Re: [Question] Betwix JAXB
- Original Message - From: James Strachan [EMAIL PROTECTED] - Original Message - From: Dmitri Plotnikov [EMAIL PROTECTED] Hi, James, Ivelin, [...snip...] In many cases all these options would be equally good to me. Rarely do I need to customize, although when it's needed it must be there. e.g. for a Map Map map = new HashMap(); map.put( a, 1234 ); map.put( b, 5678 ); how should this look as XML? e.g. ... Or Dmitri can probably help here, but I understand that the following form is becoming popular: Map map = myBean.getItem(); map.put( a, 1234 ); map.put( b, 5678 ); item id=a1234/item item id=b5678/item which is consistent with arrays: item id=11234/mapName item id=25678/mapName And thus the XPath is natural /mybean/item[@id='a'] JXPath takes a dual approach to mapping of maps, or dynamic property objects as they are called in JXPath. On the one hand, you can use XPaths like /map/foo, which are natural when you know that the map is really just a more dynamic sister of a JavaBean, so foo is really a property of a logical bean called map. A good example of such use is a java.util.Properties object. Though this approach only works when the keys of the Map are Strings, the value of which are valid XML names (no colon, , quotes, spaces etc). FWIW I spotted a SOAP encoding of a Map today in this article... http://www-106.ibm.com/developerworks/library/ws-soapmap1/ which is as follows... hash xmlns:ns2=http://xml.apache.org/xml-soap; xsi:type=ns2:Map item key xsi:type=xsd:string2/key value xsi:type=xsd:stringtwo/value /item item key xsi:type=xsd:string1/key value xsi:type=xsd:stringone/value /item /hash So using elements for the key and the value can be quite useful as they can hold type information too. A similar approach is used for Lists too. James _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
This encoding looks wise to me too. Is this how Axis works? James, did you have time to talk to the Axis folks, regarding a possible reuse of the bean - XML code? BTW, any idea why they named the enclosing tag hash/ instead of map/ ? Thanks, Ivelin - Original Message - From: James Strachan [EMAIL PROTECTED] To: Jakarta Commons Developers List [EMAIL PROTECTED] Sent: Friday, April 19, 2002 8:57 AM Subject: Re: [Question] Betwix JAXB - Original Message - From: James Strachan [EMAIL PROTECTED] - Original Message - From: Dmitri Plotnikov [EMAIL PROTECTED] Hi, James, Ivelin, [...snip...] In many cases all these options would be equally good to me. Rarely do I need to customize, although when it's needed it must be there. e.g. for a Map Map map = new HashMap(); map.put( a, 1234 ); map.put( b, 5678 ); how should this look as XML? e.g. ... Or Dmitri can probably help here, but I understand that the following form is becoming popular: Map map = myBean.getItem(); map.put( a, 1234 ); map.put( b, 5678 ); item id=a1234/item item id=b5678/item which is consistent with arrays: item id=11234/mapName item id=25678/mapName And thus the XPath is natural /mybean/item[@id='a'] JXPath takes a dual approach to mapping of maps, or dynamic property objects as they are called in JXPath. On the one hand, you can use XPaths like /map/foo, which are natural when you know that the map is really just a more dynamic sister of a JavaBean, so foo is really a property of a logical bean called map. A good example of such use is a java.util.Properties object. Though this approach only works when the keys of the Map are Strings, the value of which are valid XML names (no colon, , quotes, spaces etc). FWIW I spotted a SOAP encoding of a Map today in this article... http://www-106.ibm.com/developerworks/library/ws-soapmap1/ which is as follows... hash xmlns:ns2=http://xml.apache.org/xml-soap; xsi:type=ns2:Map item key xsi:type=xsd:string2/key value xsi:type=xsd:stringtwo/value /item item key xsi:type=xsd:string1/key value xsi:type=xsd:stringone/value /item /hash So using elements for the key and the value can be quite useful as they can hold type information too. A similar approach is used for Lists too. James _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
- Original Message - From: Ivelin Ivanov [EMAIL PROTECTED] This encoding looks wise to me too. Is this how Axis works? Well its their default mapping for Hashtable Maps I think. I think you can register your own mashallers for stuff too to tweak it. James, did you have time to talk to the Axis folks, regarding a possible reuse of the bean - XML code? Not yet. Its on my list and I'll get to it eventually. Knee deep in email, Jaxen dom4j at the moment... BTW, any idea why they named the enclosing tag hash/ instead of map/ ? I think the example in the article was actually a Hashtable. Dunno if the name is configurable yet. James _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
- Original Message - From: Ivelin Ivanov [EMAIL PROTECTED] I would love it if the new Betwix marshaling with href and id's generates an XML file, which would be equally valid to apply against /next/next/next/. Not quite familiar how XPath would treat XLink refs. From a href you can use regular XPath to walk the link for you. XLink is kinda just XPath with some extension stuff (which in this context isn't required). You can even traverse links into other XML documents using the document() XPath function (from XSLT). James _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
Hi, James, Ivelin,
[...snip...]
