Fri 12 Sep 2008

BizTalk Server 2006 (a.k.a The Beast)

Posted by Steve Knight under database, rant
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I don’t really like to repeat myself but I’ve found another example of code that isn’t. It has a name, and that name is evil BizTalk. I’ve wanted to write about BizTalk for a while but I’ve been holding back because it’s a large and complex product that I wanted to do proper justice to.

Ok, so let’s get the nasty out of the way first. BizTalk is partly the reason that I’ve done very few blog posts recently. It is also the cause of an annoying pain at the base of my skull that didn’t go away until I stopped ‘doing’ BizTalk. There are many reasons why and I could go on and on about:

  • how it neatly hides important detail from you that you need to problem solve issues;
  • cryptic error messages;
  • property boxes in property boxes in property boxes;
  • lack of effective development environment;
  • high license cost;
  • … yada yada yada …;

Ironically at the same time I was using BizTalk I was also reading the design of everyday things. Whilst not strictly a book about technology, the ubiquity of computers these days makes it a compelling read for programmers like me. Anyway, the point is that BizTalk very neatly violates almost everything that Donald Norman holds dear.

If it’s so bad then why are you using it?

Good question. You read my mind. You see it solves a couple of problems for me, firstly a very expensive software product requires it out of the box so I really have no choice. However, and here’s the interesting part, it does two “big picture” things very well. Indeed, if you ignore the nitty gritty pain of what you had to do to get it to work it solves a couple issues of system integration reasonably well.

  1. Message Handling – the BizTalk server wants to receive a message and do something with it. It is able to take messages from a variety of sources: database, file drop, FTP, HTTP, SOAP, Email, etc. Once this message is received it can be routed to an ‘Orchestration’ which takes the message and applies some logic to it. This can involve changing the shape of the message and or sending it on to a variety of other systems.
  2. Business Focus – the fact that BizTalk server can take messages from a variety of sources means that it becomes the natural place to put things that ‘process external data’. This doesn’t sound like a big deal but when you’ve worked in companies that have attempted this solution without something like BizTalk you’ll know what a mess this becomes. Many programmers, many ideas, little consistency, integration headaches.

So it’s good right?

Well yes and no. I can’t pretend that I’ve even scratched the surface of what BizTalk does, it’s a beast. However, for what I need to do I’ve created about a half a dozen or so orchestrations and a few mappings and every one was as painful as the last. It just doesn’t seem to get any easier.

You see, the bits of BizTalk I like, are relatively quite small. The bits I don’t like are the bits that try and take programming control away from me by providing me with some half-baked UI that ultimately is going to produce me a piece of executable code. And that’s my point. If it’s going to produce executable code why not just give me some powerful libraries (which must exist anyway) and let me write it? Indeed, I’ve had a couple of people tell me that they don’t really like BizTalk either and when faced with a ‘BizTalk challenge’ their solution is to write a custom pipeline to handle it (for those not in the know, this solution gets the job done but it’s like buying a tractor to get your groceries with).

The part of BizTalk that I would pay money for is probably not worth that much. However, I’m smart enough (just) to know that if I wanted to roll my own which just contained the features I wanted I would still be doing it in 2009. So for now, I guess, The Beast and I will get along fine. If there’s ever a viable alternative The Beast and I will be parting ways.

 

Fri 1 Aug 2008

Lisp. It Doesn’t Get In Your Way. Much ™

Posted by Steve Knight under lisp
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Recently I have been using Common Lisp’s eval function a bit. Since it’s eval that put’s the E in REPL it fair to say that it is a fairly fundamental part of Lisp. However, no code that I have seen appears to use it directly. I think I know why. To make (eval …) always work in the way you’d expect doesn’t appear to be that intuitive.

Paul Graham in On Lisp, has this to say about using eval in your own code:

Generally it is not a good idea to call eval at runtime, for two reasons:

  1. It’s inefficient: eval is handed a raw list, and either has to compile it on the spot, or evaluate it in an intepreter. Either way is slower than compiling the code beforehand, and just calling it.
  2. It’s less powerful, because the expression is evaluated with no lexical context. Among other things, this means that you can’t refer to ordinary variables outside the expression being evaluated

And so when I discovered a need in my project to persist and reload closures I decided that my needs would not violate either of Paul’s points. Firstly, because I don’t know what the code I’m going to persist is going to be, and secondly because no lexical context is needed to create my closures. Therefore, I would store them as strings and then I would use read, and eval to restore them. This worked fine so I put the code into the package and declared my work done.

It turned out that once the code was in a package it didn’t really work as I’d intended. When I tried to run it I got unknown symbol conditions raised when I tried to restore the closures. Qualifying all the symbols with the correct package name worked but it made my shiny new DSL all messy by requiring me to always prefix all my symbols. It turns out then that eval doesn’t work this way by design. The reason is because of this statement in the HyperSpec page of eval.

…
Description:

Evaluates form in the current dynamic environment and the null lexical environment .
…

I was expecting that since my eval was inside a package it would be able to see function symbols in that package. Not so, eval works in the dynamic environment, which implies then that the current package is a special variable and hence part of the dynamic environment.

This means my code could only ever work when the current package is the library package. Any other package and the code fails because eval is checking the dynamic environment to determine which symbols are visible without package qualifiers. Indeed it seems that, in SBCL to make my code work in the way that I should expect I need to wrap it in the following:

   (let ((*package* (find-package "MY-PACKAGE")))
      (eval ...))

And this works just fine. The most pleasing thing about this outcome is that it illuminated a point that I’d heard before but never been able to substantiate: Lisp, It Doesn’t Get In Your Way. eval has to work how it does otherwise Common Lisp would probably not work properly. However, because the package system is an accessible part of the language to the programmer it seems as if I can adapt any part of that system to suit my purpose.

