[pseudohadamard]

  X.500 was stripped down to form LDAP

No, LDAP was a student project from UMich that somehow gained mindshare because (a) it wasn't ISO, and (b) it cleverly had an 'L' in front of it. It's now more complex and heavyweight than the original DAP, but people think it isn't because of that original clever bit of marketing.

[otabdeveloper4]

It's still lightweight. I implemented a working implementation on a literal weekend.

[pseudohadamard]

That's certainly possible, you can get a basic implementation that uses it as a database lookup, "search" with baseObject/scope fixed, filter is your search string, return the attribute you want, done without too much effort. In fact a number of early LDAP databases were actually DBMSes underneath, so you take your SQL-style query (select emailAddress where name = "John Doe"), convert it into baseObject/scope/filter/attributes and send it over the wire, the other side converts it back into an SQL query and queries the Ingres database that's doing the actual work, and everyone gets to pat themselves on the back over how well "a bunch of networking types reinventing 1960s database technology" (Marshall Rose, I think) works.

However when you need to implement the whole HDAP protocol, that's when you wish you'd taken up some easier job, like maintaining the bank's COBOL accounting code.

[lukeh]

Well, it started off simpler, but, yes.