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  1. Technology
October 31, 1988


By CBR Staff Writer

X500, the Consultative Committee on International Telephony and Telegraphy, CCITT’s standard for creating a single worldwide directory of users of X400 message handling systems, appears to be making its way into the world in that time-honoured fashion for standards – amid disagreement, confusion and dissatisfaction. While some hold the view that this is all part of the standards making process, it doesn’t look as if there is much more to be finalised with X500. The bulk of the work has already been done and the specifying documents issued earlier this year, with final ratification expected to come by the New Year.

Confusion The history of the standard is varied, and demonstrates how some of the present confusion – over what the standard will actually cover – came about. Ian Valentine, technical director with Wokingham-based Open Systems Interconnection consultancy, Level-7 Ltd – which publishes a message handling newsletter that has been running tutorials in X500 – claims that the standard has now has become all things to all people. Initially, having defined X400, the standards-makers decided that in order to use it, it was necessary to have a directory so users knew who to send messages to, so the initial brief was the definition of the information to be included in such a directory, how it would be structured, entered and so on. Then the International Standards Organisation got in on the act, claiming that it was already working on a project called The Directory which would provide a way of finding applications within a network – where a particular database would be located, for instance. ISO and the CCITT eventually merged their two ideas – and, depending on your viewpoint, a wonder or a monster was created. What X4500 – or ISO 9594, to use its other name – does is to define the services offered by a global directory. The directory function has two components, first, the directory management domain, which provides the distributed information storage facility holding information about users and applications relevant to a particular organisation. These are provided by a network of directory system agents around the world, storing information about their locality. The databases would interface with one another, and also with those held by private organisations or by government departments, for instance. The second component is the directory enquiry service, which the directory user agents would interrogate on behalf of the user to get hold of the information.

Where the confusion is arising is that although X500 has defined the way the data will be stored, it has not yet specified what that data will be. According to Level-7’s Valentine, profiling standards are expected to become available by the end of the year that will list the kind of information that would be useful to have stored on such a directory. Would facsimile machine numbers be relevant, for instance? There is also the issue of who decides what data will be included on the databases. At the moment, British Telecom has an early prototype of X500 on its Gold 400 service, and it is up to individual companies whether they want to be listed, and exactly what information they are prepared to include. It is difficult to foresee a day when the UK Ministry of Defence, for instance, gaily reveals all its internal telephone numbers to anyone who’s interested. In fact, in many organisations, the internal phone list is classified information. Here issues like privacy start to come into play.

While there are hosts of X400 products around, British Telecom is claiming to be the first with an intercept of the X500 standard – what it claims is the most advanced X500 directory in the world. It is an on-line database facility held on Telecom Gold, which holds details of Gold 400 users, thus linking Telecom Gold to the private electronic mail service. Telecom refuses to reveal how many customers have taken an interest in the service, but other sources claim the figure is only around the 30 mark. The service became available to the X400 users in the summer, while the cu

rrent promotion to Telecom Gold customers has just begun. According to a spokesman for Telecom’s Gold 400 marketing department, X500 provides a mapping between the two services, giving each Gold 400 user a Telecom Gold mailbox address, and each Telecom Gold user a Gold 400 mailbox address. The listing itself is free, with Telecom determining exactly what information is given, while use of the database costs fivepence a minute. Telecom reckons that, as any organisation offering X400 will also have to offer X500 capability, there is likely to be an international X500 network established within five years. In the meantime, Telecom expects private deals to be springing up – such as its own X400 link with Dialcom. Holders of Telecom Gold software licences around the world would be expected to link up with Telecom, said a spokesman. Computer manufacturers are also expected to be readying their own X500 products for companies’ private directories, for ultimate interconnection to the global network.

Off the cuff Ray Walker, chairman of the UK’s Information Technology Users Association, has had very little direct experience of X500, but says, based on first impressions, It is unsatisfactory. Off the cuff, X500 seems to be a very theoretical system – a system for PTTs. Walker’s view is based on his own experience in an Information Technology Users trial, which found that the information you need to put in to send a message could often be longer than the message itself. Here’s just a sample: user originator: country name: adminstrative domain name: private domain name: organisation name: surname: given name: organisational unit: distribution group name – and so on. And according to Walker, data must be entered for both recipient and user, and messages cannot be sent unless both are recorded on the system. There is another argument that throws a shadow of doubt over the Telecom prediction of a global X500 system in place within five years, the one that questions the fundamental usefulness of such directories. It is a fairly basic point, but a straw poll of Telecom Gold users carried out by our sister paper Telegram showed that almost all messages are sent to mailboxes already known to the sender.

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