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From Ben Laurie <...@algroup.co.uk>
Subject Re: [RFC] Network Abstraction Layer - redux
Date Sat, 16 Jun 2001 13:15:29 GMT
Bill Stoddard wrote:
> I would argue that we do not have a good (read architecturally clean) way to abstract
> network io with filters. The NAL is a perfect compliment to the filter code. Here are
> specific itches:
> 1.  My SSL library API uses a different model than OpenSSL. Specifically, it uses uses
> secure_socket calls (e.g., secure_read(), secure_write(), etc.).  I -could- integrate
> into Apache 2.0 using filters, but I would have to replace core_inout_filter and
> core_output_filter with my own filters, possibly implement special bucket types
> (apr_bucket_secure_socket_t, etc.)  With NAL, I can just hook the network io primitives
> with my own calls and use the filters already in Apache. I hope to use OpenSSL but that
> just not a possibility now. My itch is real to me even if you don;t feel it :-)

FWIW you can also run OpenSSL in this mode, but I elected not to (coz
then SSL will work automagically over other transports).

> 2. I gave a pitch about IBM's Fast Response Cache Accelerator (aka AFPA) at ApacheCon
> few years back. The AFPA implementation on Windows uses it's own socket API (afpa_read,
> afpa_accept, afpa_send, et. al.).  Again, the NAL provides a clean way for my Apache
> module to hook the right NAL implementing my specific network io primitives with the
> minimum amount of shuffleing httpd code.
> Can I do both of these with filters? Sure, but the code architecturally ugly as sin.
> Allan Edwards solved both of these problems cleanly in early Apache 2.0 iterations using
> Dean Gaudet's IOLs. NAL is essentially a scaled back version of Dean's IOLs (NAL is
> focused just on network i/o, not filtering). And I know what Luke is talking about as
> well.  Windows NT does implement filters (AFPA uses file system filters) in addition
to a
> network io abstraction layer.  NAL is a great compliment to filters.

So ... why did we drop IOL? :-)




"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff

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