Overview
As described in the The Talon Architectural Building Blocks section a Talon application consistsof the following ingredients:
- Modeled Messages: plain old java objects that are generated from an xml model that are used to communicate between apps.
- Modeled State: plain old java objects that are generated from an xml model that make up your applications persistent state.
- A Main Class Entry Point: serves as your application's entry point. This class defines event handlers that perform your application's business logic in response to received messages. The main class
- Config DDL: An xml deployment descriptor model that configures applications, message buses, and application containers (XVMs) that together operate as a system of inerconnected and collaborating agents that provide overall business functions.
This section introduces each of these ingredients at a high level as it pertains to starting a new project with Talon. Before digging into the sections below be sure to check out:
Project Layout
Assuming you haven't already starting tweaking the starter app introduced in the Get Started section, a good way to get started with developing a new Talon application is to use the Talon maven archetypes which generate bare bones functioning applications and project structure. The folder structure shown below reflects a typical project layout for a Talon as created using the talon-sr-processor maven archetype.
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Breaking it down we can see: Java Source Folders - The main class Application.java which contains the application's business logic in defined Event Handlers
- Send and Receive drivers which are test applicatons used to drive traffic to the main application.
Model Source Folders - state.xml Contains the xml model defining the application's state
- message.xml Contains the xml model defining the applications messages.
Test Source Folders - A TestFlow class which runs all of the applications in the JVM for easy testing of the entire application in a single process.
Conf Folder - Contains the DDL config.xml which defines:
- Each applications in the project (in this case Application, Sender and Receiver
- The message buses they use to communicate with one another
- ...and The Talon XVMs, the contains used to launch instances of each application.
Maven Pom - The Talon archetypes use Maven to ease build and dependency management.
- If you are using a different build tool you might have an additional library folders and build scripts.
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The above project structure is a good starting point to use when starting to initially develop a single application. As the number of applications you are developing grows, you will likely want to consider separating out your parts of your state and message models into a separate project that is shared between multiple projects.
Message and State Modeling
Messages and State objects are generated by Talon's Application Data Modeler (ADM) from xml models.
Continue Reading: Modeling Message and State
Application Event Handlers
Config Deployment Descriptor
See Also: Understanding Configuration