Spring Roo
Encyclopedia
Spring Roo is an open source
software tool that uses convention-over-configuration
principles to provide rapid application development
of Java
-based enterprise software
. The resulting applications use common Java technologies such as Spring Framework, Java Persistence API
, Java Server Pages
, Apache Maven
and AspectJ
. Spring Roo is a member of the Spring portfolio of projects.
The technology was first demonstrated during the opening keynote at the SpringOne Europe developer conference on 27 April 2009, with an initial alpha release concurrently being published. During the keynote an application was built live on-stage that would be used by conference attendees to vote on the preferred name for the project (which at that time was codenamed "Roo" within SpringSource
). Ultimately the name "Spring Roo" was preferred over alternatives including Spring Boost, Spring Spark, Spring HyperDrive and Spring Dart.
Several releases followed, with the Roo 1.0.0.RELEASE (general availability
) released in December 2009. In October 2010, Spring Roo 1.1.0.RELEASE was released. The 1.1.0 release moved to an OSGi foundation with associated add-on discovery model, plus added support for incremental database reverse engineering, Spring MVC page complexity reduction, Google Web Toolkit, Google App Engine, Apache Solr, JSON and smaller features like serializable automation. The current Roo project engineers are employed by SpringSource and as such Roo releases typically support the latest available releases of other Spring portfolio projects.
The above list can be augmented through additional Roo add-ons, which provide Roo's method of extensibility
.
. The shell provides both a command-line interface
and also a mechanism to host plug-ins (which are called "add-ons" in Roo). One key design goal of Roo is to ensure a user can continue to work in a "natural way", which typically means using their preferred integrated development environment
(IDE) or text editor
for most tasks. As such Roo is often loaded in a separate window to the IDE or text editor, and will monitor the file system for changes made by the user outside of Roo. A startup-time scan of a user's project is also performed to determine any changes that may have been made while Roo was not running.
The user interface shell supports extensive usability
features including command line completion
(ie press TAB), online help
, hinting (a form of context-sensitive help
) and contextual awareness (which provides automatic inference of likely intentions based on recent activity). This allows a user to create a new software project via the Roo shell, or use Roo on an existing project. The following is an example of the commands used by Roo to create a new project and turn it into a WAR file:
The above commands did not need to be typed in full, but rather were completed using TAB. Additionally, the "hint" command could have been used to acquire help at any time.
While there are many ways that software can automatically generate
code, Roo operates by generating AspectJ
inter-type declarations (otherwise known as mixin
s or introductions). This achieves separation of concerns
, as the code maintained by Roo is in a different compilation unit from the code a user writes. This means Roo can incrementally modify the AspectJ inter-type declarations that it needs to and leave all other files intact.
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
software tool that uses convention-over-configuration
Convention over Configuration
Convention over configuration is a software design paradigm which seeks to decrease the number of decisions that developers need to make, gaining simplicity, but not necessarily losing flexibility....
principles to provide rapid application development
Rapid application development
Rapid application development is a software development methodology that uses minimal planning in favor of rapid prototyping. The "planning" of software developed using RAD is interleaved with writing the software itself...
of Java
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
-based enterprise software
Enterprise software
Enterprise software, also known as enterprise application software , is software used in organizations, such as in a business or government, contrary to software chosen by individuals...
. The resulting applications use common Java technologies such as Spring Framework, Java Persistence API
Java Persistence API
The Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
, Java Server Pages
JavaServer Pages
JavaServer Pages is a Java technology that helps software developers serve dynamically generated web pages based on HTML, XML, or other document types...
, Apache Maven
Apache Maven
Maven is a build automation and software comprehension tool. While primarily used for Java programming, it can also be used to build and manage projects written in C#, Ruby, Scala, and other languages. Maven serves a similar purpose to the Apache Ant tool, but it is based on different concepts and...
and AspectJ
AspectJ
AspectJ is an aspect-oriented extension created at PARC for the Java programming language. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become the widely-used de-facto standard for AOP by emphasizing simplicity and usability...
. Spring Roo is a member of the Spring portfolio of projects.
Motivation and History
Spring Roo's stated mission statement is to "fundamentally and sustainably improve Java developer productivity without compromising engineering integrity or flexibility".The technology was first demonstrated during the opening keynote at the SpringOne Europe developer conference on 27 April 2009, with an initial alpha release concurrently being published. During the keynote an application was built live on-stage that would be used by conference attendees to vote on the preferred name for the project (which at that time was codenamed "Roo" within SpringSource
SpringSource
SpringSource is a division of VMware that provides a suite of software products that accelerate the entire enterprise Java application life cycle of build, run, and manage. SpringSource employs open source leaders who created and drive innovation for Spring, a programming model for enterprise Java...
