The assemble view
The API Designer features an assemble view that you can use to create assemblies. With assemblies, you can readily tailor your APIs to include components such as activity logging and redaction of specific fields.
After creating a policy assembly, you can access the assemble view by clicking the Assemble tab while editing a draft API. This view includes a palette, which lists available components, a property sheet, which is used to configure a component, and a canvas, which is used to arrange and visualize the assembly’s components.
Create an assembly by clicking Create assembly in the Policy assembly section of the design view of an API.
The palette
The palette, shown on the left side of the assemble view, is a list of different components that
you can include in your assembly. The palette can be hidden by clicking the Show/hide
policy palette icon 
in the upper left corner.
The canvas
You can use the canvas to create a graphical representation of the assembly flow. You can drag various components from the palette on the left to the appropriate location on the canvas on the right. When you drag a component, valid positions are shown by dashed boxes. Changes that you make in the Assemble tab will be reflected in the Source tab.
API calls are made at the left, unfilled, circle, and returns at the right, filled, circle. You can insert components between the two to modify the data received from the call or returned by the response. To add a component, select it in the palette and drag it across to one of the dashed boxes that appear when you move the component over the canvas.
You can use the Show catches toggle to show and hide error catches in the
palette. A catch is a section of the assembly that is applied when an API call results in the
corresponding HTTP status code being returned. Click a Catch icon 
to open the property sheet of all your catches.
You can zoom the view of your canvas in and out by clicking the + and
- icons. To fit the canvas to size, click the Zoom to
fit icon 
.
You can specify whether catches are displayed on the canvas by using the Show catches toggle in the upper right corner of the page.
You can filter the canvas to show only the parts of it that will apply to a specific operation by
clicking the Filter by operation icon 
and then selecting the operation from the drop-down list. Click the Clear
operation filter icon 
to remove the filter.
The property sheet
When you select a component that is in the assembly by clicking it, details about the component are displayed in the property sheet on the right. In this pane, you can configure the component's properties. The options available to you in the property sheet are specific to the type of component you are working with. For some components, you can add and remove properties by clicking Object Properties and selecting the property from the drop-down menu.
You can pin or release the property sheet by clicking the Pin menu icon
.