chore: Clean up unused files, imports, and work on getting end-to-end tests and unit tests running (#2272)

2021-03-01 16:52:54 +01:00
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+# Services Overview
+
+- [Overview](#overview)
+- [Kinds of Services](#kinds-of-services)
+  - [Services (default)](#services-default)
+  - [UI Services](#ui-services)
+- [Related Patterns](#related-patterns)
+
+## Overview
+
+Services are a beefier version of [commands][commands]. They provide a set of
+operations, often tied to some shared state, and are made available to
+extensions via the `ServicesManager`. Services are particularly well suited to
+address [cross-cutting concerns][cross-cutting-concerns].
+
+Each service should be:
+
+- self-contained
+- able to fail and/or be removed without breaking the application
+- completely interchangeable with another module implementing the same interface
+
+## Kinds of Services
+
+Depending on the kind of service, we follow slightly different conventions. For
+example, a UI service often receives its implementation from a React Context
+Provider. You can read more about the different kinds of services and what makes
+them different below:
+
+### Services (default)
+
+Services are a work in progress. As we are still in the progress of creating a
+non-ui maintained service, this usage may change.
+
+[You can read more about default services: here](./default/index.md)
+
+### UI Services
+
+A typical web application will have components and state for common UI like
+modals, notifications, dialogs, etc. A UI service makes it possible to leverage
+these components from an extension.
+
+We maintain the following UI Services:
+
+- [UIDialogService](./ui/ui-dialog-service.md)
+- [UIModalService](./ui/ui-modal-service.md)
+- [UINotificationService](./ui/ui-notification-service.md)
+
+You can read more about a specific service by selecting it in the above list,
+and more about [UI services in general: here](./ui/index.md)
+
+## Related Patterns
+
+Services are "concern-specific" code modules that can be consumed across layers.
+We try to minimize the coupling they introduce by authoring services that are
+able to fail or be removed. Related patterns that may reduce coupling include:
+
+- Pub/Sub
+- Commands
+
+<!--
+  LINKS
+  -->
+
+<!-- prettier-ignore-start -->
+[commands]: ../extensions/modules/commands.md
+[core-services]: https://github.com/OHIF/Viewers/tree/master/platform/core/src/services
+[services-manager]: https://github.com/OHIF/Viewers/blob/master/platform/core/src/services/ServicesManager.js
+[cross-cutting-concerns]: https://en.wikipedia.org/wiki/Cross-cutting_concern
+<!-- prettier-ignore-end -->