iostream.h is missing from RHEL6 build. To build xerces-c-src1_7_0: 1) copy iostream.h to xerces-c-src1_7_0/src/xercesc/util/NetAccessors/Socket 2) Modify UnixHTTPURLInputStream.cpp to change include < > to include " ". Then build xerces as normal. The AAPP project team have tried building OPS-LRS with newer versions of xerces, but have not succeeded. If any AAPP users have an alternative solution to the one given above, please contact the NWP SAF Helpdesk.