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Posted to commits@jackrabbit.apache.org by ju...@apache.org on 2012/01/10 19:51:06 UTC
svn commit: r1229679 [3/12] - /jackrabbit/site/trunk/content/
Added: jackrabbit/site/trunk/content/embedded-repository.mdtext
URL: http://svn.apache.org/viewvc/jackrabbit/site/trunk/content/embedded-repository.mdtext?rev=1229679&view=auto
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--- jackrabbit/site/trunk/content/embedded-repository.mdtext (added)
+++ jackrabbit/site/trunk/content/embedded-repository.mdtext Tue Jan 10 18:50:59 2012
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+Title: Embedded Repository
+You can run Jackrabbit in embedded mode inside your application if you only
+(or mostly) access a repository from that one application. In this
+deployment model the Jackrabbit dependencies are included directly in your
+classpath and your application is in full control of the repository
+lifecycle. To use this deployment model you need to add the appropriate
+dependencies to your application and include a few lines of
+Jackrabbit-specific code to start and stop a repository. You can then use
+the standard JCR API to access and manage content inside the repository.
+
+This page describes how to embed Jackrabbit in your application.
+
+{toc:minLevel=2}
+
+<a name="EmbeddedRepository-Jackrabbitdependencies"></a>
+## Jackrabbit dependencies
+
+To use Jackrabbit in embedded mode you need to make sure that the JCR API
+and all required Jackrabbit libraries are included in your classpath. If
+you use [Maven 2](http://maven.apache.org/)
+, you can achieve this by specifying the following dependencies.
+
+
+ <dependency>
+ <groupId>javax.jcr</groupId>
+ <artifactId>jcr</artifactId>
+ <version>1.0</version>
+ </dependency>
+ <dependency>
+ <groupId>org.apache.jackrabbit</groupId>
+ <artifactId>jackrabbit-core</artifactId>
+ <version>1.5.0</version>
+ <exclusions>
+ <exclusion>
+ <groupId>commons-logging</groupId>
+ <artifactId>commons-logging</artifactId>
+ </exclusion>
+ </exclusions>
+ </dependency>
+ <dependency>
+ <groupId>org.slf4j</groupId>
+ <artifactId>jcl-over-slf4j</artifactId>
+ <version>1.5.3</version>
+ </dependency>
+ <dependency>
+ <groupId>org.slf4j</groupId>
+ <artifactId>slf4j-log4j12</artifactId>
+ <version>1.5.3</version>
+ </dependency>
+
+
+The jcr dependency includes the JCR 1.0 API in your classpath. You need to
+explicitly declare this dependency as in jackrabbit-core the JCR API
+dependency scope is _provided_ to work better in deployment models where
+the JCR API is shared between multiple applications.
+
+The jackrabbit-core dependency pulls in the Jackrabbit content repository
+implementation and a set of transitive dependencies needed by Jackrabbit.
+See the [Downloads](downloads.html)
+ page for the latest available version.
+
+Jackrabbit uses the [SLF4J](http://www.slf4j.org/)
+ for logging and leaves it up to the embedding application to decide which
+underlying logging library to use. In the example above we use the
+slf4j-log4j12 library which uses [log4j 1.2|http://logging.apache.org/log4j/1.2/]
+ for handling the log messages. Note that the commons-logging dependency
+(which is a transitive dependency from [Apache POI|http://poi.apache.org/]
+) is explicitly replaced with the jcl-over-slf4j dependency that routes
+also all [Commons Logging|http://commons.apache.org/logging/]
+ log messages through the selected SLF4J implementation. Jackrabbit 1.5.x
+uses SLF4J version 1.5.3.
+
+The full set of compile-scope dependencies included by the above
+declaration is shown below. If you use a build tool like [Ant](http://ant.apache.org/)
+ where you need to explicitly include all dependencies, you can use this
+list to correctly configure your classpath.
+
+
+ +- javax.jcr:jcr:jar:1.0:compile
+ +- org.apache.jackrabbit:jackrabbit-core:jar:1.5.0:compile
+ | +- concurrent:concurrent:jar:1.3.4:compile
+ | +- commons-collections:commons-collections:jar:3.1:compile
+ | +- commons-io:commons-io:jar:1.4:compile
+ | +- org.apache.jackrabbit:jackrabbit-api:jar:1.5.0:compile
+ | +- org.apache.jackrabbit:jackrabbit-jcr-commons:jar:1.5.0:compile
+ | +- org.apache.jackrabbit:jackrabbit-spi-commons:jar:1.5.0:compile
+ | +- org.apache.jackrabbit:jackrabbit-spi:jar:1.5.0:compile
+ | +- org.apache.jackrabbit:jackrabbit-text-extractors:jar:1.5.0:compile
+ | | +- org.apache.poi:poi:jar:3.0.2-FINAL:compile
+ | | +- org.apache.poi:poi-scratchpad:jar:3.0.2-FINAL:compile
+ | | +- pdfbox:pdfbox:jar:0.7.3:compile
+ | | | +- org.fontbox:fontbox:jar:0.1.0:compile
+ | | | \- org.jempbox:jempbox:jar:0.2.0:compile
+ | | \- net.sourceforge.nekohtml:nekohtml:jar:1.9.7:compile
+ | | \- xerces:xercesImpl:jar:2.8.1:compile
+ | | \- xml-apis:xml-apis:jar:1.3.03:compile
+ | +- org.slf4j:slf4j-api:jar:1.5.3:compile
+ | +- org.apache.lucene:lucene-core:jar:2.3.2:compile
+ | \- org.apache.derby:derby:jar:10.2.1.6:compile
+ +- org.slf4j:jcl-over-slf4j:jar:1.5.3:compile
+ \- org.slf4j:slf4j-log4j12:jar:1.5.3:compile
+ \- log4j:log4j:jar:1.2.14:compile
+
+
+Note that some of the transitive dependencies listed above may conflict
+with some other dependencies of our application. In such cases you may want
+to consider switching to a deployment model that uses separate class
+loaders for your application and the Jackrabbit content repository.
+
+<a name="EmbeddedRepository-Startingtherepository"></a>
+## Starting the repository
+
+Once you have your classpath configured you can start the repository with
+the following piece of code.
+
+{code:java}
+import javax.jcr.Repository;
+import org.apache.jackrabbit.core.RepositoryImpl;
+import org.apache.jackrabbit.core.config.RepositoryConfig;
+
+String xml = "/path/to/repository/configuration.xml";
+String dir = "/path/to/repository/directory";
+RepositoryConfig config = RepositoryConfig.create(xml, dir);
+Repository repository = RepositoryImpl.create(config);
+
+
+ See the [Jackrabbit Configuration]
+ page for more information on repository configuration. See the [RepositoryConfig|http://jackrabbit.apache.org/api/1.5/org/apache/jackrabbit/core/config/RepositoryConfig.html]
+ and [RepositoryImpl|http://jackrabbit.apache.org/api/1.5/org/apache/jackrabbit/core/RepositoryImpl.html]
+ javadocs for more details on these classes.
