How should I use Stax2 Validation API against a W3 Schema - java

I am using com.ctc.wstx.stax.WstxOutputFactory to generate XML.
I am running wstx-asl-3.2.4
I need to start validating the generated XML against a W3 Schema.
When I create an instance of org.codehaus.stax2.validation.XMLValidationSchemaFactory like this
private final static XMLValidationSchemaFactory xsdFact=
XMLValidationSchemaFactory.newInstance(XMLValidationSchema.SCHEMA_ID_W3C_SCHEMA);
I get the error
javax.xml.stream.FactoryConfigurationError: No XMLValidationSchemaFactory implementation class specified or accessible (via system property 'org.codehaus.stax2.validation.XMLValidationSchemaFactory.w3c', or service definition under 'META-INF/services/org.codehaus.stax2.validation.XMLValidationSchemaFactory.w3c')
at org.codehaus.stax2.validation.XMLValidationSchemaFactory.newInstance(XMLValidationSchemaFactory.java:208)
at org.codehaus.stax2.validation.XMLValidationSchemaFactory.newInstance(XMLValidationSchemaFactory.java:98)
I can see that woodstox is bundled with a DTD parser only.
I found this article
which contains the unhelpful instruction
Get an instance of XMLValidationSchemaFactory that knows how to parse schemas of the type you need (RelaxNG == rng for this example).
I have been looking at the Sun Multi-Schema XML Validator which is supposed to contain the bits necessary to bolt on to the XMLSchemaValidation factory.
It looks like I might be able to use com.sun.msv.reader.xmlschema.XMLSchemaReader
to write my own instance of XMLValidationSchemaFactory and get it to work this way.
My question is; do I really have to do this, or is there a pre-existing w3c schema factory that I have failed to find?
Perhaps it would be simpler just to validate the XML after I have generated it.
What are the views on this ?

I've upgraded to Woodstox 4.0.8, W3CSchemaFactory comes bundled and its all good.

Related

Writing an XML SOAP message in Java

I have the following method that accepts xml and I do some data feeding with the content.
I am supposed to return a SOAP message as well, something along these lines:
<ow-e:Envelope revision='2.0' xmlns:ow-e='http://www.url.com/test-envelope'>
<ow-e:Header>
<ow-e:Properties>
<ow-e:SentAt>2004-12-14T13:54:36</ow-e:SentAt>
<ow-e:Topic>SOME_STRING</ow-e:Topic>
</ow-e:Properties>
</ow-e:Header>
</ow-e:Envelope>
So right now what I am doing is the following:
String some_string = "qwe";
String response = "";
response = "<ow-e:Envelope revision='2.0' xmlns:ow-e='http://www.url.com/test-envelope'><ow-e:Header><ow-e:Properties><ow-e:SentAt>2004-12-14T13:54:36</ow-e:SentAt><ow-e:Topic>" + some_string + "</ow-e:Topic></ow-e:Properties></ow-e:Header></ow-e:Envelope>";
return response;
Which is absolutely terrible. Any idea how I can actually make it more bearable? Using a framework is not an option at the moment.
This is the first time I am dealing with SOAP messages/responses and it feels like hell coming from REST. I probably need to create some kind of hierarchy to populate the values correctly, but I am not sure how it can be done just by using Java without any frameworks.
You mentioned using frameworks is not an option, but something more lightweight may be available in your platform:
JAXB. JAXB allows you to map Java classes to XML representations using annotations. It's far better than doing marshaling and unmarshaling by hand or by concatenating or parsing strings. With properly structured and annotated POJOs, JAXB can handle things for you. You might even be able to cheat and use xjc with your WSDL file to create annotated classes with the -wsdl option (experimental though).
SAAJ. Bluntly put, SAAJ is just like a specific builder and parser for SOAP messages. It will handle the structure and namespaces for you. Speaking of which...
... the example you are showing isn't really valid SOAP message. SOAP is a protocol. You need to properly format it and use the right namespaces otherwise you are just returning some XML messages that look like SOAP, but aren't.

