NEWS.md

In att/rcloud.shiny: Shiny Support for RCloud

rcloud.shiny 0.6

• aligns with Shiny 1.1.0 and uses a cleaner mechanism to override Shiny functionality for RCloud (#32)

rcloud.shiny 0.5.4

• shiny cleanly shuts down and invokes hooks, so you can do session$onSessionEnded(function() { ... }) now

rcloud.shiny 0.5.3

• support for multiple Shiny sockets for flexdashboard support

rcloud.shiny 0.5.2

• rcloud.shinyApp supports options = list(display.mode = "showcase")

rcloud.shiny 0.5.1

• Errors in some reactive contexts could trigger the unhelpful error Error in self$close() : attempt to apply non-function, masking the actual error and hindering debugging. We define self$close() on our fake web socket now.

rcloud.shiny 0.5

• rcloud.shiny is now self-contained in its own package - /shiny.html forwards to shared.R/rcloud.shiny/shiny.html

rcloud.shiny 0.4.2

• Show shiny title and shiny favicon

rcloud.shiny 0.4.1

Bug Fixes

• Build proxy.R/.../ URL for <iframe> with search and hash duplicated from the parent window, so that Shiny applications have access to them through session$clientData (#12)

rcloud.shiny 0.4

New Architecture

rcloud.shiny 0.4 is a bottom-up rewrite of the Shiny implementation for RCloud. Apart from requiring some modifications to RStudio Shiny, the new implementation is much simpler: it clocks in at just over 100 lines of code.

Prior to 0.4, rcloud.shiny did not have a mechanism for HTTP requests to travel from the client to the Shiny server, so all communication had to travel over the web socket. (rcloud.shiny tunnels Shiny's web socket through the RCloud session's web socket.)

Without independent HTTP requests, it was necessary to rewrite URLs in order to load Shiny resources. That didn't always work correctly, especially with add-on packages and HTML Widgets. Also file download, data transfers, serving of temporary files, and timer messages all require separate HTTP requests, so those features were not working at all.

RCloud 1.4 introduced proxy.R, which allows tunneling of HTTP requests through RCloud to ports on the RCloud compute node where the session is running. Rserve 1.8-5 introduces an idle callback, which allows calling the Shiny HTTP message handler (shiny:::serviceApp) from inside Rserve's message handler.

With these pieces in place, we were finally able to deliver an environment where Shiny can do everything it needs to do. We put Shiny in an <iframe> which fills the window, so that we can create the R session and start the Shiny server in an initial step, before loading the Shiny page into the iframe through proxy.R in a second step. Since all Shiny HTTP requests use relative URLs, the Shiny app has complete control over the iframe.

License Status

Because rcloud.shiny 0.4 overrides a few functions in RStudio Shiny and those functions are temporarily copied into this package, this package is temporarily licensed under GPL-3.

The GPL-3 RStudio functions reside in R/shiny-overrides.R. The rest of the rcloud.shiny code is still MIT-licenced.

We recognize that this is an ugly and brittle design, but we needed to test the new functionality thoroughly to make sure we're on the right track, before making feature requests and pull requests on Shiny. We soon hope to contribute a few features to Shiny to make it possible to run in the RCloud environment, and remove the copied code.

att/rcloud.shiny documentation built on May 10, 2019, 2:12 p.m.