+
+ h2. Shutting down the repository
+
+ When your application no longer needs the content repository, you can shut
+it down with the following code.
+
+ {code:java}
+ ((RepositoryImpl) repository).shutdown();
+
+
+This will forcibly close all open sessions and make sure that all
+repository content is safely stored on disk.
+
+<a name="EmbeddedRepository-TheTransientRepositoryclass"></a>
+## The TransientRepository class
+
+Jackrabbit comes with a [TransientRepository](http://jackrabbit.apache.org/api/1.5/org/apache/jackrabbit/core/TransientRepository.html)
+ class that makes it even easier to get started with a content repository.
+This class is especially handy for quick prototyping, but using the
+RepositoryImpl class as described above gives you better control over the
+repository lifecycle and is typically a better alternative for production
+code.
+
+{code:java}
+import javax.jcr.Repository;
+import org.apache.jackrabbit.core.TransientRepository;
+
+Repository repository = new TransientRepository();
+
+
+ This creates a repository instance that starts up when the first session is
+created and automatically shuts down when the last session is closed. By
+default the repository will be created in a "jackrabbit" subdirectory using
+a default configuration file in "jackrabbit/repository.xml". See the
+TransientRepository javadocs for the ways to override these defaults.
+
+ h2. Enabling remote access
+
+ Even if you mostly use the content repository in embedded mode within your
+application, it may occasionally be useful to be able to access the
+repository for example from an external administration tool while your
+application is still running. You can use the jackrabbit-jcr-rmi library to
+make this possible. To do this, you first need to add the appropriate
+dependency.
+
+ {code:xml}
+ <dependency>
+ <groupId>org.apache.jackrabbit</groupId>
+ <artifactId>jackrabbit-jcr-rmi</artifactId>
+ <version>1.5.0</version>
+ </dependency>
+
+
+Make sure that you have [rmiregistry](http://java.sun.com/j2se/1.5.0/docs/tooldocs/solaris/rmiregistry.html)
+ running, and use the following code to export the repository. Note that
+you need to include the JCR API and the jackrabbit-jcr-rmi libraries in the
+rmiregistry classpath for the binding to work without extra RMI codebase
+settings.
+
+{code:java}
+import java.rmi.Naming;
+import org.apache.jackrabbit.rmi.server.RemoteAdapterFactory;
+import org.apache.jackrabbit.rmi.server.RemoteRepository;
+import org.apache.jackrabbit.rmi.jackrabbit.JackrabbitRemoteAdapterFactory;
+
+String url = "//localhost/javax/jcr/Repository"; // RMI URL of the
+repository
+RemoteAdapterFactory factory = new JackrabbitRemoteAdapterFactory();
+RemoteRepository remote = factory.getRemoteRepository(repository);
+Naming.bind(url, remote);
+
+
+ Use the following code to remote the repository binding from the RMI
+registry before you shutdown the repository.
+
+ {code:java}
+ Naming.unbind(url);
+
+
+You need to keep a direct reference to the RemoteRepository instance in
+your code until you call Naming.unbind as otherwise it could get garbage
+collected before a remote client connects to it.
+
+See the [Repository Server](repository-server.html)
+ page for instructions on how to access such a remote repository.
+
+<a name="EmbeddedRepository-Embeddedrepositoryinawebapplication"></a>
+## Embedded repository in a web application
+
+If your want to embed Jackrabbit in a web application, you can use the
+classes in the jackrabbit-jcr-servlet library to avoid the above startup
+and shutdown code. To do this, you first need to include
+jackrabbit-jcr-servlet as a dependency.
+
+
+ <dependency>
+ <groupId>org.apache.jackrabbit</groupId>
+ <artifactId>jackrabbit-jcr-servlet</artifactId>
+ <version>1.5.0</version>
+ </dependency>
+
+
+Then you can instruct the servlet container to automatically start and stop
+the repository as a part of your webapp lifecycle by including the
+following servlet configuration in your web.xml file.
+
+
+ <servlet>
+ <servlet-name>ContentRepository</servlet-name>
+
+<servlet-class>org.apache.jackrabbit.servlet.jackrabbit.JackrabbitRepositoryServlet</servlet-class>
+ <load-on-startup>1</load-on-startup>
+ </servlet>
+
+
+See the [JackrabbitRepositoryServlet](http://jackrabbit.apache.org/api/1.5/org/apache/jackrabbit/servlet/jackrabbit/JackrabbitRepositoryServlet.html)
+ javadocs for the available configuration options.
+
+You can then access the repository in your own servlet classes using the
+following piece of code without worrying about the repository lifecycle.
+
+{code:java}
+import javax.jcr.Repository;
+import org.apache.jackrabbit.servlet.ServletRepository;
+
+Repository repository = new ServletRepository(this); // "this" is the
+containing servlet
+
+
+ The benefit of this approach over directly using the RepositoryImpl or
+TransientRepository classes as described above is that you can later on
+switch to a different deployment model without any code changes simply by
+modifying the servlet configuration in your web.xml.
+
+ With this approach it is also easier to make your repository remotely
+available. Add the following configuration to your web.xml and your
+repository is automatically made available as a remote repository at
+.../rmi in the URL space of your webapp.
+
+ {code:xml}
+ <servlet>
+ <servlet-name>RemoteRepository</servlet-name>
+
+<servlet-class>org.apache.jackrabbit.servlet.remote.RemoteBindingServlet</servlet-class>
+ </servlet>
+ <servlet-mapping>
+ <servlet-name>RemoteRepository</servlet-name>
+ <url-pattern>/rmi</url-pattern>
+ </servlet-mapping>
+
+
+Note that you also need the jackrabbit-jcr-rmi dependency in your
+application for the above configuration to work.
Propchange: jackrabbit/site/trunk/content/embedded-repository.mdtext
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Added: jackrabbit/site/trunk/content/first-hops-with-apache-jackrabbit.cwiki
URL: http://svn.apache.org/viewvc/jackrabbit/site/trunk/content/first-hops-with-apache-jackrabbit.cwiki?rev=1229679&view=auto
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--- jackrabbit/site/trunk/content/first-hops-with-apache-jackrabbit.cwiki (added)
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@@ -0,0 +1,462 @@
+Welcome to your first hops into the world of Apache Jackrabbit! This introduction gives you a hands-on experience with Jackrabbit and the JCR API. Once you have finished hopping through this document, you should be all set to continue on your own with the official JCR specification and the documentation on this site.
+
+h2. Hop 0: Getting started
+
+Before you can start using Jackrabbit, you need to have it installed on your computer. You can do this either by downloading a binary release and all the required dependencies or by building the Jackrabbit sources.
