Try this. The top section is the queuing logic. Feed your messages in the top left hand corner. When the internet is down it will retry at the interval specified in the Retry inject node, it is currently set to 15 seconds, you probably want much longer than that.
Replace the bottom section with your processing nodes. Connect the output of the link at the top left of the bottom section to your process (instead of the delay node labelled 'process' and if the processing succeeds then send a message to the OK link at the bottom right, and if it fails then send a message to the Failed link there. So you can delete all the nodes in the bottom section except the three link nodes and put your process in there instead.
When you send in the first message there may be a delay of up to the Retry interval before it actions that message. If that is a problem for you then that can be handled fairly easily.
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messages","props":[{"p":"payload","v":"","vt":"date"},{"p":"topic","v":"","vt":"string"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":160,"y":1440,"wires":[["f82aed15.9f1a98"]]},{"id":"4ef6d24.5459eac","type":"inject","z":"bdd7be38.d3b55","name":"Retry","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"15","crontab":"","once":false,"onceDelay":0.1,"topic":"control","payload":"peek","payloadType":"str","x":170,"y":1620,"wires":[["a20949f9.306a48"]]},{"id":"4270c3f6.19012c","type":"delay","z":"bdd7be38.d3b55","name":"process","pauseType":"delay","timeout":"5","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"x":340,"y":1920,"wires":[["b0c78702.b01988"]]},{"id":"a8381ab7.d1949","type":"link out","z":"bdd7be38.d3b55","name":"","links":["5a2f45b9.929cc4"],"x":795,"y":2040,"wires":[]},{"id":"5a2f45b9.929cc4","type":"link 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down","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"internet","payload":"down","payloadType":"str","x":230,"y":2020,"wires":[["edb0af2.fd1645"]]},{"id":"edb0af2.fd1645","type":"join","z":"bdd7be38.d3b55","name":"","mode":"custom","build":"object","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":true,"timeout":"","count":"2","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":470,"y":2000,"wires":[["b7feed8e.7caf68"]]},{"id":"b0c78702.b01988","type":"change","z":"bdd7be38.d3b55","name":"topic:data","rules":[{"t":"set","p":"topic","pt":"msg","to":"data","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":480,"y":1920,"wires":[["edb0af2.fd1645"]]},{"id":"b7feed8e.7caf68","type":"switch","z":"bdd7be38.d3b55","name":"Data message?","property":"topic","propertyType":"msg","rules":[{"t":"eq","v":"data","vt":"str"}],"checkall":"true","repair":false,"outputs":1,"x":380,"y":2080,"wires":[["d96e80be.41aff"]]},{"id":"d96e80be.41aff","type":"switch","z":"bdd7be38.d3b55","name":"OK/Fail?","property":"payload.internet","propertyType":"msg","rules":[{"t":"eq","v":"up","vt":"str"},{"t":"else"}],"checkall":"true","repair":false,"outputs":2,"x":560,"y":2080,"wires":[["6ec96b3b.ec5c14","a8381ab7.d1949"],["ea9c5a96.2dcfe8","37735513.24d77a"]]},{"id":"ea9c5a96.2dcfe8","type":"debug","z":"bdd7be38.d3b55","name":"FAIL","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","statusVal":"","statusType":"auto","x":830,"y":2120,"wires":[]},{"id":"a20949f9.306a48","type":"gate","z":"bdd7be38.d3b55","name":"","controlTopic":"gate_control","defaultState":"open","openCmd":"open","closeCmd":"close","toggleCmd":"toggle","defaultCmd":"default","persist":false,"x":530,"y":1620,"wires":[["f82aed15.9f1a98"]]},{"id":"ae4b0558.378d8","type":"change","z":"bdd7be38.d3b55","name":"Close gate","rules":[{"t":"set","p":"topic","pt":"msg","to":"gate_control","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"close","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":390,"y":1580,"wires":[["a20949f9.306a48"]]},{"id":"a78ce065.5c9b68","type":"change","z":"bdd7be38.d3b55","name":"Open gate","rules":[{"t":"set","p":"topic","pt":"msg","to":"gate_control","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"open","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":400,"y":1660,"wires":[["a20949f9.306a48"]]},{"id":"e5978b76.2fb2b","type":"link in","z":"bdd7be38.d3b55","name":"","links":["b6aba10c.b691f"],"x":135,"y":1920,"wires":[["4270c3f6.19012c"]]},{"id":"b6aba10c.b691f","type":"link out","z":"bdd7be38.d3b55","name":"","links":["e5978b76.2fb2b"],"x":615,"y":1440,"wires":[]},{"id":"37735513.24d77a","type":"link out","z":"bdd7be38.d3b55","name":"","links":["7f6b726d.0cab2c"],"x":795,"y":2160,"wires":[]},{"id":"7f6b726d.0cab2c","type":"link in","z":"bdd7be38.d3b55","name":"","links":["37735513.24d77a"],"x":95,"y":1660,"wires":[["a78ce065.5c9b68"]]},{"id":"5d647435.11ea14","type":"comment","z":"bdd7be38.d3b55","name":"Processed ok","info":"","x":690,"y":2020,"wires":[]},{"id":"cda552d1.59b25","type":"comment","z":"bdd7be38.d3b55","name":"Failed","info":"","x":670,"y":2160,"wires":[]},{"id":"6777d4.5738d02c","type":"comment","z":"bdd7be38.d3b55","name":"Replace this with your message processing, sending a message to the Fail or Success outputs","info":"","x":350,"y":1820,"wires":[]},{"id":"d1158219.184d38","type":"comment","z":"bdd7be38.d3b55","name":"Messages to be processed come in here","info":"","x":200,"y":1880,"wires":[]},{"id":"4681668e.9d5cd8","type":"comment","z":"bdd7be38.d3b55","name":"Feed messages to be queued in here and remove Inject node","info":"","x":270,"y":1400,"wires":[]},{"id":"177f73a0.c29e2c","type":"status","z":"bdd7be38.d3b55","name":"","scope":["f82aed15.9f1a98"],"x":160,"y":1720,"wires":[["b95b8054.e3339"]]},{"id":"b95b8054.e3339","type":"function","z":"bdd7be38.d3b55","name":"Queue empty?","func":"// expects msg.status.text in form \"queuing: <number>\"\n// sends a message if queue is empty\nif (parseInt(msg.status.text.split(\":\")[1]) !== 0) {\n msg = null\n}\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":340,"y":1720,"wires":[["a78ce065.5c9b68"]]},{"id":"e72ba10d.c92638","type":"comment","z":"bdd7be38.d3b55","name":"Set this to appropriate retry interval","info":"","x":150,"y":1580,"wires":[]}]
