A new blog is born

I want to thank everyone who took the time reading one or more of my blog posts. This will be my latest blog over here as I started a new blog which is reachable at http://pelssersconsultancy.github.io/

Switching between maven settings.xml

Often you have to copy the maven settings.xml file which is configured for a specific customer. But while developing in my spare time I just want to use my own settings.xml file. The easiest way to switch to using a different file is shown below:

mvn -gs $M2_HOME/conf/settings_pelssers.xml clean install

Using ssh tunnel with port forwarding

Connectivity has been setup from our staging environment to the third party server (endpoint of our soap clients). However, I wanted to connect locally with SOAP UI to this server, so I needed to setup an ssh tunnel with portforwarding on my macbook. I used to do this with putty on windows in the past so it took me a bit longer to figure this out.

Let's say the endpoint used from our staging environment would be "http://3rdpartyhostname/coolservice". In this case I want to listen on port 8877, and forward traffic from this port using the ssh tunnel to 3rdpartyhostname on port 80

ssh -f username@staginghostname -L 8877:3rdpartyhostname:80 -N

Now I can connect in SOAPUI to the following endpoint "http://localhost:8877/coolservice"

Fixing collisions ObjectFactory while executing wsdl2java

Often you have to deal with WSDL's from third parties. Sometimes the WSDL including referenced schemas are setup crappy and you run into issues while converting the WSDL to Java. Below we will look into how to fix these issues.

Eclipse will complain with following message

[ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [32,3]: (Relevant to above error) another "ReasonType" is generated from here. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [32,3]: Two declarations cause a collision in the ObjectFactory class. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [26,3]: (Related to above error) This is the other declaration. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [9,3]: Two declarations cause a collision in the ObjectFactory class. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [10,3]: (Related to above error) This is the other declaration. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [15,7]: Two declarations cause a collision in the ObjectFactory class. [ERROR] file:/playground/objectfactory/src/main/resources/xsd/helloworld.xsd [14,7]: (Related to above error) This is the other declaration. A class/interface with the same name "com.pelssers.helloworld.wrapper.ReasonType" is already in use. Use a class customization to resolve this conflict.

Below a version that fixes all issues. Ps. Sometimes it might also be useful to add @underscoreBinding="asCharInWord" to the globalBindings.

Javascript promises demo

Little Ajax exercise

Javascript XPath Demo

AngularJS demo

HTML5 Web Workers demo

Javascript event delegation (bubbling)

Using HTML5 dataset attributes

Using requirejs as javascript module loader

Ceylon: annotations

What is an annotation?

An annotation is a top level function that returns a subtype of ConstrainedAnnotation.

There are 2 interfaces which satisfy ConstrainedAnnotation directly:

• OptionalAnnotation: An annotation that may occur at most once at a single program element and only on certain program elements.
• SequencedAnnotation: An annotation that may occur multiple times at a single program element, and only on certain program elements.

Let's see the type hierarchy of ConstrainedAnnotation to get a better picture.

So what you might have thought to be reserved keywords (shared, formal, actual, ...) are in fact annotations used by the compiler.  Let's see how the DocAnnotation is implemented.

Using Java's FutureTask to execute Callable tasks concurrently

In this demo we have 2 Case Providers, one for Activiti and one for WPS. I used Thread.sleep to mimic a time consuming computation (e.g. IO). Now we want to have a composite Case Provider which composes cases from both case providers. However, as we naively implement this in SequentialCaseProvider we will see that the total time it takes is the sum of having the 2 caseproviders fetch the cases (9 seconds). By using a concurrent approach in ConcurrentCaseProvider, we can reduce the time to +- the time it takes the longest CaseProvider to fetch the cases. (5 seconds)

Ceylon: building typesafe webpages with the html module

Ceylon: dealing with files

As we saw earlier Ceylon is modularized. So the API to deal with files is not part of the core language. Check Modularity for how to specify a dependency on Ceylon file.

Ceylon: modularity

Ceylon: error handling the functional way

Ceylon: creating testdata is a breeze

Ceylon: named arguments and declarative syntax for object creation