Hi guys,
Jon Roberts wrote:
Since there is a no-argument constructor DN(), perhaps the original
thinking was that null and the rootDSE "" are synonymous.
It was not really a thinking, much more a literal implementation of the
RFC :
RFC 4514 states :
2.1. Converting the RDNSequence
If the RDNSequence is an empty sequence, the result is the empty or
zero-length string.
In java, the zero-length String is "", not null. In no way null and ""
(which is _not_ representing the rootDSE - a very common misconception :
A => B does not necessarily implies that B => A - ) are synonymous.
Talking about Apache DS LdapDN implementation, our internal data
structure handling DNs, the empty constructor is used when you need to
manipulate DNs by adding RDNs to it. And if you have :
LdapDN dn = new LdapDN();
System.out.println( dn ) ;
you will obtain just a empty line (ie, ""), not 'null'.
On the other
hand, the existence of this constructor makes as much sense to me as the
redundant addRDN() and addRDNToFront() methods (ie. none at all). I
suppose *somebody* may want to build a DN instance iteratively, but I
would consider it easier to do so concatenating strings for submission
to the more relevant constructor with argument.
DN are not Strings, DNs are structures which have a String
representation (so the RFC 4514). Inside a LDAP server, it's much better
to hold DNs into such a structure instead of manipulation Strings. A
simple exemple : how do you compare those two DNs and how can you tell
if they are equal ? :
dn1: dc=example, dc=com
dn2: |0.9.2342.19200300.100.1.25=Example, ||0.9.2342.19200300.100.1.25=COM
As String, you bet they are different, but they are just representing
the very same element.
|
Hope it helps.
--
--
cordialement, regards,
Emmanuel Lécharny
www.iktek.com
directory.apache.org
