What is “abstract schema”
The part of an entity bean’s deployment descriptor that defines the bean’s persistent fields and relationships.

What is “abstract schema name”
A logical name that is referenced in EJB QL queries.

What is “access control”
The methods by which interactions with resources are limited to collections of users or programs for the purpose of enforcing
integrity, confidentiality, or availability constraints.

What is “ACID”
The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

What is “activation”Christian Dior Handbags
The process of transferring an enterprise bean from secondary storage to memory. (See passivation.) What is “anonymous access”
Accessing a resource without authentication.

What is “applet”
A J2EE component that typically executes in a Web browser but can execute in a variety of other applications or devices that
support the applet programming model.

What is “applet container”
A container that includes support for the applet programming model.

What is “application assembler”
A person who combines J2EE components and modules into deployable application units.

What is “application client”
A first-tier J2EE client component that executes in its own Java virtual machine. Application clients have access to some
J2EE platform APIs.

What is “application client container”
A container that supports application client components. What is “application client module”
A software unit that consists of one or more classes and an application client deployment descriptor.

What is “application component provider”
A vendor that provides the Java classes that implement components’ methods, JSP page definitions, and any required deployment
descriptors.

What is “application configuration resource file”
An XML file used to configure resources for a JavaServer Faces application, to define navigation rules for the application,
and to register converters, validators, listeners, renderers, and components with the application.

What is “archiving”
The process of saving the state of an object and restoring it.

What is “asant”
A Java-based build tool that can be extended using Java classes. The configuration files are XML-based, calling out a target
tree where various tasks get executed.

What is “attribute”
A qualifier on an XML tag that provides additional information.
What is authentication
The process that verifies the identity of a user, device, or other entity in a computer system, usually as a prerequisite to
allowing access to resources in a system. The Java servlet specification requires three types of authentication-basic,
form-based, and mutual-and supports digest authentication.

What is authorization
The process by which access to a method or resource is determined. Authorization depends on the determination of whether the
principal associated with a request through authentication is in a given security role. A security role is a logical grouping
of users defined by the person who assembles the application. A deployer maps security roles to security identities. Security
identities may be principals or groups in the operational environment.

What is authorization constraint
An authorization rule that determines who is permitted to access a Web resource collection.

What is B2B
B2B stands for Business-to-business.

What is backing bean
A JavaBeans component that corresponds to a JSP page that includes JavaServer Faces components. The backing bean defines
properties for the components on the page and methods that perform processing for the component. This processing includes
event handling, validation, and processing associated with navigation. What is basic authentication
An authentication mechanism in which a Web server authenticates an entity via a user name and password obtained using the Web
application’s built-in authentication mechanism.

What is bean-managed persistence
The mechanism whereby data transfer between an entity bean’s variables and a resource manager is managed by the entity bean.

What is bean-managed transaction
A transaction whose boundaries are defined by an enterprise bean.

What is binary entity
See unparsed entity.

What is binding (XML)
Generating the code needed to process a well-defined portion of XML data.

What is binding (JavaServer Faces technology)
Wiring UI components to back-end data sources such as backing bean properties.
What is build file
The XML file that contains one or more asant targets. A target is a set of tasks you want to be executed. When starting
asant, you can select which targets you want to have executed. When no target is given, the project’s default target is
executed.

What is business logic
The code that implements the functionality of an application. In the Enterprise JavaBeans architecture, this logic is
implemented by the methods of an enterprise bean.

What is business method
A method of an enterprise bean that implements the business logic or rules of an application.

What is callback methods
Component methods called by the container to notify the component of important events in its life cycle.

What is caller
Same as caller principal.

What is caller principal
The principal that identifies the invoker of the enterprise bean method. What is cascade delete
A deletion that triggers another deletion. A cascade delete can be specified for an entity bean that has container-managed
persistence.

What is CDATA
A predefined XML tag for character data that means “don’t interpret these characters,” as opposed to parsed character data
(PCDATA), in which the normal rules of XML syntax apply. CDATA sections are typically used to show examples of XML syntax.

What is certificate authority
A trusted organization that issues public key certificates and provides identification to the bearer.

What is client-certificate authentication
An authentication mechanism that uses HTTP over SSL, in which the server and, optionally, the client authenticate each other
with a public key certificate that conforms to a standard that is defined by X.509 Public Key Infrastructure.

