Tuesday, May 6, 2008
In my previous article about changing the MS Access colour scheme I had the need to allow the user to restart the database after the colour scheme was changed.
Being able to cleanly restart the application is also useful in other instances:
- Changes made to the environment
- Recovering from errors (for instance after a network disconnection)
- Forcing the user to re-log cleanly into the application
- Automatically restarting a long-running application (for instance so that it may automatically compact on close and restart afresh with or without user intervention).
The problem is that you cannot -to the best of my knowledge- close and open again the same database from within MS Access itself.
Most executables cannot do that and the way to solve the issue is usually to pass the control to another boostrap programme, close the main application and let the bootstrap programme re-open the main application again.
I wanted a simple and clean way of using it. One that would not require shipping external programmes.
How to use it
Download the sample database below, copy the Utilities module or just the Restart sub defined in it into your own application.
To use it, just call the Restart sub and the application will close and re-open.
This will work for normal databases (accdb) and also compiled (accde) and runtime (accdr) databases as well.
How it works
If you’re curious about the technical details, here is how it was put together.
The main idea is that the MS Access database application has to be self-sufficient and restart itself by performing these steps:
- create a small batch file
- run the batch file, passing the path and extension of our database
- close the main application
- the running batch file would wait for the MS Access lock file to be removed
- once the lock file disappears, we open the database
The key point here is that the batch file cannot just reopen the database right away: if the application is big or if it’s compacting on close for instance, it may take several seconds to actually close.
The only moment we can be pretty sure that the database is effectively closed is when the lock file is deleted by MS Access.
The batch file is hard-wired in the Restart sub that does all the work:
When the application runs the batch file, it passes 2 arguments:
- the full path to the database without the extension
- the database file extension without the leading “.”
This allows us to easily construct the path to the lock file at line 30 (we add the missing “L” in the extension).
The funny use of PING is actually a simple way to wait for 100ms or so before we check if the lock file is still there or not. There is not SLEEP or WAIT function provided by default in Windows so we have to be a bit creative and use the timeout option of the PING command trying to ping an inexistent, but valid, IP address.
Once the lock file has disappeared, we open the database at line 40 and then delete the batch file itself so we leave no leftovers.
Download the ColorScheme.zip (31KB) containing the ACCDB database (same as the Color Scheme sample).
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Filed under : Database, MSAccess, Programming
Saturday, May 3, 2008
Microsoft Office 2007 comes with 3 colour (color) schemes.
Users can easily change it but when you deploy an Access application under the Runtime your users have no way to set the colour scheme as the application’s options are not available.
Luckily for us, Office 2007 stores the global colour scheme setting in the registry under:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Common\Theme
The values being stored under that key are:
1: Blue scheme
2: Silver scheme
3: Black scheme
With this information, we can easily both read and set the colour scheme.
The only caveat is that I could not find a way to notify Access to reload the setting automatically once it is changed, so users will have to restart the application before the change becomes active.
A small price to pay but if anyone has a better idea, please let me know.
To write the new value to the registry I use a set of WIN 32 APIs that are more flexible than the default ones provided in VBA.
You can download the sample database as it contains all necessary files, including the definition for the Win32 API functions.
Download the ColorScheme.zip (31KB) containing the ACCDB database.
The sample also contains some code to restart the database. It will probably be the subject of a next post.
Improvements/uses:
- Find a way for Access to reload the settings without having to restart the application.
- Use the knowledge about the current scheme to change the other colour settings in the application (or even adapt the form’s theme).
References:
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Filed under : Database, MSAccess, Programming
Thursday, May 1, 2008
Rob Cooper, of the Microsoft Access Team made an interesting post and a follow-up on how to add a transparent layer that cover the screen to focus the attention of the user to a login form or other important popup window.
The trick is to use some WIN 32 API calls to modify the transparency of a standard MS Access form made to cover the screen.
The effect is quite neat and I thought I would try it and make a sample database for others to tinker with it.
My version allows you to chose between covering the whole screen or just the main Access window and it will test if it’s running under a Remote Desktop Terminal and disable the layer in that case.
Update 07MAY2008
Following Rob’s improvements I made another sample database that incorporates his code with a few improvements:
- I added the
LightBoxForm.LayerToFullScreen property so users can choose explicitly how they want the layer to be shown.
