Hi Martin,
On Wed, Oct 1, 2014 at 11:03 PM, Martin Eppel (meppel) <mep...@cisco.com>
wrote:
> Hi Reka,
>
>
>
> Are you suggesting to replace the current startupOrder definition with the
> one mentioned below ?
>
>
>
> "startupOrder" : [
>
> {
>
> "start":"aa",
>
> "after":"bb"
>
> }
>
> ]
>
>
>
> Replaced with
>
>
>
> "startupOrders": [
>
> "mypostgresGroup, myphp",
>
> "mysqlGroup, mytomcat",
>
> "mytomcat, myapimanager",
>
> "mytomcat, myesb"
>
> ]
>
>
>
> I have a couple of questions,
>
>
>
> 1. If we use the cartridge alias and the group alias in the group /
> application dependency definition how will it work when we auto scale
> groups ? My current understanding is that to get group scaling to work we
> would need 2 parameters – group name (==group.name) and group instance id
> (== group.alias), one static and one dynamic. So I would think we’ll have
> to define the application dependencies and group dependencies based on the
> name and not the alias, but, during run time we have to calculate the
> dependencies based on the alias.
>
> I think is important to make the distinction between group type (or name,)
> and group instance Id, without it we won’t be able to implement group
> scaling, wdyt ?
>
Thanks for pointing this out..Yah..As you have mentioned, if we are to
scale the groups by creating new groups, then we will be unable to use the
groups alias in place of startuporders. But stratos is tightly coupled with
subscription to cluster as one to one mapping and also, load balancer uses
one to one mapping between cluster and hostname. So, if we are to bring up
new clusters/groups, then things might get complicated in stratos. As i
explained in the [part-1] discussion, we thought of achieving scale by
group member and scale by group using constructing the deployment policy in
a more advanced manner. I will start a separate thread on that. According
to all of our opinion, we can decide on how to follow that up.
> IMHO the startupOrders in composite application and group definitions
> (json ) should look like
>
> "startupOrders": [
> “postgresGroup, php",
> "sqlGroup, tomcat",
> "tomcat, apimanager",
> "tomcat, esb”
> ]
>
> while the runtime representation of the logical relationship model for
> each group or cartridge should use the corresponding aliases (or instance
> Id) so the monitor will reference the aliases (or instance Ids) while the
> json application / group definition will reference the group name (or type)
> and cartridge type to define the dependencies, WDYT ?
>
> 2. If for example a cartridge has multiple dependencies we would
> just add another line to the the startupOrders :
>
> e.g. postgresGroup depends on php and abc would be
> represented by:
> "startupOrders": [
> "postgresGroup, php",
> "postgresGroup, “abc”
> ….
> ]
>
>
>
>
>
> Otherwise I think the proposal looks good, +1
>
Thanks,
Reka
>
>
> Thanks
>
>
>
> Martin
>
>
>
> *From:* Reka Thirunavukkarasu [mailto:r...@wso2.com]
> *Sent:* Wednesday, October 01, 2014 5:58 AM
> *To:* dev
> *Cc:* Lakmal Warusawithana; Isuru Haththotuwa; Martin Eppel (meppel);
> Udara Liyanage
> *Subject:* [Grouping][Part-2] Composite Application Dependency Tree
> building based in Autoscaler
>
>
>
> Hi
>
>
>
> As you aware, in the composite application we can define the depencies
> between groups/cartridges. Autoscaler's responsible is to parse this
> dependencies and build up a logical relationship model in order to handle
> the dependency information among the child nodes. As we have the
> hierarchical monitors in autoscaler, i propose to have dependencies
> information in each monitor that they aware of (the immediate child only).
> In that monitor, we need to identify the group/cartridge which can be
> started in parallel. So that a monitor can look at it's dependency and
> control it's immediate children based on that. Once all the children are
> active, it can pass the control to it's parent. For Eg:
>
>
>
> If we take the top level in Composite application which has mysqlGroup,
> postgresGroup, php, tomcat, apimanager and esb. If they have an alias
> saying my + cartridge/groupName then we can define the dependency
> information as follows:
>
> - myPhp depends on myPostgresGroup (means postgresGroup should
> be started before php)
>
> - myTomcat depends on myMysqlGroup
>
> - myApiManager depends on myTomcat
>
> - myEsb depends on myTomcat
>
>
>
> Like wise, groups will define their own dependency as well.
>
>
>
> In that way, we need to represent these dependency information as part of
> Composite Application definition/GroupDefinition. In order to represent
> this dependency information given above for Composite Application, i would
> suggest to have the following in Composite Application definition.
>
>
>
> "startupOrders": [
>
> "mypostgresGroup, myphp",
>
> "mysqlGroup, mytomcat",
>
> "mytomcat, myapimanager",
>
> "mytomcat, myesb"
>
> ]
>
>
>
> You can use the same format in GroupDefinition to define dependencies in a
> group.
>
>
>
> As per the example, autoscaler will build a dependency tree for
> ApplicationMonitor as below in order to identify the parallel and dependent
> ones. So that Autoscaler will start up same level children monitors as in
> parallel.
>
>
>
>
>
>
> As above, ApplicationMonitor will start GroupMonitors of myPostgresGroup
> and myMysqlGroup in parallel. Once postgres becomes active,
> ApplicationMonitor will start ClusterMonitor for myPhp. Once
> myPostgresGroup becomes active, ApplicationMonitor will start the immediate
> child myTomcat. Once myTomcat becomes active, ApplicationMonitor will start
> the myAppServer and myEsb in parallel. This will be applicable for
> GroupMonitors as well. They can look at their own dependency tree and will
> start their children.
>
>
>
> Please share your suggestions on the above model to handle the Dependency
> information of Composite Application in autoscaler.
>
>
>
>
>
> Thanks,
>
> Reka
>
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> --
>
> Reka Thirunavukkarasu
> Senior Software Engineer,
> WSO2, Inc.:http://wso2.com,
>
> Mobile: +94776442007
>
>
>
>
>
--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007