What is comment
In an XML document, text that is ignored unless the parser is specifically told to recognize it.
What is commit
The point in a transaction when all updates to any resources involved in the transaction are made permanent.

What is component
See what is J2EE component.

What is component (JavaServer Faces technology)
See what is JavaServer Faces UI component.

What is component contract
The contract between a J2EE component and its container. The contract includes life-cycle management of the component, a
context interface that the instance uses to obtain various information and services from its container, and a list of
services that every container must provide for its components.

What is component-managed sign-on
A mechanism whereby security information needed for signing on to a resource is provided by an application component.

What is connection
See what is resource manager connection.

What is connection factory
See what is resource manager connection factory.

What is connector
A standard extension mechanism for containers that provides connectivity to enterprise information systems. A connector is
specific to an enterprise information system and consists of a resource adapter and application development tools for
enterprise information system connectivity. The resource adapter is plugged in to a container through its support for
system-level contracts defined in the Connector architecture.
What is Connector architecture
An architecture for integration of J2EE products with enterprise information systems. There are two parts to this
architecture: a resource adapter provided by an enterprise information system vendor and the J2EE product that allows this
resource adapter to plug in. This architecture defines a set of contracts that a resource adapter must support to plug in to
a J2EE product-for example, transactions, security, and resource management.

What is container
An entity that provides life-cycle management, security, deployment, and runtime services to J2EE components. Each type of
container (EJB, Web, JSP, servlet, applet, and application client) also provides component-specific services.

What is container-managed persistence
The mechanism whereby data transfer between an entity bean’s variables and a resource manager is managed by the entity bean’s
container.

What is container-managed sign-on
The mechanism whereby security information needed for signing on to a resource is supplied by the container.

What is container-managed transaction
A transaction whose boundaries are defined by an EJB container. An entity bean must use container-managed transactions.What is content
In an XML document, the part that occurs after the prolog, including the root element and everything it contains.

What is context attribute
An object bound into the context associated with a servlet.

What is context root
A name that gets mapped to the document root of a Web application.

What is conversational state
The field values of a session bean plus the transitive closure of the objects reachable from the bean’s fields. The
transitive closure of a bean is defined in terms of the serialization protocol for the Java programming language, that is,
the fields that would be stored by serializing the bean instance.

What is CORBA
Common Object Request Broker Architecture. A language-independent distributed object model specified by the OMG.
What is create method
A method defined in the home interface and invoked by a client to create an enterprise bean.

What is credentials
The information describing the security attributes of a principal.

What is CSS
Cascading style sheet. A stylesheet used with HTML and XML documents to add a style to all elements marked with a particular
tag, for the direction of browsers or other presentation mechanisms.

What is CTS
Compatibility test suite. A suite of compatibility tests for verifying that a J2EE product complies with the J2EE platform
specification.

What is data
The contents of an element in an XML stream, generally used when the element does not contain any subelements. When it does,
the term content is generally used. When the only text in an XML structure is contained in simple elements and when elements
that have subelements have little or no data mixed in, then that structure is often thought of as XML data, as opposed to an
XML document.
What is DDP
Document-driven programming. The use of XML to define applications.

What is declaration
The very first thing in an XML document, which declares it as XML. The minimal declaration is . The
declaration is part of the document prolog.

What is declarative security
Mechanisms used in an application that are expressed in a declarative syntax in a deployment descriptor.

What is delegation
An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.

What is deployer
A person who installs J2EE modules and applications into an operational environment.

What is deployment
The process whereby software is installed into an operational environment.

What is deployment descriptor
An XML file provided with each module and J2EE application that describes how they should be deployed. The deployment
descriptor directs a deployment tool to deploy a module or application with specific container options and describes specific
configuration requirements that a deployer must resolve. What is destination
A JMS administered object that encapsulates the identity of a JMS queue or topic. See point-to-point messaging system,
publish/subscribe messaging system.

What is digest authentication
An authentication mechanism in which a Web application authenticates itself to a Web server by sending the server a message
digest along with its HTTP request message. The digest is computed by employing a one-way hash algorithm to a concatenation
of the HTTP request message and the client’s password. The digest is typically much smaller than the HTTP request and doesn’t
contain the password.

