The role of Application Server is to process business logic components deployed as EJB (Java / J2EE applications).
Which are the prominent Application Servers available in market?
Oracle Application Server, IBM Webshphere Application Server, BEA Web Logic
What do you mean by OC4J ?
Oracle Container for Java - OC4J is J2EE certified and provides all the containers, APIs, and services that J2EE specifies
What is a Web Service?
The term Web services describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.
What is WSDL ?
WSDL is a document written in XML. The document describes a Web service. It specifies the location of the service and the operations (or methods) the service exposes.
What is XSD ?
XSD (XML Schema Definition), a Recommendation of the World Wide Web Consortium (W3C), specifies how to formally describe the elements in an Extensible Markup Language (XML) document. This description can be used to verify that each item of content in a document adheres to the description of the element in which the content is to be placed. An XML schema represents the interrelationship between the attributes and elements of an XML object
XSD has several advantages over earlier XML schema languages, such as document type definition (DTD) or Simple Object XML (SOX). For example, it's more direct: XSD, in contrast to the earlier languages, is written in XML, which means that it doesn't require intermediary processing by a parser. Other benefits include self-documentation, automatic schema creation, and the ability to be queried through XML Transformations (XSLT)
What is RPC?
Remote Procedure Call. The ability to call a procedure residing on remote system from local system.
What do you mean by STUB ?
There is CLIENT STUB and SERVER STUB. RPC's essential concept is hiding all the network code in the stub procedures. "RPGGen" . Sun RPC offers a program called rpcgen, which takes a specification of a remote procedure and converts it to C programs containing all the network information to process the request.
What is Orion Server?
Orion is an Application Server
What is JNDI?
The Java Naming and Directory Interface (JNDI) is a Java API for a directory service that allows Java software clients to discover and look up data and objects via a name. Like all Java APIs that interface with host systems, JNDI is independent of the underlying implementation.
What is JMS?
Java messaging service is the standard API for sending and receiving messages. JMS is the standard messaging API for passing data between application components and allowing business integration in heterogeneous and legacy environments.
JMS provides two messaging domains, each associated with a JMS destination type, and a domain-specific set of Java interfaces:
Point-to-Point—Messages are sent to a single consumer using a JMS queue.
Publish/Subscribe—Messages are broadcast to all registered listeners using a JMS topic.
JMS destination objects are bound in the JNDI environment and made available to J2EE applications.
What does a JMS application typically consist of?
A JMS application is composed of the following parts:
JMS Provider - a messaging system that implements the JMS API in addition to the other administrative and control functionality required of a full-featured messaging product
JMS Clients - the Java language programs that send and receive messages
Messages - objects that are used to communicate information between the clients of an application
Administered Objects - provider-specific objects that clients look up and use to interact portably with a JMS provider
Non-JMS Clients - clients that use a message system's native client API instead of the JMS API. If the application predated the availability of the JMS API, it is likely that it will include both JMS clients and non-JMS clients.
How does JMS client execute?
A typical JMS client executes the following setup procedure:
Use JNDI to find a ConnectionFactory object
Use JNDI to find one or more Destination objects
Use the ConnectionFactory to create a JMS Connection with message delivery inhibited
Use the Connection to create one or more JMS Sessions
Use a Session and the Destinations to create the MessageProducers and MessageConsumers needed
Enable the Connection to start delivering messages to MessageConsumers
What is the difference between Quartz and Flux?
Java developers embed Flux in their applications to enable Job Scheduling, File Transfer, and Workflow. Flux is an embeddable, pure Java solution that increases productivity by meeting the challenges of Job Scheduling, File Transfer, and Workflow. By combining Flux's APIs and user-friendly graphical interfaces, Flux becomes the "engine" that enables highly scalable solutions. It is used in a variety of applications by customers across multiple industry sectors. Examples:
In banking operations, end of day reports need to be run after the close of the stock exchange. Flux can be used to schedule the time the report is to be run, kick off the report generation, and then email the report to the appropriate people
What is Context Factory?
There are two initial context factories that are used for OC4J. They are ApplicationClientInitialContextFactory, RMInitialContextFactory.
The ApplicationClientInitialContextFactory is used when looking up remote objects from standalone application clients. It uses the refs and ref-mappings found in application-client.xml and orionapplication-client.xml. It is the default initial context factory when the initial context is instantiated in a Java application. It can be used for looking up remote EJBs in the same application. It can also be used for looking up EJBs with local interface.
