About MLE Execution Contexts

An MLE execution context is a standalone, isolated runtime environment, designed to contain all runtime state associated with the execution of JavaScript code. Runtime state includes global variables as well as the state of the language environment.

Note:

An MLE execution context corresponds to an ECMAScript Execution Context for JavaScript.

MLE uses execution contexts in two different scenarios:

With dynamic MLE execution, where you can create and use dynamic MLE contexts explicitly
For calls from SQL and PL/SQL to functions exported by an MLE module

Dynamic Execution

Properties of dynamic MLE contexts are determined by the environment used at the moment the execution context is created. You have explicit control over which execution context is used for each dynamic MLE snippet, with each execution context running code on behalf of a single user.

There is no limit to how many dynamic MLE execution contexts can be created in a session, or how they are shared across different code snippets. Code snippets in JavaScript share all global variables with other code snippets running in the same execution context.

MLE Modules

Contexts for MLE module calls from SQL or PL/SQL are created implicitly on demand. Here, the properties are determined by the MLE environment referenced in the call specification at the moment of context creation. The environment can be used to specify language options and to make MLE modules available for import.

MLE modules never share an execution context with other modules or dynamic MLE snippets. Additionally, separate execution contexts are used when code from the same MLE module is executed on behalf of different users. MLE creates a dedicated execution context for each combination of MLE module and environment. Two call specifications that specify either different modules or different environments are executed in separate module contexts.