- I moved the code to hide the layer into a Hide() sub so you can just show/hide the layer using
LightboxForm.Show and LightboxForm.Hide.
- I changed the Form’s
Resize event code in the LightBoxForm class to avoid flickering: resizing the form within its Resize event actually trigger the Resize event again a second time which causes flickering.
I simply modified the code to make the form totally transparent (opacity of 0) the first time the event is fired and assign it the expected opacity when the event handler in re-entered.
Samples
There are now 2 sample databases. Ech zip contains a Microsoft Access 2007 ACCDB file and its conversion to Access 2000-2003 MDB but please note that I have not been been able to test those in older version of Access and that form transparency doesn’t work in Operating Systems older than Windows 2000.
Download TransparentLayer02.zip (95KB), recommended version
(improved, more flexible version, based on Rob’s updated article).
Download TransparentLayer01.zip (82KB), original version
(simple code, based Rob’s original article).
Troubleshooting
If you are getting security warnings: make sure that you open the database from a Trusted Location or you will receive a security prompt.
If you don’t know how to do that, check these steps.
If the layer appears on top of the login form instead of behind: make sure that the top-most form has ist Modal properties set to Yes and the frmLightBox form has its modal property set to No.
If you improve on it, please let me know and I’ll post it here for all to find.
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Filed under : Database, MSAccess, Programming
Sunday, April 13, 2008
Business Week has a recent article where the author foresee the demise of Windows in favour of Apple’s OS.
Reading it, I couldn’t help thinking I was reading one of these overenthusiastic 1925 popular-science article promising us that within just a few years we would all use our own flying car to get to work.
Yeah, right, mine is parked right under my window.
The basic premise of the article is that Apple will attack the corporate market through the back-door, using the iPhone and its forthcoming development platform.
The author contend that development to the iPhone will drive interest in the Mac and allow Apple to displace Windows by offering more business-related applications that would eventually not require Microsoft’s OS running side-by-side in your Mac, freeing you of the dominance of the evil empire.
Please read the article first.
Done?
Hmmm…
Ok, let’s see…
First, let’s be nice: if Apple want to eat at Microsoft’s dominance of the OS market, then all the better: more competition will drive innovation and choice, which is always nice.
There is certainly some truth to the idea that Apple could offer some useful tools and technologies to the corporate world.
The problem is that author of the article was a bit too much of a Mc Fanboy(TM) to make his arguments compelling.
Let’s start direct quotes from the article.
Speaking of the ability of the Mac to quickly switch from a Windows application to a Mac by using a keyboard shortcut:
“Windows users, in the very near future, will be free to switch to Apple computers and mobile devices, drawn by a widening array of Mac software, without suffering the pain of giving up critical Windows-based applications right away.”
Useful as it may be, it’s forgetting one thing: if you need to be able to run your windows application under a Mac, you will need to give Microsoft money for the Windows license, making the newly found convenience of running the two OS together seamlessly a fairly expensive one, both in terms of computer resources and money.
While it will interest a lot of people and they may use their windows apps on Apple hardware is this really compelling enough to make it a viable migration path?
About the new Mac OS kernel:
That kernel has proved easily adaptable across the entire Apple product line, from highly complex servers all the way down to the relatively simple iPod Touch. Such modularity allows Apple to add whatever functions are necessary for each product environment—all while maintaining cross-product compatibility.
By contrast, Microsoft has held on to an OS tethered to the 1980s, piling additions upon additions with each upgrade to Windows. With last year’s arrival of Vista, Windows has swollen to 1 billion bytes (a gigabyte) or more of software code. The “Mach” kernel of the Mac OS X, however, requires less than 1 million bytes (a megabyte) of data in its smallest configuration, expanding modestly with the sophistication of the application.
All this is so silly and skewed that I wonder where to start.
First, kernel size is irrelevant: a basic kernel functionality does not make an operating system. Additionally, I doubt that we’re comparing the same functionality and for desktop or server applications this is utterly irrelevant.
For small devices Windows has its own flavours and they can quickly be deployed to almost any hardware with minimal effort.
