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High availability (was Re: Question about the config branch)



sparklezou wrote:
Hello Howard Chu,

In fact, Iwould like to implement HA using replicate. Today I found that there is an session discussed before about this topic.http://www.openldap.org/lists/openldap-devel/200310/msg00068.html And the idea descriped is something the same with mine.

Yes, this has been discussed before on the -devel list and any further discussion belongs there as well, not in private email, to allow the effort to be coordinated with other project members.
     I want to implement as following:

(1)

 Client                   Master                Slave
   |------ modify(0) -->    |                     |
   |                        | --- modify(1) --->  |
   |                        |                     |
   |                        | <--- SUCCESS -----  |
   |                        |                     |
   | <---- SUCCESS  -----   |                     |

(2)
Client Slave Master
|------ modify(0) --> | (Chaining the modify request to Master) |
| | --- modify(0) -------------------------------> |
| | |
| | |
| |Master update the data,and try to update Slave |
| | <--- modify (1)---------------------------- - | | | |
| |------------SUCCESS(1)-----------------------> |
| | |
| |<------------SUCCESS(0)----------------------- |
| | |
| <---- SUCCESS(0)----- | |


But current implemented in OpenLdap2.3 is:

(3)

 Client                   Master                Slave
   |------ modify(0) -->    |                     |
   |<---- SUCCESS(0) -----  |                     |
   |                        |                     |
   |-Query the entry again->|                     |
   |                        | --- modify(1) --->  |
   |                        |                     |
   |                        | <--- SUCCESS(1)---- |
   |                        |                     |

(4)
Client Slave Master
|------ modify(0) --> | (Chaining the modify request to Master) |
| | --- modify(0) -------------------------------> |
| | |
| | |
| |<------------SUCCESS(0)----------------------- |
| | |
| <---- SUCCESS(0)----- | | | | |
|------------Query the entry on Master again----------------------------->|
| | |
| | |
| | |
| | <----------- modify(1) ------------------------|
| | |
| |---------------SUCCESS(1)---------------------->|


  It's a NOT good solution to implement the HA, because the data is not keep sync always.

  I would like to join replicate develop team to do it.

  And I want to implement failover dynamicly. If the master is down, one of the slaves will be the master.

  So I want to add some more entrys in the configure branch to let the DS know how many DSs are in the same cluster. Master and Slaves know each other. And currently in OpneLdap, the Master don't know how many Slaves; the Slave only know where is Master, but don't know another Slavers.

  So I would like to join OpenLdap to implement these functions.

Best regards, ======= At 2005-12-16, 18:12:21 you wrote: =======

sparklezou@hotmail.com wrote:
Dear all,

I read the source code of config branch. I'm puzzled that why the schema for config branch are defined in the source code, not in a .schema file? It a little dificult to extend the config schema. ^_^
Most elements of the config schema map directly to data structures in the slapd code. It would be pointless to alter the config schema without making corresponding code changes. It would be inappropriate to store the config schema in a regular file; that would imply that it can be changed freely which is incorrect.

So, since you are asking about extending the config schema, that must mean you have written code to provide a new feature. It would be helpful for the purpose of this discussion if you describe what your new feature is, so we can focus on the proper hooks for integrating it.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/

.

= = = = = = = = = = = = = = = = = = = = sparklezou sparklezou@hotmail.com 2005-12-21





--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/