In many cases all these options would be equally good to me.
Rarely do I need to customize, although when it's needed it must be there.
e.g. for a Map
Map map = new HashMap();
map.put( a, 1234 );
map.put( b, 5678 );
how should this look as XML? e.g.
...
Or
Dmitri can probably help here, but I understand that the following form is
becoming popular:
Map map = myBean.getItem();
map.put( a, 1234 );
map.put( b, 5678 );
item id=a1234/item
item id=b5678/item
which is consistent with arrays:
item id=11234/mapName
item id=25678/mapName
And thus the XPath is natural /mybean/item[@id='a']
JXPath takes a dual approach to mapping of maps, or dynamic property
objects as they are called in JXPath.
On the one hand, you can use XPaths like /map/foo, which are natural when
you know that the map is really just a more dynamic sister of a JavaBean, so
foo is really a property of a logical bean called map. A good example
of such use is a java.util.Properties object.
On the other hand, if your map is used as a generic dictionary and you may
not even know upfront what keys it will have, the alternative syntax is more
preferable: /map[@name = 'foo'], or /map[@name =
_some_expression_that_computes_the_key_]. @name is an attribute/keyword
in JXPath that represents a key or a property name in the case of a
JavaBean.
Of course, if you ask what this all means in terms of XML, the answer would
probably not be satisfactory. The same thing appears more than once in the
same document: once as an element and once as an attribute. However,
JXPath does not concern itself with these nuances. Instead of mapping every
kind of object model to the XML document model, it directly defines how
XPaths are interpreted on those models - no XML involved at all.
Here's another example of where this distinction manifests itself. Let's
say you have a cyclical graph. You couldn't map it to XML without
introducing some notion of references and all the related complexity. With
JXPath you don't need to do that, because it does not treat JavaBeans as XML
structures. For example, if we have an object like this:
class Foo {
private Foo next;
public Foo getNext(){ return next; }
public void setNext(Foo foo) {this.next = next;}
}
Foo foo = new Foo();
foo.setNext(foo);
We got ourselves a cyclical graph.
In Java, I could say: foo.getNext().getNext().getNext() and there would not
be anything wrong with it. Likewise, in JXPath,
context = JXPathContext.newContext(foo);
Foo bar = (Foo)context.getValue(/next/next/next);
Don't even ask me to what the corresponding XML document would look like.
I don't know if this is the right approach (the XPath standard, after all,
is a child of XML), but it works best for traversing graphs of JavaBeans and
does not really hurt the traversal of XML documents.
What do you think?
[...snip...]
Ivelin
James
Regards,
- Dmitri
--
To unsubscribe, e-mail: mailto:[EMAIL PROTECTED]
For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
Thanks for the clarification. So I've mistaken @id for @name.
See below.
- Original Message -
From: Dmitri Plotnikov [EMAIL PROTECTED]
To: Jakarta Commons Developers List [EMAIL PROTECTED]
Sent: Thursday, April 11, 2002 10:49 PM
Subject: Re: [Question] Betwix JAXB
Hi, James, Ivelin,
[...snip...]
In many cases all these options would be equally good to me.
Rarely do I need to customize, although when it's needed it must be
there.
e.g. for a Map
Map map = new HashMap();
map.put( a, 1234 );
map.put( b, 5678 );
how should this look as XML? e.g.
