UI creation patterns - Design and Architecture Discussion Boards

Wow Gary,

That wasn't very nice. I was asking for help, not insults.

Mental note to self... "Don't use this message board anymore"

You're silly Wauhoo.

I offered not an insult, but advice. You may take it or ignore it, but I think if you can't do the basics of your job, you should be looking for another. Just kindly advice.... Just because you can spell coder doesn't mean you are one.

Is a "mental note to self" a mental note to self when it is public and to everyone? Poke tongue | ;-P

Gary

Gotta say, with 10 years experience in something that hasn't existed for 10 years, I'd expect you to know a little more that what's evidenced in your post.

You should take advantage of "Professional Hospitality offers competative [SIC] compensation and a comprehensive benefit package which includes:

* Career training program"

Gary

Wow..... you are really a mean and nasty person.

Why do you want to insult me so much?

What on earth do you have to gain by rubbing my face in the sand?

You've made a lot of judgements about me with extremely little information.
It's hard not to take it personal when someone says you are not good at the job you've been doing for over 10 years.

" but I think if you can't do the basics of your job.."

How do you know that I cannot do the basics of my job?

Have you ever heard the statement "Two heads are better than one?"

It's always beneficial to have people review your designs, whether you're a veteran or a rookie.

Wauna wrote:
Have you ever heard the statement "Two heads are better than one?"

Especially if you're conjoined.

Deja View - the feeling that you've seen this post before.

My blog | My articles

Wauna, There is a ton that can be said about design and architecture and there is no way to fully answer you question here. That being said, after reading your summary a few things strike me.

1) Can you identify entities on the spreadsheet that are, or can be, represented by objects? If so, then you may need to rethink your architecture to leverage those objects instead of a spreadhseet.

2) Don't tie the UI for data entry to the layout of the report. Or perhaps a better way of saying this is, don't assume that the method off data entry must mirror the report layout or vis versa. A spreadhseet may not only not lend itself to easy validation in a web app, but it may not be the most optimal form of data entry for your end users.

Just a few thoughts, take 'em or leave 'em, but there they are.

The last couple of days I have been recreating Pong in Silverlight. The reasons for this are threefold:

1) I'm on holiday, and have little better to do (well, actually I have lots better to do, but no motivation to do them).
2) I wanted to play around with the Silverlight 2.0 beta
3) I wanted to investigate a UI pattern, so I picked on MVP although I realise now it has been deprecated.

All-in-all the process was extremely easy, despite a few quirks in the SL 2.0 beta, however one issue popped up related to MVP - possibly due to my naivety - which I thought I'd run past you folks.

In a business application that collects various data from various textboxes and other controls the model and the view can be cleanly separated via the presenter as the way in which the data are displayed is unimportant to the model, and the way in which the data is handled by the model is unimportant to the view.

Whilst some of this holds true for my Pong game I found - naivety again? - that there exists a coupling between the view and the model. This in my mind is because the objects involved - bat, ball etc. - do not hold data themselves as a textbox would, but because the model holds data about the position and size of these objects.

Quick aside: The reason this situation occurred is because I drew the court etc. in Expression Blend first and then came to the coding in a simulated designer + programmer type environment.

Now I could take this up a level and say well the Canvas - ie the court the game is played on - contains these objects and it should be relatively trivial, except that we might reasonably want to change the size of court and again we run into the same issues of that dependency existing between the model and the view.

By now I'm thinking whilst MVP is a powerful technique - and offered a number of benefits, including the removal of all game logic from the view - it needs tweaking for this problem domain.

So basically I think what I'm looking for is either a method of defining the game elements from the model and building the UI on the fly - which completely does away with the idea of Expression Blend, graphic designers and arty-types, or a sensible approach to sending the details of the UI (court size, ball size, bat size and position &tc.) into the model without creating a huge dependency between the two... thinking about it, this second could quite easily be accomplished by the Presenter, couldn't it - but would that create another dependency issue, or would having a SilverlightPongPresenter tied to Silverlight (and maybe a WinformsPongPresenter and a...) which implements IPongPresenter be acceptable?

/me Goes off to fiddle.

So, what happened???

Jon
Smith & Wesson: The original point and click interface

I went back to work Smile | :)

martin_hughes wrote:
I went back to work

Oh !@#$#@! Your post was great. Raised all sorts of questions in my head. Now I'm going to have to work on the answers? . . .Maybe I could post a PLS HELP URGNT about it. . .

Jon
Smith & Wesson: The original point and click interface

I have an Export Engine that uses an XML export definition to create mainly CSV files from a database. I would like to build in exception tolerance at the field and line level, so that when testing a new definition or a change to a definition, I just log all exceptions, and deal with them as a batch after a test run, rather than have the run abort at each new exception found. Exceptions that should be tolerated are invalid field names, null values etc.

Are there any established patterns for implementing this?

Pits fall into Chuck Norris.

I would use a validation engine for this, and just build up a list of validation failures. The beauty of a validation engine is that you can add rules iteratively and the engine should be able to cope. I wrote part of one a while back that you are more than welcome to take and add your rules to. Send me a mail for it.

Deja View - the feeling that you've seen this post before.

My blog | My articles

Thanks Pete, I'd love to have a look at your engine, but what are you suggesting I validate? The definition, i.e. does the query execute, do all the output fields map correctly to input fields etc? Or validate every row of input data against the output schema?

Pits fall into Chuck Norris.

It's up to you what you validate, but you could do things like validate that mandatory fields aren't null, that field types don't conflict with field values - that type of thing.

Deja View - the feeling that you've seen this post before.

