[Embedlets-dev] [Arch] Persistence vs. Management

[Ted K. <tk...@ya...>]

James stated:

> Ted's original vision was to have the Embedlet container be able to accept a
> serialised stream representing the instantiated application embedlet
> heirachy all in one go. I quite like it, the container only needs to be able
> deserialise, the task of serialisation is done by the management tool and
> all you need is some communications link to 'upload' the serialised embedlet
> application. It is certainly quite an elegant approach.

Well, you know, I thought it was an elegant approach.  A serialized object
graph only contains each object's state information (just instance variable
settings are included, no code is sent with serialization).  What can be
simpler than having a target system read what the state of each object's
instance variables are and then reconstituting it based on this information?

The TINI/TStik already supports this now through ObjectInputStream and
JStamp/JStik will be supporting it soon.

As for the serialized object graph versioning problem that Gregg pointed out,
this is the well documented weakness of trying to use the original *binary*
version of object serialization for long term persistence needs (and hense all
the warnings in the API docs about not using it for long term storage).  The
new XML based Long Term Persistence API has completely fixed this problem and
now Sun strongly recommends using the LTP API for saving object graphs of any
kind for any purpose for any length of time.  In my opinion they have made this
API bullet-proof and I strongly suggest that skeptics have a closer look at it
before rejecting this idea. 

For the purposes of getting a serialized object graph into an Embedlet
Container an object graph would only need to be converted into the binary
serialization format for the short span of time it takes to transfer it to an
Embedlet Container.

Perhaps James and I are missing something here but since the Long Term
Persistence API has fixed the versioning problem I do not see the downside of
using object serialization as a lightweight method for getting an application
into an Embedlet Container?


Ted

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