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A demo of an integration application that supports hot-deployable plugins.
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camel-bundle
flights-booking-spi
flights-booking
flights-features
flights-plugin-german-airline
flights-plugin-irish-airline
LICENSE
NOTICE
README.md
pom.xml

README.md

This projects contains a sample integration application that demostrates how to extend the integration capabilities of a core process at runtime(!) via hot-deployable application level plugins.

This sample is based around a fictional flight booking application. The core process takes flight details which were previously gathered, and if there exists a plugin for the requested airline it accept payment for the ticket and calls out to the airline's back-end to place the booking.

Airline plugins are OSGi bundles that use Camel for the integration to their respective systems.

Project layout

The Maven projects contained within are as follows:

  • flights-features - Contains an XML features file used to install the rest of the bundles.
  • flights-booking - Contains a bundle that exposes a core booking process through a REST endpoint.
  • flights-booking-spi - Defines an interface through which plugins can register their availability in the OSGi service registry.
  • flights-plugin-german-airline - A plugin into the booking process for a ficticious German airline that accepts bookings for tickets starting with "DE".
  • flights-plugin-irish-airline - A plugin into the booking process for a ficticious Irish airline that accepts bookings for tickets starting with "IE".

There is also an additional parent project camel-bundle that simplifies the Maven project configuration.

Prerequisites

Set up ServiceMix by downloading the latest 4.4.1+ version from FuseSource. The installation guide can be reached from the Documentation tab on that page.

Ensure that Maven is set up on your system.

Installation

Download this project and run

smx-bootstraps> mvn clean install

Start up ServiceMix

$SERVICEMIX_HOME> bin/servicemix console 

 ____                  _          __  __ _      
/ ___|  ___ _ ____   _(_) ___ ___|  \/  (_)_  __
\___ \ / _ \ '__\ \ / / |/ __/ _ \ |\/| | \ \/ /
 ___) |  __/ |   \ V /| | (_|  __/ |  | | |>  < 
|____/ \___|_|    \_/ |_|\___\___|_|  |_|_/_/\_\

  Apache ServiceMix (4.4.1-fuse-03-06)

Hit '<tab>' for a list of available commands
and '[cmd] --help' for help on a specific command.

Install the features file from your local Maven repo into the known collection of features:

karaf@root> features:addurl mvn:com.fusesource.examples/flights-features/1.0-SNAPSHOT/xml/features

You can now check that the features defined in that file are available for installation:

karaf@root> features:list | grep flights
[uninstalled] [1.0                 ] flights-booking                      smx-application-plugins           
[uninstalled] [1.0                 ] flights-irish-airline                smx-application-plugins           
[uninstalled] [1.0                 ] flights-german-airline               smx-application-plugins

NP: It's often a good idea to prefix all of your features and bundles with a known string, such as flights in this case, so you can easily find them via the grep command in the various listings.

Install the core booking system's OSGi bundles by installing the flights-booking feature

karaf@root> features:install flights-booking
karaf@root> list | grep flights
[ 254] [Active     ] [            ] [Started] [   60] flights-booking (1.0.0.SNAPSHOT)
[ 255] [Active     ] [            ] [       ] [   60] flights-booking-spi (1.0.0.SNAPSHOT)

Check that bookings for an Irish Airlines are unsupported by hitting the following from your web browser:

http://localhost:9191/booking?flightNumber=IE943

This should return:

Unable to book flight for IE943 - unsupported airline

Now install the feature which enables integration with Irish Airlines:

karaf@root> features:install flights-irish-airline 
karaf@root> list | grep flights
[ 254] [Active     ] [            ] [Started] [   60] flights-booking (1.0.0.SNAPSHOT)
[ 255] [Active     ] [            ] [       ] [   60] flights-booking-spi (1.0.0.SNAPSHOT)
[ 256] [Active     ] [            ] [Started] [   60] flights-plugin-irish-airline (1.0.0.SNAPSHOT)

Refresh the URL in your browser, you should now see that as the integration service has been made available, the core process will now take payment for the flight and invoke the airline's back-end.

Taking payment for IE943;Irish Airline processed booking 

Repeat again for a flight number starting with "DE" and installing the flights-plugin-german-airline feature.

Voila! Hot deployable integrations as plugins.

Next steps

Take a look at a plugin's SpringDM config in src/main/resources/META-INF/spring. Note how the plugin exposes its Camel endpoint details to the OSGi service registry.

Check out the Spring config in the flights-booking project. Note how the interfaces registered by the plugins are accessed as a Set of BookingProcessor interfaces, and read by the BookingProcessorRegistry to provide an object that is able to be used in Camel expressions to influence the routing of the core booking process.

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