Professional BlazeDS: Creating Rich Internet Applications with Flex® and Java®

6.4. A BlazeDS-Powered Messaging Application

This section covers most things about BlazeDS messaging. The explanations and discussion are in the context of a sample application.

6.4.1. The Application Use Case

Before I start with the application itself, it may be prudent to explain what the application does. This example application is a tool for effectively watching changing currency exchange rates. It does the following:

• Allows you to set up currency pairs to watch for exchange rate changes

• Updates the rates in real time on the basis of the incoming rate change messages

• Plots the changing rates on a line chart in real time

• Provides a chat window to connect with your investment advisor for questions, clarifications, and advisory services related to investment opportunities created by these rate changes

• Allows you to buy or sell either side of a currency pair

Such an application in real life would connect to a currency OTC (over the counter) exchange, an interbank system, or market data provider for real-time price quotes. It would then connect to trading venues or broker-dealer systems for trade execution. In our sample application, I don't do any of this, the reasons being:

• Access to trading venues, market data, and broker networks is neither trivial nor inexpensive.

• The complexity of connectivity to these external systems can overwhelm our sample application and overshadow the BlazeDS messaging characteristics that I want to highlight.

The dilemma though is that, without the updating ...