Monitor the application by using the instance graph
The Instance Graph in Streams Studio provides many ways to monitor what your application does and how data flows through a running job. This part of the lab explores those capabilities. There is much more to the Instance Graph than this section can cover, so don’t hesitate to go beyond these instructions and discover more on your own.
- Launch the application. In the Project Explorer, right-click the main composite (MyMainComposite) and select Launch > Launch Active Build Config To Running Instance. In the Edit Configuration dialog, click Apply if necessary, and then click Launch.
- Maximize the Instance Graph view. You now have two running jobs: the one you just launched and the one from the previous lab. The old one is dormant; it’s not getting any data. However, leave it running for now.
To the right of the Instance Graph, a layout options drop-down menu and two selection panes for Layers and Color Schemes allow you to control the display. Explore the various options.
The layout options control how the operators in the graph are grouped:
- By Composite
This is the default. You see two boxes representing the two main composites, that is, the two applications and inside each composite, you see the operators that make up the application: three for the old job and five for the new one.
- By PE
A PE is a Processing Element, which is like an operating system process. Operators can be combined (fused) into a single PE. This couples them tightly and reduces communication latencies. Operator fusion is a performance optimization topic beyond the scope of this lab. In the preconfigured instance, the default behavior is to fuse all operators running on the same resource. This layout option shows two PEs, one for each job. It looks the same as the By Composite view.
- By Resource
Because the virtual machine is only a single resource (host), all operators are shown in the same box representing the resource.
For the rest of this lab, keep the layout set to Composite.
In the Layers box, only the Alert layer is relevant; it should be selected. The other, Consistent Region, is beyond the scope of this lab. (It has to do with guaranteed tuple delivery.) Whether you select it or not has no bearing on this lab.
- By Composite