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Does the UK need the PL/1 Standard?
Like everything else language standards are born and eventually die. IST/5, the UK programming language committee, is considering whether the British Standard for PL/1 should be withdrawn (there are two standards, ISO 6160:1979 which has been reconfirmed multiple times since 1979, most recently in 2008, and a standardized subset ISO 6522:1992, also last confirmed in 2008).
A language standard is born through the efforts of a group of enthusiastic people. A language standard dies because there is no enthusiast (a group of one is often sufficient) to sing its praises (or at least be willing to be a name on a list that is willing to say, every five years, that the existing document should be reconfirmed).
It is 20 years since IST/5 last had a member responsible for PL/1, but who is to say that nobody in the UK is interested in maintaining the PL/1 standard? Unlike many other programming language ISO Standards there was never an ISO SC22 committee responsible for PL/1. All of the work was done by members of the US committee responsible for programming language PL 22 (up until a few years ago this was ANSI committee X3). A UK person could have paid his dues and been involved in the US based work; I don’t have access to a list of committee meeting attendees and so cannot say for sure that there was no UK involvement.
A member of IST/5, David Muxworthy, has been trying to find somebody in the UK with an interest in maintaining the PL/1 standard. A post to the newsgroup comp.lang.pl1 eventually drew a response from a PL/1 developer who said he would not be affected if the British Standard was withdrawn.
GNU compiler development is often a useful source of information. In this case the PL/1 web page is dated 2007.
In 2008 John Klensin, the ISO PL/1 project editor, wrote: “No activities or requests for additions or clarifications during the last year or, indeed, the last decade. Both ISO 6160 and the underlying US national document, ANS X3.53-1976 (now ANSI/INCITS-53/1976), have been reaffirmed multiple times. The US Standard has been stabilized and the corresponding technical activity was eliminated earlier this year”.
It looks like the British Standard for PL/1 is not going to live past the date of its next formal review in 2013. Thirty four years would then be the time span, from publication of last standard containing new material to formal withdrawal of all standards, to outlive. I wonder if any current member of either of the C or C++ committees will live to see this happen to their work?
C compiler validation is 21 today!
Today, 1 September 2011, is the 21th anniversary of the first formally validated C compilers. The three ‘equal first’ validated compilers were the Model Implementation C Checker from Knowledge Software, Topspeed C from JPI (run by the people who created Turbo Pascal) and the INMOS C compiler (derived from the Norcroft C compiler written by Alan Mycroft+others, the author of the longest response document seen during the review of the C89 draft standard).
Back in the day the British Standards Institution testing group run by John Souter were the world leaders in compiler validation and were very proactive in adding support for a new language. NIST, the equivalent US body, did not offer such a service until a few years later. Those companies in a position to have their compilers validated (i.e., the compiler passed the validation suite) were pressing BSI to be first; the ‘who is first’ issue was resolved by giving all certificates the same date (the actual validation process of a person from BSI, Neil Martin now Director of Test in the Winterop Team at Microsoft, turning up to ‘witness’ the compiler passing the tests happened several weeks earlier).
Testing C compilers was different from other language compilers in that sufficient demand existed to support commercial production and maintenance of test suites (the production of validation suites for previous language compilers had been government funded). After a review of the available test suites BSI chose to use the Plum Hall suite; after a similar review NIST chose to use the Perennial suite (I got involved in trying to figure out for NIST how well this suite covered the requirements contained in the C Standard).
For a while C compiler validation was big business (as in big fish, very small pond). But the compiler validation market is dependent on there being lots of compilers, which requires market fragmentation and to a lesser extent lots of different OSs and hardware platforms (each needing a separate validation). The 1990s saw market consolidation, gcc becoming good enough for commercial use and a shift of developer mind share to C++. Dwindling revenue resulted in BSI’s compiler validation group being shut down after a few years and NIST’s followed in 1998.
Is compiler validation relevant today? When the first C Standard was published a lot of compilers in common use had some significant behavioural differences compared to what the Standard specified. Over time these compilers have either disappeared or been upgraded (a potential customer once asked me the benefits I saw in them licensing the Knowledge Software front end and the reply to one of my responses, “you can tell your customers that the compiler is standard’s compliant”, was that this was not a benefit as they had been claiming this for years). Improvements in Intel’s x86 processor also had a hand in improving compiler Standard’s conformance; the various memory models used by the x86 processor was a huge headache for compiler writers whose products often behaved very differently under different memory models; the arrival of the Pentium with its flat 32-bit address space meant this issue disappeared over time.
