All posts by visionarycoder

Generic Types with Complex Constraints

I am working on a WPF app, leveraging Prism and Unity.

I have a scenario where I have lots of similar views/viewmodel. Not exactly alike, but 90%. I have 22 dimension-type datatypes. Instead of building out 88 individual MVVM scenarios, I am doing a cut-n-paste for the 22 instance of each specific activity (CRUD/Navigation). I needed to figure out how to define a generic base viewmodel that enforced inheritance for the generic type.

BTW: This is a throw-away app with an expected <3yr lifespan. It’s not worth the time/effort in building up something truly dynamic. I need to slam it out and pass it off to off-shore support. If it’s too complicated, I won’t be able to hand it off. This falls under, ‘Just get it done,’

All of the samples I could find were ‘ClassName<T,U> where T : class where U class’ examples. That doesn’t work for what I need to do. Below is how I solved the class definition issue.

public class DimensionBase : BindableBase, IChangeTracking 
{
...
}
public abstract class CollectionViewModelBase<T> : BindableBase, INavigationAware, IActiveAware where T : DimensionBase 
{
...
}
public abstract class DetailViewModelBase<T> : BindableBase, INavigationAware where T : DimensionBase 
{
...
}
public abstract class EditViewModelBase<T> : BindableBase, INavigationAware, IConfirmNavigationRequest where T : DimensionBase 
{
...
}

What I learned is that you can tack on the where clause to the end of the class definition to enforce constraints on the ‘T’ after all of the constraints are applied to the base class itself. I had been trying to manage the ‘T’ constraints first which is following my understanding of the ‘standard’ examples of where T … where U …

The delete action is managed by the collection view model, by way of the confirmation dialog hosted in the shell. I use events to manage that process.

There one more thing I want to clarify. I am using the region manager to handle all view-based navigation. I am using the event aggregator for passing messages around the system. The biggest one is telling all of the views to refresh their data when the target environment has changed. Getting navigation/confirmation dialog to fire, leverages events because the views hosted by separate modules (24 so far) that cannot directly access the notification/clarification dialogs hosted in the shell. Nor does Prism enable hosting these dialogs in a region (as far as I can tell). So there is only one way to do it. Events.

Enjoy.

TED talk: Feminism

Well worth the time to watch.

Yet Another Service Locator

I have been writing a bunch of small samples apps, trying to improve my understanding of volatility-based decomposition solutions.  As part of this effort, I needed a proxy to link calls to services without the client directly calling the services.  This is a fundamental detail in any microservice implementation and there are libraries to enable this, if I where building Service Fabric applications.  But that isn’t what I am trying to do.  I need a tool that is light-weight, super-easy to use, and something that at least vaguely follows the SF communication patterns.   Continue reading Yet Another Service Locator

A MEAN Pivot

There are inflection points in life.  It would appear that I am at another.  IT “Management” has decreed no new .Net starts.  For the last decade I have been a .Net developer.  So…???  Shrug.  Whatever.

Let’s rewind a bit.

When I got out of college, I was a LAMP guy.  I ended up making a fair amount of money doing perl programming.  I built websites, CD-ROMs, and lots of automation scripting.  I was pretty solid with *nix platforms (Debian and Solaris were my favorites).   In short, I was doing OK in the Open Source world back then.

Why did I change from open source to, what was then, closed source?

Opportunities.

I attended meetings with Microsoft where they showed what could be done with their technology.  From C# v1 to Azure v1.  Each time, Microsoft provided a clear line of thought and succession.  They created order where the open source world only provided chaos.  (Not that they haven’t had several epic missteps too.)  Too many times, I saw customers left in the lurch because a given open source community faded then died.  Ruby?  Perl 5.X?  JQuery?  Compare that to C#.  How long has it been around and still growing?

So why take the risk to pin the hopes (and profits) of the Enterprise on JavaScript?  This makes no sense when you look at the history of Open Source projects.  They never last.  Never.  They either stop dead in their tracks like Perl did or they lose market share because something new shiny comes out.  Think Ruby and JQuery.  In both instances, the community simply evaporated.  The business is left with code no one wants to support (because the skillset left the building) and no one wants to risk a feature enhancement because it might break the existing code.  So why are we doing this?  I do not understand the thought process.  No one has been able to explain it to me.  Java I can almost understand (but not really).  JavaScript?  I’m can only scratch my head.

Make no mistake.  I have no opposition to Open Source software.  I am opposed to risking a multibillion dollar business on a technology stack that has a track record of chaos and premature implosion.

But…  I am here to serve the business.  If these are the new rules of engagement, I will do my part to ram MEAN down everyone’s throat until they choke on it.  Hopefully, the business will see the writing on  the wall early in this new development technology and force a little “regime change.”  And if I’m wrong, I can still be at the tip of the spear by adopting the new models and ramming them home with brutal efficiency.   I guess it’s time to spin up on the MEAN stack.

Anyone know any good, Enterprise-grade MEAN tutorials?  I haven’t found any…

 

RegEx for LDAP

I have been working on a POC for injecting bulk entitlements into our Access Management System.  I guess you could think of our system as a big loop.  Entitlements are created in the AMS.  Users request an entitlement, which kicks off a workflow.  Once the entitlement is approved, it flows into AD.  The part I have been noodling around with is reading the permission out of AD.

I’ve been playing with this for years, literally.  I wrote some simple code a few years back.  For this POC, I dusted it off and showed it around.  I still had to migrate the code into the POC solution, so I had a chance to clean it up a bit.  No problem.  My old code uses UserPrincipals to pull the data out of AD.

var ctx = new PrincipalContext(ContextType.Domain);

var userPrincipal = await Task<UserPrincipal>.Factory.StartNew(() => UserPrincipal.FindByIdentity(ctx, request.UserId)) ?? new UserPrincipal(ctx);
response.User = userPrincipal.Convert();

It can be a bit slow.  At least the first query is slow.  It gets faster after the spin up.  Still…  I think I can make it better.

After poking around for a bit, I found the information I needed to access the AD container via LDAP.  Amazingly enough, the security team posted all of the needed info on the internal Wiki.  I’m not going to go into too much detail because I don’t really want to share any details about our network.

Anyway, once I pulled the data, I needed to parse the data into something I could use for my POC.  I looked around online and I could not find a single reference that showed a complete RegEx sample.  I saw some fragments, but nothing complete.  So here is what I came up with…

var regex = new Regex($@”CN=(?<CN>[\w]+)(,OU=(?<OU>\w+( \w+)*))+(,DC=(?<DC>\w+))+);

That’s it.  I only need the “CN” portion of the string but I thought I’d parse everything for future use.

Enjoy.

PS: I’ll fix the broken images when I have a chance.

Migrating from ClearDB to Azure MySQL

ClearDB is no longer included as part of my MSDN subscription.  I could either pay extra or migrate to the new Azure database for MySQL server.  I chose to migrate.   Continue reading Migrating from ClearDB to Azure MySQL

Azure Pass

Finally!!!

I got my Azure Pass approved yesterday.

The corporate firewall is so locked down that I can’t connect to any Azure SQL instance and the proxy setup won’t allow certificates to flow from a SF cluster into my browser.  Argh!

So, I had to find a work around.  Queue the begging.  😉

Continue reading Azure Pass