Design fossils

Mobile telephone networks have a kind of gritty Service Oriented Architecture. The Services are defined in GSM, UMTS and other standards. The protocols have hard unfashionable names like SS7, TCAP and MAP, and the bytes call themselves octets and don't waste their entropy transporting 'markup'. Even so, the basic SOA design and benefits are still visible and these benefits have enabled multi{national, operator, vendor, protocol} mobile communication to become a basic utility.

The scalability, reliability and success of the GSM network design and implementation seems to me to be an under-celebrated achievement of software and systems engineering. Perhaps the price of success is to become invisible. As the pace of technical development accelerates, major achievements of the past lose their significance and appear to be inevitable and mundane increments on the road to now.

Mobile telephony network technology is reasonably mature, and most software and system design effort goes into reducing the cost per subscriber and adding speculative features. However there is a huge resource of distilled design expertise, proven design patterns and traces of design evolution captured in these telephony systems as they have existed, and as they exist now. Unfortunately much of this information is encoded in odd and underknown languages, sealed in peculiar and fruity source code control systems and fading in the minds of ageing and modestly eccentric employees. Fortunately, this adds to the charm of investigating.

I intend to write up some of the things I have found interesting before I too forget....