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Adobe AEM Interview Questions
Here are the topmost frequently asked Adobe AEM interview questions:
- Explain the difference between Aem vs Sitecore
- Explain the Difference between Design Dialog and Edit Dialog
- What is the purpose of clientlibs?
- What is Dependency/Dependencies in the client library?
- Explain the Difference between package and bundle?
- Can you explain the life cycle of the OSGI bundle?
- What is the process step in the workflow?
- Explain the Difference between CQ5.4 and CQ5.5?
1. Explain the difference between Aem vs Sitecore?
Easy to access
Easy to access
Multiple User Access Supported
Multiple User Access Supported
Single platform support
2. Difference between Design Dialog and Edit Dialog?
Ans: Both dialog and design dialog defines the UI interface for allowing the user to configure the component.
Design Dialog of a component can be seen/edited in the design mode of the page. Design dialog is at template level so all the pages of the template will share the same design dialog and it is stored under /etc/designs folder.
Whereas Dialog of a component is at page level so each component instance will have its own dialog and information entered in the dialog will be stored under /content folder.
3. What is the purpose of clientlibs?
Ans: It is used for adding site-specific js and CSS files to the page and also third party js and CSS files.
4. What is Dependency/Dependencies in the client library?
Ans: It is a list of other client library categories on which this library folder depends. For example, given two cq: ClientLibraryFolder nodes F and G, if a file in F requires another file in G in order to function properly, then at least one of the categories of G should be among the dependencies of F.
5. What is the embed and difference between dependency and embed in the client library?
Ans: Embed: Used to embed code from other libraries. If node F embeds nodes G and H, the resulting HTML will be a concentration of content from nodes G and H.
Dependency: Please refer to the above answer.
6. Difference between package and bundle?
Ans: Package: A Package is a zip file that contains the content in the form of a file-system serialization (called “vault” serialization) that displays the content from the repository as an easy-to-use-and-edit representation of files and folders. Packages can include content and project-related data.
Bundle: Bundle is a tightly coupled, dynamically loadable collection of classes, jars, and configuration files that explicitly declare their external dependencies (if any).
7. Can you explain the life cycle of the OSGI bundle?
Ans: Following are the life cycle states of OSGI:
Installed: The bundle has been successfully installed.
Resolved: All Java classes that the bundle needs are available. This state indicates that the bundle is either ready to be started or has stopped.
Starting: The bundle is being started, the BundleActivator.start method will be called, and this method has not yet returned. When the bundle has an activation policy, the bundle will remain in the STARTING state until the bundle is activated according to its activation policy.
Active: The bundle has been successfully activated and is running; its Bundle Activator start method has been called and returned.
Stopping: The bundle is being stopped. The BundleActivator.stop method has been called but the stop method has not yet returned.
Uninstalled: The bundle has been uninstalled. It cannot move into another state.
8. What is the difference between parsys and iparsys?
Ans: parsys: It is called the “Paragraph System” component in which you can add other components at the page level.
iparsys: It is an inherited paragraph system, which inherits parent page “paragraph system”.
9. What is the process step in the workflow?
Ans: It is a workflow component that can be found at this is used for calling a java class in the workflow.
[ Related Article: Adobe (AEM) CQ5 System Administrator Interview Questions - 2021 ]
10. Difference between CQ5.4 and CQ5.5?
Ans: Versions of CQ before 5.5 were based on a servlet container (CQSE, by default, though others could be used) running with multiple web apps: One for the CRX content repository and one for the OSGi container which itself contained Sling and AEM. The Sling web app was bound to the root and handled most of the request processing.
With CQ 5.5 and AEM, the OSGi container is positioned at the root, and the OSGi HTTP service, backed by Sling acting as the sole request handling endpoint.
The CRX content repository is now just another OSGi service, alongside the various services that comprise the rest of the AEM functionality. These changes do not affect applications built on top of AEM or Sling.
The new architecture means that the quickstart jar installation of AEM can no longer support other web applications running alongside AEM.
However, the war version of AEM is designed to be deployed in an application server, where additional web applications can be deployed alongside it.
Added three new connectors to key Adobe products – Creative Suite, Scene7, Search&Promote
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The authors can directly work on mobile apps.
