node-red-contrib-bigtail

"Tail" for Big Nodes. This node captures several payloads and build a buffer of the last needed messages with or not size limit

Installation

npm install node-red-contrib-bigtail

Principles for Big Nodes

See biglib for details on Big Nodes. Big Lib and subsequent Big Nodes are a family of nodes built for my own purpose. They are all designed to help me build a complete process for production purposes. For that I needed nodes able to:

• Flow big volume of data (memory control, work with buffers)
• Work with a flow of blocks (buffers) (multiple payload within a single job)
• Tell what they are doing with extended use of statuses (color/message)
• Use their second output for flow control (start/stop/running/status)
• Reuse messages in order to propagate _msgid, topic
• Depends on state of the art libraries for parsing (csv, xml, xlsxs, line, ...)
• Acts as filters by default (1 payload = 1 action) or data generators (block flow)

All functionnalities are built under a library named biglib and all Big Nodes rely on it

Usages

Big Tail is a filter node for node-red to store data and send only the last elements needed. It waits first for a control message which all big nodes send on their second output. It looks like this:

{ "control": { "state": "start" }}

It then, store messages, trashing all old ones that won't let him satisfy its parameters (number of messages and size in Kb)

When it receives a ending control message, it sends its output as a single message. An ending control message looks like:

{ "control": { "state": "end" }}

If no control message is given, it acts as a pass-through sending all messages it receives.

It has two options:

• number of payloads. If set, the node will store only the last messages it receives
• size in Kb. If set, the node will store no more than the specified size

Dependencies

biglib library for building node-red flows that supports blocks, high volume

Example flow files

Try pasting in the flow file below that shows the node behaviour

[{"id":"819125ff.7e6ed8","type":"inject","z":"894b4f7b.76b4b","name":"trigger","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":true,"x":130,"y":540,"wires":[["d4918a0c.2b6e78"]]},{"id":"2ac3bdc8.d53c42","type":"bigtail","z":"894b4f7b.76b4b","name":"last 10","size":"10","add_cr":true,"size_kbyte":"","x":450,"y":500,"wires":[["57c9c569.a8363c"],[]]},{"id":"d4918a0c.2b6e78","type":"function","z":"894b4f7b.76b4b","name":"seeder","func":"node.send({ \"control\": { \"state\": \"start\"}});\nfor (i = 0; i < 100; i++) {\n    node.send({ \"payload\": \"This is line #\" + (i+1) });\n}\nnode.send({ \"control\": { \"state\": \"end\" }});","outputs":1,"noerr":0,"x":290,"y":540,"wires":[["2ac3bdc8.d53c42","a2b5eb7c.5d4a18"]]},{"id":"57c9c569.a8363c","type":"debug","z":"894b4f7b.76b4b","name":"","active":true,"console":"false","complete":"false","x":630,"y":500,"wires":[]},{"id":"69b31138.964cf","type":"comment","z":"894b4f7b.76b4b","name":"Big Tail sample","info":"","x":140,"y":480,"wires":[]},{"id":"a2b5eb7c.5d4a18","type":"bigtail","z":"894b4f7b.76b4b","name":"last 10","size":"","add_cr":true,"size_kbyte":"0.5","x":450,"y":580,"wires":[["84da5f92.7b25a"],[]]},{"id":"84da5f92.7b25a","type":"debug","z":"894b4f7b.76b4b","name":"","active":true,"console":"false","complete":"false","x":630,"y":580,"wires":[]}]

Author

• Jacques W

License

This code is Open Source under an Apache 2 License.

You may not use this code except in compliance with the License. You may obtain an original copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Please see the License for the specific language governing permissions and limitations under the License.

Feedback and Support

Please report any issues or suggestions via the Github Issues list for this repository.

For more information, feedback, or community support see the Node-Red Google groups forum at https://groups.google.com/forum/#!forum/node-red