). Ultimately the name "Spring Roo" was preferred over alternatives including Spring Boost, Spring Spark, Spring HyperDrive and Spring Dart.
Several releases followed, with the Roo 1.0.0.RELEASE (general availability
Development stage
A software release life cycle refers to the phases of development and maturity for a piece of computer software—ranging from its initial development, to its eventual release, and updated versions of the released version to help improve software or fix bugs still present in the software.- Pre-alpha...
) released in December 2009. In October 2010, Spring Roo 1.1.0.RELEASE was released. The 1.1.0 release moved to an OSGi foundation with associated add-on discovery model, plus added support for incremental database reverse engineering, Spring MVC page complexity reduction, Google Web Toolkit, Google App Engine, Apache Solr, JSON and smaller features like serializable automation. The current Roo project engineers are employed by SpringSource and as such Roo releases typically support the latest available releases of other Spring portfolio projects.
Standards and Technology Compatibility
Roo's default installation facilitates the creation of applications that comply with the following standards and major technologies:- Apache ActiveMQ (as an embedded JMSJava Message ServiceThe Java Message Service API is a Java Message Oriented Middleware API for sending messages between two or more clients. JMS is a part of the Java Platform, Enterprise Edition, and is defined by a specification developed under the Java Community Process as JSR 914...
implementation) - Adobe FlexAdobe FlexAdobe Flex is a software development kit released by Adobe Systems for the development and deployment of cross-platform rich Internet applications based on the Adobe Flash platform...
(via a SpringSourceSpringSourceSpringSource is a division of VMware that provides a suite of software products that accelerate the entire enterprise Java application life cycle of build, run, and manage. SpringSource employs open source leaders who created and drive innovation for Spring, a programming model for enterprise Java...
-provided plugin) - Apache MavenApache MavenMaven is a build automation and software comprehension tool. While primarily used for Java programming, it can also be used to build and manage projects written in C#, Ruby, Scala, and other languages. Maven serves a similar purpose to the Apache Ant tool, but it is based on different concepts and...
(version 2.2 or above) - Apache OpenJPAApache OpenJPAOpenJPA is an open source implementation of the Java Persistence API specification. It is an object-relational mapping solution for the Java language, which simplifies storing objects in databases. It is open source software distributed under the Apache 2.0 Licence.- History :Kodo, a Java Data...
(as a JPAJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
implementation) - Apache Solr (search server)
- Apache Tiles (default MVC views)
- Apache TomcatApache TomcatApache Tomcat is an open source web server and servlet container developed by the Apache Software Foundation...
(hosted execution support) - AspectJAspectJAspectJ is an aspect-oriented extension created at PARC for the Java programming language. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become the widely-used de-facto standard for AOP by emphasizing simplicity and usability...
(used for AOPAspect-oriented programmingIn computing, aspect-oriented programming is a programming paradigm which aims to increase modularity by allowing the separation of cross-cutting concerns...
plus mixinMixinIn object-oriented programming languages, a mixin is a class that provides a certain functionality to be inherited or just reused by a subclass, while not meant for instantiation , Mixins are synonymous functionally with abstract base classes...
s to achieve separation of concernsSeparation of concernsIn computer science, separation of concerns is the process of separating a computer program into distinct features that overlap in functionality as little as possible. A concern is any piece of interest or focus in a program. Typically, concerns are synonymous with features or behaviors...
) - AspectJ Development Tools (Eclipse plugin)
- Cloud computingCloud computingCloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network ....
(via SpringSource Cloud Foundry, Google App EngineGoogle App EngineGoogle App Engine is a platform as a service cloud computing platform for developing and hosting web applications in Google-managed data centers. It virtualizes applications across multiple servers,...
and VMforce) - Dojo ToolkitDojo ToolkitDojo Toolkit is an open source modular JavaScript library designed to ease the rapid development of cross-platform, JavaScript/Ajax-based applications and web sites. It was started by Alex Russell, Dylan Schiemann, David Schontzler, and others in 2004 and is dual-licensed under the modified BSD...
(via Spring JavaScript) - Eclipse IDEEclipse (software)Eclipse is a multi-language software development environment comprising an integrated development environment and an extensible plug-in system...