These days I suspect that the major compilers targeting platforms where portability is expected (portability is often not a big expectation in the embedded world) are sufficiently compatible that developers are willing to overlook small differences with the Standard. Differences in third party libraries, GUIs and other frameworks have been the big headache for many years now.
Would the ‘platform portability’ compilers, that’s probably gcc, Microsoft, products using EDG’s front end, and perhaps llvm in the coming years, pass the latest version of the PlumHall and Perennial suites?
- The gcc team do not have access to either company’s suite. The gcc regression tests are a poor substitute for a proper compiler validation suite (even though they cost many thousands of dollars commercial compiler writers often buy both companies products because they are good value for money as a testing resource {the Fortran 78 validation suite source gives some idea of how much work is actually involved). I would expect gcc to fail some of the tests but have no idea how many or serious the failures would be.
- Microsoft have said they don’t have plans to support C99 (it took a lot of prodding to get them interested in formally validating against C90).
- I think the llvm team are in the same position as gcc, but perhaps somebody at Apple has access to one or more of the commercial suites (I don’t know).
- EDG are into standard’s conformance and I would expect them to pass both suites.
The certificate is printed on high quality, slightly yellow paper; the template wording is in a subdued gray ink while the customer information is in a very bold black ink. I don’t know whether this is to make life difficult for counterfeiters, but I could not get any half decent photographs and the color scanner had to be switched to black&white.
Validation was good for one year and I saw no worthwhile benefit in paying BSI £5,000 to renew for another year. Few people knew about the one year rule and I did not enlighten them. In the Ada compiler market the one year rule was a major problem, but lets leave that for another time.
Ruby becoming an ISO Standard
The Ruby language is going through the process of becoming an ISO Standard (it has been assigned the document number ISO/IEC 30170).
There are two ways of creating an ISO Standard, a document that has been accepted by another standards’ body can be fast tracked to be accepted as-is by ISO or a committee can be set up to write the document. In the case of Ruby a standard was created under the auspices of JISC (Japanese Industrial Standards Committee) and this has now been submitted to ISO for fast tracking.
The fast track process involves balloting the 18 P-members of SC22 (the ISO committee responsible for programming languages), asking for a YES/NO/ABSTAIN vote on the submitted document becoming an ISO Standard. NO votes have to be accompanied by a list of things that need to be addressed for the vote to change to YES.
In most cases the fast tracking of a document goes through unnoticed (Microsoft’s Office Open XML being a recent high profile exception). The more conscientious P-members attempt to locate national experts who can provide worthwhile advice on the country’s response, while the others usually vote YES out of politeness.
Once an ISO Standard is published future revisions are supposed to be created using the ISO process (i.e., a committee attended by interested parties from P-member countries proposes changes, discusses and when necessary votes on them). When the C# ECMA Standard was fast tracked through ISO in 2005 Microsoft did not start working with an ISO committee but fast tracked a revised C# ECMA Standard through ISO; the UK spotted this behavior and flagged it. We will have to wait and see where work on any future revisions takes place.
Why would any group want to make the effort to create an ISO Standard? The Ruby language designers reasons appear to be “improve the compatibility between different Ruby implementations” (experience shows that compatibility is driven by customer demand not ISO Standards) and government procurement in Japan (skip to last comment).
Prior to the formal standards work the Rubyspec project aimed to create an executable specification. As far as I can see this is akin to some of the tools I wrote about a few months ago.
IST/5, the committee at British Standards responsible for language standards is looking for UK people (people in other countries have to contact their national standards’ body) interested in getting involved with the Ruby ISO Standard’s work. I am a member of IST/5 and if you email me I will pass your contact details along to the chairman.
A change of guard in the C standard’s world?
