N-Tier development revisited

Discussion forums on the web are full of .Net N-tier questions, especially on approaches for achieving loosely coupled layers and lightweight data passing mechanisms. Is it ok to pass a DataSet or DataTable? Should I use Custom classes? This article by Imar Spaanjaars is one of the better ones I have seen on the topic:

http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=416

He describes the pros/cons of the different approaches. He is a fan of pulling the "data only bit" out of your business layer objects and putting them into separate "business objects" (only containing data). This aids passing of data between tiers and project referencing.

Question though - does pulling the data out of your business layer objects go against pure OO principles? "An object should consist of the data and operations allowed on that data" etc. Abstract data types (ADTs), encapsulation etc bla bla...

Also, I don't like the BO (business object) terminology as it is used, as this implies more than just data... I'd prefer something like CustomerBDO (business data object) or even CustomerEntity. You could then perhaps lose the "*Manager" suffix notation he has adopted for the business logic layer.

Regardless of these points though, I think custom classes are the correct way forward for "passing data", and datatables etc should be saved for when the types of the results are dynamic, e.g. "adhoc reporting" result sets. 

Dell XPS M1710 – Vista Ultimate Upgrade

Further to my last post on Vista and my new Dell M1710 laptop.

As I said before, it came with Home Premium on it. I chose Home Premium because it seemed the logical choice for what I do (see Vista Editions)

What the comparison chart does not tell you is that some useful software won’t run on Premium, for example I came to install Virtual PC 2007, but check out system requirements and low and behold you need Vista Ultimate (despite it being Windows XP Prof compatible)! This is madness. Why should VPC need Ultimate Ed?

Anyway, I needed the software so thought I would “simply upgrade” my Home Premium edition to Ultimate via the much advertised “Vista Windows Anytime Upgrade” facility. So I went online to the Windows Anytime Upgrade site,

It indicated that I needed a windows anytime upgrade compatible Vista install disk, so I checked the Dell Vista DVD and… no official “windows anytime upgrade logo” on it. Daaarn. Would Dell really ship an install DVD that was not “upgrade” compliant?

I went ahead and purchased the Ultimate upgrade online (which automatically downloads/installs a file “product key” ready for upgrading) but played safe and paid the extra £5 for a windows anytime upgrade DVD (posted out) and subsequently closed the windows upgrade. I was assured by a message that I could put the upgrade disc in anytime in the future.

Not being very patient to wait for the DVD to arrive (I still could believe that Dell would not ship an upgrade compliant disk - digging around on the Net confirmed my thinking that all Vista DVDs come with all 6 editions on them), I put in the Dell Vista install disk and got the usual “Windows Vista – Install Now” blue/green screen… no mention of the upgrade though. Was it simply going to install Home Premium again? Aaargh! Did the Ultimate product key register correctly? I reluctantly clicked “install now” (still no mention of the Ultimate upgrade) and went through the install process.

At the end of the install I rebooted and waited with great anticipation to see what had been installed – hooray, Ultimate was now on my machine! It had worked!

So to summarise:

- if you wish to upgrade a Dell M1710 from Home Premium to Ultimate, based on my experience, you do not need to buy a separate Windows Anytime Upgrade DVD (I take no responsibility if your system is different though!)
- Despite the very poor installation wizard user feedback (come on Microsoft how did this get past your usability team?), have faith, your new edition is being installed despite what the user interface implies.

Once upgraded, all worked fine except I had no sound (a common problem with upgrades). Reinstalling the latest sound card drivers from Dell gave no joy either. Uninstalling the drivers and then letting Vista itself install appropriate drivers fixed this though. All is now fine.

Virtual PC 2007 now installs correctly and I can safely take a look at Visual Studio 2008 and .Net 3.5 ;-)

Other Useful link: Windows Anytime Upgrade Installation Overview and FAQ

Tool for choosing a colour palette

Being more of a techy than a designer, choosing a suitable colour palette for a web site is not exactly my forte.

Here's a tool that can help: http://www.nickherman.com/colormatch/

Define a colour using the RGB sliders and the system will suggest 6 matching colours for you. Works very well.