(concurrent execution and project metadata creation) - EclipseLinkEclipseLinkEclipseLink is the open source Eclipse Persistence Services Project from the Eclipse Foundation. The software provides an extensible framework that allows Java developers to interact with various data services, including databases, web services, Object XML mapping , and Enterprise Information Systems...
(as a JPAJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
implementation) - Google Web ToolkitGoogle Web ToolkitGoogle Web Toolkit is an open source set of tools that allows web developers to create and maintain complex JavaScript front-end applications in Java. Other than a few native libraries, everything is Java source that can be built on any supported platform with the included GWT Ant build files...
(since GWT 2.1, including GWT 2.1 features like request factory) - HibernateHibernate (Java)Hibernate is an object-relational mapping library for the Java language, providing a framework for mapping an object-oriented domain model to a traditional relational database...
(as a JPAJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
implementation) - Java Bean Validation (JSR 303) (including Hibernate Validator)
- Java Database ConnectivityJava Database ConnectivityJava DataBase Connectivity, commonly referred to as JDBC, is an API for the Java programming language that defines how a client may access a database. It provides methods for querying and updating data in a database. JDBC is oriented towards relational databases...
(for JPAJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
usage) - Java Message ServiceJava Message ServiceThe Java Message Service API is a Java Message Oriented Middleware API for sending messages between two or more clients. JMS is a part of the Java Platform, Enterprise Edition, and is defined by a specification developed under the Java Community Process as JSR 914...
(both message producers and consumers) - Java Persistence APIJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
(multiple implementations) - Java Transaction APIJava Transaction APIThe Java Transaction API is one of the Java Enterprise Edition APIs allowing distributed transactions to be done across multiple XA resources in a Java environment. JTA is a specification developed under the Java Community Process as JSR 907...
(via Spring transaction abstraction) - JavaJava (programming language)Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
(version 5 or above) - Java Server PagesJavaServer PagesJavaServer Pages is a Java technology that helps software developers serve dynamically generated web pages based on HTML, XML, or other document types...
(default MVC views) - JettyJetty (web server)Jetty is a pure Java-based HTTP client/server, WebSocket client/server and servlet container developed as a free and open source project as part of the Eclipse Foundation...
(hosted execution support) - JSONJSONJSON , or JavaScript Object Notation, is a lightweight text-based open standard designed for human-readable data interchange. It is derived from the JavaScript scripting language for representing simple data structures and associative arrays, called objects...
(methods in classes for serialization, deserialization and REST support) - JUnitJUnitJUnit is a unit testing framework for the Java programming language. JUnit has been important in the development of test-driven development, and is one of a family of unit testing frameworks collectively known as xUnit that originated with SUnit....
(automated tests for user projects) - Log4JLog4jApache log4j is a Java-based logging utility. It was originally written by Ceki Gülcü and is now a project of the Apache Software Foundation. log4j is one of several Java Logging Frameworks....
(installation and configuration) - OSGiOSGiThe Open Services Gateway initiative framework is a module system and service platform for the Java programming language that implements a complete and dynamic component model, something that does not exist in standalone Java/VM environments...
(the Roo tool is built on OSGi) - Representational State Transfer (REST)Representational State TransferRepresentational state transfer is a style of software architecture for distributed hypermedia systems such as the World Wide Web. The term representational state transfer was introduced and defined in 2000 by Roy Fielding in his doctoral dissertation...
- SeleniumSelenium (software)Selenium is a portable software testing framework for web applications. Selenium provides a record/playback tool for authoring tests without learning a test scripting language . It also provides a test domain-specific language to write tests in a number of popular programming languages, including...
(automated tests for user projects) - Spring Framework (version 3 or above)
- Spring Security (version 3 or above)
- Spring Web FlowSpring Web FlowSpring Web Flow is the sub-project of the Spring Framework that focuses on providing the infrastructure for building and running rich web applications...
(installation and flow definition) - SpringSource Tool Suite (STS has an embedded Roo shell and Roo command helpers)
- Web application resource (WAR file) (for deployment packaging)
The above list can be augmented through additional Roo add-ons, which provide Roo's method of extensibility
Extensibility
In software engineering, extensibility is a system design principle where the implementation takes into consideration future growth. It is a systemic measure of the ability to extend a system and the level of effort required to implement the extension...
.
User Interface
Spring Roo's main user interface is a command-line shellShell (computing)
A shell is a piece of software that provides an interface for users of an operating system which provides access to the services of a kernel. However, the term is also applied very loosely to applications and may include any software that is "built around" a particular component, such as web...