I have just gotten back from the latest ISO C meeting (known as WG14 in the language standard’s world) which finished a whole day ahead of schedule; always a good sign that things are under control. Many of the 18 people present in London were also present when the group last met in London four years ago and if memory serves this same subset of people were also attending meetings 20 years ago when I traveled around the world as UK head of delegation (these days my enthusiasm to attend does not extend to leaving the country).
The current convenor, John Benito, is stepping down after 15 years and I suspect that many other active members will be stepping back from involvement once the current work on revising C99 is published as the new C Standard (hopefully early next year meaning it will probably be known as C12).
From the very beginning the active UK participants in WG14 have held one important point of view that has consistently been at odds with a view held by the majority of US participants; we in the UK have believed that it should be possible to deduce the requirements contained in the C Standard without reference to any deliberations of WG14, while many US participants have actively argued against what they see as over specification. I think one of the problems with trying to change US minds has been that the opinion leaders have been involved for so long and know the issues so well they cannot see how anybody could possible interpret wording in the standard in anything other than the ‘obvious’ way.
An example of the desire to not over specify is provided by a defect report I submitted 18 years ago, in particular question 19; what does:
#define f(a) a*g #define g(a) f(a) f(2)(9) |
expand to? There are two possibilities and WG14 came to the conclusion that both were valid macro expansions, making the behavior unspecified. However, when it came to a vote the consensus came down on the side of saying nothing about this case in the normative body of the standard, the only visible evidence for this behavior being a bulleted item added to the annex containing the list of unspecified behaviors.
A new member of WG14 (he has only been involved for a few years) spotted this bulleted item that had no corresponding text in the main body of the standard, tracked down the defect report that generated it and submitted a new defect report asking for wording to be added. At the meeting today the straw poll of those present was in favor of adding an appropriate example to C12 {I will link to the appropriate paper once it appears on the public WG14 site}. A minor victory on the road to a full and complete specification.
It will be interesting to see what impact a standing down of the old guard, after the publication of C12, has C2X (the revision of C that is likely to be published around 10 years from now).
For those of you still scratching their head, the two possibilities are:
2*f(9) |
or
2*9*g |
ISO Standards, the beauty and the beast
Standards is one area where a monopoly can provide a worthwhile benefit. After all the primary purpose of a standard for something is having just the one document for everybody to follow (having multiple standards because they are so useful is not a good idea). However, a common problem with monopolies is that charge a very inflated price for their product.
Many years ago the International Standard Organization settled on a pricing scheme for ISO Standards based on document page count. Most standards are very short and have a very small customer base, so there is commercial logic to having a high cost per page (especially since most are bought by large companies who need a copy if they do business in the corresponding application domain). Programming language standards do not fit this pattern, often being very long and potentially having a very large customer base.
With over 18,500 standards in their catalogue ISO might be forgiven for overlooking the dozen or so language standards, or perhaps they figured there is as much profit in charging a few hundred pounds on a few sales as charging less on more sales.
How does the move to electronic distribution effect prices? For a monopoly electronic distribution is an opportunity to make more profit, not to reduce prices. The recently published revision of the Fortran Standard is available for 338 Swiss francs (around £232) from ISO and £356 from BSI (at $351 the price from ANSI in the US is similar to ISO’s). Many years ago, at the dawn of the Internet, members of the US C Standard committee were able to convince ANSI to sell electronic copies at a reasonable rate ($30) and this practice has continued ever since (and now includes C++).
The market for the C and C++ Standards is sufficiently large that a commercial publisher (Wiley) was willing to take the risk of publishing them in book form (after some prodding and leg work by the likes of Francis Glassborow). It will be interesting to see if a publisher is willing to take a chance on a print run of the revised C Standard due out in a few years (I think the answer for the revised C++ Standard is more obvious).
Don’t Standards bodies care about computer languages? Unfortunately we are thorn in their side and they would be happy to be rid of us (but their charter’s do not allow them to do this). Our standards take much longer to produce than other standards, they are large and sales are almost non-existent (at ISO/BSI prices). What is more many of those involved in creating these standards actively subvert ISO/BSI sales by making draft documents, that are very close to the final copyrighted versions, freely available over the Internet.
In a sense ISO programming language standards exist because the organizational structure requires them to accept our work proposals and what we do does not have a large enough impact within the standards world for them to try and be rid of those tiresome people whose work is so far removed from what everybody else does.
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