Here are answers to the usual getting-started questions. For an in-depth, searchable FAQ, visit our friends at JGuru.
- Why do we need Struts?
- How does Struts work?
- Is Struts compatible with other Java technologies?
- Who wrote Struts?
- Why is it called Struts?
- How is Struts licensed?
- Can Struts be used in a commercial application?
- Do I have to credit Struts on my own website?
- Where can I get a copy of Struts?
- How do I install Struts?
- When do I need the struts.jar on my classpath?
- Does Struts provide its own unit tests?
- If the framework doesn't do what I want, can I request that a feature be added?
- Where can I get help with Struts?
- Is commercial support available for Struts?
- Are there ISPs that will host my Struts application?
- What Web sites are already Powered by Struts?
- What's the difference between Struts and Turbine? What's the difference between Struts and Expresso?
- Why aren't the Struts tags maintained as part of the Jakarta Taglibs project?
- Are the Struts tags XHTML compliant?
- What about JSTL and JavaServer Faces?
- Is there a particularly good IDE to use with Struts?
Why do we need Struts?
Java technologies give developers a serious boost when creating and maintaining applications to meet the demands of today's public Web sites and enterprise intranets. Struts combines Java Servlets, Java ServerPages, custom tags, and message resources into a unified framework. The end result is a cooperative, synergistic platform, suitable for development teams, independent developers, and everyone in between.
How does Struts work?
Java Servlets are designed to handle requests made by Web browsers. Java ServerPages are designed to create dynamic Web pages that can turn billboard sites into live applications. Struts uses a special Servlet as a switchboard to route requests from Web browsers to the appropriate ServerPage. This makes Web applications much easier to design, create, and maintain.
Is Struts compatible with other Java technologies?
Yes. Struts is committed to supporting industry standards. Struts acts as an integrator of Java technologies so that they can be used in the "real world".
Who wrote Struts?
There are several active committers to the Struts project, working cooperatively from around the globe. Dozens of individual developers and committers contributed to the Struts 1.x codebase. All interested Java developers are invited to contribute to the project. Struts is a Apache Software Foundation project, with the mission to "provide secure, enterprise-grade server solutions based on the Java Platform that are developed in an open and cooperative fashion".
Struts was created by Craig R. McClanahan and donated to The Apache Software Foundation in May 2000. Craig was the primary developer of both Struts 1.x and Tomcat 4. Tomcat 4 was the basis for the official reference implementation for a servlet 2.3 and JSP 1.2 container.
Craig's current focus is as architect of the Sun Java Studio Creator (formerly Project Rave). Craig also serves as the Specification Lead for JavaServer Faces (JSR-127), and is the Web Layer Architect for the Java2 Enterprise Edition (J2EE) platform as a whole.
Why is it called Struts?
It's a reference to struts in the architectural sense, a reminder of the nearly invisible pieces that hold up buildings, houses, and bridges.
How is Struts licensed?
Struts is copyrighted software available under the Apache License, a "free-to-use, business-friendly license".
Can Struts be used in a commercial product?
Yes. The only requirements you must meet are those listed in the Apache License.
Do I have to credit Struts on my own website?
You need to credit Struts if you redistribute your own framework based on Struts for other people to use. (See the Apache License for details.) But you do not need to credit Struts just because your web application utilizes the framework. It's the same situation as using the Apache HTTPD server or Tomcat. Not required if its just running your web site. Required if you've used the source code to create your own server that you are redistributing to other people.
Where can I get a copy of Struts?
The best place to download Struts is at struts.apache.org. The nightly builds are very stable, and recommended as the best place to start today.
How do I install Struts?
To develop applications with Struts, you can usually just add the Struts JAR file
to your Java development environment. You can then start using the Struts classes as
part of your own application. A blank Struts application (in the
webapps directory, open
is provided, which you can just copy to get a quick-start on your own brainchild.
Since the full source code for Struts is available, we also provide complete instructions for compiling your own Struts JAR from scratch. (This is actually easier than it looks!)
Your Struts application can usually be deployed using a standard WAR file. In most cases, you simply deposit the WAR file on your application server, and it is installed automatically. If not, step-by-step installation instructions for various servlet containers are available.
When do I need "struts.jar" on my classpath?
When you are compiling an application that uses the Struts classes, you must have the "struts.jar" on the classpath your compiler sees -- it does not have to be on your CLASSPATH environment variable.
Why is that an important distinction? Because if you are using a servlet container on your development machine to test your application, the "struts.jar" must not be on your CLASSPATH environment variable when running the container. (This is because each Web application must also have their own copy of the Struts classes, and the container will become confused if it is on the environment path as well.)
There are several general approaches to this issue:
- Use ANT for building your projects -- it can easily assemble classpaths for the compiler. (This is how Struts itself is built, along with Tomcat and most other Java-based projects).
- Use an IDE where you can configure the "class path" used for compilation independent of the CLASSPATH environment variable.
Use a shell script that temporarily adds struts.jar to the classpath just for compilation, for example
javac -classpath /path/to/struts.jar:$CLASSPATH $@
Does Struts include its own unit tests?
Struts currently has two testing environments, to reflect the fact that some things can be tested statically, and some really need to be done in the environment of a running servlet container.
For static unit tests, we use the JUnit framework. The sources for these tests are in the "src/test" hierarchy in the source repository, and are executed via the "test.junit" target in the top-level build.xml file. Such tests are focused on the low-level functionality of individual methods, are particularly suitable for the static methods in the org.apache.struts.util utility classes. In the test hierarchy, there are also some "mock object" classes (in the org.apache.struts.mock package) so that you can package up things that look like servlet API and Struts API objects to pass in as arguments to such tests.
