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Re: [equinox-dev] [prov] ECF in P2, was request handler orientation

I admit I'm a little confused by this thread, as it seems bring up a range of issues...some of which are related to ECF functionality and some of which don't seem (to me) to be directly related to ECF per se (but rather the provisioning request handlers?).

RE: Stefan's original comments about the ECF proxy handling and authentication structure...the API supports both proxy and arbitrary auth mechanisms for whatever protocol/provider implementation is used for the underlying file transfer (http/ftp/efs/bittorrent/etc). ECF exposes extension points for adding support for other protocols (e.g. private ones like a repository-specific protocol).

RE: defining request handlers externally...I think the current version of ECFHandler (version I looked at few weeks ago anyway) is overly tied to a *particular* (default) protocol/provider (http via URLConnection). I think this handler could be abstracted and made pluggable, but I haven't yet given much thought to how this would be done as I'm not yet familiar enough with all the provisioning code to understand the external API requirements on request handlers.

Pascal Rapicault wrote:
In scenarios where size matters, or where only one well-known transport is
to be used, the handler give us the ability to remove our dependency on
ECF.
So to me, to know whether or not the handler should be kept, we have to
answer the following questions:

* Size
- Is ECF small enough for scenarios where size matters?

What would be considered 'small enough'? I know zero bytes of code is best :), but that seems a little 'severe'. Of course ECF's pluggable transport nature could be sacrificed and a return to the JRE-provided URLConnection could be used instead, but this returns things to the state prior to the equinox provisioning work (i.e. bound to a specific transport...e.g. http).


I guess I'm not clear on what benefit removing the dependency on ECF would have other than a fairly small change in code size, and it's costs (return to lack of flexibility in transports) would be pretty clear. Besides, what's the problem?

- Can the removal of the dependency on ECF be achieved by another way (for
example having a new DownloadManager)?

* Pluggability
- Can any transport be plugged into ECF, if not what is missing from the
API?

This is a very important question. I would assert than any file transfer protocol of interest can be plugged into the ECF filetransfer API...but if this turns out to be wrong for some transport and API changes (as opposed to additions) are needed, then I would like to know about that as soon as possible.


- How more complex would the handler have to become, which other
infrastructure would we have to have when ECF is not present (e.g. how do
we know which transports are supported)?

I would guess that the handler would have to become significantly more complex without ECF, because if multiple/pluggable transports are desired/required then *some* abstraction has to be introduced to provide pluggability/flexibility at the transport level. ECF is essentially that abstraction.


- How complex is it to plug a new transport?

* Functionality
- What does ECF brings us?
I would offer that it provides a consistent API to get pluggable file transfer protocols, suspendable/resumeable transfers, and other goals for transport pluggability as described here

http://wiki.eclipse.org/Equinox_Provisioning_Plan

...and probably other places.

- Will ECF be able to overcome its current limitations? Is the ECF team
aware of these?
RE: the current (implementation) limitations WRT proxy handling...we have:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=181544
https://bugs.eclipse.org/bugs/show_bug.cgi?id=192286

Beyond these, I'm not exactly clear on what people are suggesting are the limitations of ECF API or specific protocol implementations. If there are specific limitations (outside the proxy issues) that I/we should know about then I would appreciate bug and/or enhancement requests. We are completely able and willing to address any such limitations as they are identified.

Can any one take a look at this?

By take a look at this do you mean looking at redesigning/reimplementing/generalizing the provisioning request handler (ECFHandler as current impl) structure or something else? In either case, I can probably contribute if that's desired. But I would like to understand better what the current deficiencies are (beyond full impl support for proxy handling).


Scott