Partnered with hybrids software to add some nice eCommerce capabilities.
Added Undo(Ctrl+z) and Redo(Ctrl+y) functionalities.
11. Role of Dispatcher in CQ5?
Ans: The dispatcher is a CQ5 caching and/or load balancing tool. The dispatcher also helps to protect your AEM server from attack. It caches responses from publish instance, to increase the responsiveness and security of your externally facing published website
12. What is Replication? and What are the steps involved in Replication?
Ans: Replication is the process of activating/publishing the page from Author Instance to Process Instance.
Steps involved in replication:
- The author requests that certain content be published (activated); this can be initiated by a manual request, or by automatic triggers that have been preconfigured.
- The request is passed to the appropriate default replication agent; an environment can have several default agents that will always be selected for such actions.
- The replication agent “packages” the content and places it in the replication queue.
- The content is lifted from the queue and transported to the publish environment using the configured protocol; usually, this is HTTP.
- A servlet in the publish environment receives the request and publishes the received content; the default servlet is https://localhost:4503/bin/receive.
13. What is the difference between par base and parsys?
Par base: The par base allows components to inherit attributes from other components, similar to subclasses in object-oriented languages such as Java, C++, and so on.
For example, when you open the /libs/foundation/components/text node in the CRX Explorer, you see that it has a property named sling:resourceSuperType, which references the par base component.
The par base here defines tree scripts to render images, titles, and so on so that all components subclassed from this par base can use this script.
[ Related Page: Latest Core Java ]
Phrases (Paragraph System): The paragraph system (parsys) is a compound component that allows authors to add components of different types to a page and contains all other paragraph components.
Each paragraph type is represented as a component. The paragraph system itself is also a component, which contains the other paragraph components.
14. Explain the Multi-Site Manager?
Ans: Multi-Site Manager (MSM) enables you to easily manage multiple web sites that share common content. MSM lets you define relations between the sites so that content changes in one site are automatically replicated in other sites.
For example, web sites are often provided in multiple languages for international audiences. When the number of sites in the same language is low (three to five), a manual process for synchronizing content across sites is possible.
However, as soon as the number of sites grows or when multiple languages are involved, it becomes more efficient to automate the process.
15. How to customize page property dialog?
Step 1: Copy /libs/foundation/components/page/dialog node to template component’s node
Step 2: Modify dialog node
16. Classes involved in URL Resolution?
You can check available script engines for rendering by accessing the URL
17. What is the difference between the live copy and language copy?
Live Copy: Copy created from an existing site or blueprint is called Live Copy. Rollout configurations for this Live Copy can be configured from the tool's console.
Language Copy: A site that is created using a language tool is called a Language copy. Basically to create a site for different languages.
18. Role of Persistence Manager in CQ5?
Ans: The persistence manager saves the repository content to a permanent storage solution, such as the file system or a database. By default, CRX saves repository content to the Tar persistence manager. Following DB’s can be used for storing content – DB2, Oracle, SQL Server, MySQL.
[ Related Page: Online SQL Server ]
19. What is the difference between c: import, sling: include, and CQ: include? What is the advantage of each tag?
I assume this is the import tag of the Standard Tag Library. This tag is documented and does not know about Sling directly.
sling:include path=”trail” resourceType=”foundation/components/breadcrumb”
This is the include tag of the Sling JSP Tag library. This tag knows about Sling and also supports RequestDispatcherOptions.
cq:include path=”trail” resourceType=”foundation/components/breadcrumb” or cq:include script=”redirect.jsp”
This tag is Communique specific extension of the Sling JSP Tag library include tag. IIRC it supports callings scripts in addition to just including renderings of resources.
In a Communiqué application, I would suggest generally use the Communique or Sling include tag since this provides you more Sling support.
You may use the JSTL import tag if you don’t have specific requirements for Sling extended features, plan to use the JSP (fragment) outside of Communique or if you want to further process the generated (imported) content with a reader or a variable.
