Not a market order which majority of people on Robinhood are using market orders since they are the default. Most don't even know what a limit order is I'm guessing.

I have a few questions I'm curious about.

1) How are you unit testing all of this?

2) How are you source controlling all this?

3) I'm assuming you are not versioning anything but if so how are you?

4) How difficult would it be for someone else to come support this?

Number 4 has been the nightmare I've seen with excessive stored procs.

The project is end-of-life now so most of this is moot but to answer these queries:

1) SQL calls in a separate command-line application.

2) Git. It’s in a .NET Database project.

3) See 2.

4) Not overly to be honest - the organisation uses SQL procs pretty extensively as is, so this isn’t anything particularly new or out of the ordinary other than the validations are held in a different part of the stack.

We just decommissioned applications written in 1986, last modified in 2012. They were running important production code until this year.

The answer to your break point question is yes. You can debug your C# code on the front end with breakpoints. The biggest benefit is applications with a lot of domain business logic tend to have that logic copied to the front end and copied to the backend. If a object can no longer be updated if it has an expired date then you would have logic on your server to prevent that. You would also have logic on your front end to display to the user that this can not happen before even going to the server. The server would act as a backup and ensure it never happens.

With Blazor, this logic only exists in one place which helps follow DRY.Logic that is duplicated tends to get missed in testing often. This provides business value.