[infinispan-dev] [ISPN-78] RFC: Finalizing API
Continuing to work on large object support I'm now at a point where I
would like to finalize the API so that I'm free to move forward with
some confidence. This is its current incarnation
public interface StreamingHandler<K> {
void writeToKey(K key, InputStream largeObject);
OutputStream writeToKey(K key);
InputStream readFromKey(K key);
boolean removeKey(K key);
StreamingHandler<K> withFlags(Flag... flags);
}
where a user obtains a StreamingHandler through calling
Cache.getStreamingHandler(). The StreamingHandler manages large objects
on behalf of the backing cache. This doesn't look too bad to me, but
there's always room for improvement.
First a fundamental question with potentially disruptive implications:
what aspires Large Object Support to become in the long run? A
comfortable means for users to store and retrieve large objects in
Infinspan (as it seems today)? Or rather a fully fledged distributed
file system? I favor the former, without precluding the possibility that
one day Infinispan will also implement a file system interface.
Now a question regarding the implementation the answer to which might
affect the API: does it make sense to strictly separate "regular" caches
from those dealing with large objects? I think so, since I presume that
most applications will treat large objects differently from the more
comfortably sized ones. At least that is my personal experience.
Furthermore it might prove difficult to tune a cache that contains both
regular and large objects. Plus by introducing large object caches we
might be able to find a nice set of default settings for those.
If we chose to introduce dedicated large object caches I would opt for
introducing StreamingCache<K> or even LargeObjectCache<K> instead of
StreamingHandler<K> since then a StreamingHandler wouldn't handle large
objects on behalf of some backing cache. Rather it would act as *the*
interface to a cache exclusively reserved for large objects. It follows
that a user would directly access a StreamingCache, not indirectly via
Cache.getStreamingHandler().
And finally there is that eternal question of how to properly name those
interface methods. Trustin has expressed his concern that
writeToKey(...), removeKey() and readFromKey(...) might fail to convey
their semantics. And indeed there's nothing in their names to tell a
user that they deal with large objects. What about alternatives á là
- void storeLargeObject(K key, InputStream largeObject) or
putLargeObject(K key, InputStream largeObject)
- OutputStream newLargeObject(K key) or simply OutputStream
largeObject(K key)
- InputStream getLargeObject(K key)
- boolean removeLargeObject(K key)
? Rack your brains and keep those splendid ideas coming.
Cheers,
Olaf