Re: [PHP-DEV] PHP and two phase commit transactions
These are the issues I partially solved integrating LIXA with PHP. 1. XA interface is a C level interface: the PHP database drivers must be changed at C source level to avoid many leaps between C and PHP code. The most important PHP database drivers are distributed with PHP core itself = patching their source code is equivalent to patch PHP core. 2. As a consequence of the first point, the LIXA PHP wrapper itself should be distributed with PHP core to avoid dependencies between some core extensions and an external extension. 3. The TX API does not deal with the concept of connection because it's implicit: every process/thread has its own connection with every Resource Manager (database). Better explained: tx_open(), tx_begin(), tx_commit(), tx_rollback(), tx_close() (and so on...) do not specify the handlers necessary to distinguish connection objects. 4. The TX API design does not take into account the concept of persistent connections and connection pooling. I afforded issues 1 and 2 creating a global experimental patch for PHP core itself (you can find it in ext/php directory of LIXA tarball or directly at SVN repository. http://lixa.svn.sourceforge.net/viewvc/lixa/ext/php/). Issue number 3 was bypassed and, for the sake of trivial hello world equivalent examples, the integration seems to work properly. Issue 4 is quite difficult to address: I ignored persistent connection disabling LIXA feature when the application asks a persistent connection, but I was not able to deal with Oracle connection pools of oci8 driver. I have some concerns about the approach you're taking. I don't think a compile time dependency to LIXA is acceptable. Can't you add some hooks to the several database extensions? From a glance at your patch, it seems you only need to change the behavior when getting a new connection and closing one. This shouldn't be much work. Once that were done, one would be able to plug the LIXA extension (or any similar extension). I don't think this approach would get objections from the extension maintainers and it is more versatile. --Gustavo Lopes Dear Gustavo, I've appreciated you feedback and the approach I followed to produce some experimental code could be changed for sure. You correctly understood the only necessary changes are related to open/close connection to the resource manager (database); this is a consequence of XA and TX specifications. I've not completely understood your statement add some hooks to the several database extensions and I would need some more details; is this mailing list the right place to discuss about this type of details or is there a better place? Before starting to implement the interface in the right way I have to collect some feedback about the following issues: 1. Is there any interest in two phase commit inside PHP community? Without a real interest, every effort would be useless. 2. Is there anyone available to help me in implementing the interface between LIXA and database extensions in the right way? After some analysis I discovered some database extensions are really sophisticated and injecting a bug is simpler than adding a well implemented feature. I wouldn't break some working code. Any hint/suggestion would be appreciated. Ch.F. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] PHP and two phase commit transactions
1. Is there any interest in two phase commit inside PHP community? Without a real interest, every effort would be useless. I can't speak to a critical mass of interest, but as PHP and MySQL are closely coupled in the real world, until relatively recently (when Inno became the default) that meant that PHP and MyISAM were best buds. I don't know how you could do 2PC between two transaction-unaware back ends. I could see one transaction-aware and one transaction-unaware working by running synchronously w/the transactional one first (?). So my sense is that PHP, because of MyISAM's ubiquity, isn't the ideal language target for 2PC (compared to Java/.NET where the most enterprise back end is assumed, however inaccurately!). That doesn't mean there wouldn't be some interest, though. -- S. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] PHP and two phase commit transactions
On Wed, 30 May 2012 22:10:56 +0200, Christian Ferrari cam...@yahoo.com
wrote:
You correctly understood the only necessary changes are related to
open/close connection to the resource manager (database); this is a
consequence of XA and TX specifications.
I've not completely understood your statement add some hooks to the
several database extensions and I would need some more details; is this
mailing list the right place to discuss about this type of details or is
there a better place?
What I meant was that you should not couple the database extensions to
your C library. Instead of having:
struct conection *conn;
#ifdef LIXA
if (lixa_is_active()) {
conn = lixa_whatever();
} else {
#endif
conn = do_default();
}
prefer something like:
extern struct connection (*get_connection_override)(void);
...
if (get_connection_override) {
conn = get_connection_override();
} else {
conn = do_default();
}
You can do this in different ways -- by having a PHP wide variable and
generic function to retrieve and close connections that would be passed
the type of resources an other parameters; you could have a different
scheme for eachDB extension, etc. -- those details are relatively
unimportant.
1. Is there any interest in two phase commit inside PHP community?
Without a real interest, every effort would be useless.
It is very difficult to determine the future demand for something that
does not exist yet. Microsoft introduced filesystem transactions in
Windows Vista, and it's considering deprecating them. But given the
prevalence of JTA in the Java world and the developments in PHP in the
last years I would not be surprised if there was significant demand for
this. And given the current tendency to use more specialized databases
(see JCR client implementations), it may become more important in the
future.
2. Is there anyone available to help me in implementing the interface
between LIXA and database extensions in the right way? After some
analysis I discovered some database extensions are really sophisticated
and injecting a bug is simpler than adding a well implemented feature. I
wouldn't break some working code.
I can review your patches and help you along the way.
Note that stable branches generally do not receive new features, so you
should develop against the development branch (master). If it's your
thing, you can fork PHP on github: https://github.com/php/php-src
--
Gustavo Lopes
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] PHP and two phase commit transactions
On Tue, 2012-05-29 at 21:27 +0100, Christian Ferrari wrote: Dear all, I'm the author of LIXA project (http://lixa.sourceforge.net/) and I would discuss a little about two phase commit transactions for PHP applications. Besides all technical discussions etc one legal comment, on the project page I read: Which type of license applies to LIXA project? The whole LIXA project is released under the terms of GNU Public License (GPL) version 2. http://sourceforge.net/apps/mediawiki/lixa/index.php?title=FAQ:_Frequently_Asked_Questions#License It then mentions bla bla bla about restrictions imposed by the GPL. One restriction is that the GPL is not compatible with the current PHP License. Therefore lixa can't be combined with PHP. See http://www.gnu.org/licenses/license-list.html#PHP-3.01 johannes -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
