Steve Vinoski's Blog

Don says he agrees with a lot of what James has to say about Stefan’s recaps of the QCon SOA Track, listed below:

• Dan’s talk
• Pete’s talk
• Sanjiva’s talk
• my talk

I too agree with many of James’s insights. If you don’t regularly read his blog, you should subscribe immediately. I especially like this quote:

When I consider SOA and REST today, I do not see two competing visions, I see an evolution that has brought the industry back to a core set of fundamental design principles that we seemed to have lost sight of for a while.

How very true. However, I disagree with just one small point: his critique of the part of my talk where I said SOA has no constraints (as Mark Baker has been pointing out for years now).

James says that SOA has constraints, it’s just they’re just not well-documented. I know exactly what he’s saying, but I have to stick with what I said. The only official definition of SOA that I know of is the OASIS SOA Reference Model, which mentions several desirable properties for SOA systems, but it documents no constraints for inducing them AFAICS. Later in my talk, as Stefan’s notes indicate, I did say that I was willing to concede that the OASIS SOA RM promotes the client-server constraint. However, I was being really, really generous, since all the specification really does is hint that SOA systems should be distributed, and “distributed” has a lot more meanings than just “client-server.”

Since there are no official standard SOA constraints, the only constraints you get are the ones that each vendor or supplier of SOA platforms and systems decides to give you. Naturally, each different solution in this space will differ in those constraints.

As the quote from James above implies, pitting SOA and REST against each other doesn’t make a lot of sense. The reason I went to the trouble of pointing out in my talk that SOA is missing critical architectural requirements like constraints was to help illustrate the significant differences between SOA and REST. Fundamentally, as I also said in my talk, SOA isn’t really about architecture in the way that REST is. Rather, it’s about IT culture, best practices, breaking down the enterprise organizational and political barriers that needlessly increase IT costs, and following good fundamental software engineering principles like reuse, minimizing coupling, and maximizing cohesion.

I returned home from QCon San Francisco last night. In the SOA track, it was most excellent to finally get to meet Patrick Logan, Stefan Tilkov, Pete Lacey, Jim Webber, Stu Charlton (thanks again for the Dew, Stu!), and Mike Herrick in person, as well as to get to meet up again with Sanjiva Weerawarana, Glen Daniels, and Dan Diephouse. All in all the SOA/REST track was highly informative, with solid presentations through the whole day. Pete’s was especially cool due to the demo he gave of the extreme flexibility and integrability of REST-oriented solutions. It was also reasonably fun, given how much the attendees got into it with their questions, and especially due to Jim’s presentation at the end in which he mixed some serious technical chops with very funny one-liners popping out every second or third sentence.

My talk, “REST Eye for the SOA Guy” (title taken from here), went reasonably well. The only time it didn’t flow as smoothly as I would have liked was when some semi-anti-REST folk started questioning my assertions about specialized interfaces inhibiting scalability, and wondering whether REST just pushes all the coupling problems to the data. I felt like I was being pulled backwards in time by 5 years to the old W3C Web Services Architecture Working Group meetings, where very little was ever accomplished due to arguments like those. I’ll have more to say on those topics in some near-future blog postings.

An interesting thought struck me as the track progressed: in my experience it seems that most SOA/WS proponents who argue against REST on technical merits have never actually tried to build any RESTful applications. Many of their objections seem to be heavily based on emotional reactions, or based on conclusions reached only by blowing issues out of proportion (for example, I felt that many of the points in Sanjiva’s talk fell into this category). So it led me to wonder about how many, if any, dyed-in-the-wool WS advocates ever seriously, honestly, and fairly looked at REST, actually tried it, but then decided it didn’t work and so willingly chose to go back to WS. I don’t want to count those who had to go back to WS only to integrate with something else already implemented using WS, because that doesn’t fit the “willingly” part. (For example, I recently had to write a client to access a SOAP service, and I was definitely not in the “willingly” camp because the service was way more complicated than it needed to be, only because of SOAP.) I personally know of nobody who has ditched REST for WS like this, but if you have, or if you know of someone who has, I’d love to hear the whole tale, so feel free to leave it in a comment.

The conference itself was much like JAOO, which is not surprising given its JAOO roots. It was smaller, of course, given that this was the first QCon held in the U.S. And just like JAOO, there were times where I wanted to be in multiple places at the same time to see two or three different talks all scheduled concurrently. For example, I very much would have liked to sit all day in the Thursday “Architecture Quality” track, but couldn’t since it ran parallel to the track I was in.

