Multiple EM best practices

I did a multi-EM solution a while back in DevForce Classic, and used a design similar to what you have described.

1. When an edit form is opened, create a new EM and import the data that you need
   
   Of course the needed data must first be retrieved into the main EM, then imported from there into the local EM
   
   
2. Upon save, import the saved entity back into the global Entity Manager, so the changes can be seen by all. On any other action, simply discard as it is of no use.
   
   I don't think you would discard it on "any other action"; but rather, when the user explicitly indicated that she wanted to close the form and discard any changes.
   
   Note also that it's likely to be multiple entities that have been changed and are being saved, so it is those that you would import into the main EM from the local one. Then you would immediately execute a save of all modified, deleted, or new entities in the main EM.
   

An additional issue to think about is whether you want individual forms to be notified of changes made (and saved) from other forms. For example, a Customer form and a SalesRep form might both display Orders (those placed by the Customer currently being viewed, and those written by the SalesRep currently being viewed), so you might have the same Order displayed on both forms. If updated in one, do you want the copy in the other to be refreshed with the new values immediately? This gets a little trickier to write, but could be done.

That depends on how you write your code, but assuming you do a reasonable job with that, I wouldn't expect performance to be much affected. If you implement as I described above, then you will have at least twice as many entities in the cache (a local copy + a  central copy of each entity) all the time as you otherwise would. But that's a memory footprint issue, not a performance issue. Obviously some extra time will be required for copy entities back and forth between caches. But the forms could see an improvement in performance because they'd always be interacting with a smaller cache than if you were using one cache for all of them. But overall, I wouldn't expect noteworthy change in performance in either direction.

I think the question should probably hinge more on the balance between the user experience that you want versus the difficulty of coding and maintaining a multi-EM solution versus a single-EM one.

Hi!

Hi, understood.  But what about using the above signature of the async method and sending only the current form's entity instead of having multiple managers?   Imagine this entity has 2 navigation properties (one as relatedEntityList).  If I add new items to the list and a new instance to the other navigation property, if I use the above method do I only have to send the main entity (and devforce will handle the navigation properties) or do I have to apply some code to look for all the navigation properties that are added/modified for the current entity?