Skip to main content

Requirements

Recently I have been involved in collecting requirements for two separate activities; both standards activities though. One is the Service Oriented Architecture Reference Architecture and the other is the Rules Interchange Format WG.

It is interesting how difficult it can be to get technical people to understand what is really meant by requirements; although my experience with the two groups has been very different.

Being clear on requirements is, of course, critical in any venture. This is especially true for projects that are technically difficult. But the real trap, it seems to me, is where the participants already think that know how to solve the problem. For them, requirements capture is one of those necessary evils that the administration imposes but everyone will actually ignore.

Well, necessary or not, I intend to nail people's feet to the floor where requirements are concerned!


This is my first post on this blog. My intention is to cover those aspects of my work which have at least a partial public aspect to them; this means standards work at the moment. I am involved in three efforts currently: SOA, RIF and BPMN.

Popular posts from this blog

Comments Should be Meaningless

This is something of a counterintuitive idea: Comments should be meaningless What, I hear you ask, are you talking about? Comments should communicate to the reader! At least that is the received conventional wisdom handed does over the last few centuries (decades at least). Well, certainly, if you are programming in Assembler, or C, then yes, comments should convey meaning because the programming language cannot So, conversely, as a comment on the programming language itself, anytime the programmer feels the imperative to write a meaningful comment it is because the language is not able to convey the intent of the programmer. I have already noticed that I write far fewer comments in my Java programs than in my C programs.  That is because Java is able to capture more of my meaning and comments would be superfluous. So, if a language were able to capture all of my intentions, I would never need to write a comment. Hence the title of this blog.

Sub-turing complete programming languages

Here is an interesting intuition: the key to liberating software development is to use programming languages that are not, by themselves, turing-complete. That means no loops, no recursion 'in-language'. Why? Two reasons: any program that is subject to the halting problem is inherently unknowable: in general, the only way to know what a turing-complete program means is to run it. This puts very strong limitations on the combinatorics of turing-complete programs and also on the kinds of support tooling that can be provided: effectively, a debugger is about the best that you can do with any reasonable effort. On the other hand, a sub-turing language is also 'decidable'. That means it is possible to predict what it means; and paradoxically, a lot easier to provide a rich environment for it etc. etc. An interesting example of two languages on easier side of the turing fence are TeX and CSS. Both are designed for specifying the layout of text, TeX is turing complete and CSS

Existential Types are the flip side of generics

Generic types, as can now be seen in all the major programming languages have a flip side that has yet to be widely appreciated: existential types. Variables whose types are generic may not be modified within a generic function (or class): they can be kept in variables, they can be passed to other functions (provided they too have been supplied to the generic function), but other than that they are opaque. Again, when a generic function (or class) is used, then the actual type binding for the generic must be provided – although that type may also be generic, in which case the enclosing entity must also be generic. Existential types are often motivated by modules. A module can be seen to be equivalent to a record with its included functions: except that modules also typically encapsulate types too. Abstract data types are a closely related topic that also naturally connect to existential types (there is an old but still very relevant and readable article on the topic Abstract types have