+
+Once you have Jackrabbit available locally, you should make sure that you have at least version 1.4 of the Java 2 Platform, Standard Edition (J2SE) installed and the following libraries configured in your Java classpath:
+
+|| Library || Comments ||
+| jackrabbit-1.0.jar | depending on whether you use a binary release or a locally compiled version |
+| jcr-1.0.jar | for the JCR 1.0 API |
+| slf4j-log4j12-1.0.jar and log4j-1.2.8.jar | for logging using SLF4J with Log4J (you should be fine with any Log4J 1.2.x version, or you could even replace both of these jars with another SLF4J implementation) |
+| commons-collections-3.1.jar | for advanced data structures used by Jackrabbit |
+| xercesImpl-2.6.2.jar and xmlParserApis-2.0.2.jar | for advanced XML support (you should be fine with any recent Xerces2 Java Parser implementation and the extra XML API library is only needed for JDK 1.4) |
+| derby-10.1.3.1.jar | or any recent Derby release for embedded database storage |
+| concurrent-1.3.4.jar | for advanced thread synchronization |
+| lucene-1.4.3.jar | for full text indexing and searching |
+
+You should also add the current directory in your classpath to make it easy to compile and run the example classes. You may also want to copy the following log4j.properties file to the current directory to avoid warnings of missing log configuration. If you want to see the internal Jackrabbit log, just change the log level to INFO or even DEBUG.
+
+{code:title=log4j.properties}
+log4j.logger.org.apache.jackrabbit=WARN,stdout
+log4j.appender.stdout=org.apache.log4j.ConsoleAppender
+log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout
+{code}
+
+{tip}
+If you have build Jackrabbit from sources with Maven 1.x, you can get all the runtime dependencies (and some extra libraries) copied to target/lib by running maven copy-deps in the Jackrabbit project directory.
+{tip}
+
+{tip}
+You probably have an error in your classpath if you get a ClassNotFoundException message when trying to compile or run the examples below.
+{tip}
+
+h2. Hop 1: Logging in to Jackrabbit
+
+Once you are done with the setup tasks, we can start doing some real work. As a warm-up we'll create a Jackrabbit content repository and start a login session for accessing it. The full example application that does this is shown below, with line-by-line explanations following shortly after.
+
+{code:title=FirstHop.java}
+import javax.jcr.Repository;
+import javax.jcr.Session;
+import org.apache.jackrabbit.core.TransientRepository;
+
+/**
+ * First hop example. Logs in to a content repository and prints a
+ * status message.
+ */
+public class FirstHop {
+
+ /**
+ * The main entry point of the example application.
+ *
+ * @param args command line arguments (ignored)
+ * @throws Exception if an error occurs
+ */
+ public static void main(String[] args) throws Exception {
+ Repository repository = new TransientRepository();
+ Session session = repository.login();
+ try {
+ String user = session.getUserID();
+ String name = repository.getDescriptor(Repository.REP_NAME_DESC);
+ System.out.println(
+ "Logged in as " + user + " to a " + name + " repository.");
+ } finally {
+ session.logout();
+ }
+ }
+
+}
+{code}
+
+You can also download the source file as FirstHop.java. If you have your classpath set up, you can compile the application with javac FirstHop.java and run it with java FirstHop to get the following output.
+
+Logged in as anonymous to a Jackrabbit repository.
+
+In addition to producing the above status line the application copies a default repository configuration file to repository.xml and creates an initial Jackrabbit content repository in the repository subdirectory. You can use the system properties org.apache.jackrabbit.repository.conf and org.apache.jackrabbit.repository.home to set alternative configuration file and repository directory locations.
+
+Read on for a detailed breakdown of the FirstHop application:
+
+{code}
+import javax.jcr.Repository;
+import javax.jcr.Session;
+{code}
+
+ The JCR API interfaces are located in the javax.jcr package found in the jcr-1.0.jar library. The promise of the JCR API is that if you only use these interfaces in your content application, it should remain mostly independent of the underlying content repository implementation.
+
+ The Repository interface represents a given content repository instance and the Session interface represents a single login session for accessing the repository. A session is needed to access any content within a repository.
+
+ Note that a Session instance is not guaranteed to be thread-safe so you should start multiple sessions if you need to access repository content simultaneously from different threads. This is especially important for things like web applications.
+import org.apache.jackrabbit.core.TransientRepository;
+
+ The best practice for deploying Jackrabbit is to use JNDI or some other configuration mechanism in a container environment to keep the application code free of direct Jackrabbit dependencies, but since we are creating a simple standalone application we can take a shortcut by using the TransientRepository class from Jackrabbit core.
+
+{code}
+public class FirstHop
+public static void main(String[] args) throws Exception
+{code}
+
+ The FirstHop example is a simple standalone application that fits nicely in the main() method and lets the JVM take care of the possible exceptions. More substantial content applications could also be written as web application or EJB components with different setup and error handling patterns.
+
+{code}
+Repository repository = new TransientRepository();
+{code}
+
+ The TransientRepository class implements the JCR Repository interface, so you can simply assign a TransientRepository instance to a Repository variable. The default constructor contains a utility feature that will take care of the initial configuration and repository construction when the first session is started. Thus there is no need for manual configuration for now unless you want direct control over the repository setup.
+
+ The TransientRepository implementation will automatically initialize the content repository when the first session is started and shut it down when the last session is closed. Thus there is no need for explicit repository shutdown as long as all sessions are properly closed. Note that a Jackrabbit repository directory contains a lock file that prevents it from being accessed simultaneously by multiple processes. You will see repository startup exceptions caused by the lock file if you fail to properly close all sessions or otherwise shut down the repository before leaving the process that accesses a repository. Normally you can just manually remove the lock file in such cases but such cases always present a chance of repository corruption especially if you use a non-transactional persistence manager.
+
+{code}
+Session session = repository.login();
+{code}
+
+ The default Repository.login() method starts a repository session using the default workspace and no user credentials. Jackrabbit tries to use the Java Authentication and Authorization Service (JAAS) configuration in such cases, but defaults to the anonymous user if a JAAS Subject is not found.
+
+ Since we use the TransientRepository class as the Repository implementation, this step will also cause the repository to be initialized.
+
+{code}
+try { ... } finally { session.logout(); }
+{code}
+
+ It is a good practice to properly release all acquired resources, and the JCR sessions are no exception. The try-finally idiom is a good way to ensure that a resource really gets released, as the release method gets called even if the intervening code throws an exception or otherwise jumps outside the scope (for example using a return, break, or continue statement).
+
+ The Session.logout() method in the finally branch closes the session and since this is the only session we have started, the TransientRepository is automatically shut down.
+
+{code}
+String user = session.getUserID();
+{code}
+
+ The username or identifier of the user associated with a session is available using the Session.getUserID() method. Jackrabbit returns "anonymous" by default.
+
+{code}
+String name = repository.getDescriptor(Repository.REP_NAME_DESC);
+{code}
+
+ Each content repository implementation publishes a number of string descriptors that describe the various implementation properties, like the implementation level and the supported optional JCR features. See the Repository interface for a list of the standard repository descriptors. The REP_NAME_DESC descriptor contains the name of the repository implementation, in this case "Jackrabbit".
+
+h2. Hop 2: Working with content
+
+The main function of a content repository is allow applications to store and retrieve content. The content in a JCR content repository consists of structured or unstructured data modeled as a hierarchy of nodes with properties that contain the actual data.
