doc: initial draft of cross-platform section (#7)

* doc: initial draft of cross-platform section

Signed-off-by: Michael Dawson <midawson@redhat.com>

* squash: add link in README.md

Signed-off-by: Michael Dawson <midawson@redhat.com>

* squash:make the linter happy

* Update docs/front-end/cross-platform.md

* Update docs/front-end/cross-platform.md

Co-authored-by: Chris de Almeida <ctcpip@users.noreply.github.com>

* Update docs/front-end/cross-platform.md

Co-authored-by: Chris de Almeida <ctcpip@users.noreply.github.com>

* Update docs/front-end/cross-platform.md

* Update README.md

Co-authored-by: Chris de Almeida <ctcpip@users.noreply.github.com>

---------

Signed-off-by: Michael Dawson <midawson@redhat.com>
Co-authored-by: Chris de Almeida <ctcpip@users.noreply.github.com>

README.md

@@ -63,7 +63,7 @@ The reference architecture covers the following components (currently a work in
     - Offline
     - Local Storage
     - Authentication/Authorization
-    - Cross Platform
+    - [Cross Platform](docs/front-end/cross-platform.md)
     - Polyfills
     - State management
     - Graphics, Visualization, Charts

docs/front-end/cross-platform.md

@@ -0,0 +1,53 @@
+# Cross-Platform
+
+Developers often want their applications to be “cross-platform” so that they
+can run on any platform their end-users wish to use. Platforms may include
+different flavors of desktops (Windows, MacOS, Linux) or flavors of
+mobile devices (Android, iOS).
+
+Web applications are, by definition, cross-platform as they will run
+anywhere a browser runs. With the wide availability of browsers across
+platforms today, that means pretty much anywhere.
+
+However, standard web applications running in a browser are not as
+integrated into a platform as a native application, may be limited with
+respect to what services they can use from the platform, and need connectivity
+to be able to run. Organizations may want to achieve better integration
+with platforms and to have their applications run off-line.
+
+[Progressive Web Applications](https://developer.mozilla.org/en-US/docs/Web/Progressive_web_apps/Guides/What_is_a_progressive_web_app)
+(PWAs) can achieve these capabilities
+and can be used as a middle ground between native applications and
+Hybrid applications. They improve interaction with native platforms
+while staying closer to a standard Web application. However, iOS
+users may find it more difficult to install PWAs due to a more limited
+browser support and features. Additionally, users must be taught how
+to install a PWA.
+
+If more integration is needed than a PWA can provide, a common option
+is to use a hybrid application which embeds a web application built
+with standard Web technologies into a native application and
+provides a higher level of integration into the native platforms.
+
+Key ways for integrating a web application into a native application
+include WebViews, [Chrome Custom Tabs](https://developer.chrome.com/docs/android/custom-tabs/),
+and [Trusted Web Activities](https://developer.chrome.com/docs/android/trusted-web-activity/)
+although the latter two are for Android only.
+
+There are also frameworks that enable cross-platform development of native applications using a single codebase.  These produce native applications that do not use WebViews.
+
+Tools for building hybrid applications often either target desktop (Windows, MacOS and Linux) and/or Mobile (Android, iOS).
+
+## Recommended Components
+
+N/A
+
+## Guidance
+
+Some team members have experience in creating cross-platform applications
+in previous roles, but we currently don’t have any guidance to share based
+on experience within the team based on projects within Red Hat and IBM.
+
+This reflects that for the applications we develop, most often the team
+has seen either the use of a pure Web application which is accessible
+across platforms and/or the use of individual solutions for specific platforms.