Java, J2EE, JSP - Interview Questions & Answers Part 6

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Java, J2EE, JSP - Interview Questions & Answers

251. What is renderer

A Java class that can render the output for a set of JavaServer Faces UI components.

252. What is request-response messaging

A method of messaging that includes blocking until a response is received.

253. What is resource adapter

A system-level software driver that is used by an EJB container or an application client to connect to an enterprise information system. A resource adapter typically is specific to an enterprise information system. It is available as a library and is used within the address space of the server or client using it. A resource adapter plugs in to a container. The application components deployed on the container then use the client API (exposed by the adapter) or tool-generated high-level abstractions to access the underlying enterprise information system. The resource adapter and EJB container collaborate to provide the underlying mechanisms-transactions, security, and connection pooling-for connectivity to the enterprise information system.

254. What is resource adapter module

A deployable unit that contains all Java interfaces, classes, and native libraries, implementing a resource adapter along with the resource adapter deployment descriptor.

255. What is resource manager

Provides access to a set of shared resources. A resource manager participates in transactions that are externally controlled and coordinated by a transaction manager. A resource manager typically is in a different address space or on a different machine from the clients that access it. Note: An enterprise information system is referred to as a resource manager when it is mentioned in the context of resource and transaction management.

256. What is resource manager connection

An object that represents a session with a resource manager.

257. What is resource manager connection factory

An object used for creating a resource manager connection.

258. What is RMI

Remote Method Invocation. A technology that allows an object running in one Java virtual machine to invoke methods on an object running in a different Java virtual machine.

259. What is RMI-IIOP

A version of RMI implemented to use the CORBA IIOP protocol. RMI over IIOP provides interoperability with CORBA objects implemented in any language if all the remote interfaces are originally defined as RMI interfaces.

260. What is role (development)

The function performed by a party in the development and deployment phases of an application developed using J2EE technology. The roles are application component provider, application assembler, deployer, J2EE product provider, EJB container provider, EJB server provider, Web container provider, Web server provider, tool provider, and system administrator.

261. What is role mapping

The process of associating the groups or principals (or both), recognized by the container with security roles specified in the deployment descriptor. Security roles must be mapped by the deployer before a component is installed in the server.

262. What is role (security)

An abstract logical grouping of users that is defined by the application assembler. When an application is deployed, the roles are mapped to security identities, such as principals or groups, in the operational environment. In the J2EE server authentication service, a role is an abstract name for permission to access a particular set of resources. A role can be compared to a key that can open a lock. Many people might have a copy of the key; the lock doesn't care who you are, only that you have the right key.

263. What is rollback

The point in a transaction when all updates to any resources involved in the transaction are reversed.

264. What is root

The outermost element in an XML document. The element that contains all other elements.

265. What is SAX

Abbreviation of Simple API for XML.

266. What is Simple API for XML

An event-driven interface in which the parser invokes one of several methods supplied by the caller when a parsing event occurs. Events include recognizing an XML tag, finding an error, encountering a reference to an external entity, or processing a DTD specification.

267. What is schema

A database-inspired method for specifying constraints on XML documents using an XML-based language. Schemas address deficiencies in DTDs, such as the inability to put constraints on the kinds of data that can occur in a particular field. Because schemas are founded on XML, they are hierarchical. Thus it is easier to create an unambiguous specification, and it is possible to determine the scope over which a comment is meant to apply.

268. What is Secure Socket Layer (SSL)

A technology that allows Web browsers and Web servers to communicate over a secured connection.

267. What is security attributes

A set of properties associated with a principal. Security attributes can be associated with a principal by an authentication protocol or by a J2EE product provider or both.

268. What is security constraint

A declarative way to annotate the intended protection of Web content. A security constraint consists of a Web resource collection, an authorization constraint, and a user data constraint.

269. What is security context

An object that encapsulates the shared state information regarding security between two entities.

270. What is security permission

A mechanism defined by J2SE, and used by the J2EE platform to express the programming restrictions imposed on application component developers.

271. What is security permission set

The minimum set of security permissions that a J2EE product provider must provide for the execution of each component type.

272. What is security policy domain

A scope over which security policies are defined and enforced by a security administrator. A security policy domain has a collection of users (or principals), uses a well-defined authentication protocol or protocols for authenticating users (or principals), and may have groups to simplify setting of security policies.

273. What is security role

An abstract logical grouping of users that is defined by the application assembler. When an application is deployed, the roles are mapped to security identities, such as principals or groups, in the operational environment. In the J2EE server authentication service, a role is an abstract name for permission to access a particular set of resources. A role can be compared to a key that can open a lock. Many people might have a copy of the key; the lock doesn't care who you are, only that you have the right key.

