Hello Cliff,
For me, key things to think about in your persistence design are:
1. The maximum rates at which you want to write data to the
datastore.
2. Transactions: are you going to use them not at all, a lot, or
always?
3. The entity group structure of your persistent entity classes.
The first two points will have an influence on the third.
There is a maximum write rate to the data in each entity group.
Transactions, where used, may encompass one entity group only.
You can associate instances of different persistent entity classes in
two ways: using a field holding (a pointer to = a reference to) the
instance of the other class, or a field holding a key of the instance
of the other class. The difference is that the first choice
establishes an entity group relationship if this is done in the
correct way (at creation-time for the child entity).
Also, why not examine Max Ross's blog ("http://gae-java-
persistence.blogspot.com")? It's got working examples of persistence
code, and I have found this helpful.
There are persistence frameworks that act as a front-end for GAE/J
persistence (search this forum for details). I am sure that they are
good, but I personally do not use them because I want to reduce the
number of independent software components in my code (Java, Apache
Wicket, NetBeans, GAE/J and DataNucleus JDO are enough for me!) and
keep it portable outside of GAE/J.
Finally, really study the GAE/J "Storing Data" documentation. There is
a lot in it, but for us used to SQL-compliant RDMS databases, this is
a must.
Finally, enjoy!
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