. The shell provides both a command-line interface
Command-line interface
A command-line interface is a mechanism for interacting with a computer operating system or software by typing commands to perform specific tasks...
and also a mechanism to host plug-ins (which are called "add-ons" in Roo). One key design goal of Roo is to ensure a user can continue to work in a "natural way", which typically means using their preferred integrated development environment
Integrated development environment
An integrated development environment is a software application that provides comprehensive facilities to computer programmers for software development...
(IDE) or text editor
Text editor
A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....
for most tasks. As such Roo is often loaded in a separate window to the IDE or text editor, and will monitor the file system for changes made by the user outside of Roo. A startup-time scan of a user's project is also performed to determine any changes that may have been made while Roo was not running.
The user interface shell supports extensive usability
Usability
Usability is the ease of use and learnability of a human-made object. The object of use can be a software application, website, book, tool, machine, process, or anything a human interacts with. A usability study may be conducted as a primary job function by a usability analyst or as a secondary job...
features including command line completion
Command line completion
Command line completion is a common feature of command line interpreters, in which the program automatically fills in partially typed commands....
(ie press TAB), online help
Online help
Online help is topic-oriented, procedural or reference information delivered through computer software. It is a form of user assistance. Most online help is designed to give assistance in the use of a software application or operating system, but can also be used to present information on a broad...
, hinting (a form of context-sensitive help
Context-sensitive help
Context-sensitive help is a kind of online help that is obtained from a specific point in the state of the software, providing help for the situation that is associated with that state....
) and contextual awareness (which provides automatic inference of likely intentions based on recent activity). This allows a user to create a new software project via the Roo shell, or use Roo on an existing project. The following is an example of the commands used by Roo to create a new project and turn it into a WAR file:
Welcome to Spring Roo. For assistance press TAB or type "hint" then hit ENTER.
roo> project --topLevelPackage com.helloworld
Created /home/guest/hello/pom.xml
Created SRC_MAIN_JAVA
Created SRC_MAIN_RESOURCES
Created SRC_TEST_JAVA
Created SRC_TEST_RESOURCES
Created SRC_MAIN_WEBAPP
Created SRC_MAIN_RESOURCES/META-INF/spring
Created SRC_MAIN_RESOURCES/META-INF/spring/applicationContext.xml
roo> persistence setup --provider HIBERNATE --database HYPERSONIC_IN_MEMORY
Created SRC_MAIN_RESOURCES/META-INF/persistence.xml
Created SRC_MAIN_RESOURCES/META-INF/spring/database.properties
Managed SRC_MAIN_RESOURCES/META-INF/spring/applicationContext.xml
Managed ROOT/pom.xml
roo> perform package
Created ROOT/target/helloworld-1.0.0.war
The above commands did not need to be typed in full, but rather were completed using TAB. Additionally, the "hint" command could have been used to acquire help at any time.
Base Add-Ons
There are numerous commands available in Roo, depending on which "base add-ons" (those which ship with Roo) and "third-party add-ons" (those that do not ship with Roo) have been installed. The base add-ons shipping with Roo 1.1.0 include:- Add-On Creator: enables easy creation of third-party Roo add-ons
- Backup: enables backups to be made to a ZIP file by typing
backup - Bean Info: exposes JavaBean property, accessor and mutator metadata (primarily used by other add-ons)
- Configurable: introduces Spring Framework's @Configurable annotation (primarily used by other add-ons)
- Database reverse engineering: allows incremental reverse engineering of relational databases
- Data on Demand: provides seed data that is compliant with JSR 303 (JavaBean Validation)Bean ValidationJava Bean Validation is a framework that has been approved by the JCP as of 16 November 2009 and is accepted as part of the Java EE 6 specification. Bean Validation defines a metadata model and API for JavaBean validation. The metadata source is annotations, with the ability to override and extend...
annotations present in entities - Email: simplifies setup of SMTP-based emails and mail sender support via JavamailJavamailJavaMail is a Java API used to receive and send email via SMTP, POP3 and IMAP. JavaMail is built into the Java EE platform, but also provides an optional package for use in Java SE.On March 2, 2009, JavaMail 1.4.2 was released....