+
+The following example application first stores some content to the initially empty content repository, then retrieves the stored content and outputs it, and finally removes the stored content.
+
+{code:title=SecondHop.java}
+import javax.jcr.Repository;
+import javax.jcr.Session;
+import javax.jcr.SimpleCredentials;
+import javax.jcr.Node;
+import org.apache.jackrabbit.core.TransientRepository;
+
+/**
+ * Second hop example. Stores, retrieves, and removes example content.
+ */
+public class SecondHop {
+
+ /**
+ * The main entry point of the example application.
+ *
+ * @param args command line arguments (ignored)
+ * @throws Exception if an error occurs
+ */
+ public static void main(String[] args) throws Exception {
+ Repository repository = new TransientRepository();
+ Session session = repository.login(
+ new SimpleCredentials("username", "password".toCharArray()));
+ try {
+ Node root = session.getRootNode();
+
+ // Store content
+ Node hello = root.addNode("hello");
+ Node world = hello.addNode("world");
+ world.setProperty("message", "Hello, World!");
+ session.save();
+
+ // Retrieve content
+ Node node = root.getNode("hello/world");
+ System.out.println(node.getPath());
+ System.out.println(node.getProperty("message").getString());
+
+ // Remove content
+ root.getNode("hello").remove();
+ session.save();
+ } finally {
+ session.logout();
+ }
+ }
+
+}
+{code}
+
+Like in the first hop, this example source is also available as SecondHop.java. You can also compile and run this class just like you did in the first hop example. Running this example should produce the following output:
+
+{code}
+/hello/world
+Hello, World!
+{code}
+
+The basic structure of this example application is the same as in the First Hop example, so let's just walk through the differences:
+
+{code}
+import javax.jcr.SimpleCredentials;
+import javax.jcr.Node;
+{code}
+
+ These are two new classes we need for this example. The SimpleCredentials class is a simple implementation of the Credentials interface used for passing explicit user credentials to the Repository.login(Credentials) method.
+
+ The Node interface is used to manage the content nodes in a repository. There is a related interface called Property for managing content properties, but in this example we use the Property interface only indirectly.
+
+{code}
+new SimpleCredentials("username", "password".toCharArray())
+{code}
+
+ As discussed in the First Hop example, the default Repository.login() method returns an anonymous read-only session in the Jackrabbit default configuration. To be able to store and remove content we need to create a session with write access, and to do that we need to pass some credentials to the Repository.login(Credentials credentials) method.
+
+ The default Jackrabbit login mechanism accepts any username and password as valid credentials and returns a session with full write access. Thus we only need to construct and use a SimpleCredentials instance with some dummy username and password, in this case "username" and "password".
+
+ The SimpleCredentials constructor follows the JAAS convention of represenenting the username as a normal String, but the password as a character array, so we need to use the String.toCharArray() method to satisfy the constructor.
+
+{code}
+Node root = session.getRootNode();
+{code}
+
+ Each JCR session is associated with a workspace that contains a single node tree. A simple way to access the root node is to call the Session.getRootNode() method. Having a reference to the root node allows us to easily store and retrieve content in the current workspace.
+
+{code}
+Node hello = root.addNode("hello");
+Node world = hello.addNode("world");
+{code}
+
+ New content nodes can be added using the Node.addNode(String relPath) method. The method takes the name (or relative path) of the node to be added and creates the named node in the transient storage associated with the current session. Until the transient storage is persisted, the added node is only visible within the current session and not within any other session that is concurrently accessing the content repository.
+
+ This code snippet creates two new nodes, called "hello" and "world", with "hello" being a child of the root node and "world" a child of the "hello" node.
+
+{code}
+world.setProperty("message", "Hello, World!");
+{code}
+
+ To add some content to the structure created using the "hello" and "world" nodes, we use the Node.setProperty(String name, String value) method to add a string property called "message" to the "world" node. The value of the property is the string "Hello, World!".
+
+ Like the added nodes, also the property is first created in the transient storage associated with the current session. If the named property already exists, then this method will change the value of that property.
+
+{code}
+session.save();
+{code}
+
+ Even though the rest of our example would work just fine using only the transient storage of the single session, we'd like to persist the changes we've made so far. This way other sessions could also access the example content we just created. If you like, you could even split the example application into three pieces for respectively storing, retrieving, and removing the example content. Such a split would not work unless we persisted the changes we make.
+
+ The Session.save() method persists all pending changes in the transient storage. The changes are written to the persistent repository storage and they become visible to all sessions accessing the same workspace. Without this call all changes will be lost forever when the session is closed.
+
+{code}
+Node node = root.getNode("hello/world");
+{code}
+
+ Since we are still using the same session, we could use the existing hello and world node references to access the stored content, but let's pretend that we've started another session and want to retrieve the content that was previously stored.
+
+ The Node.getNode(String relPath) method returns a reference to the node at the given path relative to this node. The path syntax follows common file system conventions: a forward slash separates node names, a single dot represents the current node, and a double dot the parent node. Thus the path "hello/world" identifies the "world" child node of the "hello" child node of the current node - in this case the root node. The end result is that the method returns a node instance that represents the same content node as the world instance created a few lines earlier.
+
+{code}
+System.out.println(node.getPath());
+{code}
+
+ Each content node and property is uniquely identified by its absolute path within the workspace. The absolute path starts with a forward slash and contains all the names of the ancestor nodes in order before the name of the current node or property.
+
+ The path of a node or property can be retrieved using the Item.getPath() method. The Item inteface is a superinterface of Node and Property, and contains all the functionality shared by nodes and properties.
+
+ The node variable references the "world" node, so this statement will output the line "/hello/world".
+
+{code}
+System.out.println(node.getProperty("message").getString());
+{code}
+
+ Properties can be accessed using the Node.getProperty(String relPath) method that returns an instance of the Property interface that represents the property at the given path relative to the current node. In this case the "message" property is the one we created a few lines earlier.
+
+ A JCR property can contain either a single or multiple values of a given type. There are property types for storing strings, numbers, dates, binary streams, node references, etc. We just want the single string value, so we use the Property.getString() method. The result of this statement is the line "Hello, World!" being outputted.
+
+{code}
+root.getNode("hello").remove();
+{code}
+
+ Nodes and properties can be removed using the Item.remove() method. The method removes the entire content subtree, so we only need to remove the topmost "hello" node to get rid of all the content we added before.
+
+ Removals are first stored in the session-local transient storage, just like added and changed content. Like before, the transient changes need to be explicitly saved for the content to be removed from the persistent storage.
+
+h2. Hop 3: Importing content
+
+TODO: Update to match the style of previous hops.
