Are there really no other options (CSV, JSON, XML)?

I have some code for a DBF reader, if you're interested I can share it and you can create a DBF writer by analogue.

Good idea!

Like this:

Class ... Extends %CSP.REST
{

XData UrlMap [ XMLNamespace = "http://www.intersystems.com/urlmap" ]
{
<routes>
<route call="logout" method="GET" url="/logout">
</routes>
}

/// Logout user from current session
ClassMethod logout() As %Status
{
    #dim %session As %CSP.Session
    set sc = %session.Logout(1)
    set %session.EndSession = 1
    return sc
}
}

1. Implement %iFind.Transformation.Abstract interface with the custom transformation that would remove all property names (I assume you know property names beforehand).

After that set TRANSFORMATIONSPEC index parameter to your transformation implementation.

2. Maybe User Dictionaries could also be used.

3. Are you sure you need analytic queries? Simpler iFind indices (Minimal, Basic) can be advantageous in some situations.

Calling @Benjamin De Boe 
 

There's currently no way to do that.

You can also use this call to expand database non-interactively (size is in mb):

set $namespace = "%SYS"
set sc = ##class(SYS.Database).ModifyDatabase("/path/to/db/folder", size)

It's useful for benchmarks and such.

I just like to add that SQL Gateway is an abstraction over both JDBC and ODBC connections.

I believe so, but it depends on how large the session is that you have in mind
 

Interoperability Visual Trace starts slowing down on sessions above 100 000 messages, and considerably slows down on 300  000 messages per session.

I'm interested in a tool that would allow me to see these large sessions graphically, currently I work with them via SQL.

Great tool!

Does it work on large sessions?

You can't bypass the challenge.
Neither by $classmetho() nor any code generator as this is all static code frozen and inflexible a runtime.  

Why?

A case where user must be able to:

• create a code snippet with a predetermined interface
• choose it for execution among all the code snippets with the same interface

Can be solved in many ways, without indirection (aka executing code stored as a string).

I usually provide a base class, which a user must extend and populate with his own methods. After that in the source app, just call SubclassOf Query from %Dictionary.ClassDefinition to get all implementation and show them to a user to pick from.

Works good enough.

Might as well invoke the method directly:

<Invoke Class="%Library.EnsembleMgr" Method="SetAutoStart" CheckStatus="true" >
  <Arg Value="${MyNamespace}" />
  <Arg Value="myProd.Production" />
</Invoke>

Or is there a reason to use a proxy method?

I think OP needs non-interactive approach.