Applications built for Windows built for mobile devices can be ported to Windows without too much trouble, and vice versa. Whatever platform you’re developing on, applications for small hardware are always an exercise in compromise: there is no way that you can just recompile an app for a different target and have it just work beautifully in any device. A mobile app must take care of power requirements, limited screen estate, memory and CPU limitations and specific usability issues like the presence of a touch-screen instead of a keyboard and mouse.
The point is that you have to take the platform into consideration when crafting software.
Besides, using .Net makes it fairly easy to develop applications for any flavour of Windows.
Additionally, whether the OS under the XBox is different or not from the desktop version of Windows is also irrelevant: you can develop games under the XNA platform that compile and work just the same under Windows as they do on the Xbox.
Now, for the argument regarding the “additions upon additions” made upon Windows that contribute to its bloat, it’s an easy shot to make and an unfair one: Apple has had no regards for its legacy applications and since its primary market was consumers, it could get away with making each of its major OS release incompatible with the previous one.
We can argue whether it was a good thing for Microsoft to keep all the quirks from previous releases of its operating system alive but we must not forget that in the corporate world, Windows has close to 100% market share on the desktop.
What that means is that Microsoft could not afford not supporting business applications across versions. it would have been suicidal to even envisage dropping compatibility.
If Apple ever get into that corporate market above a few percent it will have to guarantee compatibility between versions of its OS and programming tools if it wants to have any chance at being taken seriously at all.
When companies spend money developing an application that is critical to their business, they don’t want to hear about its supporting OS becoming incompatible every couple of years.
Apple would have to support and maintain compatibility for at least 10 years for every major OS version. So far Apple hasn’t shown that it was capable of that type of commitment.
A small digression.
A couple of weeks ago I found some old files of mine on a floppy.
They were Ami Pro files, made at a time when Ami Pro 3.1 was the best word processor around.
Problem was that I could not safely open these files any longer: filters for various word processors would mangle the complex layout of the pages, making them un-usable.
Out of curiosity, I found a full version of the original Amipro 3.1.
I had no expectations of being able to run that setup package. After all, Ami Pro 3.1 came out in 1994, before Windows 95 was even released!
Well, I clicked on that setup.exe file and watched the installation process go through…
Everything went fine.
Surely, I thought, there is no way this is going to run under Windows XP. It’s going to crash for sure.
I double-clicked on the 16 colour icon and lo and behold, the whole thing actually ran! Flawlessly!
I was able to open my old files without any issue, save them under another format.
Everything worked, miraculously.
That application was written at a time the Internet didn’t even exist yet I was able to install and run it without problem on a current operating system.
Back to our regular schedule.
“Despite Apple’s relative scarcity on corporate desktops, Mac laptops are already well accepted within the enterprise, with a market share of more than 20% and growing. For business travellers, the new MacBook Air, some three pounds lighter than comparable Windows-based laptops, already offers one huge advantage.”
First, Apple has a almost 20% market share on overall laptops sales only, not corporate sales.
Second, that figure is for the US only. Apple’s laptop market share in the world is certainly not bad, but it’s a quarter of that figure, making adoption of Apple laptops outside the US very small indeed.
Third, while Apple laptops are certainly sexy, they bring their own issues to businesses: lack of in-house serviceable parts, issues with making them fit into a complex infrastructure, hardware and software compatibility problems.
Bringing Macs into your organisation can be painful. Of course, it’s never impossible, but beyond simple setups, it takes time, energy and money to make stuff work seamlessly.
So I contend that, unless you have a serious commitment to Apple, most of the Macs getting into companies are for simple usage: fetching emails, browsing, making presentations and maybe Photoshop, although it seems that the application that was once the sole reason for some to use macs is now going to switch side, at least for a little while.
For Macs to become a first-class corporate platform would require that Apple makes a very serious commitment to cross-platform development to make applications work on Windows as well.
I seriously don’t think that the ability of Macs to run Windows side-by-side will do much: as mentioned above, the expense incurred offers no real benefit to businesses and having to support both platforms would increase the cost of ownership because of the upfront cost of buying and installing multiple OS, 15% higher average cost of Apple laptops compared to other similarly specified laptops and the cost of maintaining and supporting multiple hardware and OS stacks.
