The eLandings schema changes over time . As of schema version 1.1, eLandings objects that are subject to schema versioning include the <schema_version> element. Software sending XML representations of eLandings objects must specify into which schema version their object was marshalled; software consuming XML representations of eLandings objects may search the XML string for this markup, and pre-process the XML if necessary before unmarshalling using whichever schema that software is built to accept.
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Comprehensive interface testing and certification processes must ensure that interfacing software (or human operators) is/are capable of managing the schema version setting on the user profile, and/or using other mechanisms to ensure that the interface is robust through occasional eLandings schema upgrades.
It is suggested that the eLandings test and certification service include a suite of servlets built on a foundation of prior schema versions, to provide mechanisms to exercise schema version transitions.