting users and logins?  It has 4 parameters: -

1. @Action
2. @UserNamePattern
3. @LoginName
4. @Password

The @Action one is the one that we’ve been using as ‘Auto_Fix’ (capitalisation isn’t important).  There are 2 other valid values for @Action, which are ‘Report’ and ‘Update_One’.  I’ll come back to these in a minute, but first, let’s see what else we can do with ‘Auto_Fix’.

The ‘Auto_Fix’ action has a second usage – if you specify a password in @Password then it will create the login if it doesn’t already exist.  If the login does already exist then @Password is ignored.  Either way, @LoginName must be left out or explicitly set to NULL.

The ‘Report’ action reports on any users that aren’t linked to a login.  @UserNamePattern, @LoginName and @Password should all be set to NULL or left blank.  This is useful if you want to check to see if there are any unmapped users that can be deleted or if anything has gone wrong and users have been disconnected.  This also returns the security identifier (SID) with the username.  The SID is SQL Server’s ID field for keeping track of users.  This is stored as a GUID, which is a binary field.  I’m not going to post about GUIDs here, but I may post more about them in future.

The final type of action is ‘Update_One’.  This attaches a user to a specific login.  @UserNamePattern must be set to the correct user, @LoginName must be set to the correct login name.  @Password should be left out or NULL.  Presumably this will re-map a user that is currently connected to an existing login to a different one if you want, but I haven’t actually tested this.

That’s everything that sp_change_users_login does.  The question is, how to reproduce this functionality with ALTER USER and any methods that aren’t marked as obsolete.  I see there being 5 possible operations here: -

1. reattach a user to a matching login name by just specifying the user (‘auto_fix’)
2. create a login name for a user by specifying a password (‘auto_fix’)
3. reattach a user if the login exists and if not then create it with the specified password (‘auto_fix’)
4. find users that aren’t attached to a login (‘report’)
5. connect a user to an existing login (‘update_one’) (I don’t think it is relevant whether or not the user is currently connected – this is still one operation)

I’ll go through these one at a time (please note that this bit isn’t tested, so it might need some correction, but it should work in principle)…

reattaching a user to a login: -

ALTER USER username WITH LOGIN = loginname

where username and loginname are the same.

create a login name for a user by specifying a password: -

CREATE LOGIN loginname WITH PASSWORD = password;

GO

ALTER USER username WITH LOGIN = loginname;

Again, where loginname and username are the same and password is the password.

reattach a user if the login exists and if not then create it with the specified password: -

The simplest way of doing this is actually to just do the same as above -

CREATE LOGIN loginname WITH PASSWORD = password;

GO

ALTER USER username WITH LOGIN = loginname;

Again, where loginname and username are the same and password is the password.  If the login exists, the first statement will throw an error, but the second one will use the login anyway.  This is fine if you don’t care about errors.  If you want something a bit more robust then you’d have to do something like using IF EXISTS on a query to find the name in master.sys.server_principals, checking that you are looking at a type of principle that is a login type and not a role or anything else.  If it doesn’t exist then use the above top line to create it, then end the IF and then either way run the ALTER USER statement to attach the user to the login.

to find users that aren’t attached to a login: -

select UserName = name, UserSID = sid from sysusers
where issqluser = 1
and   (sid is not null and sid <> 0x0)
and   (len(sid) <= 16)
and   suser_sname(sid) is null
order by name

ALTER USER username WITH LOGIN = loginname;

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Anyway, back to the email I got today… SagePay are warning that they are upgrading their systems between 27th and 29th August and first of all, if anyone has IP addresses of their payment gateways hard coded, they need to update them (sounds like a bad idea anyway), and secondly, to say that if anyone is using the Reporting and Admin API then please check the Reporting and Admin API Protocol document (linked to in the email) as the code may need updating.

First of all, a couple of minor observations: -

• They are allowing 14 days notice to make these changes.  That isn’t a great deal of time as many systems have a schedule of upgrades that are rolled out.  If anyone is in the middle of a big upgrade that could be a real pain in the neck.
• The new name is rubbish – which marketing guy thought that “Reporting and Admin API” is easier to remember than “Access”?

However, that’s not the real problem.  The real problem came when I looked at the document.

