Launch Services – Part 2 – Configuration

In the last blog post, you learned what the Launch Services are. In this post you will see how to configure them.

Let us study an example scenario to become acquainted with configuration. We have a database containing the highest mountains on Earth along with their heights. The user enters an elevation above sea-level and hits the enter key. The Excel sheet is then displayed listing all mountains with the given minimal elevation.

How to Configure It?

First, we must create a transformation graph that uses a dictionary to receive parameters and to store results. Create a new graph in CloverETL Designer. In the outline pane, right click on Dictionary and choose Edit. Add a new entry named heightMin: with the “As Input” field set to true, and “type” set to Integer. Then add another entry named mountains.xls of type writable.channel, content type text/csv, and “As Output” set to true.

Now we may build a transformation graph. Components can use a dictionary in three different ways:

1. Via file URL: data readers and writers may specify a File URL in the format dictionary:field-name. In our example, we set a data writer File URL to dictionary:mountains.xls.
2. In CTL: anywhere in CTL code, we can use an expression of type dictionary.field-name to read or write the dictionary. In our example we use Filter expression $0.heightM >= dictionary.heightMin
3. In Java code: using methods transformationGraph.getDictionary().getValue(String fieldName) and transformationGraph.getDictionary().setValue(String fieldName, Object value)

When a transformation graph is designed and ready, we must publish it as a Launch Service. In CloverETL Server administration, go to section Launch Services and click New launch configuration. Now enter a name, a sandbox and a graph name. Then open the Detail page for the new service, and click on Edit Parameters tab. Create a new parameter with heightMin name.

Now we may test it. When we click a test link, the server generates a simple form which executes a launch service. We can copy, customize and use this form in a web site.