Updated below as agreed on DFDL WG call Jan 29th. Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 ----- Forwarded by Steve Hanson/UK/IBM on 29/01/2010 17:40 ----- From: Steve Hanson/UK/IBM To: dfdl-wg@ogf.org Date: 26/01/2010 12:26 Subject: DFDL: TLOG proposal TLOG The individual fields are a mixture of ASCII strings, proprietary packed decimals, and the occasional pure binary data. All fields are delimited by a separator. Fields of all types can be fixed length or variable length with a maximum. Pure binary data is preceded by a field giving the actual length. All lengths in bytes. Packed decimals. Like a packed decimal in the IBM sense. These can carry negative numbers but use a leading xD sign nibble. No sign nibble if positive or unsigned. Odd number of digits (including sign if present) are padded with xF nibble. This is best illustrated using examples. 1234 => x12x34 123 => xF1x23 -1234 => xFDx12x34 -123 => xD1x23 Proposal 1) The 'variable length with a maximum' will be handled using a post-timing assertion. Note this only applies on parsing. ** 2) dfdl:lengthKind 'delimited' is permitted for numbers when dfdl:representation is 'binary' and dfdl:binaryNumberRep is 'packed' or 'bcd' because it is possible to know in advance the range of bytes being used, and therefore to choose suitable delimiters. 3) Core DFDL 1.0 will not be enhanced to handle the TLOG packed decimal type. A future version of DFDL will provide an extensibility mechanism that allows user-defined types to be handled. In the 1.0 timeframe IBM may implement its own proprietary extension to handle this type. ** While this can result in output from a DFDL unparser that can not be re-parsed, that is a problem general to the use of assertions, and a future version of DFDL may choose to change this by enhancements to the assertion annotation. Regards Steve Hanson Programming Model Architect, WebSphere Message Broker, OGF DFDL WG Co-Chair, Hursley, UK, Internet: smh@uk.ibm.com, Phone (+44)/(0) 1962-815848 Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU Unless stated otherwise above: IBM United Kingdom Limited - Registered in England and Wales with number 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU