Improvements and fixes for mf format

docs/specs/cli-specification.md

@@ -179,6 +179,15 @@ System.register([],function(e,c){var dep;return{setters:[function(_dep){dep = _d
 
 The `$pr_name` has to be replaced with the globally used name for other (lazy loaded) chunks of the pilet. The `$shared_dependencies` represent the used shared dependencies. This is a JSON object mapping the identifiers used for the shared dependencies to their bundles.
 
+**`mf`**
+
+The bundled code follows the specification and implementation of Module Federation. While originated at Webpack ("Webpack Module Federation") it is now also ported over to other bundlers. In supported bundlers the `mf` format can be used to produce compatible pilets.
+
+Pilets that are compatible must have:
+
+- Exposed entry point `./pilet` leading to the module with a `setup` function
+- Accepting a share scope with name `default` (this is also the default, so no changes required here)
+
 ## Limitations
 
 The specification does not cover things like validation, declaration generation, scaffolding, or upgrading.

docs/specs/pilet-specification.md

@@ -101,7 +101,13 @@ The script for the partial resource has to be loaded from the same base URL as t
 
 ### `v2` Format
 
-This code in this section works exclusively for `v2` pilets. `v2` pilets are using the [SystemJS format](https://github.com/systemjs/systemjs/blob/main/docs/system-register.md). For conformance to this format the SystemJS specification should be considered.
+The code in this section works exclusively for `v2` pilets. `v2` pilets are using the [SystemJS format](https://github.com/systemjs/systemjs/blob/main/docs/system-register.md). For conformance to this format the SystemJS specification should be considered.
+
+### `mf` Format
+
+The code in this section works exclusively for `mf` pilets. `mf` pilets are using [Module Federation](https://module-federation.io/) for exposing their API and taking part in (distributed) sharing of dependencies. For conformance to this format the Module Federation specification should be considered.
+
+The `mf` format does not require a spec version marker. By detecting a script that uses module federation the `mf` format is assumed.
 
 ## Package Keys
 

src/tooling/piral-cli/src/common/spec.ts

@@ -55,6 +55,15 @@ export function getPiletSpecMeta(target: string, basePath: string) {
         requireRef,
         dependencies: getDependencies(plainDependencies, basePath),
       };
+    } else if (
+      content.includes(
+        '"Container initialization failed as it has already been initialized with a different share scope"',
+      ) &&
+      /^var [A-Za-z0-9_]+;/.test(content)
+    ) {
+      return {
+        spec: 'mf',
+      };
     } else {
       // uses no arguments
       return {

src/tooling/piral-cli/src/messages.ts

@@ -2628,11 +2628,12 @@ export function failedToOpenBrowser_0170(error: string): QuickMessage {
  * the interpretation of compatible feed services slightly and has an impact of the usage
  * of the pilet in the browser.
  *
- * The selected schema version needs to be either "v0", "v1", or "v2".
+ * The selected schema version needs to be either "v0", "v1", "v2", or "mf".
  *
  * - v0: will download and evaluate the pilet explicitly
  * - v1: will use a script tag for integration of the pilet
  * - v2: will use SystemJS for integration of the pilet (default)
+ * - mf: will use Module Federation for integration of the pilet (only supported bundlers)
  *
  * The v1 version has better support for older browsers, but requires a polyfill to work
  * correctly. This polyfill is part of the `piral-ie11polyfills-utils` package.
@@ -2641,6 +2642,10 @@ export function failedToOpenBrowser_0170(error: string): QuickMessage {
  * The v2 version uses a SystemJS format for the pilet. It has the broadest browser support
  * but requires the custom format as output. Most bundlers support SystemJS directly or
  * indirectly, making it a quite broad choice.
+ * 
+ * In bundlers that support Module Federation (e.g., Webpack 5) the "mf" format may be
+ * the best choice. Keep in mind that "mf" is only supported by applications using
+ * Piral 1.4.0 or higher.
  *
  * @see
  * - [GitHub currentScript-polyfill](https://github.com/amiller-gh/currentScript-polyfill)