1. What is SSL? Why do you require SSL?
Ans.SSL or Secure Socket Layer is a protocol that authenticates Web sites to browsers. It is also used for encrypting communication between browser and Web servers. To enable SSL, you simply need to install digital certificates or Server ID.
The main role of SSL is to provide security for Web traffic. Security includes confidentiality, message integrity, and authentication. SSL achieves these elements of security through the use of cryptography, digital signatures, and certificates.
2. Explain SSL working.
Ans.SSL has two distinct entities, server and client. The client is the entity that initiates the transaction whereas the server is the entity that responds to the client and negotiates which cipher suites are used for encryption. In SSL, the Web browser is the client and the Web site server is the server. Three protocols lie within SSL, the Handshake protocol, the Record protocol, and the Alert protocol. The client authenticates the server during the Handshake protocol. When the session is initiated and the handshake is complete, the data transfer is encrypted during the Record Protocol phase. If there are any alarms at any point during the session, the alert is attached to the questionable packet and handled according to the Alert protocol.
3. What is XML? Explain in brief.
Ans.
XML is a simple, common format for representing structured information as text. You can create your own tags to define and structure data, and transmit it. The basic syntax of XML is extremely simple. As with HTML, XML represents information as text using tags to add structure. A tag begins with a name in between angular brackets (<>). In XML, every tag must have a closing tag. An opening tag, closing tag and any content in between are collectively referred to as an element of an XML document. Elements can contain other elements but they must be properly nested. Elements can also contain text or a combination of elements and text.
4. Given an overview about EJBs.
Ans.
Enterprise Java Beans (EJB) is a server-side component that executes specific business logic on a server when invoked by a local or remote client. EJB is actually a framework for writing distributed programs. It involves a standardization agreement that enables a component to run within any application server. The agreement is accomplished by implementing a set of Java interfaces from the EJB API. Note that EJBs are not GUI components.
5. What are the advantages and disadvantages of EJBs.
Ans.
Following are the advantages of EJBs:
n Many vendor application servers conform to the J2EE specification allowing you to select a best-of-breed solution.
n To handle fluctuations in resource demand server-side resources can easily be scaled by adding or removing servers.
n Application servers provide access to complex services, such as transaction and security management, resource pooling, JNDI (Java Naming and Directory Interface), and component lifecycle management.
Following are the disadvantages of EJBs:
n EJB has a large and complicated specification.
n EJBs take time to develop. Also, they are difficult to debug. Occasionally, the bug may not be in your code but in the application server itself.
n Frequently released newer versions of EJB specifications render application obsolete quickly.
6. Explain entity beans and session beans?
Ans.
An entity bean is an object with the following special properties:
n It is permanent. It does not get destroyed itself after a program finishes executing.
n It is network-based. It can be used by any program over a network provided the program is able to access the bean on the networked machine.
n It is executed remotely. Methods of an entity bean run on a server machine. When you call an entity bean’s method, your program’s thread stops executing and control passes over to the server. When the method returns from the server, the thread resumes execution.
n It is identified by a primary key. Entity beans must have a primary key. The primary key is unique – each entity bean is uniquely identified by its primary key. For example, an employee entity bean may have Social Security number as primary key. You can only use entity beans when your objects have a unique identifier field or when you add such a field.
Session beans are different from entity beans in that they are not permanent objects. They are not shareable in general although it is possible to share them using handles. Session beans can be used to distribute and isolate processing tasks. Each session bean can be used to perform a certain task on behalf
of its client. The tasks can be distributed on different machines. Session beans also do not have a primary key. Unlike entity beans, session beans are not primarily meant to be shared or found later.
7. Briefly describe the remote and home interfaces in EJBs?
Ans.A remote interface is the business end of EJB. It is the set of services provided by EJB.
The home interface is the book-keeping interface. It helps clients to create a new instance of an EJB, or to find an existing instance of an EJB. The methods used to find existing EJBs are shown as finder methods. Since session beans are not designed to be shareable, there are no session bean finder methods.
8. What is DTD?
Ans.DTD or Document Type Definitions is a document that contains grammar rules for validating an XML document. It is a schema specification method for XML