staying neutral

These are my very private thoughts on what is going on with PDO.

First of all, having decent database support is becoming more and more important to PHP because there is hardly any PHP application left that does not have some kind of database backend. And for that exact reason, a few people started PDO some time ago.

Technically speaking, right now we are on the second PDO version - well starting to count unix-like from version 0.

The initial PDO developed by Sterling Hughes and me never made it into PHP. It was, however, the base for the initial version we later put into PHP, as it proved that our main design goals worked: unified API through a base class with different database back-ends connected through drivers, where drivers are separate extensions that sit on top of the main PDO extension. After some discussions at conferences - such as the International PHP Conference and LinuxTag - it was Wez Furlong who came up with the initial implementation of PDO version 1. It had a nicely worked-out callback infrastructure that could support a bunch of database backends. And, indeed, we got a few of those in short time.

So what we have right now is a more or less working PDO that suffers from the following:

• Some databases have suboptimal drivers (often slower than native extensions).


• No support from database vendors to help improve drivers (for various reasons).


• A maintainance nightmare, where PDO in different PHP branches is completely out of synch.


• Limited functionality in PDO (like missing metadata support).


• Missing developers for the main PDO extension.

So the main questions are: how do we attract more developers to PDO, and how do we improve PDO? And all this to boot without scaring away current developers.

Now thanks to Wez for the PDO 1 specification effort and talking to a bunch of database vendors, trying to integrate them into PDO development. Because only with a good documentation can we make any progress whatsoever, be it a full rewrite or just continuous development. Btw, my thanks also go to the countless people that wrote the PDO documentation.

However, I completely disagree with the way in which PDO 2 was started. The main reason is that throughout the preparation phase not a single developer had any clue whatsoever of what was going on - not even that something was going on at all! If that is not the case, then obviously those who did know were under some kind of NDA. It actually appears that there is a PDO development mailing list, which I was not aware of until two days ago (for PDO 0 we used my private mail server). And even if I had been aware of it, it still would not have been the PHP way of doing things - where the PHP way is doing development openly, or at least openly after a short startup time. Either way, to most people who read the announcement of a CLA in the PHP ACLs some time ago and the PDO 2 development proposal recently, this is a clear indication that the upcoming PDO version won't be open source. Because open means open and the PHP community in particular has always been especially open. Even though, as we recently discussed again, we might have a reason to slow down traffic on internals@, in general we all profited from our openness.

From my very own perspective, I do not see any reason to change the ways in which we are dealing with things. That includes, first of all, that we discuss things openly. And second of all, that we have everything that is in PHP core under the PHP License - apart from bundled libraries, including the Zend engine and TSRM, of course. We btw discussed some time ago that everything in core in fact should be under the PHP License. And so far we do not have a single exception. Instead, we are continuing to replace parts of PHP that have a different license with our own rewrites/re-implementations. If we were to change the way PHP core components are developed or licensed, we would not only scare people away, but would also run the risk of this getting completely out of control.

But when we do not change anything, we do not make any progress. So let's all rethink that.

So we need a better PDO core and better PDO drivers. And that means we need to come up with a better callback infrastructure between main PDO and its various drivers. And that requires some insight in the actual databases, where there are two problems. First, some vendors would only be willing to give us PHP developers insight if we or our companies signed a NDA. And second, the vendors do not usually talk about their internals unless they absolutely have to. And if they do, then this traditionally would be done under a NDA as well. But open source development and NDAs do not really mix. So the NDA way is out.

Now something between completely open and completely closed is (and the Apache Software Foundation does this with quite some success) to use CLAs.

Since I am absolutely against any change of PHP core development because any change might spread out to larger parts of PHP development, let's only deal with PDO here.

That said, PDO main belongs in PHP core, which means that it has to be done under the PHP License which is pretty much incompatible with a CLA. But we can still develop PDO drivers in PECL. And there we can even allow different licenses, at least as long as they are compatible to our OSI approved license. Actually, we already have PECL extensions where people can only contribute after agreeing to some special terms.

At this point we could live happily ever after - if only there weren't the issue of developing a high-performing callback infrastructure. Oh, and we still would need to find people to work on PDO main.

So how do we come up with working specs and people who can contribute?

Right now, we have people contributing to PHP on a regular basis from companies like Google, IBM, MySQL, Oracle, Yahoo, Zend and a bunch of various others - be it large companies, database companies for the PDO matters, established open source companies, or small private companies to freelancers like you and I once were.

Clearly companies can find ways to work on open source without CLAs. And if any company has a problem discussing the protocol of callbacks without having everyone else first sign a CLA, then I can only say that it is their very own problem and potential market disadvantage. Pretty polemic answer, sure. But PHP has gained a lot of momentum in the previous few years and we, the PHP contributors, have accomplished that with a hell lot of effort. Private efforts for the most (and some paid efforts as well). Each and every one of us. So I do not feel the slightest temptation whatsoever, to give even the tiniest piece to any closed company. Plus having to sign a CLA might not be possible to all people working on PDO so far. And with that in mind, I would rather live with having an imperfect callback infrastructure in PDO than losing a list of respected open source contributors.

Sorry to say this, but I do not want a CLA in any part of PHP core.

That of course means that we still have to talk to database vendors. And, guess what, we probably welcome any kind of contribution. Just as we have always gladly accepted any kind of contribution. And maybe the actual problem is starting up a discourse with the vendors. Maybe the problem here is that there is currently no PHP entity. The only thing close to a PHP entity is the so-called PHP Group. But other than having a mail address that goes to some people mentioned on the credits page, the PHP Group does not appear to be doing much of anything. So maybe what we really need to do is fix this situation and recreate the PHP Group. Restart it with people that actually work on PHP and know the internals. Maybe just like PEAR Group by voting; maybe like the Apache Software Foundation; maybe in a completely different way.

Parting words: If you are wondering what PDO 2 is, well so am I. And how is this open source development?

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Labels: PHP