Glossary


This glossary provides definitions for common terms used to describe the iAS deployment and development environment. For a glossary of standard J2EE terms, please see the glossary at http://java.sun.com/j2ee/glossary.html.

ACL. Access Control List, a list of users or groups and their specified permissions. See component ACL, general ACL.

administration server. A process in iPlanet Application Server that handles administrative tasks.

API. Application Programmer Interface, a set of instructions that a computer program can use to communicate with other software or hardware that is designed to interpret that API.

applet. A small application written in Java that runs in a web browser. Typically, applets are called by or embedded in web pages to provide special functionality. By contrast, a servlet is a small application that runs on a server.

application. A computer program that performs a task or service for a user. Also see web application.

application event. A named action that you register with the iAS registry. The event occurs either when a timer expires or when the event is called (triggered) from application code at run time. Typical uses for events include periodic backups, reconciling accounts at the end of the business day, or sending alert messages.

application server. A program that runs an application in a client/server environment, executing the logic that makes up the application and acting as middleware between a web browser and a datasource.

application tier. A conceptual division of an application:

client tier: The user interface (UI). End users interact with client software (web browser) to use the application.

server tier: The business logic and presentation logic that make up your application, defined in the application's components.

data tier: The data access logic that enables your application to interact with a datasource.

AppLogic. A iAS-specific class responsible for completing a well-defined, modular task within a iPlanet Application Server application. In NAS 2.1, applications used AppLogics to perform actions such as handling form input, accessing data, or generating data used to populate HTML templates. This functionality is replaced with servlets and JSPs in iAS.

AppPath. An iAS registry entry that contains the name of the directory where application files reside. This entry defines the top of a logical directory tree for the application, similarly to the document path in a web server. By default, AppPath contains the value BasePath/APPS, where BasePath is the base iAS directory. (BasePath is also a iAS variable.)

attribute . Attributes are name-value pairs in a request object that can be set by servlets. Contrast with parameter. More generally, an attribute is a unit of metadata.

authentication. The process of verifying a user-provided username and password.

BasePath. A iAS registry entry that contains the directory where iAS is installed, including the iAS subdirectory (other iPlanet products can also be installed in BasePath). For instance, if you install into /usr/local/iPlanet on a UNIX machine, BasePath is /usr/local/iPlanet/ias. BasePath is a building block for AppPath.

bean property file. A text file containing EJB deployment information. The type of information is defined in javax.ejb.DeploymentDescriptor.

bean-managed transaction. See declarative transaction.

business logic. The implementation rules determined by an application's requirements.

business method. Method that performs a single business task, such as querying a database or authenticating a user, in the course of business logic.

C++ server. A process in iPlanet Application Server that runs and manages C++ objects.

cached rowset. A CachedRowSet object permits you to retrieve data from a datasource, then detach from the datasource while you examine and modify the data. A cached rowset keeps track both of the original data retrieved, and any changes made to the data by your application. If the application attempts to update the original datasource, the rowset is reconnected to the datasource, and only those rows that have changed are merged back into the database.

callable statement. A class that encapsulates a database procedure or function call for databases that support returning result sets from stored procedures.

class. A named set of methods and member variables that define the characteristics of a particular type of object. The class defines what types of data and behavior are possible for this type of object. Contrast with interface.

class file. A file that contains a compiled class, usually with a .class extension. See also class name, classpath. Normally referred to in terms of its location in the filesystem, as in

.../com/myDomain/myPackage/myClass.

class loader. A Java component responsible for loading Java classes, according to specific rules.

class name. The name of a class in the Java Virtual Machine. See also class file, classpath.

classpath. The path that identifies a Java class or package, in terms of its derivation from other classes or packages. See also class file, class name. For example,

com.myDomain.myPackage.myClass.

client. An entity that invokes a resource.

client contract. A contract that determines the communication rules between a client and the EJB container, establishes a uniform development model for apps that use EJBs, and guarantees greater reuse of beans by standardizing the relationship with the client. See Enterprise JavaBean (EJB).

cluster. A set of hosts running the same server software in tandem with each other.

co-locate. Positioning a component in the same memory space as a related component in order avoid remote procedure calls and improve performance.