What is distributed application
An application made up of distinct components running in separate runtime environments, usually on different platforms
connected via a network. Typical distributed applications are two-tier (client-server), three-tier
(client-middleware-server), and multitier (client-multiple middleware-multiple servers).

What is document
In general, an XML structure in which one or more elements contains text intermixed with subelements. See also data.

What is Document Object Model
An API for accessing and manipulating XML documents as tree structures. DOM provides platform-neutral, language-neutral
interfaces that enables programs and scripts to dynamically access and modify content and structure in XML documents.

What is document root
The top-level directory of a WAR. The document root is where JSP pages, client-side classes and archives, and static Web
resources are stored.
What is DTD
Document type definition. An optional part of the XML document prolog, as specified by the XML standard. The DTD specifies
constraints on the valid tags and tag sequences that can be in the document. The DTD has a number of shortcomings, however,
and this has led to various schema proposals. For example, the DTD entry says that the XML
element called username contains parsed character data-that is, text alone, with no other structural elements under it. The
DTD includes both the local subset, defined in the current file, and the external subset, which consists of the definitions
contained in external DTD files that are referenced in the local subset using a parameter entity.

What is durable subscription
In a JMS publish/subscribe messaging system, a subscription that continues to exist whether or not there is a current active
subscriber object. If there is no active subscriber, the JMS provider retains the subscription’s messages until they are
received by the subscription or until they expire.

What is EAR file
Enterprise Archive file. A JAR archive that contains a J2EE application.

What is ebXML
Electronic Business XML. A group of specifications designed to enable enterprises to conduct business through the exchange of
XML-based messages. It is sponsored by OASIS and the United Nations Centre for the Facilitation of Procedures and Practices
in Administration, Commerce and Transport (U.N./CEFACT).

What is EJB
Enterprise JavaBeans.

What is EJB container
A container that implements the EJB component contract of the J2EE architecture. This contract specifies a runtime
environment for enterprise beans that includes security, concurrency, life-cycle management, transactions, deployment,
naming, and other services. An EJB container is provided by an EJB or J2EE server. What is EJB container provider
A vendor that supplies an EJB container.

What is EJB context
An object that allows an enterprise bean to invoke services provided by the container and to obtain the information about the
caller of a client-invoked method.

What is EJB home object
An object that provides the life-cycle operations (create, remove, find) for an enterprise bean. The class for the EJB home
object is generated by the container’s deployment tools. The EJB home object implements the enterprise bean’s home interface.
The client references an EJB home object to perform life-cycle operations on an EJB object. The client uses JNDI to locate an
EJB home object.

What is EJB JAR file
A JAR archive that contains an EJB module.

What is EJB module
A deployable unit that consists of one or more enterprise beans and an EJB deployment descriptor.

What is EJB object
An object whose class implements the enterprise bean’s remote interface. A client never references an enterprise bean
instance directly; a client always references an EJB object. The class of an EJB object is generated by a container’s
deployment tools.
What is EJB server
Software that provides services to an EJB container. For example, an EJB container typically relies on a transaction manager
that is part of the EJB server to perform the two-phase commit across all the participating resource managers. The J2EE
architecture assumes that an EJB container is hosted by an EJB server from the same vendor, so it does not specify the
contract between these two entities. An EJB server can host one or more EJB containers.

What is EJB server provider
A vendor that supplies an EJB server.

What is element
A unit of XML data, delimited by tags. An XML element can enclose other elements.

What is empty tag
A tag that does not enclose any content.

What is enterprise bean
A J2EE component that implements a business task or business entity and is hosted by an EJB container; either an entity bean,
a session bean, or a message-driven bean.

What is enterprise bean provider
An application developer who produces enterprise bean classes, remote and home interfaces, and deployment descriptor files,
and packages them in an EJB JAR file.
What is enterprise information system
The applications that constitute an enterprise’s existing system for handling companywide information. These applications
provide an information infrastructure for an enterprise. An enterprise information system offers a well-defined set of
services to its clients. These services are exposed to clients as local or remote interfaces or both. Examples of enterprise
information systems include enterprise resource planning systems, mainframe transaction processing systems, and legacy
database systems.

