Framework initialization and runtime sequence

This article presents the framework initialization, runtime, and shutdown sequences.

Initialization sequence

The initialization sequence of the framework has two main phases:

• setup: this phase is performed after the configuration has been parsed. It has three separate sub-phases:
• The configuration is parsed and the applications and modules are created
• Each module preconfigure EntryPoint is called
• The module properties configuration is parsed and the values for the modules properties are set for each module
• start: this phase is performed after the framework has been started. It has two separate sub-phases:
• init: The Services are attached, and each module init EntryPoint is called
• effective start: Each module start EntryPoint is called

Note that:

• The setup phase will create definition classes which will manage the definition
• The start phase will create runtime classes which will manage the runtime

Framework preconfiguration

When a module preconfigure EntryPoint is called, the Services are still not attached for the module, but it is possible to specify programmatically modules properties. For example:

      public void preConfigure() {
        module.addPropertyType("myProperty", URL.class, null, true);
      }

Framework initialization

When a module init EntryPoint is called, the Services are attached for the module, but the module will not be notified of any service, and it will not be able to invoke a service.

It is possible to get the properties values, and the Services for which the module is a provider or a subscriber. For example:

      public void init(Module module) {
        this.module = module;
        this.inputService = module.getService("theService");
        boolean property = module.getPropertyBooleanValue("myProperty");
      }

This is also the ideal moment to perform lengthy setup or initializations for your module, if you have some code which will take a long time to complete.

Framework start

When a module start EntryPoint is called, all the framework is initialized and the Services are attached. It is possible to send services to a service subscriber. For example:

      public void start() {
        inputService.setDataValue("myValue", true);
        inputService.invoke();
      }

Runtime sequence

The runtime sequence for a Service invocation has the following phases:

• The module which is a provider sets values for the Service datas, then invokes the Service
• The modules which are subscribers for this Service are notified from the Service invocation, then gets the values for the Service datas

Shutdown sequence

When the framework is shutdown, the modules end EntryPoint will be called (for the modules which have this entry point).

Consequences from the deployment

In cases where several protoframework.jar instances are deployed, the initialization sequence will be performed for each instance. Note that in this case the instances have no way to know when the other instances are ready, which means that if you invoke services at start of one module, subscriber modules on other instances may not be ready yet to be notified^[1]

Especially if you use the UDP protocol

.