Posts tagged Java
Using JPA to persist the Tour de France Java Object Graph to relational database tables
1In a recent article – http://technology.amis.nl/blog/12786/building-java-object-graph-with-tour-de-france-results-using-screen-scraping-java-util-parser-and-assorted-facilities – I described how I retrieved the statistics for recent Tour de France editions from the official Tour de France website from my Java program and constructed an Java Object Graph for the data on stages, riders and rankings. In this article, I will show how I have persisted that data, from the Java Objects to Relational Tables in my local Oracle XE database. Note: the fact that this concerns Tour de France data is not really relevant for this story – it is a generic story about how JPA is used to map and persist Java Classes and Objects to a relational database.
The Class diagram for the classes involved looks like this:
The Java program discussed in the previous article retrieves data from the Le Tour De France website and creates an Object Graph according to these object definitions. Note: in comparison with the previous article, I have already applied a few small changes that will help with othe ORM mapping that JPA will do for me. The stage and rider references in Standing as well as the tour references More >
Building Java Object Graph with Tour de France results – using screen scraping, java.util.Parser and assorted facilities
4Last Saturday, the Tour de France 2011 departed. For people like myself, enjoying sports and working on Data Visualizations on the one hand and far fetched uses of SQL on the other, the Tour de France offers a wealth of data to work with: rankings for each stage in various categories, nationalities and teams to group by, distances and velocity, years to compare with one another and the like. So it has been my intention for some time to get hold of that data in a format I could work with.
Today I finally found some time to get it done. To locate the statistics for the Tour de France editions for the last few years and get them onto my laptop and into my database. This article describes the first part of that journey: how to get the stage results from some source on the internet into my locally running Java program in an appropriate object structure.
My starting point is the official Tour de France website:
This website goes back to 2007 and also has the latest (2011) results. It presents the result in a format pleasing to the human eye – based on an HTML structure that is fairly pleasing to my groping Java code as well.
How to call a webservice directly from Java (without webservice library)
7In this blog I will show you how you can call a webservice programmatically in Java without using a webservice library like JAX-WS or Apache Axis. Normally you would use of course a webservice library, but in some cases this can be useful and quick; for example when you have problems generating a client proxy with a webservice library or if you only need some small specific parts of the SOAP response XML tree.  It shows that a SOAP call is just XML over HTTP, from a plain piece of Java code. Then, I will show you an example how you can use this and make your own servlet webservice-tester like a simple SoapUI in JDeveloper 11.1.1.3.
Turning any XML document into a Java Object graph using JAXB 2.0
0As a followup to my recent article on how to Produce and XML document based on data in a POJO structure using JAXB (http://technology.amis.nl/blog/12499/creating-an-xml-document-based-on-my-pojo-domain-model-how-will-jaxb-help-me) I will describe in this article how to go the reverse route: how to take any XML document and process it into a Java Object graph. I will do that using JAXB.
The steps described in this article are:
- create XSD based on the XML document that I want to turn into Java objects
- generate a JAXB Java class structure based on the XSD
- use JAXB to unmarshall the XML document from file or URL into the Java objects
- retrieve information from the POJOs that are instantiated by the unmarshalling
The tool I use in this article is JDeveloper 11g. However, everything is based on standard technology and will work anywhere (except for the creation of the XSD based on an XML, that is a specific XML IDE feature).
Creating an XML document based on my POJO domain model – how will JAXB help me?
1The challenge is a common one. We have got data in a domain model, based on POJOs. And we need to marshall that data into an XML document. Note that the exact structure of that document is not so important – we will probably translate is somewhere anyway. At this point, all we have is a set of POJO definitions. There is no XSD, no predefined XML structure.
JAXB – the Java Architecture for XML Binding – seems like the technology to turn to. My experience with JAXB has mainly been from the other end: we have XML data, described by an XSD, that we want to turn into Java Objects (unmarshall XML to Java). In that case, we take the XSD that describes the XML, generate Java classes and use JAXB to unmarshall XML into objects based on those classes. The alternative round – taking classes and marshalling them into XML would be just as simple – or even simpler, now would it not?
Well, it was not as straightforward as I hoped it would be. I thought that adding a few JAXB annotations to my existing POJO model would do the trick – but no such luck. Unless I am completely misguided and mistaken, the steps required are:
- create an XSD based on the original POJO model
- generate JAXB annotated More >
How to remove unwanted SOAP header elements in JAX-WS
0In our current webservice project with JAX-WS in  JDeveloper  11.1.1.3 we have a challenge with calling a webservice. This webservice from a remote organisation does not accept specific SOAP header elements our client application creates – although we followed the contract of the WSDL correctly. Of course this webservice must follow it as well as we have to, but for now we don’t have a choice but to make a workaround.  How can we remove unwanted elements from a SOAP header? In this blog I will show you how you can do that using a JAX-WS SOAPHandler that inspects the SOAP header and removes specific addressing elements. (more…)
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