ATG Interview Questions

Q. What is an ATG Repository?
A repository is a data access layer that defines a generic representation of a data store. It simplifies the storage and retrieval of data. The manipulations of data are done through the Repository API. Application developers access data only using the interfaces such as Repository andRepositoryItem. Developers can create, modify, query and remove repository items. A repository item is more or less like a Java bean. The ATG platform  includes a set of models for repositories.

  • SQL Repository: uses the Generic SQL Adapter(GSA) to perform a mapping between ATG and data stored in a SQL database.
  • Versioned Repository: is an extension of SQL repository used in ATG Content Administration. It has versions for every set of data.For example a price for a product is edited, new entry will be made with a new version number instead of editing the price.

The SQL repository is implemented through the atg.adapter.gsa package. The main ATG component in the SQL repository is an instance of the atg.adapter.gsa.GSARepository class, which implements the interfaces atg.repository.MutableRepository and atg.repository.content.ContentRepository and which extends the class atg.repository.RepositoryImpl.
Lets keep aside the hardcore theory for now and move to more practical aspects of repositories.
A repository is a collection of repository items. In general, a repository item corresponds to the smallest uniquely identifiable entity in the underlying data store. Each repository item is made of properties and these properties store the data and thus makes a repository item. These properties of a repository item are defined inside the repository’s ITEM DESCRIPTORs. Properties of repository items may be single-valued or multi-valued.
Its still confusing…??? be patient,towards the end there is a something informative which will help you enhance your understanding.

Q. What is an Item Descriptor?
Lets keep it simple with the help of an SQL Repository, for example, each database table have its own repository item descriptor. Sometimes a JOIN of multiple tables into a single item descriptor.
Points to Note:
ATG repositories support Java collections and hence we can store a List, Map or  Arrays.
ATG repositories allow one-one, one – many and many- many relationships.
Here is what i have promised: how to setup a repository..??
We have a database table (eg:  tb_tango).
Now create a property file which specifies the repository mapping xml file, class file, data Source etc. Lets name it as ““. The mapping xml(repositoryMapping.xml) file specifies the repository item desciptors. And the final step is registering the repository with dynamo
definitionFiles=Folder Structure/repositoryMapping.xml
* The “dataSourceFile”  is yet another property file where the JDBC connections and database driver,server name, user, password etc are specified.

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Q. What is ATG Dynamo? What is ATG Framework?
ATG Dynamo or Dynamo Application Server(DAS) is a J2EE application server from Art Technology Group. Atg framework is a Web Application framework for building web applications. ATG dynamo implements the ATG framework. The application framework can also be run on all major J2EE application servers (JBoss, WebLogic, WebSphere etc…).

Q. What is the scope of Dynamo Components?
There are three different types of scopes for ATG components namely 
1. request
2. session
3. Global
Global is the default scope

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Q. What is Nucleus? 
Nucleus is ATG`s open Object Application Framework. ATG 7 is said to be a component-centric development platform. The ATG 7 Web applications are nothing but individual JavaBean components assembled together. These JavaBean components are configured and linked together by .properties files within Nucleus.
In Nucleus, each service is packaged as a JavaBean or set of JavaBeans. These JavaBeans are configured individually and mounted into a namespace. The beans then interconnect with the beans representing other services. Nucleus is responsible for interpreting the component configurations and the management of the component namespace. 
Dynamo uses the Nucleus framework to organize components into a hierarchical structure (similar to a directory structure). Each Nucleus service has a unique Nucleus name. For example, the default javax.sql.DataSource component is located at /atg/dynamo/service/jdbc/JTDataSource
Nucleus is the core of the entire ATG system. It creates and configures Nucleus components (also called beans and JavaBeans) and organizes them into a hierarchical namespace, essentially giving them a place to live so they can be referenced by other components. By reading the .properties files associated with each component, Its Nucleus which figures out that which components are to be used in an application ,initializes them to their default values and how decides about how they connect to each other. This model makes it easier for the developers to build ATG applications by configuring and using the pre-built components instead of writing a lot of Java code from scratch.

