Steve Vinoski’s Blog

Dare Obasanjo explains that “WS-* is to REST as Theory is to Practice.” Very well stated!

Like Dare, I used to work on WS-* stuff, so I’m going to echo him and tell you why I shifted entirely away from it. In the past I definitely thought WS-* had potential for solving certain vexing enterprise integration problems, especially multi-protocol integration scenarios, but I also knew it had other problems. In addition, I was aware that that particular set of vexing integration problems, in the big picture, wasn’t very large or common. Meanwhile, REST has just appealed to me more and more over the past five years since I first wrote about it. As I learned more about REST, the size of that set of vexing problems just kept shrinking.

Finally, I realized that WS-* was simply not worth it to any customer or to me. My decision to leave WS-* behind and use only REST was based entirely on real-world commercial integration issues, not because I thought REST was cool. REST is not only the better theoretical distributed systems model by far, but also the better development model as well in terms of helping deliver working solutions within budget, so ultimately I chose to completely part ways with WS-*.

Nowadays, all the distributed systems development I do is REST-oriented. I know from significant first-hand experience what both sides of the coin look like, and there’s no question that REST-oriented systems are easier and less expensive to develop, and far less costly to extend and manage. Like Dare said, anyone who thinks otherwise is either so emotionally or monetarily attached to WS-* that they can’t be objective, or they don’t actually write any code or build or maintain any actual systems. It’s no contest, really.

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.

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.

The other day, the always-insightful Patrick Logan questioned whether ESBs are worth using. It’s definitely a good question.

In a previous life, I helped develop ESBs. I’ve written about them and I’ve promoted them. But somewhere along the way, I lost the religion.

It happened over a period of years as I learned more about REST, and as I learned how simple it was to develop integration systems using dynamic languages, which I’ve always been a fan of (for example, you can still find my name in the Perl source distribution, from about 20 years back when I ported it to Apollo Domain/OS). Despite the fact that I did it for years, I can’t understand anymore why anyone would subject themselves to writing integration systems or frameworks in imperative compiled languages like Java or C++. Doing it from scratch in such languages means that you’re definitely staring at a multi-year project, if you want to do it right. Or, if you’d rather use some sort of ESB platform or middleware framework underneath, you’re still looking at a number of months just to get anything nontrivial fully written, tested, and deployed.

Some of the mindset behind ESB-type middleware is the desire to do everything in Java or C++. Many developers just want to write some code and plug it into a magical framework that transparently handles all the distribution, persistence, security, transactions, and reliability underneath. Chuckle. Underlying frameworks just grow and grow as they try to provide all this, and so they develop more bugs, more inconsistencies, more special cases, less flexibility, and less reliability as time goes on, not to mention foisting on the unwary the XML configuration hell that Patrick alluded to.

Eventually, these mono-language programmers end up completely incapable of addressing a problem unless they can see how to implement it in their One True Language™. Too many programmers I’ve encountered over the decades know only a single programming language, with many of them even lacking in that one language. They therefore tend to settle into areas that let them use that language no matter what, all day, every day, even if it means writing hundreds of lines of code that could easily be replaced by just a few lines of a language better suited to the problem.

Another mindset behind the ESB is that of the enterprise architect. Large enterprises believe they can save themselves a lot of money and trouble if they can just get the whole enterprise to agree on a single integration architecture. Unfortunately, that’s pretty much impossible because of autonomous divisions independently building/buying and deploying different solutions, because of acquisitions and mergers that bring in different technologies and tools, and because of legacy systems that never seem to go away. The ESB appeals to such architects because it’s touted as being so flexible that it can accommodate everything in the enterprise and then some. This flexibility allows the architect to mandate it as “the standard,” and then proceed to beat up the ESB vendor to add this and that, while also beating up teams within the enterprise to use the ESB for everything whether it really fits or not. The ESB becomes like one of those tools you see on late-night TV, where it’s a screwdriver and a hammer and a wrench and fishing reel and a paint brush, and plus you can flip it over and it can make you a grilled cheese sandwich. Of course, such tools always end up not doing any of those things particularly well.

So, why not just do things the way Patrick suggested: when faced with an integration problem, just grab the nearest dynamic language, such as Ruby or Python, grab the modules they provide that surely cover whatever protocols and formats are needed for the integration, and code it up in just a day or two? Well, ESB proponents would say that this would never do because you end up with way too many one-off solutions, while mono-compiled-language proponents would natter on pointlessly about type safety, compilers preventing errors, and performance. An assumption behind these arguments is that the integration problem being solved requires high performance, and that the solution will live for a long time. In my experience, these assumptions are rarely correct, especially the second one, since business rules change so rapidly nowadays that the integrations required to implement them change all the time as well.

Frankly, if I were an enterprise architect today, and I were genuinely concerned about development costs, agility, and extensibility, I’d be looking to solve everything I possibly could with dynamic languages and REST, and specifically the HTTP variety of REST. I’d avoid ESBs and the typical enterprise middleware frameworks unless I had a problem that really required them (see below). I’d also try to totally avoid SOAP and WS-*.

The only place I can imagine using an ESB would be if I had some legacy systems that just couldn’t be replaced, had to be made to talk to each other, and there were significant measured (as opposed to imagined) performance issues to be addressed within the integration. Under such circumstances, the right ESB could shine; I’ve seen those circumstances, and I’ve seen an ESB solve exactly that problem on a number of occasions, and solve it well. But on the whole, such scenarios don’t really arise that often.