External Data Representation

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eXternal Data Representation (XDR) is an IETF standard from 1995 of the presentation layer in the OSI model. XDR allows data to be wrapped in an architecture independent manner so data can be transferred between heterogeneous computer systems. Converting from the local representation to XDR is called encoding. Converting from XDR to the local representation is called decoding. XDR is implemented as a software library of functions that is portable between different operating systems and is also independent of the transport layer.

The XDR data format is in use by many systems, including:

• Open Network Computing Remote Procedure Call
• EMC's NetWorker backup software (in its newer releases)
• NetCDF (a scientific data format)
• The R language and environment for statistical computing
• High Level Architecture (simulation)
• The SpiderMonkey JavaScript engine, to serialize/deserialize compiled JavaScript code
• The Ganglia distributed monitoring system
• The sFlow network monitoring standard

[edit] XDR data types

• boolean
• char (8 bit integer/character)
• int (32 bit integer)
• hyper (64 bit integer)
• float
• double
• enumeration
• structure
• string
• fixed length array
• variable length array
• union
• opaque data

[edit] See also

• Structured Data eXchange Format (SDXF).
• Multipurpose Internet Mail Extensions (MIME) used on top of the SMTP and HTTP application protocols

[edit] External links

• RFC 4506
• jsxdrapi.c, the main source file of SpiderMonkey that uses XDR
• http://www.cs.rpi.edu/~hollingd/netprog/notes/xdr/xdr.pdf