+
+To add content a bit more efficiently, you may want to try JCR's import facilities, such as Session.importXML. The following XML document by Elliotte Rusty Harold provides an interesting example that demonstrates a repository's namespace capabilities:
+
+{code:title=test.xml}
+<xhtml:html xmlns:xhtml="http://www.w3.org/1999/xhtml"
+ xmlns:mathml="http://www.w3.org/1998/Math/MathML">
+ <xhtml:head><xhtml:title>Three Namespaces</xhtml:title></xhtml:head>
+ <xhtml:body>
+ <xhtml:h1 align="center">An Ellipse and a Rectangle</xhtml:h1>
+ <svg:svg xmlns:svg="http://www.w3.org/2000/svg"
+ width="12cm" height="10cm">
+ <svg:ellipse rx="110" ry="130" />
+ <svg:rect x="4cm" y="1cm" width="3cm" height="6cm" />
+ </svg:svg>
+ <xhtml:p>The equation for ellipses</xhtml:p>
+<mathml:math>
+ <mathml:apply>
+ <mathml:eq/>
+ <mathml:cn> 1 </mathml:cn>
+ <mathml:apply>
+ <mathml:plus/>
+ <mathml:apply>
+ <mathml:divide/>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> x </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> a </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:divide/>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> y </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> b </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ </mathml:apply>
+ </mathml:apply>
+ </mathml:apply>
+</mathml:math>
+ <xhtml:hr/>
+ <xhtml:p>Last Modified January 10, 2002</xhtml:p>
+ </xhtml:body>
+</xhtml:html>
+{code}
+
+The third example application shown below will import the XML file called test.xml from the current directory into a new content repository node called importxml. Once the XML content is imported, the application recursively dumps the contents of the entire workspace using the simple dump() method.
+
+{code:title=ThirdHop.java}
+import javax.jcr.*;
+import org.apache.jackrabbit.core.TransientRepository;
+import java.io.FileInputStream;
+
+/**
+ * Third Jackrabbit example application. Imports an example XML file
+ * and outputs the contents of the entire workspace.
+ */
+public class ThirdHop {
+
+ /** Runs the ThirdHop example. */
+ public static void main(String[] args) throws Exception {
+ // Set up a Jackrabbit repository with the specified
+ // configuration file and repository directory
+ Repository repository = new TransientRepository();
+
+ // Login to the default workspace as a dummy user
+ Session session = repository.login(
+ new SimpleCredentials("username", "password".toCharArray()));
+ try {
+ // Use the root node as a starting point
+ Node root = session.getRootNode();
+
+ // Import the XML file unless already imported
+ if (!root.hasNode("importxml")) {
+ System.out.print("Importing xml... ");
+ // Create an unstructured node under which to import the XML
+ Node node = root.addNode("importxml", "nt:unstructured");
+ // Import the file "test.xml" under the created node
+ FileInputStream xml = new FileInputStream("test.xml");
+ session.importXML(
+ "/importxml", xml, ImportUUIDBehavior.IMPORT_UUID_CREATE_NEW);
+ xml.close();
+ // Save the changes to the repository
+ session.save();
+ System.out.println("done.");
+ }
+
+ dump(root);
+ } finally {
+ session.logout();
+ }
+ }
+
+ /** Recursively outputs the contents of the given node. */
+ private static void dump(Node node) throws RepositoryException {
+ // First output the node path
+ System.out.println(node.getPath());
+ // Skip the virtual (and large!) jcr:system subtree
+ if (node.getName().equals("jcr:system")) {
+ return;
+ }
+
+ // Then output the properties
+ PropertyIterator properties = node.getProperties();
+ while (properties.hasNext()) {
+ Property property = properties.nextProperty();
+ if (property.getDefinition().isMultiple()) {
+ // A multi-valued property, print all values
+ Value[] values = property.getValues();
+ for (int i = 0; i < values.length; i++) {
+ System.out.println(
+ property.getPath() + " = " + values[i].getString());
+ }
+ } else {
+ // A single-valued property
+ System.out.println(
+ property.getPath() + " = " + property.getString());
+ }
+ }
+
+ // Finally output all the child nodes recursively
+ NodeIterator nodes = node.getNodes();
+ while (nodes.hasNext()) {
+ dump(nodes.nextNode());
+ }
+ }
+
+}
+{code}
+
+Running the ThirdHop class should produce output like the following:
+
+{code}
+Importing XML... done.
+/
+/jcr:primaryType=rep:root
+/jcr:system
+/testnode
+/testnode/jcr:primaryType=nt:unstructured
+/testnode/testprop=Hello, World.
+/importxml
+/importxml/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html
+/importxml/xhtml:html/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:head
+/importxml/xhtml:html/xhtml:head/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:head/xhtml:title
+/importxml/xhtml:html/xhtml:head/xhtml:title/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext
+/importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext/jcr:xmlcharacters=Three Namespaces
+/importxml/xhtml:html/xhtml:body
+/importxml/xhtml:html/xhtml:body/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:body/xhtml:h1
+/importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:body/xhtml:h1/align=center
+/importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext
+/importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext/jcr:xmlcharacters=An Ellipse and a Rectangle
+/importxml/xhtml:html/xhtml:body/svg:svg
+/importxml/xhtml:html/xhtml:body/svg:svg/jcr:primaryType=nt:unstructured
+/importxml/xhtml:html/xhtml:body/svg:svg/width=12cm
+/importxml/xhtml:html/xhtml:body/svg:svg/height=10cm
+.
+.
+.
+{code}
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+Title: First Hops with Apache Jackrabbit
+Welcome to your first hops into the world of Apache Jackrabbit! This
+introduction gives you a hands-on experience with Jackrabbit and the JCR
+API. Once you have finished hopping through this document, you should be
+all set to continue on your own with the official JCR specification and the
+documentation on this site.
+
+<a name="FirstHopswithApacheJackrabbit-Hop0:Gettingstarted"></a>
+## Hop 0: Getting started
+
+Before you can start using Jackrabbit, you need to have it installed on
+your computer. You can do this either by downloading a binary release and
+all the required dependencies or by building the Jackrabbit sources.
+
+Once you have Jackrabbit available locally, you should make sure that you
+have at least version 1.4 of the Java 2 Platform, Standard Edition (J2SE)
+installed and the following libraries configured in your Java classpath:
+
+<table>
+<tr><th> Library </th><th> Comments </th></tr>
+<tr><td> jackrabbit-1.0.jar </td><td> depending on whether you use a binary release or a
+locally compiled version </td></tr>
+<tr><td> jcr-1.0.jar </td><td> for the JCR 1.0 API </td></tr>
+<tr><td> slf4j-log4j12-1.0.jar and log4j-1.2.8.jar </td><td> for logging using SLF4J with
+Log4J (you should be fine with any Log4J 1.2.x version, or you could even
+replace both of these jars with another SLF4J implementation) </td></tr>
+<tr><td> commons-collections-3.1.jar </td><td> for advanced data structures used by
+Jackrabbit </td></tr>
+<tr><td> xercesImpl-2.6.2.jar and xmlParserApis-2.0.2.jar </td><td> for advanced XML
+support (you should be fine with any recent Xerces2 Java Parser
+implementation and the extra XML API library is only needed for JDK 1.4) </td></tr>
+<tr><td> derby-10.1.3.1.jar </td><td> or any recent Derby release for embedded database
+storage </td></tr>
+<tr><td> concurrent-1.3.4.jar </td><td> for advanced thread synchronization </td></tr>
+<tr><td> lucene-1.4.3.jar </td><td> for full text indexing and searching </td></tr>
+</table>
+
+You should also add the current directory in your classpath to make it easy
+to compile and run the example classes. You may also want to copy the
+following log4j.properties file to the current directory to avoid warnings
+of missing log configuration. If you want to see the internal Jackrabbit
+log, just change the log level to INFO or even DEBUG.