In short, if you didn’t go to QCon, you missed a great conference. Stefan, thanks again for inviting me.

When you read stuff like this, you can’t help but feel that IT is, without a doubt, doomed.

The gist of the posting is

• REST is too hard for the average developer
• Dynamic languages are too hard for the average developer

Along these same lines, a couple of folks told me in person that my recent blog entries about REST, dynamic languages, and ESBs were misguided because today’s enterprises are interested only in approaches, frameworks and platforms that allow average developers to produce quality systems.

This all strikes me as nothing but wrong-headed thinking.

On the dynamic language front, the worst code I have seen in my career has always, always, always been in compiled imperative languages, most often Java and C++. I would much rather let an average developer loose with a dynamic language, because the surface area is smaller, there’s a lot less rope available for self-hanging, and if they’re going to fail, they’ll fail way faster and thus allow much more time for recovery. The fact that dynamic language programs are usually smaller than their compiled counterparts means that they’re easier to read and review, and statistically, they’re likely to have fewer bugs. Furthermore, counting on the static language compiler to save you is simply wishful thinking. To paraphrase Tim Ewald from a conversation he and I had during lunch a week or so ago, compilation really amounts to just another unit test.

On the REST front, if you’re claiming that it’s harder than the alternatives, to me that’s just a sign that you don’t understand it. Is REST simple? No, but neither is SOA. However, unlike SOA, which is fairly wishy-washy, noncommittal, and loose, REST’s constraints provide real, actual guidance for developers, and those same constraints also provide opportunities for significant flexibility, extensibility, performance, scalability, and serendipity. SOA’s contracts come with no rules or constraints, and thus can easily result in a system that’s extremely brittle, tightly-coupled, and virtually impossible to upgrade. SOA itself isn’t inherently bad, as it’s certainly a step above the “every application for itself” mode of development that’s so widely practiced. Unlike REST, though, SOA doesn’t go nearly far enough to provide real, useful guidance to the poor developer who has to actually write the stuff, make it work, and keep it running.

And finally, regarding the overall notion that enterprises cater only to average developers, I’m not sure I agree. In my former life I met countless enterprise developers who were extremely sharp. While I have no doubt that there are numerous bean-counting CIOs and middle IT managers out there who think they can build high-quality IT systems with low-quality developers, at the end of the day, businesses generally know better than to think they can get something for nothing. Or to put it another way, they know they get what they pay for, and if they pay only for average developers or worse, they’ll get only average software and average systems, or worse. That’s a no-brainer.

If you’re in a position of technical leadership or project management and you’re asked to come in ahead of schedule and under budget, my advice is that you’re generally more likely to succeed with REST and dynamic languages than with the alternatives because their inherent constraints allow for better focus. Also, if you find yourself in such a position, you owe it to yourself and your team to continually lobby your superiors to help them understand the very real costs of their budgetary stinginess.

In a comment to the many comments on my post entitled “The ESB Question,” Bill de hÓra gets it right:

I’m disappointed with the responses here. Steve’s an expert technologist in this domain. There’s a real opportunity for learning when the ESB approach is *appropriate* – instead we see the same old reactionary web v enterprise positioning and the usual suspect arguments being rolled out against REST style integration.

Bill’s right; the discussion has unfortunately mostly degenerated into the usual no-light-all-heat “us vs. them” argument. I especially object to the folks who twist what I say and accuse me of saying things that I never even remotely hinted at, but I guess that’s the price of blogging publicly.

I’m not going to try to address the comments individually, especially the ones from the guys who, amusingly, wrote lengthy diatribes explaining to me just what ESBs are, what they’re supposed to do, and why they’re beneficial. Yes, guys, I get all that. Perhaps you should go back and read some of my publications from 3, or 4, or 5 years ago? Funny how I don’t recall any of you being around back then, when I felt more positive about ESBs (hint, it was before that term was coined) and I was blogging and writing to that effect.

Arguing this issue on technical merits is rather pointless. One of the best comments in this thread was from Dan Hatfield:

Honestly, I see the ESB as primarily a political thing. It allows for a greater degree of control on delivered solutions. In large companies, we don’t often do architecture – we do politecture…The politics drive the architecture. Not the way it should be…but that’s the way it is.

