Hi Reka,

I need some clarification on how the DependencyBuilder is supposed to work 
(while I am trying to replace the code with the new scheme to represent the 
startup order).

In the class StartupOrder.java we maintain a structure “private List<String> 
startList;” which is being used later in the “DependencyBuilder.java”, see code 
snipplet below. However, I can’t find anywhere in the code that the “startList” 
is initialized or set (getStartList(…) being invoked). I am not really sure 
what the intention is how this code is supposed to work ?

Thanks

Martin

DependencyBuilder.java

Set<StartupOrder> startupOrderSet = dependencyOrder.getStartupOrders();
            ApplicationContext foundContext = null;
            for (StartupOrder startupOrder : startupOrderSet) {
                foundContext = null;
                for (String start : startupOrder.getStartList()) {
                    ApplicationContext applicationContext = 
ApplicationContextFactory.
                                    getApplicationContext(start, component, 
dependencyTree);
                    String id = applicationContext.getId(); //TODO change the id

                    ApplicationContext existingApplicationContext =
                            dependencyTree.findApplicationContextWithId(id);
                    if (existingApplicationContext == null) {
                        if (foundContext != null) {
                            //appending the start up order to existing 
group/cluster
                            
foundContext.addApplicationContext(applicationContext);
                            if (log.isDebugEnabled()) {
                                log.debug("Found an existing [dependency] " + 
foundContext.getId() +
                                        " and adding the [dependency] " + id + 
" as the child");
                            }
                        } else {
                            //adding list of startup order to the dependency 
tree
                            
dependencyTree.addApplicationContext(applicationContext);
                        }
                    } else {
                        if (foundContext == null) {
                            //assigning the found context to the later use.
                            foundContext = existingApplicationContext;
                            if (log.isDebugEnabled()) {
                                log.debug("Found an existing [dependency] " + 
id + " and setting it " +
                                        "for the next dependency to follow");
                            }
                        } else {
                            //TODO Throw exception, since another same start 
order already found
                            log.warn("Startup order is not consistent. It 
contains the group/cluster " +
                                    "which has been used more than one in 
another startup order");
                        }

                    }

                }

            }

From: Reka Thirunavukkarasu [mailto:r...@wso2.com]
Sent: Wednesday, October 08, 2014 9:00 AM
To: Martin Eppel (meppel)
Cc: Isuru Haththotuwa (isu...@wso2.com); dev@stratos.apache.org
Subject: Re: [Grouping][Part-2] Composite Application Dependency Tree building 
based in Autoscaler

Hi Martin,

On Wed, Oct 8, 2014 at 3:56 AM, Martin Eppel (meppel) 
<mep...@cisco.com<mailto:mep...@cisco.com>> wrote:
Hi Reka,

Just wanted to clarify, the changes suggested below should completely  replace 
the previous structure (StartupOrder with before, after), not only in the json 
definition but also in all subsequent object models, correct ?
Yah..We need to change the json, application parser and the Topology.

Btw, what triggered this change ?
As i think, it is naming issue. If we change it to terminate, then it will be 
more consistent with the naming that we currently use in cloud controller. Or 
did you mean something else?

Thanks,
Reka

Thanks

Martin

From: Reka Thirunavukkarasu [mailto:r...@wso2.com<mailto:r...@wso2.com>]
Sent: Monday, October 06, 2014 2:22 AM
To: dev
Subject: Re: [Grouping][Part-2] Composite Application Dependency Tree building 
based in Autoscaler

Hi Imesh,

On Mon, Oct 6, 2014 at 2:45 PM, Imesh Gunaratne 
<im...@apache.org<mailto:im...@apache.org>> wrote:
Hi Reka,

I have a small concern on using the term "kill" in this scenario, I think it 
would be much more elegant if we call it something like "terminate". WDYT?
+1. It's more appropriate to use terminate. Will change it to terminate.

Thanks,
Reka



On Mon, Oct 6, 2014 at 11:44 AM, Reka Thirunavukkarasu 
<r...@wso2.com<mailto:r...@wso2.com>> wrote:
Hi all,

I have implemented the dependency tree as mentioned in my mail earlier. It will 
return the immediate children for the start able dependencies.

FYI: a composite application has  postgresGroup, php, mysqlGroup, app server 
and esb as it's immediate children and their start up order is as mentioned in 
the mail earlier.

"startupOrders": [
“postgresGroup, php",
"sqlGroup, tomcat",
"tomcat, apimanager",
"tomcat, esb”
]

So, if we look at the kill behaviour of this composite Application, it will be 
like below:

kill-none : none of them will be returned

kill-all: all the elements in that dependency tree will be returned
    For eg: if something happened to postgresGroup, then all the children of 
dependency tree would be returned as php, mysqlGroup, app server and esb will 
be get killed.

kill-dependent: all the children of that particular node in the dependency tree 
will be returned.
    For eg: If something happened to mysqlGroup, then subsequently tomcat, app 
server and esb would be get killed.

Question: in case when we get more than one dependencies to be killed, can we 
kill all of them in parallel or do we have to wait until it's dependent 
cluster/group got killed?

Thanks,
Reka

On Thu, Oct 2, 2014 at 5:58 PM, Reka Thirunavukkarasu 
<r...@wso2.com<mailto:r...@wso2.com>> wrote:
Hi Martin,

On Wed, Oct 1, 2014 at 11:03 PM, Martin Eppel (meppel) 
<mep...@cisco.com<mailto: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<http://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<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.

[cid:image001.jpg@01CFE2F0.D6DA4190]
​
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
























--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007<tel:%2B94776442007>


​



--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007<tel:%2B94776442007>




--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007<tel:%2B94776442007>




--
Imesh Gunaratne

Technical Lead, WSO2
Committer & PMC Member, Apache Stratos



--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007<tel:%2B94776442007>




--
Reka Thirunavukkarasu
Senior Software Engineer,
WSO2, Inc.:http://wso2.com,
Mobile: +94776442007

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