+
+<DIV class="code panel" style="border-style: solid;border-width: 1px;"><DIV class="codeHeader panelHeader" style="border-bottom-width: 1px;border-bottom-style: solid;"><B>log4j.properties</B></DIV><DIV class="codeContent panelContent">
+ log4j.logger.org.apache.jackrabbit=WARN,stdout
+ log4j.appender.stdout=org.apache.log4j.ConsoleAppender
+ log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout
+
+
+{tip}
+If you have build Jackrabbit from sources with Maven 1.x, you can get all
+the runtime dependencies (and some extra libraries) copied to target/lib by
+running maven copy-deps in the Jackrabbit project directory.
+{tip}
+
+{tip}
+You probably have an error in your classpath if you get a
+ClassNotFoundException message when trying to compile or run the examples
+below.
+{tip}
+
+<a name="FirstHopswithApacheJackrabbit-Hop1:LoggingintoJackrabbit"></a>
+## Hop 1: Logging in to Jackrabbit
+
+Once you are done with the setup tasks, we can start doing some real work.
+As a warm-up we'll create a Jackrabbit content repository and start a login
+session for accessing it. The full example application that does this is
+shown below, with line-by-line explanations following shortly after.
+
+<DIV class="code panel" style="border-style: solid;border-width: 1px;"><DIV class="codeHeader panelHeader" style="border-bottom-width: 1px;border-bottom-style: solid;"><B>FirstHop.java</B></DIV><DIV class="codeContent panelContent">
+ import javax.jcr.Repository;
+ import javax.jcr.Session;
+ import org.apache.jackrabbit.core.TransientRepository;
+
+ /**
+ * First hop example. Logs in to a content repository and prints a
+ * status message.
+ */
+ public class FirstHop {
+
+ /**
+ * The main entry point of the example application.
+ *
+ * @param args command line arguments (ignored)
+ * @throws Exception if an error occurs
+ */
+ public static void main(String[]
+ args) throws Exception {
+ Repository repository = new TransientRepository();
+ Session session = repository.login();
+ try {
+ String user = session.getUserID();
+ String name =
+repository.getDescriptor(Repository.REP_NAME_DESC);
+ System.out.println(
+ "Logged in as " + user + " to a " + name + "
+repository.");
+ } finally {
+ session.logout();
+ }
+ }
+
+ }
+
+
+You can also download the source file as FirstHop.java. If you have your
+classpath set up, you can compile the application with javac FirstHop.java
+and run it with java FirstHop to get the following output.
+
+Logged in as anonymous to a Jackrabbit repository.
+
+In addition to producing the above status line the application copies a
+default repository configuration file to repository.xml and creates an
+initial Jackrabbit content repository in the repository subdirectory. You
+can use the system properties org.apache.jackrabbit.repository.conf and
+org.apache.jackrabbit.repository.home to set alternative configuration file
+and repository directory locations.
+
+Read on for a detailed breakdown of the FirstHop application:
+
+
+ import javax.jcr.Repository;
+ import javax.jcr.Session;
+
+
+ The JCR API interfaces are located in the javax.jcr package found in
+the jcr-1.0.jar library. The promise of the JCR API is that if you only use
+these interfaces in your content application, it should remain mostly
+independent of the underlying content repository implementation.
+
+ The Repository interface represents a given content repository instance
+and the Session interface represents a single login session for accessing
+the repository. A session is needed to access any content within a
+repository.
+
+ Note that a Session instance is not guaranteed to be thread-safe so you
+should start multiple sessions if you need to access repository content
+simultaneously from different threads. This is especially important for
+things like web applications.
+import org.apache.jackrabbit.core.TransientRepository;
+
+ The best practice for deploying Jackrabbit is to use JNDI or some other
+configuration mechanism in a container environment to keep the application
+code free of direct Jackrabbit dependencies, but since we are creating a
+simple standalone application we can take a shortcut by using the
+TransientRepository class from Jackrabbit core.
+
+
+ public class FirstHop
+ public static void main(String[]
+ args) throws Exception
+
+
+ The FirstHop example is a simple standalone application that fits
+nicely in the main() method and lets the JVM take care of the possible
+exceptions. More substantial content applications could also be written as
+web application or EJB components with different setup and error handling
+patterns.
+
+
+ Repository repository = new TransientRepository();
+
+
+ The TransientRepository class implements the JCR Repository interface,
+so you can simply assign a TransientRepository instance to a Repository
+variable. The default constructor contains a utility feature that will take
+care of the initial configuration and repository construction when the
+first session is started. Thus there is no need for manual configuration
+for now unless you want direct control over the repository setup.
+
+ The TransientRepository implementation will automatically initialize
+the content repository when the first session is started and shut it down
+when the last session is closed. Thus there is no need for explicit
+repository shutdown as long as all sessions are properly closed. Note that
+a Jackrabbit repository directory contains a lock file that prevents it
+from being accessed simultaneously by multiple processes. You will see
+repository startup exceptions caused by the lock file if you fail to
+properly close all sessions or otherwise shut down the repository before
+leaving the process that accesses a repository. Normally you can just
+manually remove the lock file in such cases but such cases always present a
+chance of repository corruption especially if you use a non-transactional
+persistence manager.
+
+
+ Session session = repository.login();
+
+
+ The default Repository.login() method starts a repository session using
+the default workspace and no user credentials. Jackrabbit tries to use the
+Java Authentication and Authorization Service (JAAS) configuration in such
+cases, but defaults to the anonymous user if a JAAS Subject is not found.
+
+ Since we use the TransientRepository class as the Repository
+implementation, this step will also cause the repository to be initialized.
+
+
+ try { ... } finally { session.logout(); }
+
+
+ It is a good practice to properly release all acquired resources, and
+the JCR sessions are no exception. The try-finally idiom is a good way to
+ensure that a resource really gets released, as the release method gets
+called even if the intervening code throws an exception or otherwise jumps
+outside the scope (for example using a return, break, or continue
+statement).
+
+ The Session.logout() method in the finally branch closes the session
+and since this is the only session we have started, the TransientRepository
+is automatically shut down.
+
+
+ String user = session.getUserID();
+
+
+ The username or identifier of the user associated with a session is
+available using the Session.getUserID() method. Jackrabbit returns
+"anonymous" by default.
+
+
+ String name = repository.getDescriptor(Repository.REP_NAME_DESC);
+
+
+ Each content repository implementation publishes a number of string
+descriptors that describe the various implementation properties, like the
+implementation level and the supported optional JCR features. See the
+Repository interface for a list of the standard repository descriptors. The
+REP_NAME_DESC descriptor contains the name of the repository
+implementation, in this case "Jackrabbit".
