openPage starts a server and opens a new page with a websocket connection between it and the current
R session. After that, messages can be exchanged between R session and the web page to generate content on the
web page and to trigger calculations in R as a response to user activity on the page.
openPage(
useViewer = TRUE,
rootDirectory = NULL,
startPage = NULL,
port = NULL,
browser = NULL,
allowedFunctions = NULL,
allowedVariables = NULL,
allowedDirectories = getwd(),
connectionNumber = Inf,
sessionVars = NULL,
onStart = NULL
)If TRUE, the new web page will be opened in the RStudio Viewer. If FALSE,
a default web browser will be used (if other is not specified with the browser argument).
A path to the root directory for the server. Any file, requested by the server
will be searched for in this directory. If rootDirectory is not
defined, the http_root in the package directory will be used as a root directory.
A path to an HTML file that should be used as a starting page of the app.
It can be an absolute path to a local file, or it can be relative to the rootDirectory
or to the current R working directory. If startPage is not defined, an empty page will be used.
The file must have .html extension.
Defines which TCP port the server will listen to. If not defined, random available port
will be used (see randomPort).
A browser in which to open a new web page.
If not defined, default browser will be used. For more information check browseURL.
If this argument is specified, useViewer will be ignored.
List of functions that can be called from a web page without any additional actions
on the R side. All other functions will require authorization in the current R session before they are called.
This argument should be a vector of R function names. Check authorize and allowFunctions
for more information.
List of variables that can be modified from a web page without any additional actions
on the R side. All other variable reassignments must be confirmed in the current R session.
This argument should be a vector of variable names. Check authorize and allowVariables
for more information.
List of directories that can be accessed by the server. This argument should be a vector of
paths (absolute or relative to the current working directory) to existing directories. Check allowDirectories
for more information.
Maximum number of connections that is allowed to be active simultaneously.
Named list of variables, that will be declared for each session, when a new connection is opened.
Any changes to these variables will affect only a certain session. Thus they can be used, for instance, to
store a state of each session. For more information, please, check setSessionVariables.
A callback function that will be executed when a new connection is opened. This function gets a single
argument, which is an object of class Session. General purpose of the function is to populate each
new web page with some default content.
Object of class App.
jrc supports four types of messages:
Commands are pieces of R or JavaScript code that will be evaluated on the receiving side. Note,
that any command from a web page must be authorized in the R session for security reasons. A message
with information about how to do that is printed in the console each time a command is received. For more
information, please, check sendCommand.
Data is any variable that is sent to or from the R session. It must always come with a
name of the variable to which it should be assigned on the receiving side. For more information, please,
check sendData.
Function calls can be triggered on each side of the websocket connection. Alongside the function name,
one can also send a list of arguments and name of a variable to which the returned value of the function will
be assigned. For more information, please, check callFunction.
Unlike other types of messages, HTML code can be sent only from the R session to a web page. This code will be added to the body of the page.
openPage function is a wrapper around several methods of class App. First, it creates an
instance of this class. Then it starts a server that listens to the given port. And finally, it attempts
to open a new web page. It also stores a new app object in the package namespace, which allows other
wrapper functions to access it.
closePage, setEnvironment, limitStorage, allowVariables,
allowFunctions, setSessionVariables.