...
Or
Dmitri can probably help here, but I understand that the following form
is
becoming popular:
Map map = myBean.getItem();
map.put( a, 1234 );
map.put( b, 5678 );
item id=a1234/item
item id=b5678/item
which is consistent with arrays:
item id=11234/mapName
item id=25678/mapName
And thus the XPath is natural /mybean/item[@id='a']
JXPath takes a dual approach to mapping of maps, or dynamic property
objects as they are called in JXPath.
On the one hand, you can use XPaths like /map/foo, which are natural
when
you know that the map is really just a more dynamic sister of a JavaBean,
so
foo is really a property of a logical bean called map. A good
example
of such use is a java.util.Properties object.
On the other hand, if your map is used as a generic dictionary and you may
not even know upfront what keys it will have, the alternative syntax is
more
preferable: /map[@name = 'foo'], or /map[@name =
_some_expression_that_computes_the_key_]. @name is an
attribute/keyword
in JXPath that represents a key or a property name in the case of a
JavaBean.
Of course, if you ask what this all means in terms of XML, the answer
would
probably not be satisfactory. The same thing appears more than once in the
same document: once as an element and once as an attribute. However,
JXPath does not concern itself with these nuances. Instead of mapping
every
kind of object model to the XML document model, it directly defines how
XPaths are interpreted on those models - no XML involved at all.
Here's another example of where this distinction manifests itself. Let's
say you have a cyclical graph. You couldn't map it to XML without
introducing some notion of references and all the related complexity.
With
JXPath you don't need to do that, because it does not treat JavaBeans as
XML
structures. For example, if we have an object like this:
class Foo {
private Foo next;
public Foo getNext(){ return next; }
public void setNext(Foo foo) {this.next = next;}
}
Foo foo = new Foo();
foo.setNext(foo);
We got ourselves a cyclical graph.
In Java, I could say: foo.getNext().getNext().getNext() and there would
not
be anything wrong with it. Likewise, in JXPath,
context = JXPathContext.newContext(foo);
Foo bar = (Foo)context.getValue(/next/next/next);
Don't even ask me to what the corresponding XML document would look like.
I would love it if the new Betwix marshaling with href and id's generates an
XML file,
which would be equally valid to apply against /next/next/next/.
Not quite familiar how XPath would treat XLink refs.
I don't know if this is the right approach (the XPath standard, after
all,
is a child of XML), but it works best for traversing graphs of JavaBeans
and
does not really hurt the traversal of XML documents.
What do you think?
[...snip...]
Ivelin
James
Regards,
- Dmitri
--
To unsubscribe, e-mail:
mailto:[EMAIL PROTECTED]
For additional commands, e-mail:
mailto:[EMAIL PROTECTED]
--
To unsubscribe, e-mail: mailto:[EMAIL PROTECTED]
For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
Hi James, Thanks for the detailed response. Yes, choice is healthy. I will hope however that the coices stay limited to 1 or 2 alternatives. More than that, it will almost sound like waste of brain. I am very happy with JXPath and therefore I would think that Betwix is the tool I'd use for marshaling in future. What I really appreciate about JXPath is that it is quite smart about auto handling mapping for various types. An inconvenience of Castor is that it's virtually useless without explicit mapping. If Betwix is going to be a lot more transparent and not require mapping for most cases, I'd certainly enjoy it. BTW, when mapping is not provided, how does betwix handle circular references during marshaling? Xlink? Cheers, Ivelin - Original Message - From: James Strachan [EMAIL PROTECTED] To: Jakarta Commons Developers List [EMAIL PROTECTED] Sent: Monday, April 08, 2002 10:32 PM Subject: Re: [Question] Betwix JAXB Hi Ivelin From: Ivelin Ivanov [EMAIL PROTECTED] Is there a rundown available on the reasons why Betwix is developing in paralel with JAXB? Good question :-) I've used Castor for quite some time and have been happy with its performance. JAXB takes the approach that a DTD (and one day an XML schema) is used to generate beans that can parse/output the XML, then you can derive from them to add behaviour. Betwixt takes a different approach, that starting with any bean, it already has a default XML representation; then betwixt can be customized with just the differences you want (moving elements around, adding arbitrary extra XML nestings, renaming elements/attributes etc). Then betwixt can parse XML (using Digester, it essentially defaults digester rules) or