Q. What is Atg Pipeline?
Atg Pipeline is a variant of Servlet Pipeline, In an ATG pipeline the sequence of Programs are executed in a queue. 
Below is the ATG servlet pipeline 
It starts with the DynamoHandler which adds the Dynamo specific request and response objects to the request’s context. Actually the list of servlets you will see depends on which modules you have running. This is the DAS configuration DPS and other modules can and do add more servlets to the pipeline.

Q. What is ATG tag library? 
Atg tag library is a variant of jsp standard tag library. However atg provides its own set of tag libraries e.g. dsp,dspel, core

Q. What is ATG DPS? What are its elements? 
ATG DPS refers to the ATG Dynamo personalization system. It is driven by User Profile Data and business rules designed to deliver the right content to the right user. 
There are three key elements of the ATG DPS personalization System.

  • User Profile Management
  • Content Targetting
  • Targeted E-mail 

User Profile Management
When a person visits a website driven by ATG Dynamo Personalization Server(ATG DPS) website for the first time, The person is allowed to create its own User Profile.
Once created, DPS stores that User`s Profile in its database repository. This profile contains a list of properties that describe the person`s characteristics, such as the name they entered in a registration form or the date of their last login. ATG DPS uses this profile information stored in its database repository to provided targeted content to each other. 
Content Targeting
Targeting is the process of displaying 

  • Content items
  • To a particular user
  • At a particular time
  • In a particular context and
  • On a particular rule set.

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In the DPS rule based system, business managers create rule sets called content targeters that control how content is displayed on the web site. 
Targeting Email
DPS includes a Targeted Email service for composing and delivering personalized email using the same profile groups and targeting rules you use to deliver content on your web site. Also if you have Dynamo Scenario Server installed, you can use scenarios to deliver targeted email. You can use targeted email to perform below activities.

  • Send a confirmation message to a new user who registers at your site.
  • Notify frequent customers of special sales.
  • Notify all users that have not logged into your site in several months that their accounts will be closed soon.
  • Send out a mass mailing with each message tailored to its recipient.

Q. Which class to extend while creating ATG Droplets?

Q. What are ATG Form Handlers?
ATG Formhandler is the intermediate class that comes in between a jsp form value and its bean class. They are there to evaluate the validity of form data before it is submitted, write data to and read data from a database or repository, and direct the user to different pages, depending on the results of the form submission

Q. What is Base class for all ATG Formhandlers?

Q. What is class Hierarchy for ATG Formhandlers?How to create a FormHandler?
At the top of ATG formhandler class heirarchy there exists the DropletFormHandlerinterface. Then come, three different classes provided by Dynamo which extend this interface. They are as below 
The EmptyFormHandler is the most simplest to implement. It implements the DropletFormHandler interface and defines blank body implementations of the methods in this interface. 
GenericFormHandler extends EmptyFormHandler. It defines the simple implementations of the DropletFormHandler interface’s methods and the basic error handling logic. If errors occur in processing a form that uses GenericFormHandler, the errors are saved and exposed as properties of the form handler component. TransactionalFormHandler extends GenericFormHandler, It treats the form processing operation as a transaction. Though the methods invoked by this form handler are processed discretely, but their results are saved simultaneously. The beforeGet and afterGet methods do the transaction management. This establishes the transaction before any of your properties are set or handler methods are called. 

Q. What are the two methods in a component?
getters & setters

Q. Name 2 types of tables?
primary and auxillary

Q. Have you worked on shopping carts?
CartModifierFormHandler , ShoppingCartFormHandler

Q. Name 2 types of checkout?
Express Checkout, Guest Checkout

Q. Difference between Express Checkout and Checkout?
Express- Logged in user has information stored
Guest- will enter all information (shipping, billing, review steps) and information is not saved

Q. What is BCC?
Business Control Center- UI for Business Users (to upload content to Catalogs, create promotions etc)

Q. What are custom dsp tags?
Custom tags is written by the developer.
Dsp is all ready to use. you can use to render content dynamically by linking Nucleus components directly to your JSPs. Essentially, the DSP tag libraries let you connect your JSP content to the Java code at work behind the scenes so you can separate your application logic from your presentation layer.
ATG 7 provides you with three tag libraries: JSTL, DSP/DSPEL, and Core. You can find these tag libraries in /DAS/taglib.