Running VS 2005, Oracle 10g client and ODT/ODP.Net on Vista

I've not long received a new laptop (went for the Dell M1710 in the end, not the most portable by any means but a real powerhouse desktop replacement style laptop, just the job when you are running VMs, virtual PCs, Oracle, SQL Server etc all on one machine). Gorgeous 17" screen 1920x1200 which copes nicely with the IDEs of today, although I am not convinced by the current trend of glossy reflective screens - sexy looking they may be but I don't really want to see a reflection of myself whilst coding thank you very much - non-reflective screens (as on my old Inspiron 5150) are much more usable in bright environments. Viewing angles are good though. Came with Vista Home Premium on.

Anyway... once I'd uninstalled all the free 30day trial 'crap' that is installed by default I set out to install all my standard apps that I use day to day.

On the list was of course trusty Visual Studio 2005, along with Oracle 10g client, ODP.Net and Oracle developer tools (ODT).

VS 2005 Prof and SP1 were not a problem, although I did get a couple of "known compatibility issue" pop-ups.

The Oracle versions I'd been using on XP, however were not compatible with Vista (unless you did registry hacks). Oracle have now released officially supported products.

Hence here's what you need if you want Vista compatibility 'out of the box' with Oracle:

Oracle Database 10g Client Release 2 (10.2.0.3)
http://www.oracle.com/technology/software/products/database/oracle10g/htdocs/10203vista.html

Seems to install fine although if you use the Aero interface in Vista you will see a message indicating that the installer is not compatible with that.

ODAC 10.2.0.2.21 (inc. ODP.net plus ODT if you want it) see
http://www.oracle.com/technology/software/tech/windows/odpnet/index.html

Note only the installer has been upgraded to make it compatible with Vista, not the individual ODAC products, so if you are using ODAC 10.2.0.2.20 on another Windows platform (as I do on XP), you don't need to upgrade. See C Shay's article http://cshay.blogspot.com/ for more info.

The above is official released software so can be used in production code.

There is also some nice beta stuff in the pipeline, see 11g stuff http://www.oracle.com/technology/software/tech/windows/odpnet/index_11gbeta.html

Live Writer - on/off-line publishing to your blogs

This is worth a look if you blog a lot (still beta):

http://writer.live.com/

Talks to Windows Live Spaces, Sharepoint, WordPress, Blogger, LiveJournal, TypePad, Moveable Type, Community Server plus others. I've not tried it in 'offline mode' yet but online seems to work fine. Just got it working easily with blogger and community server (which needs a little more work, see http://wlwplugins.com/how-to-configure-windows-live-writer-for-community-server.php).
Great for managing multiple blogs.

IIS6 app pools and session state

We've intermittently been having some sessions dropping on various web sites, after about 20mins (umm sounds familiar that value...), despite having session timeout settings of say 2 hours in our web app config files (both ASP and ASP.net). After some digging, I came across this:

http://blogs.msdn.com/david.wang/archive/2005/09/19/Why_do_I_lose_ASP_Session_State_on_IIS6.aspx

If you use in-proc session state (which is the default and very popular), your application pool's "shut down worker process after being idle" setting in IIS6 is likely to be 20 mins. Thus ignoring your web app config setting if your application pool is *idle* for 20 mins or more.

Easiest solution is to increase this idle timeout value. The other option is to store state out of process.

ViewState improvements in ASP.Net 2

I’ve recently been upgrading a project from ASP.Net 1.1 to ASP.Net 2. I’d seen documented that ViewState sizes had been significantly reduced, quoted as up to 50% smaller in some cases. A new serialization format, incorporated in a new formatter class (ObjectStateFormatter) is behind the improvements. See http://www.nikhilk.net/ViewStateImprovements.aspx for further info on how it all works.

Anyhow, I thought it would be interesting to see how much of an improvement I would get on some 'heavy' DataGrid driven data entry intranet pages. Here’s the stats in bytes:

ViewState Size ASP.Net 1.1 (ASP.Net 2)

Page 1: 9892 (7456 75%)
Page 2: 44492 (25696 58%)
Page 3: 39900 (24800 62%)
Page 4: 46300 (23500 51%)

So my worst case was ‘only’ a 75% reduction, but on some pages my ViewState was 51% of the original. Not bad. My advice of course is still to turn off ViewState when not needed ;-)