On Wed, Oct 2, 2013 at 8:55 AM, Srinath Perera <[email protected]> wrote:

> Hi Lasantha,
>
>
> On Wed, Oct 2, 2013 at 9:06 PM, Lasantha Fernando <[email protected]>wrote:
>
>> Hi all,
>>
>> The following changes were proposed to CEP 3.0.0 to improve the usability
>> of CEP.
>>
>> 1) EventStream UI is the central place to store all the event streams.
>> Event stream management will be decoupled from the EB/EF/EP components and
>> a separate component will be created to manage event streams.
>>
>> 2) Execution Plan UI is the main UI that user is going to use. It will
>> popup a dialog to create event streams if a new event stream is needed. It
>> will also pop up event builder creation dialog and event formatter creation
>> dialog if it is needed for the user.
>>
>> But it will not store any values in the backend until the execution plan
>> is saved and will save all the related configurations once as an atomic
>> transaction.
>>
> It is OK to do that if that make it easier for you to implement (but it is
> not a requirements).
>
>
>>
>> The saving of the execution plan can include the following sub steps.
>>
>> 1. Create a related event-builder (optional)
>>
>> 2. Create an execution plan (mandatory)
>>
>> 3. Create related event-formatters (optional)
>>
>> 4. Create stream definitions
>>
>> Out of the above sub steps, only step 4 will be persisted to the backend
>> immediately (since stream definitions are independent from the flow
>> configuration). Persisting configuration of sub steps 1-3 would go to
>> backend at once and the event-processor component will have the
>> responsibility of creating the needed event-builders/formatters and ensure
>> the wiring of the flow properly.
>>
>> Also, for the case of custom mapping for event builders, changing the
>> event builder mapping will effectively change the stream definition that is
>> exported by the event builder. Since this stream definition is managed by
>> another component, I think we would have to decide on a policy on whether
>> we cascade changes for a builder or not. Some possible options regarding
>> this will be
>>
>> 1. When event builder mapping is changed, the exported stream definition
>> will change
>>
>> 2. When the event builder mapping is changed, we force the user to change
>> the associated streamdef name or version
>>
>> Similarly, when changing the stream definition, we would need to decide
>> how the changes will be handled by the separate components.
>>
>
> Stream definition is the first class thing. There is no concept of builder
> importing an stream definition. Builder must agree with stream definition.
> If user change stream definition, we mark corresponding builders/
> formatters as faulty. If user try to change the builder/ formatter and it
> does not agree with stream definition, we throw an error.  So you first fix
> stream definition, then fix the builder.
>

+1 for this approach


Suho

>
>> We would also have to address the issue of the event processor component
>> attempting to deploy artifacts related to two other components in a
>> transactional manner as well.
>>
> IMHO this is not a requirement. Number of CEP artifact deployments will be
> small, and we do not need to worry about transactions here. We make similar
> assumptions with Carbon Admin UI.
>
>
>>
>> Please share your thoughts/suggestions on the proposed changes.
>>
>> @Mohan, Rajeev, Suho - Please add if I’ve missed anything from the
>> changes discussed.
>>
>>
>> Thanks,
>>
>> Lasantha
>>
>>
>> --
>> *Lasantha Fernando*
>> Software Engineer - Data Technologies Team
>> WSO2 Inc. http://wso2.com
>>
>> email: [email protected]
>> mobile: (+94) 71 5247551
>>
>
>
>
> --
> ============================
> Srinath Perera, Ph.D.
>   Director, Research, WSO2 Inc.
>   Visiting Faculty, University of Moratuwa
>   Member, Apache Software Foundation
>   Research Scientist, Lanka Software Foundation
>   Blog: http://srinathsview.blogspot.com/
>   Photos: http://www.flickr.com/photos/hemapani/
>    Phone: 0772360902
>



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