Adam Flinton wrote: > >> Other limitations on using XML - it's a no-show for enterprise scale >> databases >> or information processing. All that wasted space starts to count when you >> have >> to buy two ?20,000 high availability RAID disk arrays instead of one....and >> plus >> the bandwidth wastage when there are millions of messages rather than just a >> few. Yes, binary compression helps, but it just shifts disk and bandwidth >> loss >> to the CPU. There are many better ways to represent data for large-scale >> deployments than XML (even the dADL syntax from ADL does 100% better in >> space, >> and represents all object-oriented constructs unambiguously). >> >> > You have got to be kidding me on this one. > > no kidding. You just have to do the maths. 2 years ago I was in a CfH meeting where it was made clear that the volumetrics on the projected number x size of HL7v3 prescription (and related) messages was going to blow out the budget for telecomms expenditure by over 50%. Database volume estimates made by Oracle for the Spine on the basis of whole of UK, HL7 XML messages were shown to be simply uneconomic. In our own EHR product we have had to resort to various kinds of compression, which impact on performance, and we have to have larger disc arrays than would be needed if the data were represented in a more efficient way. Our engineers are currently looking at replacing XML altogether in the persistence layer.
Of course organisations that have unlimited budgets may not notice this, but for everyone else it's important. > Having done XML messaging in very large retail systems (major > supermarket chains in the EU & US), mobile phone systems, home > office/criminal justice system & now the CFH....you simply have got to > be kidding. > it's not the size of the organisation that matters, it's the amount of data generated and rate of data generation. The more data (and users), the more disk space / bandwidth / CPU (if using compression/decomprssion) you need. Fact of life - if your data gets big enough, you will hit a wall just using XML. > ummmmmm.......where to even start....oh yes how about... > > "XML is a very commonly used standard with thousands of tools in > existence from routing engines, to processing engines to parsers to > database layers ...." > > or maybe > > "XML is THE standard in enterprise level messaging systems with > standards such as SOAP, EbXML, OAGI BODS etc.etc." > > or maybe : > > "XML integrates easily with existing web infrastructures by use of such > mechanisms as AJAX, Rest JSON etc". > > > Now wrt ADL..... > > Adam > > Although the above are just marketing statements, the standards do indeed exist - how else would industry even start to cope with XML? My point is that it is so horribly ineffcient that that there is a general need for solutions (and these are emerging) to the concomitant costs of very large amounts of data. That's why all the binary XML work and work on alternative representations - once you get over a certain size, you have to use something else, or a serious compression approach. - thomas BTW you only need one good open source parser for any language on each platform. I'm not quite sure of the value of having 20 competing ones, all with different sets of bugs, maintainers and conformance statements.... * *
