Declaring Variables, Functions, Events and Actions

Server plugins and drivers, along with Java-based Agents, usually create their own definitions of variables, functions and events. These definitions are added to the contexts using addVariableDefinition(), addFunctionDefinition() and addEventDefinition() methods. There are also corresponding removal methods: removeVariableDefinition(), removeFunctionDefinition() and removeEventDefinition().

There is no generic way to remotely manage/modify server-side context tree structure and variable/function/event definitions. Thus, addChild(), removeChild(), addVariableDefinition(), removeVariableDefinition(), addFunctionDefinition(), removeFunctionDefinition(), addEventDefinition(), removeEventDefinition(), and similar methods called on a proxy context (e.g. via Iotellect Server API) will not affect server-side context tree.

Declaration of variables, functions and events assume specification of TableFormat, i.e. format of variable values, function input/output and event data.

Generally, creation of formats is described in Creating Data Tables article.

However, it's very important to understand that in the majority of cases instances of TableFormat class should be re-used between definitions of the same variable/function/event added to multiple contexts.

Thus, table format instances should be static in most cases. This will greatly reduce memory usage in case if, let's say, the same variable definition was added to ten thousand contexts.

A typical TableFormat instance may occupy one kilobyte of memory. Thus, adding ten variables with non-static formats to ten thousand contexts (e.g. instances of your custom resource) will occupy 100 megabytes of memory that can be saved by using a single static format instance.

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