So true, so true. Another non-technical way to look at it is from the viewpoint of Clayton Christensen’s classic book, The Innovator’s Dilemma. For quite a few years now, we’ve seen a series of sustaining innovations in the “object/service RPC” line of descent originally popularized by CORBA and COM, both of which built on earlier RPC, distributed object, and TP monitor technologies. RMI, EJB, SOAP, WS-*, and ESB are all offspring in that line, and there are surely more to come. I feel that REST, on the other hand, fits the definition of a disruptive innovation perfectly (and if you’re too lazy to read the book, then please at least follow the link, otherwise you won’t understand this at all). The proponents of the sustaining technologies look at REST and say, “well it can’t solve this and it can’t solve that” and voice numerous other complaints about it, precisely as Christensen predicts they would. But Chistensen also explains why, at the end of the day, any real or perceived technical shortcomings simply don’t matter (and in this case, they’re mostly perceived, not real). HTTP-based REST approaches have a lower barrier to entry and are less complex than anything the sustaining technologies have to offer, and REST is disrupting them, whether all the smart folks pushing ESBs like it or not. It’s not a technical issue, and there’s no amount of technology the non-REST tribe can throw at it to stop it because it’s based on how markets work, not on the technical specifics.

At the end of the day, if you don’t think REST is viable or you don’t like dynamic languages, then don’t use them. It just means that you’re at a different point than I am on the Technology Adoption Lifecycle curve. Like I already said in my first follow-up, I’m not in that business anymore, so it doesn’t matter to me at all. I’ll just keep using what I know to be generally superior to all the other approaches I’ve worked on over the years.

Comments and reactions to my previous post have been interesting. Rather than responding to comments by adding more comments to that post, let me address them here:

• Mark says what I’m recommending isn’t entirely new. And you know what: he’s exactly right! What might be interesting, though, is why he’s right. I pushed these ideas surrounding REST and dynamic languages for a number of years in my former position before finally leaving that position, partly because those ideas were not getting the level of attention I felt they deserved. So yes, the ideas are certainly nothing new today, but they were reasonably new back then.
• REST is unproven. Sigh. I can’t decide if people say this because they’re just trying to stir up an argument, or they’re so heavily biased toward their non-REST approaches that they just can’t even consider that there might be viable alternatives, or they really have no clue about what REST is, how it works, and why it works, and they’re not interested in learning it, so they just react badly whenever they hear it, or all of the above. If you’re anti-REST or REST-ignorant, and you haven’t read RESTful Web Services, then don’t even talk to me about REST. The book is absolutely wonderful, and its explanations and answers are extremely clear. If you consider yourself informed and capable when it comes to distributed systems and integration, but you don’t know REST, then there’s simply no way you can read that book and not have it lead you to seriously question your core beliefs regarding how you think such systems should be built, unless you’re completely close-minded of course.
• Are you saying we should throw everything out and redo it with REST and dynamic languages? No, not at all. I would never advocate wholesale rip-and-replace, because the cure is almost always worse than the disease. I’m simply saying that many integration projects can be done easier and with less expense if you use those tools and approaches (and please notice I said “many,” not “all”).
• Steve’s thrown out the baby with the bathwater. It seems that people might not have read my entire post, because a number seem to think I said that ESBs should never be used at all. That’s not what I said; if you read all the way to the bottom, you’ll see that I explained some conditions under which I thought they can come in mighty handy.
• What do mono-language programmers have to do with ESBs? It’s all part of the same culture, the “one size fits all” approach, where you have answers looking for problems rather than the other way around, and where people intentionally wear blinders to less expensive, more productive, and far more flexible and agile approaches because “it’s just not the way we do things around here.”
• Are you seriously recommending dynamic languages for enterprise integration projects?! Hmm, that’s mighty enterprisey of you to ask that. Yes, that’s exactly what I’m recommending, because they’re solid, fast, flexible, smaller and therefore less buggy, easily deployed, easily maintained, and the solutions you get by using them will be in production well ahead of your traditional compiled languages.

At the end of the day, if you want to ignore my advice on using REST and dynamic languages, that’s your own problem. You won’t get any arguments from me, because I’m not in that business anymore. All I know is that I’m using them very successfully as part of what I’m working on these days, and it’s simply glorious.