SpreadNode is a message node that process stats data carried by the messages. SpreadNode retrieves data from JMS messages and spreads them according to the predefined rulesets. It filters them into three outlinks: bypass for all the spread messages, nohit for those messages do not belong to any predefined rulesets, failure for the messages failed at the spread operations. SpreadNode will create a set of new messages as the result of the spread operations for each spread message. These new messages go to the outlink of done. Also all the new messages will be in TextMessage. Any incoming messages will go out via one of the three other outlinks.

SpreadNode contains a number of predefined rulesets. These rulesets categorize messages into non-overlapping groups. Therefore, each ruleset defines a unique message group. Ruleset also defines the MaxDuration and the Interval for spread operations. Each group maintains its own data cache and the state. If any data set expires, SpreadNode will create a new TextMessage loaded with the data. The new messages will be flushed out. The flushed messages can be displayed via node based DisplayMask and StringProperty. The number of the data points in cache is tracked by RULE_PEND field. SpreadNode always creates an extra ruleset, nohit, for all messages not hitting any patterns.

SpreadNode also supports checkpointing of the internal data cache. In order to do checkpointing, the CheckpointDir and SAXParser must be defined.

You are free to choose any names for the four fixed outlinks. But SpreadNode always assumes the first outlink for done, the second for bypass, the third for failure and the last for nohit. Any two or more outlinks can share the same outlink name. It means these outlinks are sharing the same output channel.

Apart from the common properties, there are some implementation specific properties for SpreadNode.

Property Name	Data Type	Requirement	Description	Examples
Heartbeat	integer	optional	timeout in second for a session	300 (default: 3600)
CheckpointDir	string	optional	max number of cached groups	1024 (default: 1024)

The spread operation is executed via the pre-defined rulesets. Therefore, the configuration of the rulesets is critical to the operations of SpreadNode. Here are complete properties of rulesets for SpreadNode.

Property Name	Data Type	Requirement	Description	Examples
Name	alphanumeric with no spaces	mandatory	name of the ruleset	event
MaxDuration	integer	optional	seconds to expire the cache items
Interval	string	optional	type of the requests	jdbc
Scale	string	optional	name of the target ruleset
TimeTemplate	string	mandatory	template for the timestamp	##Count##
TimePattern	string	optional	pattern for the timestamp	##Count##
SpreadData	string	optional	template for the cache key	##Count##
PreferredOutLink	alphanumeric with no spaces	mandatory only for bypass	name of the preferred outlink	bypass
JMSPropertyGroup	list	optional	list of pattern groups on properties to select messages	see example
XJMSPropertyGroup	list	optional	list of pattern groups on properties to exclude messages	see example
PatternGroup	list	optional	list of pattern groups on body to select messages	see example
XPatternGroup	list	optional	list of pattern groups on body to exclude messages	see example
StringProperty	map	optional	for logging of message properties	see example
DispalyMask	integer	optional	mask to display new messages	see example

{
  ...
  "Ruleset": [{
    "Name": "bypass",
    "PreferredOutLink": "done",
    "JMSPropertyGroup": [{
      "JMSType": "^score$"
    }]
  }],
  ...
}

Here is an example of SpreadNode:

{
  "Name": "node_spread",
  "ClassName": "org.qbroker.node.SpreadNode",
  "Description": "spread messages",
  "Operation": "spread",
  "LinkName": "spread",
  "Capacity": "128",
  "DisplayMask": "2",
  "Debug": "1",
  "Heartbeat": "30",
  "CheckpointDir": "/var/log/qbroker/checkpoint/STATS",
  "StringProperty": {
    "type": "",
    "hostname": "",
    "LogTime": ""
  },
  "Ruleset": [{
    "Name": "tape",
    "JMSPropertyGroup": [{
      "type": "^tsm_trace$"
    }],
    "MaxDuration": "3600",
    "Interval": "60",
    "Scale": "1000",
    "TimeTemplate": "##LogTime## 2010",
    "TimePattern": "MMM d HH:mm:ss yyyy",
    "SpreadData": [{
      "DataField": "RBytes",
      "DurationField": "RTime",
      "CountField": "RCount"
    },{
      "DataField": "WBytes",
      "DurationField": "WTime",
      "CountField": "WCount"
    }],
    "StringProperty": {
      "type": ""
    }
  }],
  "OutLink": [{
    "Name": "merged",
    "Capacity": "256",
    "partition": "0,64"
  },{
    "Name": "null",
    "Capacity": "128",
    "Partition": "0,64"
  },{
    "Name": "failure",
    "Capacity": "256",
    "Partition": "128,16"
  },{
    "Name": "nohit",
    "Capacity": "256",
    "Partition": "128,16"
  }]
}