# Runtime usage

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### Runtime

After running the binding compiler the modified classes are ready to be used. You'll need to include the /lib/jibx-run.jar and /lib/xpp3.jar jar files from the distribution in your application classpath (but not the /lib/bcel.jar and /lib/jibx-bind.jar files, which are only used by the binding compiler). You'll also need to add a little code at whatever point you want to marshal or unmarshal a document. This uses the `org.jibx.runtime.BindingDirectory` class that's included in the JiBX runtime jar, along with a class that JiBX generates in the same package as your code (or as the first class file it modifies, if your code is spread across multiple packages). You don't need to worry about the details of getting at this generated class, though. Instead, you access it by passing one of the classes defined by a global mapping (one that's a child of the root binding element) in your binding to the `BindingDirectory` (if you've compiled more than one binding into the code, you'll also need to pass the name of the binding you want to use). The code is simple:

        IBindingFactory bfact =
            BindingDirectory.getFactory(Customer.class);

Here Customer is the name of a class with a global mapping in the binding. The `org.jibx.runtime.IBindingFactory` interface that gets returned provides methods to construct marshalling and unmarshalling contexts, which in turn allow you to do the actual marshal and unmarshal operations. Here's an unmarshal example:

        IUnmarshallingContext uctx = bfact.createUnmarshallingContext();
        Object obj = uctx.unmarshalDocument
            (new FileInputStream("filename.xml"), null);

This is just one of several variations of an unmarshal call, in this case to unmarshal an XML document in the file filename.xml. You can pass a reader instead of a stream as the source of the document data if you want, and can also specify an encoding for the document - see the JavaDocs for details. The returned object will be an instance of one of your classes defined with a global mapping in the binding - you can either check the type with instanceof or cast directly to your object type, if you know what it is.

Marshalling is just as easy. Here's an example:

        IMarshallingContext mctx = bfact.createMarshallingContext();
        mctx.marshalDocument(obj, "UTF-8", null,
            new FileOutputStream("filename.xml"));

As with the unmarshal example, this is just one of several variations that can be used for the marshal call. This marshals the object to an XML document written to the file filename.xml, with UTF-8 character encoding (the most common choice for XML). The code as shown writes the output document with no extra whitespace; you can use the `setIndent()` method of the context to add whitespace for readability, if you wish. You can pass a writer instead of a stream, as well as some other variations - see the following section for details on character encoding usages, and the JavaDocs for the different types of marshal calls. The object to be marshalled must always be an instance of a class defined with a global mapping in the binding.

### Character encodings

The Java core classes provides `java.io.Writer` implementations that support a wide variety of character encodings. These can wrap simple output streams, and handle the conversions from Java characters to bytes as appropriate for the particular encoding used by the writer. This direct conversion of characters to bytes is not sufficient for use with XML, though. The problem is that character encodings may not allow for all the legal XML character codes. Any XML characters that are not supported by the output encoding need to be converted to character references for output (see the XML recommendation for details).

Because of this need to use character references, JiBX supports the use of character escapers for output conversion handling. For the widely-used UTF-8 and ISO-8859-1 (Western European character set) encodings implementations are included that handle both stream and writer output formats automatically (though using a stream will provide the best performance). The US-ASCII 7-bit format is also handled automatically, though in this case a `java.io.Writer` is always used internally.

Other character encodings can be used for output if you supply an appropriate `org.jibx.runtime.ICharacterEscaper` instance to be used with the output stream or writer. Depending on the encoding, you may even be able to use one of the existing character escaper implementation classes from the `org.jibx.runtime.impl` package directly, or at least base your own escaper code on one of those implementation classes. For most users the standard encodings are all that will ever be needed, but this approach allows other alternatives to be used when necessary for special requirements.

### Output formats

JiBX also provides the ability to generate output formats other than text, by using different implementations of the `org.jibx.runtime.IXMLWriter` interface. The only implementations of this interface currently provided are for text output to streams or writers. In the future, implementations that output marshalled documents as SAX2 or XMLPull parse event streams are planned to become part of the standard JiBX distribution. Until then, users with special requirements in this area can implement their own versions of this interface and use it directly.

### StAX support

The 1.1 release adds support for StAX parser input and StAX writer output. To select which parser you want to use dynamically, set the system property org.jibx.runtime.impl.parser to the value org.jibx.runtime.impl.XMLPullReaderFactory to select the XPP3 XMLPull parser, or the value org.jibx.runtime.impl.StAXReaderFactory to select the StAX parser. By default, JiBX uses whichever parser implementation it finds at runtime, with preference given to the XPP3 XMLPull parser if both XPP3 and a StAX parser are present. If you never want to use the XPP3 parser, simply remove the /lib/xpp3.jar file from your JiBX installation.

Some StAX parsers support schema validation of input. If you wish to make use of this feature you'll need to substitute an appropriate StAX parser implementation for the /lib/wstx-asl.jar StAX parser included in the JiBX distribution, and take whatever action is needed to enable schema validation.

JiBX 1.1 also includes support for StAX output (using the `javax.xml.stream.XMLStreamWriter` interface). This is mainly useful when fitting JiBX into other frameworks, including newer Web services frameworks. To use this form of output you'll need to set the XML writer directly on the JiBX marshalling context, using the special JiBX `org.jibx.runtime.impl.StAXWriter` class which wraps the target `javax.xml.stream.XMLStreamWriter` instance. Here's a sample of code for this purpose:

            // marshal root object back out to document in memory
            IMarshallingContext mctx = bfact.createMarshallingContext();
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            try {
                XMLOutputFactory ofact = XMLOutputFactory.newInstance();
                XMLStreamWriter wrtr = ofact.createXMLStreamWriter(bos, enc);
                mctx.setXmlWriter(new StAXWriter(bfact.getNamespaces(), wrtr));
                mctx.marshalDocument(obj);
            } catch (XMLStreamException e) {
                throw new JiBXException("Error creating writer", e);
            }