serveHTTP: Conveniently create HTTP server using httpuv::startServer()...

In webdeveloper: Functions for Web Development

Conveniently create HTTP server using httpuv::startServer() or httpuv::runServer().

Description

Conveniently create HTTP server using httpuv::startServer() or httpuv::runServer().

Usage

serveHTTP(
  host = "127.0.0.1",
  port = 5001,
  persistent = FALSE,
  async = FALSE,
  static = list(),
  dynamic = list(),
  lapply_staticPath = TRUE,
  static_path_options = list(indexhtml = TRUE, fallthrough = FALSE, html_charset =
    "utf-8", headers = list(), validation = character(0), exclude = FALSE)
)

Arguments

host	A string that is a valid IPv4 or IPv6 address that is owned by this server, which the application will listen on. "0.0.0.0" represents all IPv4 addresses and "::/0" represents all IPv6 addresses. Refer to host parameter of httpuv::startServer() for more details.
port	The port number to listen on. Refer to port parameter of httpuv::startServer() for more details.
persistent	TRUE/FALSE. If FALSE, calls httpuv::startServer(), which returns back to the R session (and would therefore not work with launching a persistent server through a system service as the R session would continue and likely exit/end). If TRUE, calls httpuv::runServer(), which does not return to the R session unless an error or interruption occurs and is suitable for use with system services to start or stop a server.
async	TRUE/FALSE, if TRUE, dynamic path requests will be served asynchronously using multicore evaluation, if possible. This is an advanced option and might make it more confusing to debug your app.
static	A named list, names should be URL paths, values should be paths to the files to be served statically (such as a HTML file saved somewhere) or staticPath objects if lapply_staticPath is FALSE.
dynamic	A named list, names should be URL paths, values should be named alists (use alist instead of list) with alist names equaling a HTTP method (such as "GET" or "POST") and the values being expressions that when evaluated return a named list with valid entries for status, headers, and body as specified by httpuv::startServer(). Refer to httpuv::startServer() for more details on what can be returned as the response. ex. list("/" = alist("GET" = get_function(req), "POST" = post_function(req)))
lapply_staticPath	TRUE/FALSE, if TRUE, httpuv::staticPath will be applied to each element of static to create staticPath objects.
static_path_options	A named list, passed to httpuv::staticPathOptions.

Details

serveHTTP is a convenient way to start a HTTP server that works for both static and dynamically created pages. It offers a simplified and organized interface to httpuv::startServer()/httpuv::runServer() that makes serving static and dynamic pages easier. For dynamic pages, the expression evaluated when a browser requests a dynamically served path should likely be an expression/function that has "req" as a parameter. Per the Rook specification implemented by httpuv, "req" is the R environment in which browser request information is collected. Therefore, to access HTTP request headers, inputs, etc. in a function served by a dynamic path, "req" should be a parameter of that function. For the dynamic parameter of serveHTTP, list("/" = alist("GET" = get_homepage(req))) would be a suitable way to call the function get_homepage(req) when the root path of a website is requested with the GET method. The req environment has the following variables: request_method = req$REQUEST_METHOD, script_name = req$SCRIPT_NAME, path_info = req$PATH_INFO, query_string = req$QUERY_STRING, server_name = req$SERVER_NAME, server_port = req$SERVER_PORT, headers = req$HEADERS, rook_input = req[["rook.input"]]$read_lines(), rook_version = req[["rook.version"]]$read_lines(), rook_url_scheme = req[["rook.url_scheme"]]$read_lines(), rook_error_stream = req[["rook.errors"]]$read_lines()

Value

A HTTP web server on the specified host and port.

Examples

# Run both functions and go to http://127.0.0.1:5001/ in a web browser
get_example <- function(req){

html <- doctype(
html(
head(),
body(
h1("Hello"),
p("Here is a list of some of the variables included in the req environment
that were associated with this request:"),
ul(
li(paste0("req$REQUEST_METHOD = ", req$REQUEST_METHOD)),
li(paste0("req$SCRIPT_NAME = ", req$SCRIPT_NAME)),
li(paste0("req$PATH_INFO = ", req$PATH_INFO)),
li(paste0("req$QUERY_STRING = ", req$QUERY_STRING)),
li(paste0("req$SERVER_NAME = ", req$SERVER_NAME)),
li(paste0("req$SERVER_PORT = ", req$SERVER_PORT))
),
p("You can use parseQueryString to deal with inputs passed through query strings as
well as passed through the input stream."),
p("params <- parseQueryString(req[[\"rook.input\"]]$read_lines()) will give you a
named list of parameters. See also parseHTTP.")
)
)
)
return(
list(
status = 200L,
headers = list('Content-Type' = 'text/html'),
body = html
)
)
}

serveHTTP(
host = "127.0.0.1",
port = 5001,
persistent = FALSE,
static = list(),
dynamic = list(
"/" = alist(
"GET" = get_example(req)
)
)
)

webdeveloper documentation built on Oct. 18, 2022, 9:06 a.m.