You are reading the documentation for an outdated Corteza release. 2024.9 is the latest stable Corteza release.

Corteza Server

The second important bit of the automation system is the Corteza server. On it’s own, Corredor server is unable to perform any script execution without an explicit invocation (either by the Corteza server or manually via BloomRPC or similar).

Main responsibilities

  1. Load and register automation scripts on the event bus,

  2. run scheduler for deferred automation script execution,

  3. setup http handler for sink routes,

  4. setup http handler for explicit server script invocation,

  5. setup http handler for automation script listing,

  6. setup http handler for automation script bundles,

  7. request script execution based on the provided event.

Event bus

In order to implement a powerful and flexible automation system, we have decided to base it around an event bus. With the help of an event bus, we are able to trivially handle any combination of automation scripts in a unified, robust manner.

Server side event bus and client side event bus are not the same, so both should receive equal attention when reading.

Server script trigger registration

Firstly we need to register implicit, deferred, sink and iterator server scripts on the event bus, so they can listen and respond to dispatched events.

There is a slight difference between iterator automation scripts and other types of automation scripts (excluding explicit scripts) when it comes to their execution. Iterator scripts are executed for each resource in the matched set, so their handler functions differ.

If the script is an iterator

When an iterator script is provided, the handler function invokes the automation script for each resource in the given set,

If the script is any other (except explicit scripts)

When any other script is provided (excluding explicit scripts), the handler function is a generic function that executes for the given event on the given resource.

Other than that, the flow is as follows:

  1. fetch available automation scripts from Corredor server,

  2. for each trigger of every valid automation script (excluding explicit scripts):

    1. prepare a handler function with respect to the above comment,

    2. register the trigger with the handler function on the event bus.

Event handling and script execution

Finally we discuss event dispatching, handling and script execution. Events are dispatched over the event bus either synchronously or asynchronously. When an event is dispatched, the following happens:

  1. find all scripts that can be executed for the given event,

  2. execute every automation script in the filtered set,

  3. if an error is thrown (other then 'Aborted'), stop the execution.

Scheduler

The scheduler system is responsible for deferred automation script execution. The system ticks every minute, at the minute, and dispatches events via the event bus.

There is no mechanism in place that would prevent the automation scripts to overlap. Either simplify/optimize the script or in the case of complex operations, move to batch processing.

For example:

  • Script A runs every minute and the execution takes 1.5min,

  • on first tick, script A is executed,

  • on second tick, script A is executed again along side the old instance.

Sink

The sink system allows us to implement custom endpoints on the Corteza server. System’s flow:

  1. intercept any HTTP request on the /sink endpoint,

  2. basic request validation (provided required parameters),

  3. validate request against the sink’s signature,

  4. process request based on:

    • Content-Type or any other HTTP header,

    • remote address (IP),

    • request method and path,

    • username and password (HTTP basic auth)

    • GET (query string) parameters

    • POST parameters

  5. dispatch the event via event bus.