- Entity: extensive support for automatically maintaining Java Persistence APIJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
@Entity classes - Dynamic Finder: creates typesafe, code-completion compatible JPA query language finders
- Java Bean: automatically maintains JavaBean getters/setters for classes with an @RooJavaBean annotation
- JDBC: encapsulates OSGi-compliant access to JDBC drivers shipped in different bundles (primarily used by other add-ons)
- JMS: simplifies connecting to a JMSJava Message ServiceThe Java Message Service API is a Java Message Oriented Middleware API for sending messages between two or more clients. JMS is a part of the Java Platform, Enterprise Edition, and is defined by a specification developed under the Java Community Process as JSR 914...
provider (or embedding ActiveMQ) and sending/receiving JMS messages - JPA: installs a specified JPAJava Persistence APIThe Java Persistence API, sometimes referred to as JPA, is a Java programming language framework managing relational data in applications using Java Platform, Standard Edition and Java Platform, Enterprise Edition....
provider and sets up JDBCJava Database ConnectivityJava DataBase Connectivity, commonly referred to as JDBC, is an API for the Java programming language that defines how a client may access a database. It provides methods for querying and updating data in a database. JDBC is oriented towards relational databases...
accordingly - JSON: adds JSONJSONJSON , or JavaScript Object Notation, is a lightweight text-based open standard designed for human-readable data interchange. It is derived from the JavaScript scripting language for representing simple data structures and associative arrays, called objects...
related serialization and deserialization methods to POJOs - Logging: sets up Log4jLog4jApache log4j is a Java-based logging utility. It was originally written by Ceki Gülcü and is now a project of the Apache Software Foundation. log4j is one of several Java Logging Frameworks....
, including command-based log level configuration - Maven: enables use of Apache MavenApache MavenMaven is a build automation and software comprehension tool. While primarily used for Java programming, it can also be used to build and manage projects written in C#, Ruby, Scala, and other languages. Maven serves a similar purpose to the Apache Ant tool, but it is based on different concepts and...
as the build system for the user's project - Pluralization: provides pluralization of nouns (primarily used by other add-ons)
- Property Editor: manages property editors, as required by Spring MVC
- Property File: manages JavaJava (programming language)Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
properties files and provides shell commands to read, set and remove property values - RooBot Client: simplifies discovery, searching, installation and security verification of third-party Roo add-ons
- Security: sets up Spring Security, including login pages, filters and dependencies
- Serializable: adds java.io.Serializable support (such as UID maintenance) to requested Java types
- Solr: integrates with Apache Solr by linking into the entity persistence lifecycle and introducing search-related methods to classes
- Integration Test: produces JUnitJUnitJUnit is a unit testing framework for the Java programming language. JUnit has been important in the development of test-driven development, and is one of a family of unit testing frameworks collectively known as xUnit that originated with SUnit....
integration tests for project entities - ToString: produces a valid toString method for any class with the @RooToString annotation
- Web (various): maintains Spring MVC controllers, Spring Web Flow and JSPJavaServer PagesJavaServer Pages is a Java technology that helps software developers serve dynamically generated web pages based on HTML, XML, or other document types...
files
Roo Core Modules
Roo also includes a core set of modules that provide a hosted execution environment for different add-ons. These major modules include:- Support: used by core modules and add-ons for common utility classUtility classIn computer programming, a utility class is a class that defines a set of methods that perform common, often re-used functions. Most utility classes define these common methods under static scope...
support services - Metadata: provides a metadataMetadataThe term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
service provider interface and implementation that includes dependency registration and caching - File monitor: publishes eventsEvent (computing)In computing an event is an action that is usually initiated outside the scope of a program and that is handled by a piece of code inside the program. Typically events are handled synchronous with the program flow, that is, the program has one or more dedicated places where events are handled...
following detected file system changes (the default implementation uses auto-scaled disk polling) - File undo: provides a file undoUndoUndo is a command in many computer programs. It erases the last change done to the document reverting it to an older state. In some more advanced programs such as graphic processing, undo will negate the last command done to the file being edited....
facility for use by the process manager - Project: abstracts typical end user project build systems like Apache MavenApache MavenMaven is a build automation and software comprehension tool. While primarily used for Java programming, it can also be used to build and manage projects written in C#, Ruby, Scala, and other languages. Maven serves a similar purpose to the Apache Ant tool, but it is based on different concepts and...
and Apache AntApache AntApache Ant is a software tool for automating software build processes. It is similar to Make but is implemented using the Java language, requires the Java platform, and is best suited to building Java projects.... - Process manager: offers an ACIDACIDIn computer science, ACID is a set of properties that guarantee database transactions are processed reliably. In the context of databases, a single logical operation on the data is called a transaction...