The document says

All requests are sent to one gateway at address:

https://test.sagepay.com/Reporting and Admin API/Reporting and Admin API.htm (Test)

https://live.sagepay.com/Reporting and Admin API/Reporting and Admin API.htm (Live)

https://test.sagepay.com/access/access.htm (Test)

https://live.sagepay.com/access/access.htm (Live)

The XML field will contain the XML message, which always takes the following format:

<vspReporting and Admin API>

<command>whatever</command>

<vendor>Vendor Name</vendor>

<user>User name</user>

<other command specific parameters in here…./>

<signature>MD5 Hash Signature</signature>

</vspReporting and Admin API>

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Since I didn’t want to waste any money on buying custom hardware to connect up a push button to the PC, and I couldn’t be bothered with too much complicated circuit design, I decided to cheat and disassemble an old (cheap) keyboard that I had lying around. It happened to be a PS/2 one, which is fine, since I’m using an A-Tech space saving keyboard on my server anyway which is USB, so the PS/2 port is free. The same principle would work just as well with a USB keyboard and of course that way you could probably have multiple ones plugged in, but then you might as well just assign different hot keys on the same controller if you want multiple buttons.

I elected to use the F11 key, since I don’t use it very much, especially on the server (which I rarely use directly anyway – it is mostly a file server, energy data upload for our Current Cost Envi 128 and it displays our CCTV cameras on a monitor by the front door). In hind sight, it is probably better to choose a different key, as F11 is usually used for making things like browsers full screen, but it isn’t such an issue for me anyway.

I discovered that the keyboard controller has 2 sets of contacts, numbered (I think) R1-R6 and D1-D12. When you press a key, it connects an R contact to a D contact, numbered depending on which key you pressed. I couldn’t really be bothered trying to trace the circuitry, so I downloaded a piece of software from http://www.passmark.com/products/keytest.htm and tried connecting different combinations of Rs to Ds until I found the right combination to give me F11. That only took a few minutes.

Once that was done, I screwed on a doorbell button that I bought for £3 on eBay next to my front door and ran the cable through the door frame. I wired up the 2 wires to the selected contacts and tested it. It appeared to be functioning as an F11 key correctly!

The next stage was dealing with the software. I realised that I was going to need a method of listening for global key presses in Windows, so I could use it as a hot key. Fortunately, I already had a project that I had downloaded from http://www.codeproject.com/KB/cs/globalhook.aspx?msg=3110732 – this allowed me to catch the F11 key being pressed.

I set it up to play a sound file when it receives the key down event. However, I didn’t want someone pressing the doorbell 20 times a minute, so I added a variable to keep track of when the doorbell was last pressed and not trigger anything unless it has been at least 10 seconds.

The next problem was playing the sound. I had selected an mp3 file, which I was rather disappointed to find that My.Computer.Audio.Play does not support (it only handles wave files apparently). I dug out the code for the old MCI command mciSendString and used that instead, which works very nicely.

That was basically it. I set it up to auto-load on Windows starting, although you’d be better off running it as a Windows service really, but I couldn’t be bothered setting that up and my server is always logged in for the CCTV and the CurrentCost software anyway.

Other improvements I’ve thought of: -

• I’m currently using a “ding dong” sound for it.  From a usability point of view, this may confuse people slightly, as they are used to a normal doorbell going “ding” when they press, and “dong” when they release, whereas my doorbell goes “ding dong” when you press.  I could split the mp3 file into “ding.mp3″ and “dong.mp3″ and catch the keyup event to handle dong in it, and put ding in keydown where the full sound is at the moment.
• Windows service I already mentioned
• Network messaging – when the doorbell is pressed, it sends a network message and PCs can display a message/play a sound in case eg. I’m listening to music at the other end of the house and I don’t hear it.  Equally, you could rig it up to send an email, SMS, twittweet or whatever you like, but I’m not sure why you’d want to.

Code: -

Public Class Form1
    Declare Function mciSendString Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Integer, ByVal hwndCallback As Integer) As Integer

Private LastPlay As Date?

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        AddHandler Gma.UserActivityMonitor.HookManager.KeyDown, AddressOf _GlobalEvents_KeyDown
    End Sub

    Private Sub _GlobalEvents_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs)
        If e.KeyCode = Keys.F11 Then
            If LastPlay.HasValue AndAlso Now.Subtract(LastPlay.Value).TotalMilliseconds < 10000 Then
                Exit Sub
            End If
            mciSendString("play """ & IO.Path.Combine(Application.StartupPath, "doorbell.mp3") & """", "", 0, Me.Handle)
            LastPlay = Now
        End If
    End Sub

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I’ve noticed something strange happening occasionally. The extension methods in one of the class libraries stop functioning as extension methods for no apparent reason. This is even if they are called from within the same class library. It is usually after I have changed something, but not anything significant, and the namespace references all appear to be correct when I check. This isn’t just intellisense either – the build fails compilation.

The simple solution to this problem that I have found (which may solve other weird compilation bugs as well) is simply to clean the solution, close Visual Studio, reopen it and build again. This has worked every time that I’ve tried it so far.

This applies to Visual Studio 2010 Professional, and possibly 2008 as well, but I can’t remember if I had that problem then.

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