Reactions to the ESB Question

October 4th, 2007  |  Published in enterprise, integration, REST, services, WS-*  |  Bookmark on Pinboard.in

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 ESB Question

October 4th, 2007  |  Published in enterprise, integration, REST, services, WS-*  |  Bookmark on Pinboard.in

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 Languageā„¢. 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.