column. A field in a database table.

commit. Complete a transaction by sending the required commands to the database. See transaction.

component. A servlet, Enterprise JavaBean (EJB), or JavaServer Page (JSP).

component ACL. A property in a servlet or EJB configuration file that defines that defines the users or groups that may execute.

component contract. A contract that establishes the relationship between an Enterprise JavaBean (EJB) and its container. See Enterprise JavaBean (EJB).

configuration. The process of providing metadata for a component. Normally, the configuration for a specific component is kept in a file that is uploaded into the registry when the component executes.

container. A process that executes and provides services for an EJB.

context, server. A programmatic view of the state of the server, represented by an object.

control descriptor. A set of Enterprise JavaBean (EJB) configuration entries that enable you to specify optional individual property overrides for bean methods, plus EJB transaction and security properties.

cookie. A small collection of information that can be transmitted to a calling web browser, then retrieved on each subsequent call from that browser so the server can recognize calls from the same client. Cookies are domain-specific and can take advantage of the same web server security features as other data interchange between your application and the server.

CORBA. Common Object Request Broker Architecture, a standard architecture definition for object-oriented distributed computing.

data access logic. Business logic that involves interacting with a datasource.

database. A generic term for Relational Database Management System (RDBMS). A software package that enables the creation and manipulation of large amounts of related, organized data.

database connection. A database connection is a communication link with a database or other datasource. Components can create and manipulate several database connections simultaneously to access data.

datasource. A handle to a source of data, such as a database. Datasources are registered with the iAS and then retrieved programmatically in order to establish connections and interact with the datasource. A datasource definition specifies how to connect to the source of data.

declarative security. Declaring security properties in the component's configuration file and allowing the component's container (i.e., a bean's container or a servlet engine) to manage security implicitly. This type of security requires no programmatic control. Opposite of programmatic security.

declarative transaction. Declaring the transaction's properties in the bean property file and allowing the bean's container to manage the transaction implicitly. This type of transaction requires no programmatic control. Opposite of programmatic transaction.

deploy. To create a copy of all the files in a project on one or more servers, in such a way that one or more iPlanet Application Servers and optionally one or more web servers can run the application.

deployment descriptor. An attribute that determines how and where an Enterprise JavaBean (EJB) is deployed. See Enterprise JavaBean (EJB).

Directory Server. An LDAP server that is bundled with iPlanet Application Server. Every instance of iPlanet Application Server uses Directory Server to store shared server information, including information about users and groups.

distributable session. A user session that is distributable among all servers in a cluster.

distributed transaction. A single transaction that can apply to multiple heterogeneous databases that may reside on separate servers.

dynamic reloading. Updating and reloading a component without restarting the server. By default, servlet and JavaServer Page (JSP) components can be dynamically reloaded.

e-commerce. Industry buzzword, a term meaning electronic commerce, indicating business done over the Internet.

Enterprise JavaBean (EJB). A business logic component for applications in a multitiered, distributed architecture. EJBs conform to the Java EJB standard specifications, which defines beans in terms of their expected roles. An EJB encapsulates one or more application tasks or application objects, including data structures and the methods that operate on them. Typically they also take parameters and send back return values. EJBs always work within the context of a container, which serves as a link between the EJBs and the server that hosts them. See also container, session EJB, and entity EJB.

entity EJB. An entity Enterprise JavaBean (EJB) relates to physical data, such as a row in a database. Entity beans are long-lived, because they are tied to persistent data. Entity beans are always transactional and multiuser aware. Also see session EJB.

executive server. Process in iPlanet Application Server that handles executive functions such as load balancing and process management.

failover recovery. A process whereby a bean can transparently survive a server crash.

finder method. Method which enables clients to look up a bean or a collection of beans in a globally available directory. See Enterprise JavaBean (EJB).

form action handler. A specially defined method in a servlet or AppLogic that performs an action based on a named button on a form.

general ACL. A named list in the Directory Server that relates a user or group with one or more permissions. This list can be defined and accessed arbitrarily to record any set of permissions.

generic application. A collection of globally available components, loosely organized into an application structure for configuration purposes.

generic servlet. A servlet that extends javax.servlet.GenericServlet. Generic servlets are protocol independent, meaning that they contain no inherent support for HTTP or any other transport protocol. Contrast with HTTP servlet.

global database connection. A database connection available to multiple component. Requires a resource manager.

global transaction. A transaction that is managed and coordinated by a transaction manager and can span multiple databases and processes. The transaction manager typically uses the XA protocol to interact with the database backends. Also see local transaction.

group. A group of users that are related in some way, maintained by a local system administrator. See also user, role.