274. What is security technology domain

A scope over which the same security mechanism is used to enforce a security policy. Multiple security policy domains can exist within a single technology domain.

275. What is security view

The set of security roles defined by the application assembler.

276. What is server certificate

Used with the HTTPS protocol to authenticate Web applications. The certificate can be self-signed or approved by a certificate authority (CA). The HTTPS service of the Sun Java System Application Server Platform Edition 8 will not run unless a server certificate has been installed.

277. What is server principal

The OS principal that the server is executing as.

278. What is service element

A representation of the combination of one or more Connector components that share a single engine component for processing incoming requests.

279. What is service endpoint interface

A Java interface that declares the methods that a client can invoke on a Web service.

280. What is servlet

A Java program that extends the functionality of a Web server, generating dynamic content and interacting with Web applications using a request-response paradigm

281. What is servlet container

A container that provides the network services over which requests and responses are sent, decodes requests, and formats responses. All servlet containers must support HTTP as a protocol for requests and responses but can also support additional request-response protocols, such as HTTPS.

282. What is servlet container, distributed

A servlet container that can run a Web application that is tagged as distributable and that executes across multiple Java virtual machines running on the same host or on different hosts.

283. What is servlet context

An object that contains a servlet's view of the Web application within which the servlet is running. Using the context, a servlet can log events, obtain URL references to resources, and set and store attributes that other servlets in the context can use.

284. What is servlet mapping

Defines an association between a URL pattern and a servlet. The mapping is used to map requests to servlets.

285. What is session

An object used by a servlet to track a user's interaction with a Web application across multiple HTTP requests.

286. What is session bean

An enterprise bean that is created by a client and that usually exists only for the duration of a single client-server session. A session bean performs operations, such as calculations or database access, for the client. Although a session bean can be transactional, it is not recoverable should a system crash occur. Session bean objects either can be stateless or can maintain conversational state across methods and transactions. If a session bean maintains state, then the EJB container manages this state if the object must be removed from memory. However, the session bean object itself must manage its own persistent data.

287. What is SGML

Standard Generalized Markup Language. The parent of both HTML and XML. Although HTML shares SGML's propensity for embedding presentation information in the markup, XML is a standard that allows information content to be totally separated from the mechanisms for rendering that content.

288. What is SOAP

Simple Object Access Protocol. A lightweight protocol intended for exchanging structured information in a decentralized, distributed environment. It defines, using XML technologies, an extensible messaging framework containing a message construct that can be exchanged over a variety of underlying protocols.

289. What is SOAP with Attachments API for Java (SAAJ)

The basic package for SOAP messaging, SAAJ contains the API for creating and populating a SOAP message.

290. What is SQL

Structured Query Language. The standardized relational database language for defining database objects and manipulating data.

291. What is SQL/J

A set of standards that includes specifications for embedding SQL statements in methods in the Java programming language and specifications for calling Java static methods as SQL stored procedures and user-defined functions. An SQL checker can detect errors in static SQL statements at program development time, rather than at execution time as with a JDBC driver.

292. What is SSL

Secure Socket Layer. A security protocol that provides privacy over the Internet. The protocol allows client-server applications to communicate in a way that cannot be eavesdropped upon or tampered with. Servers are always authenticated, and clients are optionally authenticated.

293. What is stateful session bean

A session bean with a conversational state.

294. What is stateless session bean

A session bean with no conversational state. All instances of a stateless session bean are identical.

295. What is system administrator

The person responsible for configuring and administering the enterprise's computers, networks, and software systems.

296. What is tag

In XML documents, a piece of text that describes a unit of data or an element. The tag is distinguishable as markup, as opposed to data, because it is surrounded by angle brackets (< and >). To treat such markup syntax as data, you use an entity reference or a CDATA section.

297. What is template

A set of formatting instructions that apply to the nodes selected by an XPath expression.

298. What is tool provider

An organization or software vendor that provides tools used for the development, packaging, and deployment of J2EE applications.

299. What is transaction attribute

A value specified in an enterprise bean's deployment descriptor that is used by the EJB container to control the transaction scope when the enterprise bean's methods are invoked. A transaction attribute can have the following values: Required, RequiresNew, Supports, NotSupported, Mandatory, or Never.

300. What is transaction

An atomic unit of work that modifies data. A transaction encloses one or more program statements, all of which either complete or roll back. Transactions enable multiple users to access the same data concurrently.