ainod.conf

NAME

ainod.conf - JSON daemon configuration file

SYNOPSIS

/etc/ainod/ainod.conf

DESCRIPTION

This file configures various parameters of the JSON daemon

OPTIONS

All options are configured in the “[Daemon]” section:

Workers

Takes a positive integer. Determines the number of worker child processes to create on daemon start up. If not specified, it will be set to the number of processor cores which is a nice conservative minimum.

Increasing this number will increase capacity and performance but being set too high can cause “thundering herd” type symptoms where the increased processing cost of concurrency outweighs any benefit.

Twice the number of processor cores is a reasonable setting but the best approach is to test your application and system for the ideal number. In God we trust; all others must bring data.

Datadir

The location for JSON data files to be stored. If not specified, the default is /var/lib/ainod

Require-protocol-version

Takes a boolean argument of true or false. Defaults to false. If true, the client’s request will be rejected if it does not contain {“jsonrpc”: “2.0”}

Require-request-id

Takes a boolean argument of true or false. Defaults to false. If true, the client’s request will be rejected if it does not contain an id field identifying the request. Incidentally, this was the behaviour outlined in JSON-RPC 1.0 specification.

Silent-notifications

Takes a boolean argument of true or false. Defaults to false.

Note: if Require-request-id (see above) is set to true, a missing request id will always result in an error and no further processing; obviously making this setting irrelevant in that case. The remaining text below assumes Require-request-id is set to false (the default).

If this setting is false (the default) then a missing request id or a request id set to null will result in no special behaviour. The daemon will carry on and return a successful result or error as normal.

If this setting is true then a missing request id or a request id set to null will result in the request being processed but no response at all being returned, even if there was an error in the request and the processing failed.

The JSON-RPC specifications name such a request as a ‘notification’. However, it is confusing for new users to send a request and receive no response; especially when they have simply forgotten the id (or sent null by mistake or design). Furthermore, use cases where the user never cares about errors seem quite obscure. In the words of Tim Peters:

Errors should never pass silently. Unless explicitly silenced.

Remote-schemas

Takes a boolean argument of true or false. Whether to fetch JSON schema files from remote servers. Defaults to false. true is not currently implemented.

EOF-marker

Takes a boolean argument of true or false. Whether the data ends with an End of File marker. If true then the daemon will reject any incoming data without the EOF marker; this way it rejects incomplete data earlier but reduces compatibility with some third party clients.

Req-id-format

Determines the format of the request id (if present). Available options are:

• default - allows anything in the request id
• rpc - allows strings, ints, numbers and null but not arrays or objects
• int - only allows int ids
• string - only allows string ids

If you have a real use case for another format, let us know.

Path-format

Affects how data is organised and stored.

• 0 - Traditional layout: /store/schema/id/
• 1 - Open collection layout: /store/collection/id/
• 2 - Collection of mixed schema layout: /store/id/schema/

Warning: Changing the Path-format while there is data in Ainod requires writing your own script for moving the data into the new format.