+
+<a name="FirstHopswithApacheJackrabbit-Hop2:Workingwithcontent"></a>
+## Hop 2: Working with content
+
+The main function of a content repository is allow applications to store
+and retrieve content. The content in a JCR content repository consists of
+structured or unstructured data modeled as a hierarchy of nodes with
+properties that contain the actual data.
+
+The following example application first stores some content to the
+initially empty content repository, then retrieves the stored content and
+outputs it, and finally removes the stored content.
+
+<DIV class="code panel" style="border-style: solid;border-width: 1px;"><DIV class="codeHeader panelHeader" style="border-bottom-width: 1px;border-bottom-style: solid;"><B>SecondHop.java</B></DIV><DIV class="codeContent panelContent">
+ import javax.jcr.Repository;
+ import javax.jcr.Session;
+ import javax.jcr.SimpleCredentials;
+ import javax.jcr.Node;
+ import org.apache.jackrabbit.core.TransientRepository;
+
+ /**
+ * Second hop example. Stores, retrieves, and removes example content.
+ */
+ public class SecondHop {
+
+ /**
+ * The main entry point of the example application.
+ *
+ * @param args command line arguments (ignored)
+ * @throws Exception if an error occurs
+ */
+ public static void main(String[]
+ args) throws Exception {
+ Repository repository = new TransientRepository();
+ Session session = repository.login(
+ new SimpleCredentials("username",
+"password".toCharArray()));
+ try {
+ Node root = session.getRootNode();
+
+ // Store content
+ Node hello = root.addNode("hello");
+ Node world = hello.addNode("world");
+ world.setProperty("message", "Hello, World!");
+ session.save();
+
+ // Retrieve content
+ Node node = root.getNode("hello/world");
+ System.out.println(node.getPath());
+ System.out.println(node.getProperty("message").getString());
+
+ // Remove content
+ root.getNode("hello").remove();
+ session.save();
+ } finally {
+ session.logout();
+ }
+ }
+
+ }
+
+
+Like in the first hop, this example source is also available as
+SecondHop.java. You can also compile and run this class just like you did
+in the first hop example. Running this example should produce the following
+output:
+
+
+ /hello/world
+ Hello, World!
+
+
+The basic structure of this example application is the same as in the First
+Hop example, so let's just walk through the differences:
+
+
+ import javax.jcr.SimpleCredentials;
+ import javax.jcr.Node;
+
+
+ These are two new classes we need for this example. The
+SimpleCredentials class is a simple implementation of the Credentials
+interface used for passing explicit user credentials to the
+Repository.login(Credentials) method.
+
+ The Node interface is used to manage the content nodes in a repository.
+There is a related interface called Property for managing content
+properties, but in this example we use the Property interface only
+indirectly.
+
+
+ new SimpleCredentials("username", "password".toCharArray())
+
+
+ As discussed in the First Hop example, the default Repository.login()
+method returns an anonymous read-only session in the Jackrabbit default
+configuration. To be able to store and remove content we need to create a
+session with write access, and to do that we need to pass some credentials
+to the Repository.login(Credentials credentials) method.
+
+ The default Jackrabbit login mechanism accepts any username and
+password as valid credentials and returns a session with full write access.
+Thus we only need to construct and use a SimpleCredentials instance with
+some dummy username and password, in this case "username" and "password".
+
+ The SimpleCredentials constructor follows the JAAS convention of
+represenenting the username as a normal String, but the password as a
+character array, so we need to use the String.toCharArray() method to
+satisfy the constructor.
+
+
+ Node root = session.getRootNode();
+
+
+ Each JCR session is associated with a workspace that contains a single
+node tree. A simple way to access the root node is to call the
+Session.getRootNode() method. Having a reference to the root node allows us
+to easily store and retrieve content in the current workspace.
+
+
+ Node hello = root.addNode("hello");
+ Node world = hello.addNode("world");
+
+
+ New content nodes can be added using the Node.addNode(String relPath)
+method. The method takes the name (or relative path) of the node to be
+added and creates the named node in the transient storage associated with
+the current session. Until the transient storage is persisted, the added
+node is only visible within the current session and not within any other
+session that is concurrently accessing the content repository.
+
+ This code snippet creates two new nodes, called "hello" and "world",
+with "hello" being a child of the root node and "world" a child of the
+"hello" node.
+
+
+ world.setProperty("message", "Hello, World!");
+
+
+ To add some content to the structure created using the "hello" and
+"world" nodes, we use the Node.setProperty(String name, String value)
+method to add a string property called "message" to the "world" node. The
+value of the property is the string "Hello, World!".
+
+ Like the added nodes, also the property is first created in the
+transient storage associated with the current session. If the named
+property already exists, then this method will change the value of that
+property.
+
+
+ session.save();
+
+
+ Even though the rest of our example would work just fine using only the
+transient storage of the single session, we'd like to persist the changes
+we've made so far. This way other sessions could also access the example
+content we just created. If you like, you could even split the example
+application into three pieces for respectively storing, retrieving, and
+removing the example content. Such a split would not work unless we
+persisted the changes we make.
+
+ The Session.save() method persists all pending changes in the transient
+storage. The changes are written to the persistent repository storage and
+they become visible to all sessions accessing the same workspace. Without
+this call all changes will be lost forever when the session is closed.
+
+
+ Node node = root.getNode("hello/world");
+
+
+ Since we are still using the same session, we could use the existing
+hello and world node references to access the stored content, but let's
+pretend that we've started another session and want to retrieve the content
+that was previously stored.
+
+ The Node.getNode(String relPath) method returns a reference to the node
+at the given path relative to this node. The path syntax follows common
+file system conventions: a forward slash separates node names, a single dot
+represents the current node, and a double dot the parent node. Thus the
+path "hello/world" identifies the "world" child node of the "hello" child
+node of the current node - in this case the root node. The end result is
+that the method returns a node instance that represents the same content
+node as the world instance created a few lines earlier.
+
+
+ System.out.println(node.getPath());
+
+
+ Each content node and property is uniquely identified by its absolute
+path within the workspace. The absolute path starts with a forward slash
+and contains all the names of the ancestor nodes in order before the name
+of the current node or property.
+
+ The path of a node or property can be retrieved using the
+Item.getPath() method. The Item inteface is a superinterface of Node and
+Property, and contains all the functionality shared by nodes and
+properties.
+
+ The node variable references the "world" node, so this statement will
+output the line "/hello/world".
+
+
+ System.out.println(node.getProperty("message").getString());
+
+
+ Properties can be accessed using the Node.getProperty(String relPath)
+method that returns an instance of the Property interface that represents
+the property at the given path relative to the current node. In this case
+the "message" property is the one we created a few lines earlier.
+
+ A JCR property can contain either a single or multiple values of a
+given type. There are property types for storing strings, numbers, dates,
+binary streams, node references, etc. We just want the single string value,
+so we use the Property.getString() method. The result of this statement is
+the line "Hello, World!" being outputted.
