Kodo Tan

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Recent posts by Kodo Tan

Hi
According to W3C definition, if I'm not wrong, a web services application need to use XML. If that's the case, why do we still call it XML WebServices ?
Regards and have a nice day.

Cheers
Kodo
17 years ago
Hi all
Sorry for asking this dumb question - "Must all web services come with WSDL ?" Are there any web services that work without any WSDL files ?
Thanks in advance.

Cheers
Kodo
17 years ago
Hi all
There are 3 modes for JAX-RPC, 2 of which are the following:
1. One-way RPC
2. Non-Blocking RPC Invocation
Both modes do not block or wait until they receive a return. So anyone knows what are the subtle differences between these two and what are the deciding criteria to determine which mode to use in some scenarios.
Checked the FAQs at Sun but they do not seem to have the answer there.
Regards and have a nice day.
Cheers
Kodo
17 years ago
Hi
Thanks to all who replied ... I'm now clearer on the differences between JAXB and SAX/DOM.
Found the following from the sun's site. Hope that it's useful .
* JAXB simplifies access to an XML document from a Java program:
- JAXB allows you to access and process XML data without having to
know XML or XML processing. Unlike SAX-based processing, there's no
need to create a SAX parser or write callback methods.
- JAXB allows you to access data in non-sequential order, but unlike
DOM-based processing, it doesn't force you to navigate through a
tree to access the data.
- By unmarshalling XML data through JAXB, Java content objects that
represent the content and organization of the data are directly
available to your program.
* JAXB uses memory efficiently: The tree of content objects produced
through JAXB tends can be more efficient in terms of memory use than
DOM-based trees.
* JAXB is flexible:
- You can unmarshal XML data from a variety of input sources,
including a file, an InputStream object, a URL, a DOM node, or a
transformed source object.
- You can marshal a content tree to a variety of output targets,
including an XML file, an OutputStream object, a DOM node, or a
transformed data object
- You can unmarshal SAX events -- for example, you can do a SAX
parse of a document and then pass the events to JAXB for
unmarshalling.
- JAXB allows you to access XML data without having to unmarshal it.
Once a schema is bound you can use the ObjectFactory methods to
create the objects and then use set methods in the generated
objects to create content.
- You can validate source data against an associated schema as part
of the unmarshalling operation, but you can turn validation off if
you don't want to incur the additional validation overhead.
- You can validate a content tree, using the Validator class,
separately from marshalling. For example, you can do the
validating at one point in time, and do the marshalling at another
time.
* JAXB's binding behavior can be customized in a variety of ways.
17 years ago
Hi
I've this question but was not able to find any answers to it from the web services book I had.
Generally, what's the way (best practice) to protect web services ? For instance, from the WSDL, any client can know what are the available methods to call. How do we protect the application from clients who are supposed to deny access to certain services ? Is this to be done in the usual ACL application module ?
Thanks for any reply ....
17 years ago
SAX and DOM are approaches for parsing an XML document while JAXB defines a binding between a specific XML schema and a corresponding Java object hierarchy.

Hi Lasse
Thanks for the reply .... sorry I'm still a bit confused here ... We can use SAX or DOM to parse an XML document and create the necessary objects or create a DOM tree and generate the XML document. These tasks can be done using JAXB too.
So my question is - "Since most of the things can be done by these 3 methods (SAX, DOM or JAXB), what are the main deciding criteria to determin which to use ?
Thanks and have a nice day.
17 years ago
Anyone knows the difference between these 3 ways of reading XML files ? I mean when should we use JAXB instead of the other 2 and vice versa.
Must we always JAXB for webservices ?
Sorry for this silly questions as I'm very new to XML and webservices.
17 years ago
Hi all
I have a code that implements 2 phase commit using programmatic transaction control. The code basically accesses 2 database running at 2 physical location with 2 different datasources.
The code works fine in 1 application server but hit the following error in bea. I have also ensure that I had clicked the 2 phase commit option in bea admin console.
Any one knows how to resolve this ?
java.sql.SQLException: Connection has already been created in this tx context fo r pool named KernlPool. Illegal attempt to create connection from another pool: EmanPool
at
weblogic.jdbc.jts.Driver.getExistingConnection(Driver.java:292)
at weblogic.jdbc.jts.Driver.connect(Driver.java:123)
at weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSour
ce.java:214)
at org.exolab.castor.jdo.engine.DatabaseRegistry.createConnection(Unknow
n Source)
at org.exolab.castor.jdo.engine.TransactionContextImpl.getConnection(Unk
nown Source)
at org.exolab.castor.persist.ClassMolder.create(Unknown Source)
at org.exolab.castor.persist.LockEngine.create(Unknown Source)
at org.exolab.castor.persist.TransactionContext.create(Unknown
Source)
at org.exolab.castor.jdo.engine.DatabaseImpl.create(Unknown
Source)
at com.ekernel.examples.echo.service.EchoServiceBean.test2db(EchoService
Bean.java:270)
at com.ekernel.examples.echo.service.EchoServiceBean.doProcess(EchoServi
Hi all
I have a code that implements 2 phase commit using programmatic transaction control. The code basically accesses 2 database running at 2 physical location with 2 different datasources.
The code works fine in 1 application server but hit the following error in bea. I have also ensure that I had clicked the 2 phase commit option in bea admin console.
Any one knows how to resolve this ?
java.sql.SQLException: Connection has already been created in this tx context fo r pool named KernlPool. Illegal attempt to create connection from another pool: EmanPool
at
weblogic.jdbc.jts.Driver.getExistingConnection(Driver.java:292)
at weblogic.jdbc.jts.Driver.connect(Driver.java:123)
at weblogic.jdbc.common.internal.RmiDataSource.getConnection(RmiDataSour
ce.java:214)
at org.exolab.castor.jdo.engine.DatabaseRegistry.createConnection(Unknow
n Source)
at org.exolab.castor.jdo.engine.TransactionContextImpl.getConnection(Unk
nown Source)
at org.exolab.castor.persist.ClassMolder.create(Unknown Source)
at org.exolab.castor.persist.LockEngine.create(Unknown Source)
at org.exolab.castor.persist.TransactionContext.create(Unknown
Source)
at org.exolab.castor.jdo.engine.DatabaseImpl.create(Unknown
Source)
at com.ekernel.examples.echo.service.EchoServiceBean.test2db(EchoService
Bean.java:270)
at com.ekernel.examples.echo.service.EchoServiceBean.doProcess(EchoServi
18 years ago
Hi all
Anyone knows the difference between Groups and Complex Type Ref ? It seems that both can be used to achieve the same objective for extensibility and reusability.
When should we use Group and when should we use complex type reference instead ?
Thanks
Hi Jayadhara
Thanks for the information. Anyone knows where can I download good references on XML Architecture ?
Hi all
Would like to check with you guys if XML Schema is covered heavily for the Test 141 exams. Anyone knows (roughly) the weightage of questions for the following topics:
- XML Schema
- XML Architecture
- DOM2
- SAX2
- XML 1.0
- XSL:FO (is this included for the exams ?)
- XSL
- XSLT
- XPath
- XPointer
- XLink
- Web Services
- UUDI
- WSDL
Hi all
Do we need to study topics like XLink, XPointer, RDF for the 141 certification ?
Hi Simon
the log said that http is listening successfully at 9080 but I cannot access http://localhost:9080
19 years ago
Hi
Anyone knows where can I find information to set up Struts in WebSphere 4.0?
Thanks !
19 years ago