Slickness can only get you so far I suppose.
“While Mac desktops offer a growing number of superior features over Windows desktops”
Seriously dude, what superior features?
“Apple’s recently introduced Leopard servers compete in a market of unhappy Vista server buyers where Microsoft’s market share is only 40%. Leopard has a decent chance to expand from its small beachhead.”
Huh? Vista servers?
WTF is that?
You can’t be talking about Windows 2003 because it’s actually a rock-solid platform and there isn’t much to complain about.
Windows 2008 is just coming out and it looks just as promising.
Apple has some seriously nice server hardware, it’s so beautiful to look at all this engineering that it gets me all hot and bothered.
Seriously though, on the server side, Leopard would not be in competition with Windows but with *nix.
Server-side applications like ASP, Exchange, Sharepoint, SQL Server and the myriad other Microsoft-only server software will only work on Windows.
Apple is not going to compete as a platform for hosting these which means it will host services traditionally found on Linux/Unix/BSD systems.
In that *nix camp Apple would certainly be a good contender, although it would have to prove that it can compete with the low license and hardware cost of its competitors and offer more.
One more thing to remember: Apple is in the hardware business: it uses software to lock people into its hardware business.
I’m all for competition but at least using Linux or Microsoft products doesn’t lock me into a single hardware/software platform pair: I have orders of magnitude more choices when it comes to my servers, desktops and laptops than what Apple can offer me.
Apple products may be slick and beautifully engineered but they certainly don’t offer more freedom: chose an iPhone and get stuck with a single network provider, buy an iPod and get stuck with iTune, buy a mac and get stuck with Apple, limited software offerings, no serious games and limited hardware support.
One other thing to keep in mind is that Microsoft has acquired a huge weight in terms of software development power: new technologies have been pouring out of Redmond at a pace that is impossible to follow.
The number of developers and companies able to develop software for Windows platforms is wayyy above what Apple can dream of at the moment (we’re talking about millions of developer making a living off Windows).
Apple will need to make serious efforts to woo the huge amounts of developers it needs to bring enough business and non-business applications to its platforms before it can become a serious competitor to Windows in the corporate world.
Whether Apple has the capacity and will to do that instead of remaining a consumer-oriented company remains to be seen.
That being said I wouldn’t mind developing software for Apple platforms. I would love to be able to use a generic “surface laptop”, a sort of larger iPhone that could be used by sales people for taking orders and showing off new products.
Anyway, the point of all this was simply to offer a modest reality-check to an article that should have been a bit more measured and balanced in its fanboy-ish enthusiasm.
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Filed under : Business, Reviews, sysadmin
Sunday, February 10, 2008
Decoupling the User Interface from the underlying code has been one of the holy grails of application development.
Layers of indirection and new patterns have been invented over time to try to separate what the user does from the back-end data. It’s been a long and difficult journey but WPF is the last attempt at completely separating the user interface from the gut of an application, leaving graphic designer do what they do best and programmers do what they do best.
I think this disconnect has actually hindered the adoption of WPF to a great extent.
I also believe that Silverlight, while showing great promises, is going to take a long time to get off the ground.
Good graphic designers who work on User Interfaces are too few and far between, and large organisations will take time to get staff with a sufficient level of expertise to be useful in developing meaningful WPF/Silverlight applications.
Until now, the bulk of the development effort was done by developers. Most ISV only have developers onboard.
As far as I can tell, it seems that main reason behind this slow adoption is that WPF/Silverlight has only been noticed by developers and they don’t know what to make with it.
WPF/Silverlight are not really developer-friendly: the development infrastructure is there but we’re left with a blank canvas and nothing to drag and drop onto it.
There will be a great gap, probably lasting a few years, before there are enough experiments in these new user interfaces that some useful lowest common denominator can be exploited by non-designers.
We’ll have to wait for tool vendors to provide the bulk of user interface blocks and for a few new patterns to appear before all the designer-challenged developers like me can make decent interfaces without requiring a professional graphic designer in their midst.
In the mean time, we’ll probably have useless, but pretty, applications, some useful, but ugly ones and a lot of people scratching their head trying to couple the designers and the developers in a working relationship.
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Filed under : Musing, Programming
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