I just noticed the new  ‘@’ symbol for operator annotations in SPL Graphical Editor in Streams Studio 4.0.  It is also visible in the instance graph view (which displays running applications or jobs).  When the ‘@’ is grayed out, it means the operator invocation does not have any annotation.  When it is black, it means it has at least one annotation.

noannotation

I wondered if it would be possible to add notes to SPL applications, and then click on the ‘@’ symbol when the job is running to provide information for developers trying to understand the application.

So I added a notes to the HTTPTupleInjectAndView sample from the Github streamsx.inet toolkit. To do this I right clicked on the operator in the SPL Graphical Editor and selected ‘Add Note’.

Having added the explanatory notes, the visual editor view looked like this:

editorannotations

I then submitted the application, and looked at it in the Studio instance graph, which visualizes the running jobs in an instance, and indeed hovering the cursor over the ‘@’ symbol in the operator produced a pop-up containing the contents of the note:

instancegraphannotations

This is a useful technique, new to Streams 4.0, to allow developers to understand applications more easily when looking at running jobs.

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