The external system recording was just an example, not a specific use case. The idea is to provide comprehensive information to populateDAG as to the context it is being called under. It is akin to the test mode or simulate flag that you see with various utilities. The platform cannot control what populateDAG does, even without this information, in multiple calls that you mention the application can return different DAGs by depending on any external factor such as time of day or some external variable. This is to merely provide more context information in the config. It is upto the application to do what it wishes with it.
On Tue, Dec 19, 2017 at 2:28 PM, Vlad Rozov <vro...@apache.org> wrote: > -0.5: populateDAG() may be called by the platform as many times as it > needs (even in case it calls it only once now to launch an application). > Passing different parameters to populateDAG() in simulate launch mode and > actual launch may lead to different DAG being constructed for those two > modes. Can't the use case you described be handled by a plugin? > > Thank you, > > Vlad > > > On 12/19/17 10:06, Sanjay Pujare wrote: > >> +1 although I prefer something that is more enforceable. So I like the >> idea >> of another method but that introduces incompatibility so may be in 4.0? >> >> On Tue, Dec 19, 2017 at 9:40 AM, Munagala Ramanath < >> amberar...@yahoo.com.invalid> wrote: >> >> +1 >>> Ram >>> On Tuesday, December 19, 2017, 8:33:21 AM PST, Pramod Immaneni < >>> pra...@datatorrent.com> wrote: >>> >>> I have a mini proposal. The command get-app-package-info runs the >>> populateDAG method of an application to construct the DAG but does not >>> actually launch the DAG. An application developer does not know in which >>> context the populateDAG is being called. For example, if they are >>> recording >>> application starts in an external system from populateDAG, they will have >>> false entries there. This can be solved in different ways such as >>> introducing another method in StreamingApplication or more parameters >>> to populateDAG but a non disruptive option would be to add a property in >>> the configuration object that is passed to populateDAG to indicate if it >>> is >>> simulate/test mode or real launch. An application developer can use this >>> property to take the appropriate actions. >>> >>> Thanks >>> >>> >>> >