If the framework doesn't do what I want, can I request that a feature be added?
First, it's important to remember that Struts is an all-volunteer project. We don't charge anyone anything to use Struts. Committers and other developers work on Struts because they need to use it with their own applications. If others can use it too, that's "icing on the cake". If you submit a patch for a feature that a Committer finds useful, then that Committer may choose to volunteer his or her time to apply the patch. If you just submit an idea without a patch, it is much less likely to be added (since first someone else has to volunteer their time to write the patch).
We are grateful for any patches, and we welcome new ideas, but the best way to see that something gets added to the framework is to do as much of the work as you can, rather than rely on the "kindness of strangers". Worst case, you can apply the patch to your copy of Struts and still use the feature in your own application. (Which is what open source is ~really~ all about.)
Where can I get help with Struts?
The Struts package comes complete with a
Users Guide to
introduce people to the framework and its underlying technologies. Various components
also have their own in-depth Developers Guide, to cover more advanced topics. Comprehensive
Javadocs are included
along with the full source code. For your convenience, these are bundled together as
a self-installing application. The
struts-documentation.war is the same
bundle that is deployed as the
Struts Web site.
The Strut's mailing list is also very active, and welcomes posts from new users. Before posting a new question, be sure to consult the MAILING LIST ARCHIVE and the very excellent How To Ask Questions The Smart Way by Eric Raymond. Please do be sure to turn off HTML in your email client before posting.
Is commercial support available?
There is no official, commercial support for Struts, though third parties may offer different degrees of support.
Are there ISPs that will host my Struts application?
For a listing of some Java and Struts ISPs, visit the Struts Community Resources area on SourceForge.
What's the difference between Struts and Turbine? What's the difference between Struts and Expresso?
If you are starting from scratch, packages like Turbine and Expresso can be very helpful since they try to provide all of the basic services that your team is likely to need. Such services include things like data persistence and logging.
If you are not starting from scratch, and need to hook up your web application to an existing infrastructure, then "plain vanilla" Struts can be a better choice. The core Struts framework does not presuppose that you are using a given set of data persistence, presentation, or logging tools. Anything goes =:0)
Compared to other offerings, Struts endeavors to be a minimalist framework. We try leverage existing technologies whenever we can and provide only the missing pieces you need to combine disparate technologies into a coherent application. This is great when you want to select your own tools to use with Struts. But, if you prefer a more integrated infrastructure, then packages like Turbine or Expresso (which uses Struts) are perfectly good ways to go.
Why aren't the Struts tags maintained as part of the Jakarta Taglibs project?
Development of both products began about the same time. Leading up to the release of 1.0, it was thought better to continue to develop the taglibs alongside the controller. Now that 1.0 is out, the JavaServer Pages Standard Taglib is in active development. Once work on JSTL stabilizes, the Struts taglibs will be revisited. Tags which are not linked directly to the framework may be hosted at Jakarta Taglibs instead.
Are the Struts tags XHTML compliant?
If you use an <html:html xhtml="true> or <html:xhtml/> element on your page, the tags will render as XHTML (since Struts 1.1).
Will the Struts tags support other markup languages such as WML
Struts itself is markup neutral. The original Struts taglibs are only one example of how presentation layer components can access the framework. The framework objects are exposed through the standard application, session, and request contexts, where any Java component in the application can make use of them.
For more about using WAP/WML with Struts see the article WAP up your EAserver.
What about JSTL and JavaServer Faces?
JSTL, the JavaServer Standard Tag Library, is a set of JSP tags that are designed to make it easier to develop Web applications. JavaServer Faces (JSF) is a specification for a new technology that promises to make it easier to write MVC applications, both for the Web and for the desktop.
The inventor of Struts, Craig McClanahan, is the specification co-lead for JavaServer Faces (JSR 127), and architect of the reference implemenation as well as Java Studio Creator. Both JSTL and JSF are complementary to Struts.
The mainstay of the Struts framework is the controller components, which can be used with any Java presentation technology. As new technologies become available, it is certain that new "glue" components will also appear to help these technologies work as well with Struts.
Struts originally came bundled with a set of custom JSP tags. Today, several extensions are available to help you use Struts with other popular presentation technologies, like XSLT and Velocity. Likewise, extensions for JSTL and JSF are now available as well.
The JSF specification and reference implementation is available through Sun's The JSF specification and reference implementation is available through Sun's Java ServerFaces page. An early-release JavaServer Faces taglib for Struts, Struts-Faces, is also in early release and available through the nightly build. The Struts Faces taglib is expected to work with any compliant JSF implementation, including MyFaces.
For more about what JavaServer Faces means to the Struts community, see the StrutsMoreAboutJSF wiki page.
Is there a particularly good IDE to use with Struts
Struts should work well with any development environment that you would like to use, as well as with any programmers editor. The members of the Struts development team each use their own tools such as Emacs, IDEA, Eclipse, and NetBeans.
See the Howto Guides for more about configuring IDEs to work with Struts.
Is there a digest for the User list?
If you are subscribed to the digest, you can also post to the list. Just be sure to send your post to the user list rather than trying to reply to the digest.
Is there a Struts newsgroup?
Not a usenet group, but the Struts User list can be accessed with your
favorite newsgroup reader from the
GMane News Site. Subscribe to groups
gmane.comp.jakarta.struts.devel for the developer list, or
gmane.comp.jakarta.struts.user for the user list.