Introducing Spring Framework

Chapter 20 ■ Your First Spring XD Application
Now let’s start the Spring XD shell. This tool will be used to create the stream and tap that you are going to use to
count how many PDFs the My Documents Spring application receives. The Spring XD shell uses a high-level DSL to
define all the tasks needed.
You can open a new terminal and run the following command to start the Spring XD shell tool, as shown in
Figure 20-4:
xd-shell
Figure 20-4. Spring XD Shell
Figure 20-4 shows the Spring XD shell, a tool that will interact with the Spring XD itself. Next, you are going
to create the stream that will be listening from the RabbitMQ on one of your queues, in this case the docs-pdf. The
following command will create the stream you need:
xd:> stream create –-name docs-pdf –-definition "rabbit | log"
The above command will create a rabbit stream and it will log all the incoming messages into the console. It is
important to note that the name parameter is key and is related to the name of a queue. So the name “docs-pdf” is the
name of the queue in RabbitMQ; if this name does not exist in RabbitMQ, it will be created.
Next, let’s create the tap that will end in a sink (counter) that will have the number of the PDFs. The following
command in the Spring shell will create the tap (see Figure 20-5):
xd:> stream create --name pdftap --definition "tap:stream:docs-pdf > counter --name=pdfcount"
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