In the last two years, we presented our experimental work that enables developers to precompile scripts to allow them to build Sling applications that are compiled ahead-of-time. Our saga continues: since the last adaptTo() we made several improvements to make this idea a reality, including: * Support for any Sling-supported Script Engine * Support for precompiled units in the JSP Script Engine * Support for both versioned and non-versioned resource types * Support for servlet resolution based on the current resource and path, so that language-specific features like data-sly-include and sling:call work just as before We actively worked on reducing the migration efforts required to take advantage of the Apache Sling Scripting Bundle Tracker, allowing it to work in existing projects. In this talk, we will show our progress and demonstrate how you can adapt your existing projects with minimal effort. As an example, we have converted the Sling Starter application, including the Composum content browser, to perform rendering with precompiled scripts. Finally, we will provide an outlook on how this paves the way for a future natively compiled Sling, that will help make applications more cloud-friendly. For more details head over to https://adapt.to/2020/en/schedule/paving-the-way-to-a-native-sling.html.

1. Europe's leading AEM Developer Conference
28 - 30 SEPTEMBER 2020
Paving the way to a native Sling
Radu Cotescu, Karl Pauls - Adobe
rev. 4.20200916

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3. Mr. Scripting
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▪ Computer Scientist @ Adobe, Basel, Switzerland
▪ Member of the Apache Software Foundation
▪ Apache Sling PMC member
▪ Maintainer of HTL for Apache Sling

4. Mr. Classloader
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▪ Computer Scientist @ Adobe, Basel, Switzerland
▪ Member of the Apache Software Foundation
▪ Apache Sling and Apache Felix PMC (VP) member
▪ Co-Author of OSGi in Action

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Episode VI*. The end.
* we’re happy you know your Star Wars episodes

6. Why the end?
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2018 - we presented a novel approach towards script bundling and
pre-compilation, based on OSGi capabilities [1]
2019 - based on our previous year’s work, we then showed the
bigger picture: running Apache Sling as a distributed rendering
service [2]
2020 - support for precompiled bundled scripts is now production
ready

7. These two core bundles now provide full support for packing scripts (resource types) into bundles.
Scripts can be interpreted or precompiled (HTL and JSP for now). However, any script engine can be
used.
Specific tooling helps developers for both precompiling their scripts and generating the required
metadata.
Servlets Resolver & Scripting Core
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8. Bundle headers (Provide-Capability, Require-Capability) can be generated with:
<plugin>
<groupId>org.apache.sling</groupId>
<artifactId>scriptingbundle-maven-plugin</artifactId>
<version>0.2.2</version>
<executions>
<execution>
<phase>prepare-package</phase>
<goals>
<goal>metadata</goal>
</goals>
</execution>
</executions>
</plugin>
With a little help from…
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9. And then use the following two properties in your favourite OSGi bundle plugin:
${org.apache.sling.scriptingbundle.maven.plugin.Provide-Capability}
${org.apache.sling.scriptingbundle.maven.plugin.Require-Capability}
You’ll also need the following requirement:
osgi.extender;filter:="(&amp;(osgi.extender=sling.scripting)(version>=1.0.0)(!
(version>=2.0.0)))"
With a little help from…
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10. If you precompile HTL (assuming your scripts are in src/main/scripts):
<plugin>
<groupId>org.apache.sling</groupId>
<artifactId>htl-maven-plugin</artifactId>
<version>2.0.0-1.4.0</version>
<executions>
<execution>
<id>validate-htl-scripts</id>
<goals>
<goal>validate</goal>
</goals>
<phase>generate-sources</phase>
<configuration>
<generateJavaClasses>true</generateJavaClasses>
</configuration>
</execution>
</executions>
</plugin>
With a little help from…
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11. If you precompile JSP (assuming your scripts are in src/main/scripts):
<plugin>
<groupId>org.apache.sling</groupId>
<artifactId>jspc-maven-plugin</artifactId>
<version>2.2.2</version>
<executions>
<execution>
<goals>
<goal>jspc</goal>
</goals>
</execution>
</executions>
</plugin>
With a little help from…
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Can we precompile Composum?

13. ✓ Faster startup of the web application
✓ Leaner instances
✓ Explicit dependencies
✓ Resource type versioning
✓ Ahead of time verification
✓ Native compilation (in the not so distant future)
Why change something that works?
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What about AEM?

15. We’re glad you asked.
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The AEMaaCS SDK already provides the AEM resource types
(/libs) as precompiled Java classes via the aem-precompiled-
scripts bundle.
The available resource types are exposed via the Provided-
Capabilities bundle header.

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Precompiling scripts for AEM

17. Existing applications will need a tool to help with migration, which will be made available soon:
• help repack scripts from content packages and precompile them into bundles
• provide build-time checks
Explore OSGi Connect and Native images as a way to deploy applications.
Next steps
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Q&A

19. [1] – https://adapt.to/2018/en/schedule/apache-sling-scripting-reloaded.html
[2] – https://adapt.to/2019/en/schedule/from-0-to-hero-in-under-10-seconds.html
[3] – https://github.com/apache/sling-org-apache-sling-servlets-resolver
[4] – https://github.com/apache/sling-org-apache-sling-scripting-bundle-tracker-it
[5] – https://github.com/raducotescu/adaptTo2020-demo
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Resources
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