Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc
Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc
- Subject: Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc
- From: Ken Tozier <email@hidden>
- Date: Sat, 6 Dec 2008 20:47:00 -0500
On Dec 6, 2008, at 6:45 PM, Andrew Farmer wrote:
This is incorrect. A "connection refused" error in this context
means that you're either trying to connect to a host/port which is
not configured to accept a connection, or the host is behind a
firewall which blocks incoming connections. In this case, it's
probably the former. But what you're probably running into here is
simply the fact that MySQL doesn't accept TCP connections at all by
default - instead, it uses a UNIX domain socket in either /var/tmp/
mysql.sock or /tmp/mysql.sock.
The host and client are both on my laptop so I don't think the config/
firewall stuff applies. I got my custom socket class working and was
able to connect, at least up to receiving the handshake packet, using
TCP. Not sure what Apple is doing in the guts of NSSocketPort, but my
class is able to connect and fetch the handshake. When I try the same
thing with NSSocketPort's file descriptor, no go.
More to the point, though, why are you trying to reimplement the
MySQL client library? You haven't even gotten to the wire protocol
yet, which I guarantee is going to pose you even more problems than
just connecting to the server. If you're just concerned about having
to include the library, you can link statically against the
libmysqlclient library to avoid having to drag the shared library
around with you. (Note, however, that libmysqlclient is licensed
under the GPL, so you'll need to talk to Sun if you want to use it
in non-free software.)
I love a challenge :) It's an interesting problem and I'm learning how
to use sockets. I wouldn't have even thought of bypassing the library,
but I stumbled across this really cool flash library that connects to
MySQL completely via sockets (http://asql.mooska.pl/release/srcview/)
and thought it would be cool to do something like that in Cocoa.
The MySQL protocol isn't all that difficult. I found a good resource
here (http://forge.mysql.com/wiki/
MySQL_Internals_ClientServer_Protocol) The trickiest part seems to be
scrambling the user password with the seed MySQL sends in the
handshake. I already wrote a nice, simple packet parser to handle the
different types of MySQL messages and am working my way through the
password stuff.
What I'm writing will be installed on about 50 to 100 machines and I
have no interest in installing the client lib on all of them. I
actually got some code working with the client lib but it broke as
soon as it was installed on a different architecture (PowerPC) and OS
version (10.4 vs 10.5) These four combinations of OS and processors
are a given and I can't do anything about that. Each configuration
requires a client lib specifically compiled for it and I don't want to
support 4 different versions of my app or the support calls when they
do a clean install or an upgrade and suddenly my app stops working.
With my own sockets, I'll only ever have to worry about MySQL protocol
changes which are much less frequent than MySQL updates.
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| References: | |
| | >Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: Ken Tozier <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: John Pannell <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: Ken Tozier <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: "Michael Ash" <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: Ken Tozier <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: "Michael Ash" <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: Ken Tozier <email@hidden>) |
| | >Re: Big picture relationships between NSConnection, NSInputStream, NSOutputStream etc (From: Andrew Farmer <email@hidden>) |