What is enterprise information system resource
An entity that provides enterprise information system-specific functionality to its clients. Examples are a record or set of
records in a database system, a business object in an enterprise resource planning system, and a transaction program in a
transaction processing system.

What is Enterprise JavaBeans (EJB)
A component architecture for the development and deployment of object-oriented, distributed, enterprise-level applications.
Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure.

What is Enterprise JavaBeans Query Language (EJB QL)
Defines the queries for the finder and select methods of an entity bean having container-managed persistence. A subset of
SQL92, EJB QL has extensions that allow navigation over the relationships defined in an entity bean’s abstract schema.

What is an entity
A distinct, individual item that can be included in an XML document by referencing it. Such an entity reference can name an
entity as small as a character (for example, <, which references the less-than symbol or left angle bracket, <). An entity
reference can also reference an entire document, an external entity, or a collection of DTD definitions.
What is entity bean
An enterprise bean that represents persistent data maintained in a database. An entity bean can manage its own persistence or
can delegate this function to its container. An entity bean is identified by a primary key. If the container in which an
entity bean is hosted crashes, the entity bean, its primary key, and any remote references survive the crash.

What is entity reference
A reference to an entity that is substituted for the reference when the XML document is parsed. It can reference a predefined
entity such as < or reference one that is defined in the DTD. In the XML data, the reference could be to an entity that is
defined in the local subset of the DTD or to an external XML file (an external entity). The DTD can also carve out a segment
of DTD specifications and give it a name so that it can be reused (included) at multiple points in the DTD by defining a
parameter entity.

What is error
A SAX parsing error is generally a validation error; in other words, it occurs when an XML document is not valid, although it
can also occur if the declaration specifies an XML version that the parser cannot handle. See also fatal error, warning.

What is Extensible Markup Language
XML.

What is external entity
An entity that exists as an external XML file, which is included in the XML document using an entity reference.

What is external subset
That part of a DTD that is defined by references to external DTD files.

What is fatal error
A fatal error occurs in the SAX parser when a document is not well formed or otherwise cannot be processed. See also error,
warning.
What is filter
An object that can transform the header or content (or both) of a request or response. Filters differ from Web components in
that they usually do not themselves create responses but rather modify or adapt the requests for a resource, and modify or
adapt responses from a resource. A filter should not have any dependencies on a Web resource for which it is acting as a
filter so that it can be composable with more than one type of Web resource.

What is filter chain
A concatenation of XSLT transformations in which the output of one transformation becomes the input of the next.

What is finder method
A method defined in the home interface and invoked by a client to locate an entity bean.

What is form-based authentication
An authentication mechanism in which a Web container provides an application-specific form for logging in. This form of
authentication uses Base64 encoding and can expose user names and passwords unless all connections are over SSL.

What is general entity
An entity that is referenced as part of an XML document’s content, as distinct from a parameter entity, which is referenced
in the DTD. A general entity can be a parsed entity or an unparsed entity.

What is group
An authenticated set of users classified by common traits such as job title or customer profile. Groups are also associated
with a set of roles, and every user that is a member of a group inherits all the roles assigned to that group.

What is handle
An object that identifies an enterprise bean. A client can serialize the handle and then later deserialize it to obtain a
reference to the enterprise bean. What is home handle
An object that can be used to obtain a reference to the home interface. A home handle can be serialized and written to stable
storage and deserialized to obtain the reference.

What is home interface
One of two interfaces for an enterprise bean. The home interface defines zero or more methods for managing an enterprise
bean. The home interface of a session bean defines create and remove methods, whereas the home interface of an entity bean
defines create, finder, and remove methods.

What is HTML
Hypertext Markup Language. A markup language for hypertext documents on the Internet. HTML enables the embedding of images,
sounds, video streams, form fields, references to other objects with URLs, and basic text formatting.

What is HTTP
Hypertext Transfer Protocol. The Internet protocol used to retrieve hypertext objects from remote hosts. HTTP messages
consist of requests from client to server and responses from server to client.

What is HTTPS
HTTP layered over the SSL protocol.

What is IDL
Interface Definition Language. A language used to define interfaces to remote CORBA objects. The interfaces are independent
of operating systems and programming languages.

What is IIOP
Internet Inter-ORB Protocol. A protocol used for communication between CORBA object request brokers.

