I've been poking through the ConnectionInterceptor and StreamInterceptor
interfaces in Http Client, and I'm confused by a couple of things.
I was unable to find an example implemenation of either interceptor in
Slide, although Slide exposes setters that may be used to set the
interceptor reference, so maybe somebody's using them somewhere and can
comment on their expectations.
StreamInterceptor:
Although it's not documented, I think it is pretty clear from the code that
StreamInterceptor provides a mechansim for an "external" class to be
notified of the (body but not head) bytes read from or written to the
server.
* Is that correct?
* Is it reasonable to assert (that is, restrict by contract) that the byte
data sent to StreamInterceptor is read only, or is the intention to allow
the interceptor to somehow change the data being exchange?
* When precisely should the bytesRead and bytesWritten methods be called?
Just before the data is sent to the server? Just after the data is read back
(but before the data is processed)?
* Also, I note that there is no reference to or notice of the specific
HttpMethod being invoked, or when we switch from one request/response pair
to another. I can't tell, for example, if a given request body is a PUT or
a POST request by the methods in StreamInterceptor alone. If that's the
case, it's not clear to me what the utility of StreamInterceptor really is.
ConnectionInterceptor:
This one is more vexing. I *think* I understand the general intent, but if
I do, the kind of information supplied to ConnectionInterceptor isn't quite
adequate for that purpose. Also, it would seem that the current
implementation doesn't adhere to the apparent contract very uniformly. Some
specific questions/issues:
* ConnectionInterceptor.retry(int) returns a boolean, and the JavaDoc
comment says "return true if a retry should be attempted". Yet:
a) This method is not uniformly applied (i.e., it is not invoked every time
a request is to be retried)
b) The returned boolean value is ignored (in fact, it is not even
collected.)
* ConnectionInterceptor.info(int,Hashtable) also returns a boolean, with the
same comment, which isn't quite clear in this case. Keep going I assume?
But again, this returned value is ignored by HttpClient. Also, it isn't
clear to me when this method will be/should be invoked. Only when we get the
intermediate response codes (100 Continue, etc.)?
* Same with error(int,Exception)
* When precisely should the remaining methods be invoked?
* As with StreamInterceptor, there is no reference to or notice of the
specific HttpMethod being invoked, to which server we are
connecting/disconnecting, the way in which we are authenticating, the realm
to which we are authentciating, the credentials that are being posted, etc.
Can someone clarify how the Interceptors are to be used? Are they being
used anywhere? If not, maybe we should simply remove these classes for a
1.0 release, and wait until the role and contract details can be worked out.
- Rod
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