IntelliJ PyCharm is an advanced IDE developed by JetBrains and
focused on developer productivity. PyCharm provides smart code
completion, code inspections, on-the-fly error highlighting and
quick-fixes, along with automated code refactorings and rich
The core of the Struts framework is a flexible control layer based
on standard technologies like Java Servlets, JavaBeans,
ResourceBundles, and Extensible Markup Language (XML), as well as
various Jakarta Commons packages. Struts encourages application
architectures based on the Model 2 approach, a variation of the
classic Model-View-Controller (MVC) design paradigm.
Struts provides its own Controller component and integrates with
other technologies to provide the Model and the View. For the
Model, Struts can interact with any standard data access
technology, including Enterprise Java Beans, JDBC, and Object
Relational Bridge. For the View, Struts works well with JavaServer
Pages, including JSTL and JSF, as well as Velocity Templates, XSLT,
and other presentation systems.
The Struts framework provides the invisible underpinnings every
professional web application needs to survive. Struts helps you
create an extensible development environment for your application,
based on published standards and proven design patterns.
Provides a library of matcher objects (also known as
constraints or predicates) allowing 'match' rules to
be defined declaratively, to be used in other frameworks.
Typical scenarios include testing frameworks, mocking libraries
and UI validation rules.
InfoBus enables dynamic exchange of data between JavaBeans(TM) component
architecture by defining a small number of interfaces between cooperating
Beans and specifying the protocol for use of those interfaces. The
protocols are based on a notion of an information bus. All components
which implement these interfaces can plug into the bus. As a member of the
bus any component can exchange data with any other component in a
structured way, including arrays, tables, and database rowsets.
Commons Codec provides implementations of common encoders and decoders
such as Base64, Hex, various phonetic encodings, and URLs.
A suite of classes that extend or augment the Java Collections Framework.
There are certain holes left unfilled by Sun's implementations, and the
Jakarta-Commons Collections Component strives to fulfill them. Among the
features of this package are:
Special-purpose implementations of Lists and Maps for fast access Adapter
classes from Java1-style containers (arrays, enumerations) to Java 2-style
collections. Methods to test or create typical set-theory properties of
collections such as union, intersection, and closure.
The DBCP Component
Many Jakarta projects support interaction with a relational database.
Creating a new connection for each user can be time consuming (often
requiring multiple seconds of clock time), in order to perform a
database transaction that might take milliseconds. Opening a
connection per user can be unfeasible in a publicly-hosted Internet
application where the number of simultaneous users can be very large.
Accordingly, developers often wish to share a "pool" of open
connections between all of the application's current users. The number
of users actually performing a request at any given time is usually a
very small percentage of the total number of active users, and during
request processing is the only time that a database connection is
required. The application itself logs into the DBMS, and handles any
user account issues internally.
There are several Database Connection Pools already available, both
within Jakarta products and elsewhere. This Commons package provides
an opportunity to coordinate the efforts required to create and
maintain an efficient, feature-rich package under the ASF license.
The commons-dbcp package relies on code in the commons-pool package to
provide the underlying object pool mechanisms that it utilizes.
The Discovery Component is about discovering, or finding, implementations for
pluggable interfaces. It provides facilities instantiating classes in general,
and for lifecycle management of singleton (factory) classes.
Fundamentally, Discovery locates classes that implement a given Java interface.
The discovery pattern, though not necessarily this package, is used in many
projects including JAXP (SaxParserFactory and others) and commons-logging
(LogFactory). By extracting this pattern, other projects can (re)use it and
take advantage of improvements to the pattern as Discovery evolves.
Discovery improves over previous implementations by establishing facilities for
working within managed environments. These allow configuration and property
overrides without appealing to the global System properties (which are scoped
across an entire JVM).
The Jakarta Commons HttpClient component provides an efficient, up-to-date,
and feature-rich package implementing the client side of the most recent HTTP
standards and recommendations.
Designed for extension while providing robust support for the base HTTP
protocol, the HttpClient component may be of interest to anyone building
HTTP-aware client applications such as web browsers, web service clients,
or systems that leverage or extend the HTTP protocol for distributed
The standard Java libraries fail to provide enough methods for
manipulation of its core classes. The Lang Component provides
these extra methods.
The Lang Component provides a host of helper utilities for the
java.lang API, notably String manipulation methods, basic
numerical methods, object reflection, creation and serialization,
and System properties. Additionally it contains an inheritable
enum type, an exception structure that supports multiple types of
nested-Exceptions and a series of utlities dedicated to help with
building methods, such as hashCode, toString and equals.