What is impersonation
An act whereby one entity assumes the identity and privileges of another entity without restrictions and without any
indication visible to the recipients of the impersonator’s calls that delegation has taken place. Impersonation is a case of
simple delegation. What is initialization parameter
A parameter that initializes the context associated with a servlet.

What is ISO 3166
The international standard for country codes maintained by the International Organization for Standardization (ISO).

What is ISV
Independent software vendor.

What is J2EE
Java 2 Platform, Enterprise Edition.

What is J2EE application
Any deployable unit of J2EE functionality. This can be a single J2EE module or a group of modules packaged into an EAR file along with a J2EE application deployment descriptor. J2EE applications are typically engineered to be distributed across multiple computing tiers.

What is J2EE component
A self-contained functional software unit supported by a container and configurable at deployment time. The J2EE specification defines the following J2EE components:
Application clients and applets are components that run on the client.
Java servlet and JavaServer Pages (JSP) technology components are Web components that run on the server.
Enterprise JavaBeans (EJB) components (enterprise beans) are business components that run on the server.
J2EE components are written in the Java programming language and are compiled in the same way as any program in the language. The difference between J2EE components and “standard” Java classes is that J2EE components are assembled into a J2EE application, verified to be well formed and in compliance with the J2EE specification, and deployed to production, where they are run and managed by the J2EE server or client container.
What is J2EE module
A software unit that consists of one or more J2EE components of the same container type and one deployment descriptor of that type. There are four types of modules: EJB, Web, application client, and resource adapter. Modules can be deployed as stand-alone units or can be assembled into a J2EE application.

What is J2EE product
An implementation that conforms to the J2EE platform specification.

What is J2EE product provider
A vendor that supplies a J2EE product.

What is J2EE server
The runtime portion of a J2EE product. A J2EE server provides EJB or Web containers or both.

What is J2ME
Abbreviate of Java 2 Platform, Micro Edition.

What is J2SE
Abbreviate of Java 2 Platform, Standard Edition.

What is JAR
Java archive. A platform-independent file format that permits many files to be aggregated into one file. What is Java 2 Platform, Enterprise Edition (J2EE)
An environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multitiered, Web-based applications.

What is Java 2 Platform, Micro Edition (J2ME)
A highly optimized Java runtime environment targeting a wide range of consumer products, including pagers, cellular phones, screen phones, digital set-top boxes, and car navigation systems.

What is Java 2 Platform, Standard Edition (J2SE)
The core Java technology platform.

What is Java API for XML Processing (JAXP)
An API for processing XML documents. JAXP leverages the parser standards SAX and DOM so that you can choose to parse your data as a stream of events or to build a tree-structured representation of it. JAXP supports the XSLT standard, giving you control over the presentation of the data and enabling you to convert the data to other XML documents or to other formats, such as HTML. JAXP provides namespace support, allowing you to work with schema that might otherwise have naming conflicts.

What is Java API for XML Registries (JAXR)
An API for accessing various kinds of XML registries.

What is Java API for XML-based RPC (JAX-RPC)
An API for building Web services and clients that use remote procedure calls and XML. What is Java IDL
A technology that provides CORBA interoperability and connectivity capabilities for the J2EE platform. These capabilities enable J2EE applications to invoke operations on remote network services using the Object Management Group IDL and IIOP.

What is Java Message Service (JMS)
An API for invoking operations on enterprise messaging systems.

What is Java Naming and Directory Interface (JNDI)
An API that provides naming and directory functionality.

What is Java Secure Socket Extension (JSSE)
A set of packages that enable secure internet communications

.

What is Java Transaction API (JTA)
An API that allows applications and J2EE servers to access transactions.

What is Java Transaction Service (JTS)
Specifies the implementation of a transaction manager that supports JTA and implements the Java mapping of the Object Management Group Object Transaction Service 1.1 specification at the level below the API.

What is JavaBeans component
A Java class that can be manipulated by tools and composed into applications. A JavaBeans component must adhere to certain property and event interface conventions.
What is JavaMail
An API for sending and receiving email.

What is JavaServer Faces Technology
A framework for building server-side user interfaces for Web applications written in the Java programming language.

What is JavaServer Faces conversion model
A mechanism for converting between string-based markup generated by JavaServer Faces UI components and server-side Java objects.

