Adobe CQ5 (AEM) Interview Questions

You can check available script engines for rendering by accessing the URL

HTTP://:/SYSTEM/CONSOLE/CONFIG/SLINGSCRIPTING.TXT

17. What is the difference between the live copy and language copy?

Ans:

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.

19. What is the difference between c: import, sling: include, and CQ: include? What is the advantage of each tag?

Ans:

c:import url=”redirect.jsp”

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 a Communique-specific extension of the Sling JSP Tag library include tag. IIRC 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 an 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.

Related Article: ­AEM Vs Open Source Content Management

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

1. 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.

2. It uses RESTfulApache Sling framework to map the request URL to the corresponding node in the content repository

3. 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, and 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, and 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?

Ans:

• 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.

REPLICATION PROCESS:

• 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

HTTP://LOCALHOST:4502/BIN/RECEIVE.

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 acts 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?

Ans:

• 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 content to be loaded into the repository.
• Helps the bundles to be loaded, and 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 the layout engine frequently for generating content when in dynamic.
• Load-balancing: To increase the performance by load-balancing.

35. State various strategies used by dispatchers?

Ans:

• Cache as much content as possible as static pages.
• Access the layout engine as little as possible.

36. Explain the methods of Caching adopted by the Dispatcher?

Ans:

• 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 you plan 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 the OSGi bundle and the Normal Jar file?

Ans:

• 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.

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