setLimits {jrc}

Set security limits

Description

This function allows to control memory usage and limit number of messages processed per second or simultaneously active connections to the app.

If an app is deployed on a server and is publicly available, it may be useful to limit resources that are available to each user. There are various things that can be controlled by this function: storage size and number of stored messages, maximal variable size, number of messages processed per second and bytes received per second.

Messages are all the communication received via web socket from an opened web page. Each message contains a command that is to be evaluated in the R session, name of a function to call or variable to store. If number or size of messages exceeds the preset limit, they are completely ignored by the app.

Usage

setLimits(
  maxCon = NULL,
  storageSize = NULL,
  storedMsg = NULL,
  varSize = NULL,
  msgPerSec = NULL,
  msgSize = NULL,
  bytesPerSec = NULL
)

Arguments

maxCon

Maximal allowed number of web socket connections simultaneously. A new connection is established whenever someone requests an HTML page from the server or when the openPage method of class App is used. If number of the allowed connections is reached the newly opened web socked will be immediately closed and the user will see a warning.

storageSize

Maximal total size of all stored messages in bytes.

storedMsg

Maximal number of messages that can be stored simultaneously.

varSize

Maximal size of a variable that can be received from a web page. Attempt to assign data of larger size to a variable will be ignored.

msgPerSec

Maximal number of messages that can be received per second. All extra messages will be disposed of immediately without any attempt to process their content.

msgSize

Maximal allowed size of a message in bytes. Note, that here a size of character string that contains all the received information is estimated. All larger messages will be ignored.

bytesPerSec

Number of bytes that can be received per second. After the limit is reached, all the incoming messages will be ignored.

Details

For security reasons, some messages has to be first authorized by the authorize function, before they can be processed. Such messages are saved until they are manually removed or authorized. If number or total size of the stored messages exceeds the limits, new messages are still saved, but the older ones are removed from the memory. If storage size is set to zero no messages can be stored and every message that requires authorization will be automatically discarded.

Size of variables or messages is estimated in object.size and is always measured in byte.

The limits are set for the entire app and are applied for each new connection. One can also change security limits for any connection separately by using method setLimits of a corresponding object of class Session.

This function is a wrapper for method setLimits of class App.

See Also

authorize, allowFunctions, allowVariables.

Examples

## Not run: 
# to run this example an installed web browser is required
openPage()
setLimits(maxCon = 10)
setLimits(varSize = 10 * 1024^2)
closePage()
## End(Not run)