+
+
+ root.getNode("hello").remove();
+
+
+ Nodes and properties can be removed using the Item.remove() method. The
+method removes the entire content subtree, so we only need to remove the
+topmost "hello" node to get rid of all the content we added before.
+
+ Removals are first stored in the session-local transient storage, just
+like added and changed content. Like before, the transient changes need to
+be explicitly saved for the content to be removed from the persistent
+storage.
+
+<a name="FirstHopswithApacheJackrabbit-Hop3:Importingcontent"></a>
+## Hop 3: Importing content
+
+TODO: Update to match the style of previous hops.
+
+To add content a bit more efficiently, you may want to try JCR's import
+facilities, such as Session.importXML. The following XML document by
+Elliotte Rusty Harold provides an interesting example that demonstrates a
+repository's namespace capabilities:
+
+<DIV class="code panel" style="border-style: solid;border-width: 1px;"><DIV class="codeHeader panelHeader" style="border-bottom-width: 1px;border-bottom-style: solid;"><B>test.xml</B></DIV><DIV class="codeContent panelContent">
+ <xhtml:html xmlns:xhtml="http://www.w3.org/1999/xhtml"
+ xmlns:mathml="http://www.w3.org/1998/Math/MathML">
+ <xhtml:head><xhtml:title>Three Namespaces</xhtml:title></xhtml:head>
+ <xhtml:body>
+ <xhtml:h1 align="center">An Ellipse and a Rectangle</xhtml:h1>
+ <svg:svg xmlns:svg="http://www.w3.org/2000/svg"
+ width="12cm" height="10cm">
+ <svg:ellipse rx="110" ry="130" />
+ <svg:rect x="4cm" y="1cm" width="3cm" height="6cm" />
+ </svg:svg>
+ <xhtml:p>The equation for ellipses</xhtml:p>
+ <mathml:math>
+ <mathml:apply>
+ <mathml:eq/>
+ <mathml:cn> 1 </mathml:cn>
+ <mathml:apply>
+ <mathml:plus/>
+ <mathml:apply>
+ <mathml:divide/>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> x </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> a </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:divide/>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> y </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ <mathml:apply>
+ <mathml:power/>
+ <mathml:ci> b </mathml:ci>
+ <mathml:cn> 2 </mathml:cn>
+ </mathml:apply>
+ </mathml:apply>
+ </mathml:apply>
+ </mathml:apply>
+ </mathml:math>
+ <xhtml:hr/>
+ <xhtml:p>Last Modified January 10, 2002</xhtml:p>
+ </xhtml:body>
+ </xhtml:html>
+
+
+The third example application shown below will import the XML file called
+test.xml from the current directory into a new content repository node
+called importxml. Once the XML content is imported, the application
+recursively dumps the contents of the entire workspace using the simple
+dump() method.
+
+<DIV class="code panel" style="border-style: solid;border-width: 1px;"><DIV class="codeHeader panelHeader" style="border-bottom-width: 1px;border-bottom-style: solid;"><B>ThirdHop.java</B></DIV><DIV class="codeContent panelContent">
+ import javax.jcr.*;
+ import org.apache.jackrabbit.core.TransientRepository;
+ import java.io.FileInputStream;
+
+ /**
+ * Third Jackrabbit example application. Imports an example XML file
+ * and outputs the contents of the entire workspace.
+ */
+ public class ThirdHop {
+
+ /** Runs the ThirdHop example. */
+ public static void main(String[]
+ args) throws Exception {
+ // Set up a Jackrabbit repository with the specified
+ // configuration file and repository directory
+ Repository repository = new TransientRepository();
+
+ // Login to the default workspace as a dummy user
+ Session session = repository.login(
+ new SimpleCredentials("username", "password".toCharArray()));
+ try {
+ // Use the root node as a starting point
+ Node root = session.getRootNode();
+
+ // Import the XML file unless already imported
+ if (!root.hasNode("importxml")) {
+ System.out.print("Importing xml... ");
+ // Create an unstructured node under which to import the
+XML
+ Node node = root.addNode("importxml", "nt:unstructured");
+ // Import the file "test.xml" under the created node
+ FileInputStream xml = new FileInputStream("test.xml");
+ session.importXML(
+ "/importxml", xml,
+ImportUUIDBehavior.IMPORT_UUID_CREATE_NEW);
+ xml.close();
+ // Save the changes to the repository
+ session.save();
+ System.out.println("done.");
+ }
+
+ dump(root);
+ } finally {
+ session.logout();
+ }
+ }
+
+ /** Recursively outputs the contents of the given node. */
+ private static void dump(Node node) throws RepositoryException {
+ // First output the node path
+ System.out.println(node.getPath());
+ // Skip the virtual (and large!) jcr:system subtree
+ if (node.getName().equals("jcr:system")) {
+ return;
+ }
+
+ // Then output the properties
+ PropertyIterator properties = node.getProperties();
+ while (properties.hasNext()) {
+ Property property = properties.nextProperty();
+ if (property.getDefinition().isMultiple()) {
+ // A multi-valued property, print all values
+ Value[]
+ values = property.getValues();
+ for (int i = 0; i < values.length; i++) {
+ System.out.println(
+ property.getPath() + " = " + values[i]
+.getString());
+ }
+ } else {
+ // A single-valued property
+ System.out.println(
+ property.getPath() + " = " + property.getString());
+ }
+ }
+
+ // Finally output all the child nodes recursively
+ NodeIterator nodes = node.getNodes();
+ while (nodes.hasNext()) {
+ dump(nodes.nextNode());
+ }
+ }
+
+ }
+
+
+Running the ThirdHop class should produce output like the following:
+
+
+ Importing XML... done.
+ /
+ /jcr:primaryType=rep:root
+ /jcr:system
+ /testnode
+ /testnode/jcr:primaryType=nt:unstructured
+ /testnode/testprop=Hello, World.
+ /importxml
+ /importxml/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html
+ /importxml/xhtml:html/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:head
+ /importxml/xhtml:html/xhtml:head/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:head/xhtml:title
+ /importxml/xhtml:html/xhtml:head/xhtml:title/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext
+ /importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:head/xhtml:title/jcr:xmltext/jcr:xmlcharacters=Three
+Namespaces
+ /importxml/xhtml:html/xhtml:body
+ /importxml/xhtml:html/xhtml:body/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:body/xhtml:h1
+ /importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:body/xhtml:h1/align=center
+ /importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext
+ /importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:body/xhtml:h1/jcr:xmltext/jcr:xmlcharacters=An
+Ellipse and a Rectangle
+ /importxml/xhtml:html/xhtml:body/svg:svg
+ /importxml/xhtml:html/xhtml:body/svg:svg/jcr:primaryType=nt:unstructured
+ /importxml/xhtml:html/xhtml:body/svg:svg/width=12cm
+ /importxml/xhtml:html/xhtml:body/svg:svg/height=10cm
+ .
+ .
+ .
+
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