-like file systemFile systemA file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
abstraction that includes disk rollback and process synchronization - Classpath: performs abstract syntax treeAbstract syntax treeIn computer science, an abstract syntax tree , or just syntax tree, is a tree representation of the abstract syntactic structure of source code written in a programming language. Each node of the tree denotes a construct occurring in the source code. The syntax is 'abstract' in the sense that it...
parsing and type binding of Java and AspectJAspectJAspectJ is an aspect-oriented extension created at PARC for the Java programming language. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become the widely-used de-facto standard for AOP by emphasizing simplicity and usability...
compilation units - Felix: integrates with Apache Felix, such as providing "osgi" commands in the Roo shell
- OBR: adds Apache Felix OSGi Bundle Repository capabilities
- URL Stream: encapsulates access to downloads in different host environments (Roo shell, IDE embedding) and enforces the Pretty Good PrivacyPretty Good PrivacyPretty Good Privacy is a data encryption and decryption computer program that provides cryptographic privacy and authentication for data communication. PGP is often used for signing, encrypting and decrypting texts, E-mails, files, directories and whole disk partitions to increase the security...
-based httppgp:// protocol handler
While there are many ways that software can automatically generate
Automatic programming
In computer science, the term automatic programming identifies a type of computer programming in which some mechanism generates a computer program to allow human programmers to write the code at a higher abstraction level....
code, Roo operates by generating AspectJ
AspectJ
AspectJ is an aspect-oriented extension created at PARC for the Java programming language. It is available in Eclipse Foundation open-source projects, both stand-alone and integrated into Eclipse. AspectJ has become the widely-used de-facto standard for AOP by emphasizing simplicity and usability...
inter-type declarations (otherwise known as mixin
Mixin
In object-oriented programming languages, a mixin is a class that provides a certain functionality to be inherited or just reused by a subclass, while not meant for instantiation , Mixins are synonymous functionally with abstract base classes...
s or introductions). This achieves separation of concerns
Separation of concerns
In computer science, separation of concerns is the process of separating a computer program into distinct features that overlap in functionality as little as possible. A concern is any piece of interest or focus in a program. Typically, concerns are synonymous with features or behaviors...
, as the code maintained by Roo is in a different compilation unit from the code a user writes. This means Roo can incrementally modify the AspectJ inter-type declarations that it needs to and leave all other files intact.
Differentiation
Spring Roo differentiates from other convention-over-configuration rapid application development tools in the following major ways:- Java platform productivity: Roo provides a productivity solution for Java developers. It does not require the user to program in any language other than JavaJava (programming language)Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
. It also uses mainstream Java enterprise application standards and technologies (as listed above) to maximize reuse of existing developer knowledge, skills and experience. - Usability: Roo's shell is designed to provide a discoverable, easy-to-use environment that minimizes training requirements. Roo annotations all start with @Roo to facilitate code assist (command line completionCommand line completionCommand line completion is a common feature of command line interpreters, in which the program automatically fills in partially typed commands....
in IDEs). Users can use their IDE for all operations and do not need to be aware of Roo running. Roo also supports users editing their files when Roo is not running. - No runtime: Roo does not provide a runtime API or require specific runtime components. This ensures there is no Roo-related CPU, memory and disk storageDisk storageDisk storage or disc storage is a general category of storage mechanisms, in which data are digitally recorded by various electronic, magnetic, optical, or mechanical methods on a surface layer deposited of one or more planar, round and rotating disks...
resource consumption at runtime. Roo code is optimized for small-footprint cloudCloud computingCloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a utility over a network ....
deployment and high scalabilityScalabilityIn electronics scalability is the ability of a system, network, or process, to handle growing amount of work in a graceful manner or its ability to be enlarged to accommodate that growth...
use cases. - Avoids lock-in: Roo can be rapidly removed from a user project, which is useful to protect against vendor lock-inVendor lock-inIn economics, vendor lock-in, also known as proprietary lock-in or customer lock-in, makes a customer dependent on a vendor for products and services, unable to use another vendor without substantial switching costs...
. This is possible because there is no runtime component to remove, @Roo annotations are "source retention" only (ensuring they are not preserved in compiled *.class files) and Roo's AspectJ inter-type declarations can be "pushed in" to standard *.java compilation units. - Extensibility: Roo's separation of core infrastructure and base add-ons intends to allow third parties to easily extend Roo.