The RMIInitialContextFactory is used when looking up remote objects between different containers. It is also used when browsing the complete JNDI namespace and not using the application context.
What is Connection Factory?
A ConnectionFactory object encapsulates a set of connection configuration parameters that has been defined by an administrator. A client uses it to create a connection with a JMS provider ( eg IBM MQ Series).
A ConnectionFactory object is a JMS administered object and supports concurrent use.
JMS administered objects are objects containing configuration information that are created by an administrator and later used by JMS clients. They make it practical to administer the JMS API in the enterprise.
Although the interfaces for administered objects do not explicitly depend on the Java Naming and Directory Interface (JNDI) API, the JMS API establishes the convention that JMS clients find administered objects by looking them up in a JNDI namespace.
All Known Subinterfaces: QueueConnectionFactory, TopicConnectionFactory, XAQueueConnectionFactory, XATopicConnectionFactory
What is difference between Managed and Native Data Source?
A managed data source is one where OC4J provides critical system infrastructure such as global transaction management, connection pooling, statement caching and error handling. A native data source is one that implements the java.sql.DataSource interface and does not make use of OC4J's connection pooling or statement caching capabilities. A native data source can only participate in local transactions.
What is difference between XA and non XA Datasource ?
XA Datasource represents Managed Connection , Connection pool creation is required when an XA Datasource is to be created.
An XA data source is a data source that can participate in an XA global transaction.
A non-XA data source generally can't participate in a global transaction.
An XA transaction, in the most general terms, is a "global transaction" that may span multiple resources. A non-XA transaction always involves just one resource. An XA transaction involves a coordinating transaction manager, with one or more databases (or other resources, like JMS) all involved in a single global transaction. Non-XA transactions have no transaction coordinator, and a single resource is doing all its transaction work itself (this is sometimes called local transactions).
What is the purpose of importing/exporting shared library oracle.xml in different modes of gateway deployments?
A shared library consists of a set of code-sources from which Java classes can be loaded by a class loader. A shared library has a name and a version. By default, an application deployed to OC4J inherits a number of pre-defined shared-libraries. Oracle.xml is a shared library
What is the use of Resource Adapter?
A resource adapter is a driver that an application server or an application client uses to connect to a specific EIS. Examples of resource adapters are a JDBC driver to connect to a relational database, an ERP resource adapter to connect to an ERP system, and a transaction processing (TP) resource adapter to connect to a TP monitor. The J2EE 1.3 specification requires application servers to support both standalone and embedded resource adapters.
What protocols can I use to access an EJB remotely?
You can use three protocols to access EJBs remotely. You can use ORMI (Oracle's implementation of RMI
Protocol) for Java clients, ORMI over SSL, RMI-IIOP for CORBA clients or ORMI tunneling over HTTP to
access EJBs from remote client through firewall. See the OC4J Services Guide for more information.
What is the use of ra.xml file?
The ra.xml descriptor is the standard J2EE deployment descriptor for resource adapters
What is oc4j-ra.xml?
The oc4j-ra.xml descriptor provides OC4J-specific deployment information for resource adapters. The file contains one or more
You can do the following using oc4j-ra.xml:
Configure and bind instances of connection factories.
Connection factories are used by application components to obtain connections to the EIS. The name of the connection factory class is specified in the connectionfactory-impl-class element, defined in ra.xml. OC4J allows the deployer to configure instances of this class and to bind them to the Java Naming and Directory Interface (JNDI) name space.
The deployer can do this by creating
The list of configurable properties is specified in ra.xml, as
How many Deployment Descriptors are there for Resource Adapter?
OC4J supports three deployment descriptors: ra.xml, oc4j-ra.xml, and oc4j-connectors.xml. The ra.xml descriptor is always supplied with the resource adapter. Whenever you deploy a resource adapter, OC4J generates oc4j-ra.xml if the file doesn't already exist in the archive. In addition, for an embedded resource adapter, OC4J generates oc4j-connectors.xml if it doesn't exist in the archive.
What do you mean by administered objects?
There are two types of JMS administered objects:
ConnectionFactory - the object a client uses to create a connection with a provider
Destination - the object a client uses to specify the destination of messages it is sending and the source of messages it receives
· Administered objects are placed in a Java Naming and Directory InterfaceTM (JNDI) namespace by an administrator. A JMS client typically notes in its documentation the JMS administered objects it requires and how the JNDI names of these objects should be provided to it.
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