Q. Difference between droplet, FormHandler and servlet: ?
Servlet is a java class. Droplet is from ATG
Droplet is used to render or put data in the db
Servlet is used to submit data, it acts as a controller. It is not used to put data.
Servlet also renders the portion of JSP page.
FormHandlers are used when there are forms. They help to perform validation for the forms.

Q. Difference between dsp and dspel tags?
The DSP tag library tags support runtime expressions, such as references to scripting variables. These tags use a id attribute to name the scripting variables they create.
The DSPEL tag library tags support JSTL Expression Language (EL) elements that are also evaluated at runtime. These tags often produce a result object named by the var attribute.
For custom tags we need to write the properties file and a class file to define the functions. We need to include a tag file with extension .tld. (tag library definition) and in the droplet include the path of the tag uri <% tag uri…..%>
For example we can write a custom tag to calculate the shipping rate with promotion and save it and then extend wherever required.

Q. Difference between dsp: include and jsp:include?
Dsp imports all objects of type class also, where as jsp imports only primitive types.
Jsp includes are dynamic where as dsp include are for data which is smaller than 64 kb.
ATG created the DSP tag library as a mechanism for accessing all data types, including those that exist in ATG’s Nucleus framework. Other functions provided by these tags manage transactions and determine how data is rendered in a JSP. It’s best to use tags from the DSP tag library only for tasks that involve Dynamo Application Framework (DAF) resources. Dsp tag support for the passing of object parameters between pages. In particular, use dsp:include rather than jsp:include, and use dsp:param rather than jsp:param.

Q. How to implement shopping cart?

Q. What is the main formhandler you use for Shopping cart?
ShoppingCartFormHandler & CartModifierFormHandler

Q. What are the Advantages of DAF?
It is used to maintain huge data
It has repositories which help is data anywhere architecture.
Dependency injection
It can write any object of type 1 call in to the db.
Dynamo messaging using patch bay and jms
“Inversion of Control” design pattern, whereby software components are discrete entities coupled together by the Nucleus container, rather than through direct reference.

Q. What is a Component?
Is a Java bean

Q. What are scenarios?
Scenario anticipates and tracks the actions of the people who visit your Web site and responds appropriately by, for example, tailoring the content of the site, offering price promotions, or sending targeted e-mail messages

Q. Is DAS for high volume or low volume traffic?
High volume

Q. What are the performance issues with ATG?
Performance problems come in many shapes and sizes, but they all mean that the processing of some task is not happening at the expected, and previously observed speed. Performance issues include CPU utilization problems, slow response times, high levels of database activity, long running SQL queries, slow CA deployments, just to name a few.

Q. Why is Eclipse used with ATG?
Eclipse IDE

Q. Which is the IBM product used with ATG?
WebSphere Application Server
Eclipse IDE

Q. What are derived properties?
Enables one repository item to derive property values from another repository item or from another property in the same repository item.

Q. Difference between Item Cache and Query cache?
For each item descriptor, an SQL repository maintains two caches:
a. ItemCache
b. QueryCache
Item caches hold the values of repository items, indexed by repository IDs. Item caching can be explicitly enabled for each item descriptor.
Query caches hold the repository IDs of items that match given queries. When a query returns repository items whose item descriptor enables query caching, the result set is cached as follows:

  • The query cache stores the repository IDs.
  • The item cache stores the corresponding repository items.

Q. What are different modes caching?
Caching modes are set at the item descriptor level, through the tag’s cache-mode attribute. The default caching mode is simple caching. To set a different caching mode on an item descriptor, set cache-mode to one of the following values:

  • Simple
  • Locked
  • Distributed (distributed TCP caching)
  • distributedJMS (distributed JMS caching)
  • distributeHybrid (distributed hybrid caching)

Q. Which are the handleX methods in ?
HandleX methods contain the actual function to be performed. its a method. Like in ProfileFormHandler- handleLogin

Q. What are priceLists?
Price Lists allow you to target a specific set of prices to a specific group of customers. Price lists are managed through a single interface in the ACC. For example, price lists can be used to implement business to business pricing where each customer can have its own unique pricing for products based on contracts, RFQ and pre-negotiated prices.


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