[Ctk-developers] data exchange in the DICOM Hosting implementation / QtSoap Limitation

Mon Jun 6 19:35:24 UTC 2011

Hi Sascha,

First thanks a lot for the quick reply I got on my previous post.  I decided to go for the first approach and created my own CTK plugin as we should stay in the context of a hosting application. I managed to start and run my hosted application through the DICOM Application Host interface with this approach.

I am now looking into passing some dataset to the hosted application.  I wanted to start with something simple where the end-user select a folder that contains a list of DICOM files (one series) and pass it to my application. After choosing the folder; I am updating the AvailableData structure and then publish it to the hosted application when I am starting it. By the time the SOAP request is done I could see that the SOAP message will contains my list of uuids I created for one series but when the message is received (ctkSoapMessageProcessorList::process method) on the hosted application; the message is not the same and only contains one uuid now for the series. Is there any limitation currently within QtSoap to support arrays that you are aware of?  I have seen some discussion regarding on the ctk website (http://www.commontk.org/index.php/Documentation/DicomApplicationHosting:DataExchangeDevelopment) but I am not sure what the status here.

If there is still some restriction with QtSoap regarding the array; should I send multiple notifyDataAvailable messages to the application; one for each file I am willing to get on the application side. Is there any other best alternative beside my first approach?

Best,
Michael

-------------------------------------------------------------------------------------------------------------------------------
From: Sascha Zelzer <s.zelzer at dkfz-heidelberg.de>
Subject: Re: [Ctk-developers] How to wrap a Qt App into an hosted app
        confirming to DICOM Supplement 118 / Working Group 23
To: ctk-developers at commontk.org
Message-ID: <4DCD447F.7060402 at dkfz-heidelberg.de>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

Hi Michael,

Welcome to the CTK mailing list.

DICOM Application Hosting support in CTK is still work in progress, so please be aware that not everything will work yet. Especially the data exchange interface needs more work. Nevertheless, I hope my comments below will get you started to experiment with your own Qt based DICOM App. Comments, bug reports, patches etc. are also always welcome!

Best,
Sascha

On 05/13/2011 03:56 AM, Caylus, Michael (SCR US) wrote:
> Hello,
> I am new to the CTK SDK and would like to wrap my Qt application into
> an hosted app. I have seen such an example by turning on in the CMake
> configuration:  ctkExampleHost and ctkExampleHosted App.  I came up
> with the following questions after playing with it:
>
>    1. In order to make this wrap-up for my app; I was considering to
>       edit the org_commontk_dah_exampleapp plug-in which relies on the
>       org_commontk_dah_app and org_commontk_dah_core plug-in and keep
>       the ctkExampleHostedApp. Is this approach the right way to
>       proceed? This implies splitting my app into the hostedApp and a
>       CTK plugin; with most of the work to be done on the plug-in
>       level I guess. I have seen some doc explaining how to embed the
>       CTK plugin framework in my app too. Can I achieve the same
>       result with this approach and how?
>
As you have already seen, it is possible to use the plugin framework from inside your own application and this is also the preferred way (instead of modifying the existing CTK plug-ins directly). In the case of a DICOM App, I can think of two different approaches, depending on your requirements:

1.) Your app is a "pure" DICOM App, i.e. you do not need run it outside the context of a "Hosting Application"

This is the easier approach. You would create your own plug-in, equivalent to org.commontk.dah.exampleapp, which contains all your app code (logic, widgets, etc.). Additionally, you create your own ctkExampleHostedApp executable, which is essentially the same code as in the CTK repository (just adapt paths and plug-in names).

The
http://www.commontk.org/index.php/Documentation/CTK_Plugin_Framework:_Setting_up_a_project?action=purge
tutorial explains how to create a CTK-based project.

2.) You want to use your app both "stand-alone" and as a "hosted app"

This involves a little bit more knowledge about the plugin framework, but should also be easy to achieve. What the org.commontk.dah.exampleapp plug-in actually does, is to register a class containing the DICOM "application logic" as a service within the plugin-framework. You could either create this class (similar as the ctkExampleDicomAppLocig class) inside your current project (not in a separate plug-in) and register an instance by using the plugin framework context, or create a small plug-in containing this class and taking care of the registration itself. Then start the plugin framework from inside your executable, if you recognize the host and app url command line parameters (otherwise, create a QMainWindow yourself).

Depending on how fancy you would like to get concerning the minimization of dependencies of your app in stand-alone mode to the CTK libraries, you could think of a more complex set-up containing two small wrapper executables, one for "app mode" starting the CTK plugin framework and one for "stand-alone mode", both linked to a library containing your application gui and logic...

>    1. I couldn?t find to which QMainWindow is the button attached to
>       in the ctkExampleDicomAppLogic::do_something()function.It
>       doesn?t look like thectkExampleDicomAppLogic is heritating from
>       a widgetalso. Which object is responsible of the creation of the
>       mainwindow?
>

The org.commontk.dah.exampleapp plugin does not create a QMainWindow. It just create a button an shows it (moved and resized to respect the prescribed screen area from the host). In Qt, widgets become top-level windows if they don't have a parent widget and are "shown".

>    1. Is there any doc that explains how to create a CTK plug-in and
>       App from scratch. It would be probably better in my case to
>       create a new plugin instead of editing an existing one.
>

There is no doc about creating a plug-in yet, but you can easily create one by using the ctkPluginGenerator executable (you may have to enable it in CMake). It might have some rough edges though...

A CTK "app" is actually nothing special. Any executable can do, which links to the CTK libraries. The tutorial linked above explains how to use the plugin framework in an arbitrary executable.

>    1. How can I add additional includes directories through a
>       CMakeLists in the CTK framework.  I couldn?t find a way to
>       define additional directories in the CMakeList of a plug-in (no
>       include_directories). Is that define somewhere else?
>

Inside CTK itself, include directories are set-up auto-magically through our custom CMake dependency system. If you need to use external libraries in your own CTK plug-in (contained in your own project), just use standard CMake INCLUDE_DIRECTORIES (before calling the ctkMacroBuildPlugin macro) and LINK_LIBRARIES(${PROJECT_NAME} ...) (after the ctkMacroBuildPlugin call) commands.

Happy coding,

Sascha
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