20. How to connect to an external Database?
Ans: To connect to external DB, a connection pool needs to be configured by creating a node of type sling: OsgiConfig. The below screenshot is for connecting to the SQL database, but if you want to connect to another DB then properties values need to be changed accordingly:
Use the below code to get a connection:
DataSourcePool dspService = sling.getService(DataSourcePool.class); DataSource ds = (DataSource) dspService.getDataSource(“hsqldbds”);
21. Explain DAM Renditions?
Ans: The DAM allows you to create renditions of an image that include different sizes and versions of the same asset. You can use those renditions in the content of your website, and that can be helpful when you need to create thumbnails or smaller views of large, high-resolution images.
When you are creating multi-device websites where Internet bandwidth is a varying concern, this feature becomes even more important. After all, you want to minimize the size of any files a site visitor has to download to view your site. Making your site load faster improves your search engine optimization and the user experience.
22. What is CQ5? Why Content Management System is Required? Advantages of CQ5 over other CMS?
Ans: CQ5 is a java based content management system from adobe, previously Day CQ5
It is based on a content repository(i.e it uses a content repository to store the content of a website) and uses JCR(Java content repository) specification to access the content repository.
It uses RESTfulApache Sling framework to map request URL to the corresponding node in the content repository
It uses a powerful OSGi framework internally to allow modular application development. It means individual pieces of your application(called bundles in terms of OSGi) can be independently started and stopped.
CQ5 uses Apache Felix as the OSGi container. Therefore different parts of cq5 can be independently started and stopped.
Why a content management system is required? Some websites are very dynamic in nature, content needs to be updated frequently, so it is easier to manage the content of such websites using a CMS.
Advantages of CQ5 over other CMS:
Implementation of workflows for creating, editing, and publishing content
Managing a repository of digital assets like images, documents and integrating them into the websites.
Usage of search queries to find content no matter where it is stored in your organization.
Setting up easily the social collaboration blogs, groups.
Tagging utility to organize digital assets such as images.
23. What is the technology stack of cq5?
Ans: Cq5 uses the following technologies :
- JCR: Java specification for accessing a content repository JSR-283 specification JCR 2.0, cq5 uses its own implementation of JCR called CRX. Apache Jackrabbit is an open-source implementation of the jcr 2.0 specification.
- Apache Sling: RESTful framework to access a JCR over HTTP protocol. It maps the request URL to the node in JCR.
- OSGi(Apache Felix): a framework for modular application development using java. Each module called bundle can be independently started and stopped.OSGi container provides implementation classes for the OSGi framework.
24. What is a content repository? What is JCR?
Ans: A Content repository is basically a place where digital content is stored. Generally, the structure of the content repository is hierarchical and represented as a tree structure where each node of the tree is used to store content.
Java Content Repository is a specification provided by the Java community to access the content repository in a uniform way (platform-independent and vendor-independent way). The specification was initially released as JSR-170(JCR 1.0) and then later revised version 2 as (JCR-283).The java.JCR API provides the various classes and interfaces to access a content repository.
25. What is REST? What is a RESTful Framework?
Ans: REST stands for Representational State Transfer. REST-style architectures consist of clients and servers. Clients initiate requests to servers; servers process requests and return appropriate responses. Requests and responses are built around the transfer of representations of resources.
A resource can be essentially any coherent and meaningful concept that may be addressed. A representation of a resource is typically a document that captures the current or intended state of a resource.
Apache Sling is a RESTful framework to access a java content repository over http protocol.
26. What is the role of a Dispatcher in CQ5?
Ans: A dispatcher is a CQ5 tool for caching and load-balancing. It has 2 responsibilities.
- Caching: To cache as much content as possible, so that it doesn't need to access the layout engine frequently for generating content dynamically.
- Load-balancing: To increase the performance by load-balancing.
27. What is Replication in CQ5?
- Publish (activate) content from an author to publish the environment.
- Explicitly flush content from the dispatcher cache.
- Return user input from the publish environment to the author's environment.
- First, the author requests that certain content be published (activated).
- The request is passed to the appropriate default replication agent.
- The replication agent packages the content and places it in the replication queue.
- The content is lifted from the queue and transported to the publish environment using the configured protocol.
- A servlet in the publish environment receives the request and publishes the received content, the default servlet is
28. What is Reverse Replication?
Ans: Reverse replication is used to get user content generated on a publish instance back to the author instance. To do this you need a reverse replication agent in the author environment. This act as the active component to collect information from the outbox in the publish environment.
