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Table of Contents

Why Use AEM

...Leader in Gartner Quadrant in 2017, now 7 years in a row.

Architecture Components

Component Front-End to BackPurposeSummaryNotesKey Reading Material





Content Delivery Network





AkamaiCDN (Content Distribution Network)







Content Management System





Apache Web Server with Adobe Dispatcher ModuleWeb Server, Caching and Load Balancing

Caches into static content pages generated by Publisher to improve performance and provides a layer of security protection.

Requests from User stops at Dispatcher which initiates a cleaner request to the Publisher.

The Adobe Dispatcher Module is proprietary Adobe software.

The Adobe Dispatcher module loads like any other Apache module but is closed source.

Note that there are two versions (standard and SSL) with the same extracted name.

(question) Is the Adobe Dispatcher module what also receives cache expirey information from the Publisher?






AEM PublisherCMS Publisher

Assembles and serves the published content as static html.


Content RepositoryCMS Database CacheSee Content. Repository further below AEM Instance for Author for details.






AEM Instance for AuthorCMS Author

Create, upload and edit content and to administer the website.

Powered as follows,

  • Uses Apache Sling for Web framework to expose the repository RESTfully.
  • Bundles CRXDE Lite web interface to manage the repository.
  • Powered by Apache Felix (implementation of OSGi) running inside of Jetty.

Has two user interfaces, old and new (add more to this later).

If possible, ensure only available within the Intranet.
Content RepositoryCMS Database

NoSQL File based data storage for content-centric applications, implementing Content Repository API for Java Technology (JCR 2.0).

Uses Apache Jackrabbit as JCR implementation and Apache Jackrabbit Oak as module manager (searching, versioning, transactions, etc.) of repository with additional customization on top of Oak called CRX3 (Code Repository Extreme 3) to add features (synchronous updates, key-value persistence, clustering, static extension, individual workspace index).

This finally communicates to a MK (MicroKernel).

Default and recommended storage format is to use tar files TARMK (Tar Micro Kernel) which also offers Cold Standby to sync repositories.

Alternative is MongoDB but not Adobe does not recommended except for specfic use cases. More details on selection further down in Technical Notes.

Note Azure blob storage is not supported. AWS S3 is supported with Adobe's S3 Datastore Connector.

There are always limits to any type of file store, for example maximum number of files in a directory. Adobe is not clear on how the product deals with this.

Planning should also be done around categories of assets, ie media, images and normal content. It especially becomes a problem when restoring.

Gliffy Diagram
nameAdobe AEM Repository Architecture

DAM (Digital Asset Management System)Management of Production ready Digital AssetsAs best practice, the DAM connected to AEM should be used for production ready, not high fidelity digital assets.






Deep Content Management Technology Components
TarMK



Mongo
Sharding no longer supported. Only added as of 6.1.

Solr powered by LuceneNative System Search EngineUsed by the native system to perform lookups and performs indexing.

Solr powered by LuceneSite Search EngineBonsai Framework evaluation is to not use embedded and keep the CMS function purely to Authoring. Instead use an external Solr based search engine.







CMS Author Database







AD or Single Sign-OnCentralized Authentication Directory

In companies with effective identity onboarding it is strongly recommended to leverage.

Out of the box, AEM's authentication does not meet minimal standards (enforcing password complexity, password recovery, etc...).

Optional and should fail back to local authentication repository if AD fails.

Currently AEM does not support one-time email users. As such decision is to not use AD in a large org to quickly provision Business users in and out of the system.

Confirm users deactivated do not take license seats (question). Check if deleted users can be recreated with same GUID to more easily pass audit and compliance (question).







CRXDE Lite

Adobe's web user interface to interface with Apache Sling. CRXDE Lite looks to be Adobe's own extension sitting on top of Apache Sling Web Console and Apache Felix Web Console.



Apache FelixImplementation of OSGi Specification

Can redeploy code pieces without requiring a restart.

Each bundle requires a unique name space.

Manages service discovery and registry.



Apache SlingControl to expose and access resources.REST Architecture.

JCRObject Oriented Database


JackRabbit
Handles multi version control with refresh function to handle real-time updates.






Microkernel
Provides an abstraction layer for the storage of content in JSON.

Vault
Extract out of TarMK for normal file system.

JettyContainerAhhh... not super clear but in Error 404 starting up noticed it's powered by Jetty.






Granite








Roy FieldingSenior Principal Scientist at Adobe SystemsSignificant achievements include, HTTP Specifications (Principle Author), originator of the Representational State Transfer (REST), co-founder of the Apache Software Foundation.

David N
JCR



Note to incorporate more clarity from this article in https://www.terrabeata.com/2015/03/aem-interview-questions-what-is-the-technology-stack-of-adobe-experience-manager/

Also more good stuff in this technical deep dive http://dev.day.com/content/ddc/en/gems/technical-deep-dive-of-the-aem-6-platform.html








Site Search





Solr powered by LuceneWebsite SearchUsed internally for DAM but also available as module for Customer facing website.

Keep distinct from CMS system for Customer facing website.

Some products offer as a plugin, but only implement if outside of the CMS system for load and security purposes.


Development - Author





Kits
Samples, Tools and Commons

...