GUID. 128-bit hexadecimal number, guaranteed to be globally unique, used to identify components in an iAS application.

home interface. A mechanism that defines the methods that enable a client to create and remove an Enterprise JavaBean (EJB). See Enterprise JavaBean (EJB).

HTML. Hypertext Markup Language. A coding markup language used to create documents that can be displayed by web browsers. Each block of text is surrounded by codes that indicate the nature of the text.

HTML page. A page coded in HTML and intended for display in a web browser.

HTTP. A protocol for communicating hypertext documents across the Internet.

HTTP servlet. A servlet that extends javax.servlet.HttpServlet. These servlets have built-in support for the HTTP protocol. Contrast with generic servlet.

iAS registry. A collection of application metadata, organized in a tree, that is continually available in active memory or on a readily-accessible Directory Server.

iASRowSet. A RowSet object that incorporates iAS extensions. The iASRowSet class is a subclass of ResultSet.

IIOP. Internet Inter-Orb Protocol. Transport protocol for RMI clients and servers, based on CORBA.

inheritance. A mechanism in which a subclass automatically includes the method and variable definitions of its superclass. A programmer can change or add to the inherited characteristics of a subclass without affecting the superclass.

instance. An object that is based on a particular class. Each instance of the class is a distinct object, with its own variable values and state. However, all instances of a class share the variable and method definitions specified in that class.

instantiation. The process of allocating memory for an object at run time. See instance.

interface. Description of the services provided by an object. An interface defines a set of functions, called methods, and includes no implementation code. An interface, like a class, defines the characteristics of a particular type of object. However, unlike a class, an interface is always abstract. A class is instantiated to form an object, but an interface is implemented by an object to provide it with a set of services. Contrast with class.

isolation level. (JDBC) Sets the level at which the datasource connection makes transactional changes visible to calling objects such as ResultSets.

jar file contract. A contract that specifies what information must be in the Enterprise JavaBean (EJB)'s package (jar file). See Enterprise JavaBean (EJB).

JavaBean. A discrete, reusable Java object.

Java server. Process in iPlanet Application Server that runs and manages Java objects.

JavaServer Page (JSP). A text page written using a combination of HTML or XML tags, JSP tags, and Java code. JSPs combine the layout capabilities of a standard browser page with the power of a programming language.

JDBC. Java Database Connectivity APIs. A standards-based set of classes and interfaces that enable developers to create data-aware components. JDBC implements methods for connecting to and interacting with datasources in a platform- and vendor-independent way.

JNDI. Java Naming and Directory Interface. JNDI provides a uniform, platform-independent way for applications to find and access remote services over a network. iAS supports JNDI lookups for datasources and Enterprise JavaBean (EJB) components.

JTA. Java Transaction API. This is an API that allows applications and J2EE servers to access transactions.

J2EE. Java 2 Enterprise Edition. This is an environment for developing and deploying multi-tiered, Web-based enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing these applications.

kas. See administration server.

kcs. See C++ server.

kjs. See Java server.

kxs. See executive server.

LDAP. Lightweight Directory Access Protocol. LDAP is an open directory access protocol that runs over TCP/IP. It is scalable to a global size and millions of entries. Using Directory Server, a provided LDAP server, you can store all of your enterprise's information in a single, centralized repository of directory information that any application server can access via the network.

load balancing. A technique for distributing the user load evenly among multiple servers in a cluster. Also see sticky load balancing.

local database connection. The transaction context in a local connection is not distributed across processes or across datasources; it is local to the current process and to the current datasource.

local session. A user session that is only visible to one server.

local transaction. A transaction that is native to one database and is restricted within a single process. Local transactions can work against only a single backend. Local transactions are typically demarcated using JDBC APIs. Also see global transaction.

