# Runtime isolation Use named imports from `marionette` when the application shares one configuration. These exports belong to the default runtime: ```javascript import { View, Radio, setRenderer } from 'marionette'; ``` `createMarionette()` creates an isolated runtime for applications that need more than one Marionette configuration in the same JavaScript process. This configuration fragment assumes the application supplies the two renderers and templates: ```javascript import { createMarionette } from 'marionette'; const admin = createMarionette(); const storefront = createMarionette(); admin.setRenderer(adminRenderer); storefront.setRenderer(storefrontRenderer); const AdminView = admin.View.extend({ template: adminTemplate }); const StorefrontView = storefront.View.extend({ template: storefrontTemplate }); ``` Each call returns its own `Application`, `Behavior`, `CollectionView`, `MnObject`, `Region`, and `View` classes. It also owns independent `DataApi`, `DomApi`, `StateApi`, EventDelegator configuration, renderer configuration, and `Radio` channel registry. Changing one runtime does not change the default runtime or another isolated runtime. New runtimes start from Marionette's built-in adapter and renderer defaults, not from later configuration applied to the default runtime. Apply shared application configuration explicitly to each runtime that needs it. Implicit composition stays inside the selected runtime. Declarative Regions, CollectionView's empty Region, and Application's root Region use the owning runtime's classes. A Region or child Application from another runtime is rejected as an ownership conflict; construct it from the receiver's runtime instead. Isolation controls implicit class composition and mutable runtime configuration. It is not a security boundary: explicitly showing a View-like object from another runtime remains allowed under the existing Region and CollectionView display contracts. The factory is optional. Calling it does not replace the default exports, and ordinary imports do not create a runtime per View or Application instance. Class-level setters remain subclass-local within either form. Configure object-style adapters against the selected runtime's setters. For example, pass the `@mnjs/adapters/dom/jquery` export to `isolated.setDomApi()`. Likewise, pass the `@mnjs/adapters/backbone` export to the isolated runtime's `setDataApi()` and `setStateApi()` methods when it consumes Backbone data or state. No implicit adapter configuration crosses runtime boundaries. ## Configuration method contract Configure a runtime or subclass before creating its instances. The setters run synchronously; they do not render Views or replace existing event subscriptions. Changing a class prototype during a live feature is not a coordinated migration of the feature's adapters or resources. | Setter | Classes configured by the root or runtime function | Update | | --- | --- | --- | | `setDataApi(api)` | `View`, `CollectionView` | Overlays own enumerable methods on each class's current DataApi. | | `setDomApi(api)` | `View`, `CollectionView`, `Region` | Overlays own enumerable methods on each class's current DomApi. | | `setStateApi(api)` | `Application`, `Behavior`, `CollectionView`, `MnObject`, `View` | Overlays own enumerable methods on each class's current StateApi. | | `setRenderer(renderer)` | `View`, `CollectionView` | Replaces template evaluation with the supplied function. | | `setEventDelegator(delegator)` | `Behavior`, `CollectionView`, `View` | Replaces the delegator with an object exposing `delegate(options)` that returns the cleanup function for that registration. | Root and runtime setter functions return `undefined`. Corresponding class methods, such as `CustomView.setDataApi(api)`, return that class and configure its prototype. Subclasses inherit configuration until they receive their own override. An existing subclass override is not overwritten by subsequently configuring its parent class. Omitting an argument is not a reset operation. In particular, object API setters retain the current overlay, while `setRenderer(undefined)` removes the configured renderer rather than restoring the default. Use a fresh `createMarionette()` when a new independent configuration should start from built-in defaults. [Canonical source](/docs/markdown/docs/runtime-isolation.md) · [Source identity](/docs/manifest.json)