You’d be right in thinking too much of this sort of thinking is bad for maintainability, but this single line hack allows me to safely persist executable-code at run time. Since there’s few languages that have closures to begin with, making a minor hack to make them easily persisted too (with the help of macro) seems a small price to pay.

“Lisp. It Doesn’t Get In Your Way. Much.” – I like the phrase so much I think I’m going to trade-mark it.

 

Sun 22 Jun 2008

Evolved Programmers Wanted. No Returns.

Posted by Steve Knight under programming
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Here’s an interesting quote from Jeff Attwood (emphasis is mine):

“I use implicit variable typing whenever and wherever it makes my code more concise. Anything that removes redundancy from our code should be aggressively pursued — up to and including switching languages.”

It sounded like something I’d heard before. Here’s another quote from Paul Graham:

“The kind of dirtiness Arc seeks to avoid is verbose, repetitive source code. The way you avoid that is not by forbidding programmers to write it, but by making it easy to write code that’s compact.”

I’m not in anyway claiming that Jeff is lacking originality I’m suggesting that when two influential people with a large audience express the same thought … well something ought to happen right? Perhaps programming languages are going to become more expressive and concise. This certainly seems to be one of Paul’s aims at least.

Programming is changing, that’s for sure. It seems like only yesterday that Python was new and I was bending my head around it and liking being released from static types and embracing dynamic languages. Indeed if you watch this video (and I highly recommend you do) you can get a feel for how far Python itself has come in about 5 minutes.

The point though is our industry is still evolving. Natural selection finds the best parts of all those programming languages and software products and begats them into new ones. 10 years ago I believed that the future had arrived and that we would all use C++ where performance mattered and Java everywhere else. It seems that I was hopelessly naive to believe that evolution had ended. It had scarcely even begun.

I’m also eternally grateful to the innovators and early adopters that I don’t have to write much of either C++ or Java anymore. But that’s another story.

 

Tue 17 Jun 2008

The Silver Lining Of A Lead Balloon

Posted by Steve Knight under project management
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The Heathrow Terminal 5 story is not all bad. Yes it was a bit of a shambles, yes senior management was fired. But today I found some joy in BA’s misery.

A Metaphor

Now don’t get me wrong this isn’t just me deriving pleasure from others misfortune. Although admittedly as a Brit I am innately very good at that. So good in fact that it’s a constant surprise that the Germans managed to invent a word for what is typically a British malaise: schadenfreude.

No, the silver lining of BA’s lead balloon is that T5 has become a common intellectual currency. It’s failure has so clearly underlined the pitfalls of not doing enough testing that I heard T5 being used as an analogy in a recent implementation meeting. A.N.Other said:

“I would not be happy committing to that deadline if we had to cut testing. The last thing I want is for this to become another T5 …”

Nothing gives a better fuzzy feeling than completing a long testing phase. However if testing is getting squeezed out then you have to get management to agree to extending the deadline before you’ve actually reached that deadline. Indeed cutting testing is to invite what Steve Connell has coined as “Wishful Thinking”, and is the 13th classic mistake of software project management:

Wishful thinking isn’t just optimism. It’s closing your eyes and hoping something works when you have no reasonable basis for thinking it will. … It undermines meaningful planning and may be at the root of more software problems than all other causes combined.

Amen.

 

Fri 9 May 2008

Educate A Business Person Today!

Posted by Steve Knight under article
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One recurring theme I have noticed with users of systems I’ve worked on, is that they aren’t nearly as stupid as I think. They often try to make sense of the system thrust in-front of them. This is mostly out of necessity since it stands between them and them doing their job, and so they need to make sense of it. Having written some truly awful systems myself I wish all of them the very best of luck.

Another, seemingly unrelated observation, is that business people are truly astounded, and often suspicious, of how long it takes to provide a solution to a particular problem. Writing software is simply hard so that partly explains it. Sometimes however some of the solutions that are asked for can come quickly. This might happen if the system was expressly designed to handle new cases of the particular solution being requested or if producing the solution requires little more than a configuration or script change. Or it might just be dumb luck that the release cycle has worked in their favour.

Disconnect

This disconnect between implementation times, with no apparent reason to the business user can cause problems. Sometimes it feeds the suspicion that they are being ‘had’ in some elaborate con:

“If change ‘x’ takes a week then surely change ‘y’ should take half as long. How could it not? It only takes half as many words to say out loud. Those guys in IT need firing.”

When that business person is a manager it can lead to awkward situations for developers:

“Change ‘x’ took a week, change ‘y’ will take half as long. How can it not? It’s the only thing that stands between us and product success. If it doesn’t I’ll fire those IT guys”.

The simple truth is that unless a business person has also the developer’s view of the system they will not be able to make sound judgements about it. Hell, I have a developers view and not even my judgements are particularly sound.

However humans are pretty adaptable creatures, and rather than telling them the answer we should explain the answer in a way that they can understand. If they want to listen then educating them has a few potential benefits. For one thing it might make you look like you care about your users, rather than being that IT jerk who steals everyone’s food from the refrigerator. However, if you get your point across without sounding (to them) like a lunatic then you might improve their mental model of how the system actually works.

Breed

There is a breed of programmer out their in the world today that has either evolved or engineered themselves into a situation where they are the only one who ‘knows’. Yes, you know who you are. Sometimes they do this as a survival instinct to make themselves indispensable, sometimes because they’re not great communicators or educators. These are the people that need to be fired because their value is way-less than they think it is. They actually harm the productivity of the company by being obstructive or uncommunicative, plus they’re a real pain-in-the-ass to work with.

Yes you will need to keep a watchful eye on your newly educated fledglings. Especially the managers, but there’s nothing knew about that.

 

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