OverviewDaemonSkySparkLifecycleSteady State


All system components are packaged into a single top-level object called the runtime. The runtime is accessed via the HxRuntime API. It is possible to run multiple runtimes within a single JVM.


The Haxall daemon is the default implementation of the runtime. A daemon is created via the hx init command, and executed via hx run. These commands are covered in the Setup chapter.

You can customize the bootstrap of a deamon using the Fantom class hxd::HxdBoot. Here is an example to illustrate using custom config and required libs:

boot := HxdBoot
  it.dir = myDatabaseDir
  it.config["serialSpi"] = "myPod::SerialSpiImpl"

Default behavior of the the daemon:

  • creates an instance of HxFolio for the database
  • simple user manager which stores users in the runtime database
  • HTTP API with all the standard ops
  • simple Axon shell as the UI
  • provides basic in-memory historian using circular buffers


SkySpark is multi-tenant and supports multiple project runtimes. SkySpark implements one runtime for the host via Sys.rt. Each project is also a full runtime via Proj.rt.

SkySpark runs some low-level libs at the host level as SysMods. For example, there is only one instance of the http, api, and user libs (shared by all projects as SysMods). Then each run project runs its own instance of Exts which includes libs like point, task, conn, etc. The Haxall documentation will often use the term library/lib and extension/ext interchangeability for this reason.


The runtime lifecycle defines a multi-stage series of phases for startup and shutdown. Startup phases are:

  1. Instantiation: libs are created, but only basic info is available
  2. Start: libs can lookup services and other libs, kick off background processing
  3. Ready: all libs have completed their onStart callback, HTTP port is opened
  4. Steady state: delay after ready to given apps and connectors time to spin up

The shutdown phases are:

  1. Unready: shutdown external ports
  2. Stop: cease all background processing

Shutdown happens automatically when the runtime process is killed via Env.addShutdownHook.

See the lib chapter for how these phases map to the HxLib callbacks.

Steady State

Steady state is a configurable delay after bootstrap used to give the system time to reach equilibrium. This gives internal services time to spin up before interacting with external systems. By default the steady state delay is 10sec. It may be tuned by applying the steadyState tag to the projMeta record.

The configured delay starts after the database is loaded and all libraries have completed their onStart and onReady callbacks. Once the delay expires, the steady state flag transitions to true and libraries receive the onSteadyState callback.

Activities which occur before steady state:

  • Applications which require current point values should initialize their watches
  • Connectors should begin polling/subscribing to watched points to ensure data is up-to-date once steady state is reached

Activities which occur after steady state:

  • Tasks do not subscribe to their observables until steady state (including scheduled tasks)
  • Local history collection is suppressed until steady state
  • Connector writes are suppressed until steady state, then the current write level of all writable points is broadcast to connectors which may issue a remote write if the writeOnStart tuning policy is configured
  • Rule engine (SkySpark only) does not begin to compute rules until after steady state