My blog | My articles

I've decided, in light of this being a financial application, any exception handling or avoidance, is not worth the risk, so I'm revising my strategy to only possibly increase the number of exceptions thrown. Applying a validation engine here would be overkill, as most operations generate exceptions for fault conditions, e.g. invalid field names, but I'd still like to see your engine and maybe use it as inspiration elsewhere.

Brady - send me an email (through the email link here) so that I can get an address to send the project to.

Deja View - the feeling that you've seen this post before.

My blog | My articles

Maybe have it raise events rather than throw exceptions, perhaps when in a "testing" mode or something.

try
{
    // Do something
}
catch ( System.Exception err )
{
# if Testing
    OnExceptionCaught ( err ) ;
# else
    throw ( err ) ; // Hopefully with additional info, of course
# endif
}

Hi at all,

my team is stuck with a problem that we get not solved reading books as we do not get answers from reading rather than more questions.
To be honest, we are OO-novices.

Situation:
We are developing as 3-tier application with .Net 2.0 using remoting for the communication between the client and the application server.

We have some complex business logic to implement that requieres certain checks that may result in terminating the business process.
Problem: we have to give the user a exact status information what went wrong to give him a chance to correct the problem. A message "your action was not completed successfully" is not enough, we have to be very precise.

Our first approach was to use exceptions (user exception classes derived form "ApplicationExcpetion") but as far as we found out by further reading this is not recommended as exception should only be used as the "emergency exit" if something unexcpected happens. This is expected behaviour of the method.
And now the question: how else can we solve the problem?

Status values can not be return values (which is also bad design), and just returning "NOTHING" in a object doesn't do the job for us. Remote events are critical to coordinate with the running business process that will terminate.

Any solution or a hint for further reading on this problem is greatly appreciated.

Thank's in advance

Thomas

Hi,

I would use Exceptions for everything that isn't the normal flow of things; they are not
just for "emergency exit", they can signal whatever it is you want signalled. And the
advantages are clear: they are objects, can't get lost, and can be chained thru InnerException.

Smile | :)

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Theres nothing wrong with throwing an exception containing a list of business rule violations.

The "exceptions should not be used in normal program flow" is because exceptions take a non-trivial amount of time to throw. This rule refers to constructs like so:

while(i++)
{
  // do something
  if(i>10) throw;
}

If an action is occuring, and a business rule is broken such that the action can't proceed, then an exception is ideal to signal this. It backs up through the call stack, letting every catch/finally block perform its tasks, and effectively backs cleanly out of the action.

A benefit of exceptions is that its difficult to ignore them without explicitly 'eating' them. I've seen several bugs due to people ignoring return codes (usually with crappy code-generated data layers with bool businessObject.Save() - and people ignoring the return code).

Mark Churchill
Director
Dunn & Churchill
Free Download:
Diamond Binding: The simple, powerful, reliable, and effective data layer toolkit for Visual Studio.

I too wouldn't hesitate to use exceptions for exceptional circumstances, that being said, broken business rules are a little too common for exceptions:

Normally the business objects would do the validation, check business rules in the middle tier assuming your bottom tier is your data access tier. Also normally the business object has some state for the validity of itself so it should have something like an IsValid property that the ui layer can check and use to allow or disallow saving etc. Also a collection of the current broken rules and a easy to retrieve text property of all of them.

For example the UI layer has a save button, the save button is disabled as long as the IsValid property is false. It also has a little icon representing broken rules, maybe a red asterisk, you mouse over it and a list of broken business rules pops up. In my apps the property is linked to the field on the form so that each field can display a red asterisk if a rule is broken on that input field or area of the app, when you mouse over it you get the localized text of the problem.

I.E. the UI layer should check *before* attempting to save / update so that there is no need to throw an exception in the first place.

In my code it throws an exception mostly if someone using my business objects in my api ignore the isvalid and attempt to save anyway.

So let's say you have a middle tier business object with a set of properties, upon setting a particular property it checks a business rule / validates, something is wrong then it sets the IsValid flag to false and sets a text of the broken rule in the collection.

Of course if an error develops at the remote server then the practical way to pass back that status is through an exception and you can easily set the text of the exception to anything you want so detailed info can come back this way as well.

"The pursuit of excellence is less profitable than the pursuit of bigness, but it can be more satisfying."
- David Ogilvy

Hi,

Please try to implement Single Tone pattern design in you Application:
Managing Methods and events in listener place hold.

1.Using event Listeners Pattrens

Eg:If You want Display Exact error messages for your events: You need to develop cusstome message class.

this class having methods and properties to get data and relevent data it compare in DB.

If any Action is going wrong those data recorded in event Logs:

Process Like: Create Custome Message class
2.Inherite properties at event firing place.
3.All record your meesages in Db
4.Compare control Id and Status with message.
5.Dispaly Your Message.

If you wana more clear let me know on mail: msudhanreddy@gmail.com

with Regards,
MAdhu.k

If your looking to pass error details to the presentation layer i would recommend taking a look at the Notification pattern http://martinfowler.com/eaaDev/Notification.html[^]

A minor, but somewhat important nit to pick. When you talk about passing data between tiers, you imply that you are talking about physical machines. From your question, however, it would appear that you mean that you have three layers. Although it's possible, even likely, that each layer will be hosted on a separate machine, that is not a requirement of multi-layer design. (It's also possible, even likely that you'll end up with more than three layers, but its usual to only have three tiers. For instance you might have a UI Layer that hosts both a UI Component layer and an Application layer that serve both a Win and a Web version of the app.)

Jon
Smith & Wesson: The original point and click interface