Axis2 error: Invalid white space character (0x4) in text to output

I have created a Java client to interact with a SOAP webservice using Axis2 (1.7.6) as code generator. The problem is with some inputs the client is throwing an exception with the message:
org.apache.axis2.AxisFault: Invalid white space character (0x4) in text to output (in xml 1.1, could output as a character entity)
It seems the serialiser is hitting some chars considered invalid to XML spec. I have seen that problem around but no definitive answer or the fix. I'm not using Spring or any other dependency injection framework, it's a standalone application, so I need to configure the inners of Axis2 by hand.
Any ideas on how to fix/configure the client properly?
After some research I found this behaviour is due to one default setting of the lib Woodstox (Axis2 dependency), that uses the class com.ctc.wstx.api.InvalidCharHandler.FailingHandler as default implementation of the interface com.ctc.wstx.api.InvalidCharHandler, used inside com.ctc.wstx.sw.XmlWriter and invoked in the serialisation process. This means: when the component hits characters considered invalid to XML, it’ll throw an error.
Woodstox provides another implementation of the interface com.ctc.wstx.api.InvalidCharHandler, the one called com.ctc.wstx.api.InvalidCharHandler.ReplacingHandler that instead of throwing errors will replace those chars for something else. But how to do that?
The class com.ctc.wstx.stax.WstxOutputFactory inside Woodstox contains several configurations, one of them being the invalid char handler. Though, it's not configurable by some magic system wide property, instead, by the method com.ctc.wstx.stax.WstxOutputFactory#setProperty, that takes as arguments one string and one object.
So first, you'll have to extend that factory and set the property com.ctc.wstx.outputInvalidCharHandler with an instance of com.ctc.wstx.api.InvalidCharHandler.ReplacingHandler that takes as argument the char you want to replace the invalid ones with. Like this:
package my.package;
import com.ctc.wstx.stax.WstxOutputFactory;
public class MyWstxOutputFatory extends WstxOutputFactory {
public MyWstxOutputFatory() {
setProperty(
com.ctc.wstx.api.WstxOutputProperties.P_OUTPUT_INVALID_CHAR_HANDLER,
new com.ctc.wstx.api.InvalidCharHandler.ReplacingHandler(' '));
}
}
The second, trickiest and undocumented step is how to register your implementation as the factory Woodstox'll use. You'll have to create a file named META-INF/services/javax.xml.stream.XMLOutputFactory simply containing the name of your factory, in this case, the string:
my.package.MyWstxOutputFatory
Place this file in such a way it's included in your project's resulting jar. In my case I placed like: src/main/resources/META-INF/services/javax.xml.stream.XMLOutputFactory.
And you're done!

Java API for XML Schema manipulation

I am familiar with JAXB, JAXP and DOM. I know JAXB provides java2xml and xml2java generation(and validation against XML Schema(XSD)). What I want is convenient way to produce XML schema programmatically from scratch. I do not want to produce XSD from java classes. I want to have an object representing the schema itself. For example:
XMLSchemaFactory factory = XMLSchemaFactory.newInstance();
XMLSchema schema = factory.newSchema();
schema.setTargetNameSpace("http://www.example.com");
...
schema.addComplexType(complexTypeElement);
...
schema.addElement(name, type);
...
schema.export(new File("mySchema.xsd"));
I know XML schema is itself XML, so I can use Document, Element, Node and other classes/interfaces from org.w3c.dom, but I wonder is there something more convenient ?
Why I want this - I have some IDL, which I have to translate to WSDL. I have lexer/parser for the IDL and I have convenient representation of it as java objects. Now I want to produce the WSDL using this objects => a lot of XML schemas have to be generated !
From my point use WSDL4J it would be pretty easier for your xml manipulations.
Refer this pdf for more details.
http://wsdl4j.sourceforge.net/downloads/JSR110_proposed_final_draft.pdf

JAXP: How to dynamically resolve a Schema during XML parsing?

Imagine a xml file which refers to a schema using noNamespaceSchemaLocation.
I'd like to resolve the value defined in noNamespaceSchemaLocation dynamically using some kind of resolving technique (like ResourceResolver for resolving schema includes) during parsing (default values in the schema have to be considered)
Is there a way to do this?
I would guess that when you call Validator.setResourceResolver(), the LSResourceResolver you supply is used for this purpose (it is in the Saxon implementation of the JAXP interface, but you would need to run a test to check that it's also true of the Xerces implementation).

JAX-WS and Enunciate - How to change Enunciate's default XSD naming convention

I'm using Enunciate to generate a SOAP endpoint for a Wicket web application I am working on and I have a couple of questions that I haven't figured out the solution to yet.
1 How do I change the name of the xsd files? I've looked through the FAQ and it tells me to do something similar to this:
<xml>
<schema namespace="http://api.example.com/data" file="data.xsd"/>
</xml>
However, I haven't quite figured out how to set the targetNamespace for my data objects. I've done this for my service via #WebService ( targetNamespace="blah" ), but how do I annotate my data objects to let Enunciate know which namespace they should belong to?
2 Enunciate generates my XSDs just fine, but I don't particularily like the element names it uses. I have a ServiceRequest and ServiceResponse object. The ServiceRequest object has a List of User objects. The ServiceResponse has a list of Group objects. Enunciate suggests that every "User" object within the ServiceRequest should be using the tag "<users>". I feel that it would make more sense to use the singular form, "<user>" since the tag does in fact only contain a single user. Is it possible to change this behaviour, and if so, how?
Thanks in advance.
So just to be clear, with the exception of the question about naming your schema files, your questions are really more about JAXB than they are about Enunciate. JAXB is the spec that defines how your Java objects are (de)serialized to/from XML and Enunciate conforms to that spec.
Anyway, the easiest way to apply a namespace to your Java objects is with a package-info.java file in the package of your Java classes. Annotate your package with #XmlSchema and set the namespace to be the value you want.
Customizing how your accessors are serialized to/from XML can be done with the #XmlElement annotation, e.g.:
public class MyClass {
...
#XmlElement (name="user")
List<User> users;
...
}
Here are the JAXB javadocs
https://jaxb.dev.java.net/nonav/2.1.9/docs/api/
Or google for a good JAXB tutorial.

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