Introduction

First and foremost, Open MCT uses a “object-oriented” approach: everything in the system is an object. Objects come in different types, and some objects can contain other objects of given types. This is a very familiar and ubiquitous model, very similar to how the file management system of all modern computers work. For example, a folder object can contain any other type of object. A presentation file can contain an image. This is conceptually the same in Open MCT.

As you develop plugins for Open MCT, consider how a generalized component might be combined with others when designing to create a rich and powerful larger object, rather than adding a single monolithic, non-modular plugin. To solve a particular problem or allow a new feature in Open MCT, you may need to introduce more than just one new object type.

In the same way that different types of files might be opened and edited by different applications, objects in Open MCT also have different types. For example, a Display Layout provides a way that other objects that display information can be combined and laid out in a canvas area to create a recallable display that suits the needs of the user that created it. A Telemetry Panel allows a user to collect together Telemetry Points and visualize them as a plot or a table.

Object types provide a containment model that guides the user in their choices while creating a new object, and allows view normalization when flipping between different views. When a given object may only contain other objects of certain types, advantages emerge: the result of adding new objects is more predictable, more alternate views can be provided because the similarities between the contained objects is close, and we can provide more helpful and pointed guidance to the user because we know what types of objects they might be working with at a given time.

The types of objects that a container can hold should be based on the purpose of the container and the views that it affords. For example, a Folder’s purpose is to allow a user to conceptually organize objects of all other types; a Folder must therefore be able to contain an object of any type.

Views are simply different ways to view the content of a given object. For example, telemetry data could be viewed as a plot or a table. In each view, all of the data is present; it’s just represented differently. If we looked at the contents of a Folder and certain files disappeared because we switched from a list to a grid view, the user would find this unexpected and confusing. When providing views for an object, all the content of the object should be present in each view.