The Mango framework in three minutes

A screencast showing the key features of the Mango framework for web applications in three minutes.

By |February 25th, 2015|development, gwt, mango|

New feature: Entity webhooks

Mango already offers numerous APIs (SOAP Webservices, REST and plain XML) to access the data contained in an application but to get the data you have to actively ask the application for the data. A new feature resembling the well known webhooks from Github lets you register callback URLs that get triggered with HTTP post requests when certain events occur, for example the creation of a new country entity.

From Wikipedia

Webhooks are “user-defined HTTP callbacks”. They are usually triggered by some event, such as pushing code to a repository or a comment being posted to a blog. When that event occurs, the source site makes an HTTP request to the URI configured for the webhook. Users can configure them to cause events on one site to invoke behavior on another.
Webhooks can be either registered using a REST Api or alternatively using a UI that is included in Mango.

example entity webhook registration

When a webhook is triggered for example when a new entity is created, the request body of the following post request to the webhook URL looks like this:

example request body for an entity ON_CREATE webhook event

list entity webhooks example

delete entity webhook example

Of course all of the above can also be done using the webhook UI webhook UI mango_entity_webhooks1

A running example is as always contained in the Showcase, more information in the documentation.

By |February 18th, 2015|development, gwt, mango|

New feature: Entity REST API

A still experimental but already working feature is the entity REST API. For all modeled entities a REST API is generated supporting the retrieval of entities by id/natural key or even a custom query. The API overview page is can be reached from the entity editor.

API overview page mango_entity_api1

load by id example

$ curl
"id": 1,
"countryIsoCode2": "AF",
"countryIsoCode3": "AFG",
"countryRating": null,
"countryName": "Afghanistan",

load by natural key example

$ curl
"id": 1,
"countryIsoCode2": "AF",
"countryIsoCode3": "AFG",
"countryRating": null,
"countryName": "Afghanistan",

load by query expression example

To load more than one entity you can use a query to match the entities send as query parameter {baseUrl}/query?query={query} or as content of the HTTP request. The expression is based on the Spring Expression Language (SpEL).

// query = countryName matches 'a%' $ curl


p>[ { "id": 1, "countryIsoCode2": "AF", "countryIsoCode3": "AFG", [...] }, { "id": 6, "countryIsoCode2": "AS", "countryIsoCode3": "ASM", [...] }, { "id": 7, "countryIsoCode2": "VI", "countryIsoCode3": "VIR", "countryRating": null, "countryName": "Virgin Islands, U.s.", [...] } ]

An small page listing all relevant URLs for each entity that also includes a minimal REST client to try the API right away is automatically provided.

API index page example mango_entity_api2

You can try out the country API from the showcase application at:

By |February 11th, 2015|development, gwt, mango|

Jenkins walldisplay version 0.6.28

Time for a new Jenkins walldisplay release, version will be 0.6.28 and should show up in the Jenkins repository within the next few hours. This release contains the following changes (nearly 100% from Github pull request, thanks to all comitters):

  • JENKINS-25022 Walldisplay is not shown, if the project has the same name as the current view (thanks to
  • only show “Loading jobs…” in debug mode
    displaying the loading jobs message clears the whole screen from all jobs.
    this commit only displays the message when in debug mode which results
    in a better user experience when not in debug mode. (thanks to linki)
  • JENKINS-23620 Screen repaint without disturbing glitches (thanks to pvelder)
  • Support showing Junit results in the wall whenever available (both thanks to jaby)


By |January 30th, 2015|development, jenkins|

Mango GWT commons available on maven central

I started to extract all GWT utils that are not specific to Mango into an own project that is now available on maven central, so you can use it with your favorite dependency management system. Artifact name is mango-gwt-commons.


gradle example

maven example

By |January 30th, 2015|development, gwt|

GWT wrapper for toastr

I added an thin wrapper for the toastr non blocking notification library to my GWT commons project. Usage is pretty much straightforward form the usage of toastr in JavaScript itself (same methods in Java/JavaScript) so the toastr documentation mostly applies to the wrapper.


For more example see the online demo here.

By |January 28th, 2015|development, gwt|

Integrating JavaScript libraries into GWT using JSNI

From time to time when developing GWT applications, I reach the point where the functionality I needed is already perfectly implemented by a JavaScript library. Currently I needed some kind of user friendly non-blocking notification system that displays warnings/errors/.. in the form colored overlays depending on the notification message level. The first match in Google (toastr) seemed like a perfect fit:

toastr is a Javascript library for Gnome / Growl type non-blocking notifications. jQuery is required. The goal is to create a simple core library that can be customized and extended. so in this post I will show the key points that need to be done to use a JavaScript library from GWT (Java) code using toastr as an example.

