Adobe CQ-5 Interview Questions | Part - 2

6)    What is Reverse Replication?

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.

7) How is resource resolution done in Sling? 

The below images tells us how a URL is resolved and mapped to a resource.

https://adobecq5interviewquestions.files.wordpress.com/2013/11/sling.gif?w=640

Consider the URL

GET-http://www.mywebsite.com/products/product1.printable.a4.html/a/b?x=12

Using these principles:

• the mapping uses the content path extracted from the request to locate the resource
• when the appropriate resource is located, the sling resource type is extracted, and used to locate the script to be used for rendering the content

The request is broken down and the necessary information extracted. The repository is searched for the requested resource (content node): 

• first Sling checks whether a node exists at the location specified in the request; e.g. ../
• content/corporate/jobs/developer.html
• if no node is found, the extension is dropped and the search repeated; e.g. ../content/
• corporate/jobs/developer
• if no node is found then Sling will return the http code 404 (Not Found). 
  

8) What is OSGi? What is the benefit of OSGi? What is Felix?

OSGi is a framework which allows modular development of applications using java.

A large application can be constructed using     small reusable components(called bundles in terms of OSGi) each of which can be independently started, stopped, and also can be configured dynamically while running without requiring a restart.

Consider a scenario where you have a large application which uses a logging framework. This logging framework can be deployed as an OSGi Bundle, which can be managed independently. Therefore, it can be started when required by our application and can be stopped when not in use. Also the OSGi container makes these bundles available as services, which can be subsribed by other parts of application.

The main advantages of using OSGi :

1)    reduces the complexity of the system.

2)    Makes the components loosely couples and easy to manage.

3)    Increases the performance of the system, since parts of application which are not in use,need not to be loaded in the memory(although there is not a drastic change in performance and also some people argue that running an OSGi container itself takes huge memory).

9)    What is the role of Dispatcher in CQ5?

Dispatcher is a CQ5 tool for caching and load-balancing. It has 2 responsibilities.

1)    Caching – To cache as much content as possible, so that it doesnt need to access layout engine frequently for generating content dynamically.

2)    Load-balancing – To increase the performance by load-balancing.

10)    What is Replication in CQ5?

1)    Publish (activate) content from author to publish environment.

2)    Explicitly flush content from the dispatcher cache.

3)    Return user input from the publish environment to the author environment.

REPLICATION PROCESS:

1)    First, the author requests that certain content to be published (activated).

2)    The request is passed to the appropriate default replication agent.

3)    Replication agent packages the content and places it in the replication queue.

4)    the content is lifted from the queue and transported to the publish environment using the   configured protocol.

5)    a servlet in the publish environment receives the request and publishes the received content, the default servlet is http://localhost:4502/bin/receive.