[HDFS-1123] Need HDFS Protocol Specification

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: documentation
• Assignee: Unassigned
• Reporter: bc Wong
• Created: 30/Apr/10 00:58
• Updated: 04/May/10 10:37

Description

It'd be great to document (in a spec, not in the code) the HDFS wire protocol:

• The layout of the different request and reply messages.
• The semantics of the various calls.
• The semantics of the various fields.

For example, I stumbled upon the goldmine of comments around DataNode.java:1150. It looks correct, but the version number of 9 doesn't inspire confidence that it's up-to-date. (It's also a random place to put such an important comment.)

Having a formal spec is a big step forward for compatibility. It also highlights design decisions and helps with protocol evolution.

Issue Links

• is related to: HDFS-1069 Write HDFS wire protocols in AVRO IDL