h2. Csn

The *CSN* (Change Sequence Number) is used to track modifications done on an entry. It's used during replication. You are not likely to use it, unless you want to implement some replication system.

*CSN* are described in [http://tools.ietf.org/html/draft-ietf-ldup-model-09]


A *CSN* is seen as a String, which syntax is :

{code}
<CSN>            ::= <timestamp> # <changeCount> # <replicaId> # <modifierNumber>
<timestamp>      ::= A GMT based time, YYYYmmddHHMMSS.uuuuuuZ
<changeCount>    ::= 000000-ffffff
<replicaId>      ::= 000-fff
<modifierNumber> ::= 000000-ffffff
{code}

In order to create a *CSN*, the best is to use the *CsnFactory* class :


{code}
int replicaId = 001;
CsnFactory defaultCSNFactory = new CsnFactory( replicaId );
Csn csn = defaultCSNFactory.newInstance();
System.out.println( csn );
{code}

produces :


{code}
20110318165008.941000Z#000000#001#000000
{code}