memory cache. An iAS feature that enables a servlet to cache its results for a specific duration in order to improve performance. Subsequent calls to that servlet within the duration are given the cached results so that the servlet does not have to execute again.

metadata. Information about a component, such as its name, and specifications for its behavior.

package. A collection of related classes that are literally packaged together in a Java archive (.jar) file.

parameter. Parameters are name-value pairs sent from the client, including form field data, HTTP header information, etc., and encapsulated in a request object. Contrast with attribute. More generally, an argument to a Java method or database prepared command.

passivation. A method of releasing an EJB's resources without destroying the bean. In this way, a bean is made to be persistent, and can be recalled without the overhead of instantiation. See Enterprise JavaBean (EJB).

permission. A set of privileges granted or denied to a user or group. See also ACL.

persistent. Refers to the creation and maintenance of a bean throughout the lifetime of the application. In iAS, beans are responsible for their own persistence, called bean-managed persistence. Opposite of transient.

pooling. Providing a number of preconfigured resources to improve performance. If a resource is pooled, a component can use an existing instance from the pool rather than instantiating a new one. In iAS, database connections, servlet instances, and Enterprise JavaBean (EJB) instances can all be pooled.

prepared command. A database command (in SQL) that is precompiled to make repeated execution more efficient. Prepared commands can contain parameters. A prepared statement contains one or more prepared commands.

prepared statement. A class that encapsulates a query, update, or insert statement that is used repeatedly to fetch data. A prepared statement contains one or more prepared command.

presentation layout. Creating and formatting page content.

presentation logic. Activities that create a page in an application, including processing a request, generating content in response, and formatting the page for the client.

primary key class name. A variable that specifies the fully qualified class name of a bean's primary key. Used for JNDI lookups.

principal. This is the identity assigned to an entity as a result of authentication.

process. A sequence of execution in an active program. A process is made up of one or more threads.

programmatic security. Controlling security explicitly in code rather than allowing the component's container (i.e., a bean's container or a servlet engine) to handle it. Opposite of declarative security.

programmatic transaction. Controlling a transaction explicitly in code rather than allowing an Enterprise JavaBean (EJB)'s container to handle it. Opposite of declarative transaction.

property. A single attribute that defines the behavior of an application component.

registration. The process by which iAS gains access to a servlet, Enterprise JavaBean (EJB), and other application resource, so named because it involves placing entries in the iAS registry for each item.

remote interface. Describes how clients can call a Enterprise JavaBean (EJB)'s methods. See Enterprise JavaBean (EJB).

remote procedure call (RPC). A mechanism for accessing a remote object or service.

request object. An object that contains page and session data produced by a client, passed as an input parameter to a servlet or JavaServer Page (JSP).

resource manager. Object that controls globally-available datasources.

response object. An object that references the calling client and provides methods for generating output for the client.

ResultSet. An object that implements the java.sql.ResultSet interface. ResultSets are used to encapsulate a set of rows retrieved from a database or other source of tabular data.

reusable component. A component created so that it can be used in more than one capacity, i.e., by more than one resource or application.

RMI. Remote Method Invocation (RMI), a Java standard set of APIs that enable developers to write remote interfaces that can pass objects to remote processes.

role. A functional grouping of subjects in an application, represented by one or more groups in a deployed environment. See also user, group.

rollback. Cancel a transaction. See transaction.

row. One single data record that contains values for each column in a table.

RowSet. An object that encapsulates a set of rows retrieved from a database or other source of tabular data. RowSet extends the java.sql.ResultSet interface, enabling a ResultSet to act as a JavaBeans component.

security. A condition whereby application resources are only used by authorized clients.

serializable. An object is serializable if it can be deconstructed and reconstructed, which enables it to be stored or distributed among multiple servers.

server. A computer or software package that provides a specific kind of service to client software running on other computers. A server is designed to communicate with a specific type of client software.

servlet. An instance of the Servlet class. A servlet is a reusable application that runs on a server. In iAS, a servlet acts as the central dispatcher for each interaction in your application by performing presentation logic, invoking business logic, and invoking or performing presentation layout.

