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Node initialization and deinitialization

The initialization and deinitialization of nodes is a multi-step process. Not all functions are available in every step.

Initialization

  1. init: Right after the node is loaded init is called. A Struct with information about the node (id, name, configuration parameters, ...) is passed to init. All initilialization that can be done at this point, should be done here. When initialization fails, false must be returned, which aborts the initialization of that node. Homegear waits for init to complete for all nodes before continuing with the next step.
  2. start: In start there are no restrictions on what is allowed to do. Just note, that start mustn't hang (don't sleep or wait). As with init false can be returned to abort the initialization of that node.
  3. Once start is finished for all nodes, Homegear calls configNodesStarted. This method must not hang as well.
  4. After calling configNodesStarted on all nodes, Homegear executes startUpComplete. As with the other start methods, startUpComplete is not allowed to hang.

Deinitialization

  1. stop: The deinitialization is started by Homegear calling stop. In stop all RPC methods and all other nodes are still available. Stop must not hang. For threads that means, you should trigger the stopping of threads in stop, but don't join them here. Homegear waits for all calls to stop to finish before continuing.
  2. waitForStop: This method is made for one purpose: Joining threads. The stopping of threads should be triggered within stop. Every single thread should be stopped after 1 second and with this construct, all threads are finished after about one second.

Overview

See the following table for an overview on what is allowed or available in the initialization/deinitialization methods:

init start configNodesStarted startUpComplete stop waitForStop
Node information available yes yes yes yes yes yes
RPC methods available no yes yes yes yes no
Get parameters from configuration nodes no (yes) yes yes yes no
Must return immediately yes yes yes yes yes no
Can abort loading of node yes yes yes no no no

‚Äč

See the following table on the availability of the initialization/deinitialization methods for different programming languages:

init start configNodesStarted startUpComplete stop waitForStop
PHP (simple) no no no no no no
PHP (stateful) yes yes yes yes yes yes
JavaScript no1 no no no no2 no
Python no yes3 no yes yes4 yes5
C++ yes yes yes yes yes yes

  1. JavaScript nodes are started and available before init is called on nodes of other languages. 

  2. JavaScript nodes are stopped after all nodes written in other languages are stopped. 

  3. The Python script is started in start

  4. Signal 15 is sent to the Python script in stop

  5. Node-BLUE waits until the process exits.