[stargate] Required ordering of JSON name/value pairs when performing 
Insert/Update
-----------------------------------------------------------------------------------

                 Key: HBASE-2475
                 URL: https://issues.apache.org/jira/browse/HBASE-2475
             Project: Hadoop HBase
          Issue Type: Bug
            Reporter: Andrew Purtell
            Assignee: Andrew Purtell
             Fix For: 0.20.5, 0.21.0


>From Tyler Coffin up on hbase-user@

{quote}
I am using the Stargate REST interface to HBase for inserting data. When using 
JSON to transmit the query content, I have found that specific ordering of 
key/value pairs within the JSON string is required in order for the query to 
succeed (otherwise a response of 'HTTP/1.1 500 Row key is invalid' error is 
thrown if "key" and "Cell" are reversed).

Example:
This string receives the above error:

{noformat}
{"Row":[{"Cell":[{"column":"bWVzc2FnZTptc2c=","$":"Zm9vYmFy"}],"key":"MTIzNAo="}]}
{noformat}

This is the valid equivalent string:

{noformat}
{"Row":[{"key":"MTIzNAo=","Cell":[{"column":"bWVzc2FnZTptc2c=","$":"Zm9vYmFy"}]}]}
{noformat}

As you can see the only difference between these two instances is that the 
"key" and "Cell" name/value pairs have their order reversed.

In the equivalent XML notation, the ordering is specifically required per the 
schema. However with JSON Objects (i.e. name/value pairs) order is not required 
(JSON Arrays are ordered, but not Objects). Some JSON libraries will preserve 
ordering of Objects but not all  which is how I discovered this problem in the 
first place because I was using the Perl JSON library which does not guarantee 
order). 
I'm unsure if this is a bug in the REST implementation or an inconvenient 
ambiguity in the JSON specification. Regardless I thought I'd share this 
discovery with the community for feedback (or at the very least to document 
this for users' future reference).

For reference this is the table schema for the above query:

{noformat}
{NAME => 'reftrack', FAMILIES => [{NAME => 'message', COMPRESSION =>
'NONE', VERSIONS => '1', TTL => '2147483647', BLOCKSIZE => '65536',
IN_MEMORY => 'false', BLOCKCACHE => 'true'}]}
{noformat}
{quote}

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