What is JavaServer Faces event and listener model
A mechanism for determining how events emitted by JavaServer Faces UI components are handled. This model is based on the JavaBeans component event and listener model.

What is JavaServer Faces expression language
A simple expression language used by a JavaServer Faces UI component tag attributes to bind the associated component to a bean property or to bind the associated component’s value to a method or an external data source, such as a bean property. Unlike JSP EL expressions, JavaServer Faces EL expressions are evaluated by the JavaServer Faces implementation rather than by the Web container.

What is JavaServer Faces navigation model
A mechanism for defining the sequence in which pages in a JavaServer Faces application are displayed.

What is JavaServer Faces UI component
A user interface control that outputs data to a client or allows a user to input data to a JavaServer Faces application.
What is JavaServer Faces UI component class
A JavaServer Faces class that defines the behavior and properties of a JavaServer Faces UI component.

What is JavaServer Faces validation model
A mechanism for validating the data a user inputs to a JavaServer Faces UI component.

What is JavaServer Pages (JSP)
An extensible Web technology that uses static data, JSP elements, and server-side Java objects to generate dynamic content for a client. Typically the static data is HTML or XML elements, and in many cases the client is a Web browser.

What is JavaServer Pages Standard Tag Library (JSTL)
A tag library that encapsulates core functionality common to many JSP applications. JSTL has support for common, structural tasks such as iteration and conditionals, tags for manipulating XML documents, internationalization and locale-specific formatting tags, SQL tags, and functions.

What is JAXR client
A client program that uses the JAXR API to access a business registry via a JAXR provider.

What is JAXR provider
An implementation of the JAXR API that provides access to a specific registry provider or to a class of registry providers that are based on a common specification.

What is JDBC
An API for database-independent connectivity between the J2EE platform and a wide range of data sources.

What is JMS
Java Message Service.
What is JMS administered object
A preconfigured JMS object (a resource manager connection factory or a destination) created by an administrator for the use of JMS clients and placed in a JNDI namespace.

What is JMS application
One or more JMS clients that exchange messages.

What is JMS client
A Java language program that sends or receives messages.

What is JMS provider
A messaging system that implements the Java Message Service as well as other administrative and control functionality needed in a full-featured messaging product.

What is JMS session
A single-threaded context for sending and receiving JMS messages. A JMS session can be nontransacted, locally transacted, or participating in a distributed transaction.

What is JNDI
Abbreviate of Java Naming and Directory Interface.

What is JSP
Abbreviate of JavaServer Pages.

What is JSP action
A JSP element that can act on implicit objects and other server-side objects or can define new scripting variables. Actions follow the XML syntax for elements, with a start tag, a body, and an end tag; if the body is empty it can also use the empty tag syntax. The tag must use a prefix. There are standard and custom actions.
What is JSP container
A container that provides the same services as a servlet container and an engine that interprets and processes JSP pages into a servlet.

What is JSP container, distributed
A JSP container that can run a Web application that is tagged as distributable and is spread across multiple Java virtual machines that might be running on different hosts.

What is JSP custom action
A user-defined action described in a portable manner by a tag library descriptor and imported into a JSP page by a taglib directive. Custom actions are used to encapsulate recurring tasks in writing JSP pages.

What is JSP custom tag
A tag that references a JSP custom action.

What is JSP declaration
A JSP scripting element that declares methods, variables, or both in a JSP page.

 What is JSP directive

A JSP element that gives an instruction to the JSP container and is interpreted at translation time.

 What is JSP document

A JSP page written in XML syntax and subject to the constraints of XML documents.

What is JSP element

A portion of a JSP page that is recognized by a JSP translator. An element can be a directive, an action, or a scripting element.

 What is JSP expression

A scripting element that contains a valid scripting language expression that is evaluated, converted to a String, and placed into the implicit out object.

 What is JSP expression language

A language used to write expressions that access the properties of JavaBeans components. EL expressions can be used in static text and in any standard or custom tag attribute that can accept an expression.

 What is JSP page

A text-based document containing static text and JSP elements that describes how to process a request to create a response. A JSP page is translated into and handles requests as a servlet.

What is JSP scripting element

A JSP declaration, scriptlet, or expression whose syntax is defined by the JSP specification and whose content is written according to the scripting language used in the JSP page. The JSP specification desc