Hello All,

IMO, the most appropriate demo for our use case is the Rsync replicated
file system
http://helix.incubator.apache.org/recipes/rsync_replicated_file_store.html.

Is it correct that the ONLY difference between Leader-Standby and
Master-Slave state models is that Master-Slave has one more state that
calls Offline?

Thanks,
Erwin



On Mon, May 13, 2013 at 7:46 AM, Erwin Karbasi <[email protected]> wrote:

> *Sorry, same message with typo correction.*
>
>
> hank you a lot Kishore.
> Your first pointed out option could be appropriate to our requirement.
> If the Server A will get up to date routing table from the server group B,
> it could be sufficient.
>
> Our requirement is that server A will access one of the members in cluster
> B (that is the leader) and this leader will be active for any operation.
> After that server will be unavailable other member in the cluster B will
> take the place of the leader, *but server A should be updated about this
> change.
> *
> Thanks again,
> Erwin
>
> On Sun, May 12, 2013 at 8:44 PM, kishore g <[email protected]> wrote:
>
>> Hi Erwin,
>>
>> The code i sent basically shows how Server A can send the request
>> directly to current Leader in server B group. Note, when leader changes in
>> server B, server A dynamically discovers that change and updates it routing
>> table.
>>
>> But looks like what you want is server A sends request to any one of the
>> server in Server B cluster and that server will re-direct the request to
>> the leader. In this case, the code i sent you must be included in every
>> server in Server B group. To server A you can simply provide list of
>> ip:port address and it can randomly select one of server and send the
>> request to it.
>>
>>
>> thanks,
>> Kishore G
>>
>>
>>
>>
>> On Sun, May 12, 2013 at 10:27 AM, Erwin Karbasi <[email protected]>wrote:
>>
>>> Hi Kishroe,
>>>
>>> Thank for the information.
>>> I'll deep dive into the code that you sent tomorrow.
>>> Is that code will ensure that I have one cluster that i can send to it
>>> requests and one member from that cluster (leader) will grab the request
>>> and treat it.
>>>
>>> Thanks again,
>>> Erwin Karbasi
>>> AT&T, Senior Software Architect
>>>
>>>
>>> On Sun, May 12, 2013 at 7:57 PM, kishore g <[email protected]> wrote:
>>>
>>>> Hi Erwin,
>>>>
>>>> Thanks for looking into Helix. In Helix, most of the time the only
>>>> configuration needed is the zookeeper address and cluster name. This is the
>>>> code you can use to contact a server.
>>>>
>>>> //in the server A code at start up
>>>> final RoutingTableProvider routingTable = new RoutingTableProvider();
>>>> //Default Externalview implementation
>>>> manager = HelixManagerFactory.getZKHelixManager(clusterName,
>>>> instanceName, InstanceType.SPECTATOR, zkConnectString)
>>>> manager.connect();
>>>> manager.addExternalViewChangeListener(routingTable)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> //Any time you want to talk to servers B
>>>> //you can get a instances for a specific resource, partition in specific 
>>>> state. e.g getInstances("LockGroup", "lockGroup_0", "LEADER");
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> List<InstanceConfig> instances = getInstances(String resourceName, String 
>>>> partitionName, String state)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> //Get all instances in given resource in a specific state e.g 
>>>> getInstances("LockGroup", "LEADER");
>>>> Set<InstanceConfig> instances = getInstances(String resource, String state)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> InstanceConfig can give you all details about the server like host,
>>>> port or anything else you want to add.
>>>>
>>>> Hope this helps. Thanks for bringing this up, we need to add an example
>>>> code for this.
>>>>
>>>> Thanks,
>>>> Kishore G
>>>>
>>>> On Sun, May 12, 2013 at 9:00 AM, Erwin Karbasi <[email protected]>wrote:
>>>>
>>>>>
>>>>>  Hello Masters,
>>>>>
>>>>> We'd like to use Helix for Leader Election mechanism.
>>>>> Following our scenario:
>>>>>
>>>>> We have one server (server A) that need to connect to group of other
>>>>> servers (server B).
>>>>> How server A can access the server B's group - cluster.
>>>>>
>>>>> As I know from other cluster frameworks, we can concatenate multiple
>>>>> server ip:port and the cluster will pass the requests to the leader 
>>>>> process
>>>>> that in the cluster.
>>>>>
>>>>> How above scenario could be implemented by using Helix leader election
>>>>> (Distributed lock manage) as demonstrated here:
>>>>> http://helix.incubator.apache.org/recipes/lock_manager.html
>>>>>
>>>>> Your insight would be highly appreciated.
>>>>>
>>>>> Thanks,
>>>>> Erwin Karbasi <[email protected]>
>>>>> AT&T, Senior Software Architect
>>>>>
>>>>>
>>>>
>>>
>>
>

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