29. Difference between Dialog and Design Dialog?
Ans: Dialog is a key element of your component as they provide an interface for authors to configure and provide input to that component. The user input will be stored at the page level.
Design dialog will share the content at the template level. Also, we can dynamically change the content in design mode.
30. Explain the OSGi[Open Systems Gateway initiative] in CQ5?
- Dynamic module system for Java.
- Universal Middleware Category.
- It helps applications to be constructed from small, reusable, and collaborative components.
- OSGi bundles can contain compiled Java code, scripts, or any contents to be loaded in the repository.
- Helps the bundles to be loaded, installed.
31. How bundles are loaded and installed in CQ5?
Ans: This is managed by the Sling Management Console of CQ5.
32. How clustering is done in CQ5?
Ans: CQ5 CRX is pre-loaded to run within a cluster, even when running a single instance. Hence the configuration of multi-node clusters with little effort happens in CQ5.
33. What is the contribution of the Servlet Engine in CQ5?
Ans: Servlet Engine pretends as a server within which each CQ (and CRX if used) instance runs. Even though you can run CQ WCM without an application server, always a Servlet Engine is needed.
34. Explain the role of the Dispatcher in CQ5?
Ans: In CQ5 Dispatcher helps to cache and load-balance. The main responsibilities are,
- Caching: Cache as much content as possible[ It helps to reduce the continuous functioning of layout engine frequently for generating content when in dynamic.
- Load-balancing: To increase the performance by load-balancing.
35. State various strategies used by Dispatcher?
- Cache as much content as possible as static pages.
- Accessing the layout engine as little as possible.
36. Explain the methods of Caching adopted by the Dispatcher?
- The dispatcher invalidates those pages whose content has been updated and replaces it with new content.
- Auto-Inavidation automatically removes the contents which are not relevant.
37. How you can inherit the properties of one dialog to another dialog?
Ans: For inheriting properties we have to create two components with unique names in the base component dialog. For eg. If your plan is to have two rich text areas in the dialog of components that inherit from the base, then you must include two rich text areas with unique names in the base component dialog.
In any case, every input field of a dialog must have a unique name, else they will point to the same property path relative to the JCR: content node of the component when used on a page.
38. Can we restrict certain users not to display some digital assets?
Ans: You can always limit who can access certain folders in CQ Digital Assets by making the folder part of a CUG(closed user group).
Steps to make a folder part of a CUG:
- In CQ DAM, right-click the folder you want to add closed user group properties for and select Properties.
- Click the CUG tab.
- Select the Enabled checkbox to make the folder and its assets available only to a closed user group.
- Browse to the login page, if there is one, to add that information. Add admitted groups by clicking Add item. If necessary, add the realm. Click OK to save your changes.
39. Difference between OSGi bundle and the Normal Jar file?
OSGi bundles are jar files with metadata inside. Much of this metadata is in the jar’s manifest, found at META-INF/MANIFEST.MF. This metadata, when read by an OSGi runtime container, is what gives the bundle its power.
With OSGi, just because a class is public doesn’t mean you can get to it. All bundles include an export list of package names, and if a package isn’t in the export list, it doesn’t exist in the outside world. This allows developers to build an extensive internal class hierarchy and minimize the surface area of the bundle’s API without abusing the notion of package-private visibility. A common pattern, for instance, is to put interfaces in one package and implementations in another and only export the interface package.
All OSGi bundles are given a version number, so it’s possible for an application to simultaneously access different versions of the same bundle (eg: JUnit 3.8.1 and JUnit 4.0.). Since each bundle has its own classloader, both bundle classes can coexist in the same JVM.
OSGi bundles declare which other bundles they depend upon. This allows them to ensure that any dependencies are met before the bundle is resolved. Only resolved bundles can be activated. Because bundles have versions, versioning can be included in the dependency specification, so one bundle can depend on version JUnit version 3.8.1 and another bundle depends on JUnit version 4.0.
In the OSGi bundle, there will be an Activator.java class in OSGi which is an optional listener class to be notified of bundle start and stop events.