I think the simplest answer to the question is that you can use the NIO random access file methods to read or write any file using 64 bit XRBA addressing with any length you want. Once you have read a block of data from a file such as an SMF record you can wrap the block in a buffer and then use methods to retrieve any particular field you want addressed by offset and field type such as byte, short, integer, long, BFP floating point, text string, etc.
For lots of examples including emulation of QSAM, BSAM, BDAM, and VSAM file access you can check out open source z390 HLASM compatible assembler, linker, and emulator written entirely in J2SE Java on www.z390.org. All the VSAM java code is in vz390.java source module and all the other access method code is in sz390.java. You will find code that maps DCB's and ACB's and fetches byte flags, full word addresses, and text fields for DDNAME's etc. For more examples of heavy duty field manipulation on data fetched from load module file (executable z9/z10 mainframe instructions) and memory data fields see pz390.java which handles all the instructions including HFP, BFP, and DFP short, long, and extended among other things. Once you download and install z390 v1.5.01 using InstallShield for Windows or flat file zip for Linux, you will find all the java sources including the above in the z390\src directory. The executable class files are all included in z390.jar which can be invoked from GUI or command line. For example you can assemble, link, and execute simple WTO 'Hello World' demo with the command: asmlg demo\DEMO which reads demo\DEMO.MLC and generates and executes demo\DEMO.390 with display of the WTO message on console and on the log file demo.DEMO.LOG. There are also lots of file access regression tests included in the optional RT.ZIP download file. Another example is the z390 \linklib\REPRO.MLC utility to load and unload VSAM ESDS, RRDS, or KSDS files. Don Higgins d...@higgins.net ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