servlet engine. An internal object that handles all servlet metafunctions. Collectively, a set of processes that provide services for a servlet, including instantiation and execution.

servlet runner. Part of the servlet engine that invokes a servlet with a request object and a response object. See servlet engine.

session cookie. A cookie that is returned to the client containing a user session identifier.

session EJB. A session Enterprise JavaBean (EJB) relates to a unit of work, such as a request for data. Session beans are short lived—the lifespan of the client request is the same as the lifespan of the session bean. Session beans can be stateless or stateful, and they can be transaction aware. See stateful session EJB and stateless session EJB. Also see entity EJB.

session timeout. A specified duration after which iAS can invalidate a user session. See user session.

SQL. Structured Query Language (SQL) is a language commonly used in relational database applications. SQL2 and SQL3 designate versions of the language.

state. 1. The circumstances or condition of an entity at any given time. 2. A distributed data storage mechanism which you can use to store the state of an application using the iAS feature interface IState2.

stateful session EJB. An Enterprise JavaBean (EJB) that represents a session with a particular client and which automatically maintains state across multiple client-invoked methods.

stateless session EJB. An Enterprise JavaBean (EJB) that represents a stateless service. A stateless session bean is completely transient and encapsulates a temporary piece of business logic needed by a specific client for a limited time span.

sticky cookie. A cookie that is returned to the client to force it to always connect to the same executive server process.

sticky load balancing. A method of load balancing where an initial client request is load balanced, but subsequent requests are directed to the same process as the initial request. Also see load balancing.

stored procedure. A block of statements written in SQL and stored in a database. You can use stored procedures to perform any type of database operation, such as modifying, inserting, or deleting records. The use of stored procedures improves database performance by reducing the amount of information that is sent over a network.

streaming. A technique for managing how data is communicated via HTTP. When results are streamed, the first portion of the data is available for use immediately. When results are not streamed, the whole result must be received before any part of it can be used. Streaming provides a way to allow large amounts of data to be returned in a more efficient way, increasing the perceived performance of the application.

system administrator. The person who is responsible for installing and maintaining iPlanet Application Server software and for deploying production iAS applications.

table. A named group of related data in rows and columns in a database.

thread. A sequence of execution inside a process. A process may allow many simultaneous threads, in which case it is multithreaded. If a process executes each thread sequentially, it is single-threaded.

transaction context. A transaction's scope, either local or global. See local transaction, global transaction.

transaction manager. Object that controls a global transaction, normally using the XA protocol. See global transactions.

transaction. A set of database commands that succeed or fail as a group. All the commands involved must succeed for the entire transaction to succeed.

transient. A resource that is released when it is not being used. Opposite of persistent.

URI. Universal Resource Identifier, describes specific resource at a domain. Locally described as a subset of a base directory, so that /ham/burger is the base directory and a URI specifies toppings/cheese.html. A corresponding URL would be http://domain:port/toppings/cheese.html.

URL. Uniform Resource Locator. An address that uniquely identifies an HTML page or other resource. A web browser uses URLs to specify which pages to display. A URL describes a transport protocol (e.g. HTTP, FTP), a domain (e.g. www.my-domain.com), and optionally a URI.

user. A person who uses your application. Programmatically, a user name, password, and set of attributes that enables an application to recognize a client. See also group, role.

user interface (UI). The pages that define what a user sees and with which a user interacts in a web application.

user session. A series of user-application interactions that are tracked by the server. Sessions maintain user state, persistent objects, and identity authentication.

versioning. See dynamic reloading.

web application. A computer program that uses the World Wide Web for connectivity and user interface (UI). A user connects to and runs a web application by using a web browser on any platform. The user interface of the application is the HTML pages displayed by the browser. The application itself runs on a web server and/or application server.

web browser. Software that is used to view resources on the World Wide Web, such as web pages coded in HTML or XML.

web connector plug-in. An extension to a web server that enables it to communicate with a iPlanet Application Server.

web server. A host that stores and manages HTML pages and web applications. The web server responds to user requests from web browsers.

XA protocol. A database industry standard protocol for distributed transactions.

XML. XML, the Extensible Markup Language, uses HTML-style tags to identify the kinds of information used in documents as well as to format documents.