output XML straight away, then customize to make it esthetically nicer XML later. On the list of things planned are SAX reader/writers and a DOM implementation using betwixt's mappings, then XSLT can be used on beans (like the Maven project does). Also I should finally get around to using Betwixt to add a bean Navigator to the Jaxen XPath engine. Betwixt essentially mirrors the Introspector / BeanInfo classes from java.beans but for mapping information of beans to XML, so there's an XMLIntrospector and XMLBeanInfo etc. Both the JAXB betwixt approaches are equally valid; JAXB is useful if you want some beans generated from some kind of XML 'schema', betwixt is better if you already have the beans and want to customize what the XML looks like, or to automatically default digester rules for you, then maybe customize things later. So if you're starting from beans and want nice XML then betwixt is a good tool for the job; if you're starting with a DTD and want to write some beans, then look at JAXB. Castor is kinda in the middle between them with a bit more complexity thrown in for good measure but its got some good stuff in there. Though I always get the impression Castor is trying to do too much together at the same time rather than just doing one thing well, but maybe thats just me. I can't help think of the phrase 'jack of all trades and master of none'. e.g. Castor is JDO-like without being compliant, its kind of an O/R mapping tool, its a reasonable O/XML mapping tool and a kinda OQL engine all thrown in together. An impressive body of work though. As an aside, betwixt focusses on the mapping metadata of how beans should map to XML, so betwixt could maybe be used to generate Castor java - XML bindings - though I'm not sure why you'd want to do that ;-) Apache Axis build their own JavaBean-XML mapping and Betwix is yet another development in the area. Its on my list to investigate using Betwixt in Axis. SOAP supports various different encodings, 1 of which (usually called the 'soap encoding') is a well defined mapping of SOAP to java objects, so Axis probably implements that spec. However for some of the other encodings (such as none where you just get XML), then maybe betwixt could be used to map a SOAP schema to some implementation beans. i.e. to have a flexible, customizable mapping. I'd certainly like try out a Betwixt based serializer/deserializer for Axis and see if it works neatly. James _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
Hi, It is also JavaBean-XML mapping framefork : http://joda.sourceforge.net/ And it is no problem if you will decide to implement a new one, if you think it can be better or have something unique. Users will decide bad or good. Is there a rundown available on the reasons why Betwix is developing in paralel with JAXB? I've used Castor for quite some time and have been happy with its performance. Apache Axis build their own JavaBean-XML mapping and Betwix is yet another development in the area. Thanks, Ivelin -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED] -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
Re: [Question] Betwix JAXB
This is true, Joda also performs Java-XML mappings. And like Betwixt it is not intended for use starting from just any old XML. (Java is king, XML is just a data format). Joda got written because I could find no alternative that met my requirements. JAXB is XML focussed, I needed a Java focussed solution. Castor had an unsuitable licence (you can't use it in a development kit), plus it doesn't support Maps and I found a problem with Lists too. JOX (@sourceforge) was focussed on mapping XML style names to Java ones using a DTD, and also didn't support Maps or infinite recursion. At the time of writing it, I didn't know about Betwixt. Now I am considering if Betwixt and Joda may integrate - not quite sure yet. Joda currently handles Maps and ids in a way I don't think betwixt does yet. But betwixt offers a greater range of output formats and operates on plain JavaBeans.. And as Juozas said, more choice is generally good. Stephen Hi, It is also JavaBean-XML mapping framefork : http://joda.sourceforge.net/ And it is no problem if you will decide to implement a new one, if you think it can be better or have something unique. Users will decide bad or good. Is there a rundown available on the reasons why Betwix is developing in paralel with JAXB? I've used Castor for quite some time and have been happy with its performance. Apache Axis build their own JavaBean-XML mapping and Betwix is yet another development in the area. Thanks, Ivelin -- To unsubscribe, e-mail: mailto:[EMAIL PROTECTED] For additional commands, e-mail: mailto:[EMAIL PROTECTED]