Including the needed resources

The first step is that the JavaScript library itself (and often accompanying cascading stylesheets) need to be available in the HTML page hosting the GWT application. Of course placing the *.js and *.css files in the GWT module public folder and then using them in the page using <stylesheet ..> and <script ..> is a perfectly feasible solution I prefer to inject the needed resources into to page because when you wrap an external JavaScript library, the GWT module wrapping the library tends to get reused in other contexts and injecting the resources can be done in the modules entrypoint so the developer using your module does not need to modify the applications page an can start using your wrapper right away.

In the case of toastr we need the sources for toastr itself toastr.min.js, the stylesheet toastr.min.css and of course JQuery jquery-1.11.2.min.js. GWT provides the ClientBundle interface which apart from providing an aggressive caching strategy comes with compile time sanity checks. The first sentence of the documentation sums it up nicely:

The resources in a deployed GWT application can be roughly categorized into resources to never cache (.nocache.js), to cache forever (.cache.html), and everything else (myapp.css). The ClientBundle interface moves entries from the everything-else category into the cache-forever category.

So to actually uses the resource in a ClientBundle extend the ClientBundle interface and point it to the needed files:

now instantiate this interface using the GWT.create(...) method:

now you can read the actual file contents via:

Inject the resources

The next step is to inject the resources into the page. GWT provides injectors for JavaScript and CSS that take care of injecting the script/styles into the right parts of the DOM tree:

Call the “native” JavaScript functions

Now that our JavaScript library is available, we can start using it. Interaction with native code from Java is done using the Java native interface (JNI) or in this case the JavaScript Native Interface (JSNI) as it is called in GWT. The contract is, that in the native method declaration everything written between /*-{ and }-*/ is treated as JavaScript by the GWT compiler. When writing JavaScript you have to keep in mind that the script runs in a nested frame and hence window and document are not directly accessible, but GWT guarantees that they are available in $wnd and $doc. To call the warning function toastr offers the Java method looks like this:

You always have to keep in mind, that the JavaScript code you write in native methods is not checked by the compiler, so you will not notice an errors until it is actually used during runtime. There are also some (smaller limitations) on the argument types (especially concerning varargs and long types) that are summed up on the documentation page for JSNI.

By |January 27th, 2015|development, gwt, Uncategorized|

GWT star rating widget

Of course there are numerous GWT implementations of the ubiquitous star based rating widget that is used on nearly every website. For some reason none of them hat the exact features I needed, so based on the approach shown by Austin in this post I created a reusable rating widget for GWT.

The widget comes in two flavors, first a widget where only full stars can be selected, and another one that lets you chose half stars:


full star example

The full star widget implements the HasValue<Integer> interface for the selected ratings.


half star example

To support semi-star ratrings, the half star widget implements the HasValue<Float> interface.


using other images example

The used images, can be altered by providing a resource containing your own images, three image sets are already provided (standard, large and small)



More example are available in the mango-gwt-commons build artifacts, sourcecode as always on GitHub.

By |January 23rd, 2015|development, gwt|

GWT inline editing (editable label)

I started to extract some smaller GWT parts from my current project that may be reusable in other situations into an independent project to eliminate dependencies on internal structures and ease up reusability.

A functionality that I needed and was unable to find in other libraries was an inline edit control for simple labels (like the X-Editable project for jQuery)

Currently three types (String, Boolean and Integer) are supported. If the value of the control is empty an (configurable) empty string is displayed, the following screenshot shows editable labels of all three types without content.


Clicking on the underlined label opens the inline editor, here for example the editor to input an ordinary string: editable_label2

The next screenshot show the editor show an editor for an integer with an invalid value (the editor wont close with an invalid value): editable_label3

And finally the editor for boolean values: editable_label4

Usage is as follows (the editable controls all support GWTs HasValue interface):

All CSS styles can be altered to suite your needs:

The three editable label types can be seen in action in the Mango showcase (Administration -> Properties), source code is available on GitHub.

By |January 19th, 2015|development, gwt, mango|

New Feature: Inherited label/width from datatype

A little new feature that can help to reduce the noise in the model is the support for inherited with/label definitions from the datatype. Before the change the width for an control had to be defined in each control (inheritance from other controls was supported, but not from datatypes). This lead to errors especially if an datatype was used in several dictionaries:

The above example can now be expressed like this:

The width is only defined once in the datatype and the controls fall back to this width if they don’t contain an width definition. The same rules now apply for labels, see the documentation for common datatype and controls attributes here and here.

By |January 15th, 2015|development, gwt, mango, Uncategorized|