node-red-semaphore-plus

An advanced set of semaphore Nodes for Node RED, with a dynamic fail-safe.

Uh... what is it

This is a set of Nodes for Node RED, that allows messages to be queued, and signalled to pass, once a message has reached the end of the flow. But at the same time, allowing an optional fail-safe, that can be controlled dynamically.

Furthermore, messages can be flagged to bypass the semaphore and 'sneak' past the messages waiting for the lock to be released.
This is achieved with either a single messge property, or a JSONata expression.

| Node | What's it for? | |------|----------------| |Semaphore Take | Queues and passes a message through when signalled (or when the optional fail-safe triggers) | |Semaphore Release | Raises the signal to allow a message to pass | |Semaphore FS Reset | Alters the current fail-safe time |

Message Properties

Semaphore Take and Semaphore FS Reset Optional Properties | Property | What's it for? | |----------|----------------| |smp_failsafeTimeout (number) (IN) | Overrides the default fail-safe time | |smp_appliedFailsafe (number) (OUT) | The fail-safe time that was applied | |smp_isFailsafe (boolean) (Semaphore Take only) (OUT) | If the release was due to a fail-safe condition |

Semaphore Release Optional Properties | Property | What's it for? | |----------|----------------| |reset (boolean) (IN) | Resets the queue state, and does not pass on the incoming msg | |smp_reset (boolean) (IN) | Resets the queue state, and passes on the incoming msg |

Yeah but why?

Working in an enterprise environment, where strict API access is enforced/monitored, I needed to come up with a way to control processing. Having tried various nodes to accomplish this, i was either creating messy flows to try and emulate this approach, or using no longer maintained or buggy nodes.

License

MIT License

Copyright (c) 2023 Marcus Davies

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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