Async client for different request types
An async client to do many requests, each with different URLs, curl options, etc.
An object of class AsyncVaried with variables and methods.
HttpResponse objects are returned in the order they are passed in.
We print the first 10.
HTTP requests mostly fail in ways that you are probably familiar with, including when there's a 400 response (the URL not found), and when the server made a mistake (a 500 series HTTP status code).
But requests can fail sometimes where there is no HTTP status code, and no agreed upon way to handle it other than to just fail immediately.
When a request fails when using synchronous requests (see HttpClient) you get an error message that stops your code progression immediately saying for example:
"Could not resolve host: https://foo.com"
"Failed to connect to foo.com"
"Resolving timed out after 10 milliseconds"
However, for async requests we don't want to fail immediately because that would stop the subsequent requests from occurring. Thus, when we find that a request fails for one of the reasons above we give back a HttpResponse object just like any other response, and:
capture the error message and put it in the content slot of the
response object (thus calls to content and parse() work correctly)
give back a 0 HTTP status code. we handle this specially when testing
whether the request was successful or not with e.g., the success()
method
print()
print method for AsyncVaried objects
AsyncVaried$print(x, ...)
xself
...ignored
new()
Create a new AsyncVaried object
AsyncVaried$new(..., .list = list())
..., .listAny number of objects of class HttpRequest(),
must supply inputs to one of these parameters, but not both
A new AsyncVaried object
request()
Execute asynchronous requests
AsyncVaried$request()
nothing, responses stored inside object, though will print messages if you choose verbose output
responses()
List responses
AsyncVaried$responses()
a list of HttpResponse objects, empty list before
requests made
requests()
List requests
AsyncVaried$requests()
a list of HttpRequest objects, empty list before
requests made
parse()
parse content
AsyncVaried$parse(encoding = "UTF-8")
encoding(character) the encoding to use in parsing. default:"UTF-8"
character vector, empty character vector before requests made
status_code()
Get HTTP status codes for each response
AsyncVaried$status_code()
numeric vector, empty numeric vector before requests made
status()
List HTTP status objects
AsyncVaried$status()
a list of http_code objects, empty list before requests made
content()
Get raw content for each response
AsyncVaried$content()
raw list, empty list before requests made
times()
curl request times
AsyncVaried$times()
list of named numeric vectors, empty list before requests made
clone()
The objects of this class are cloneable with this method.
AsyncVaried$clone(deep = FALSE)
deepWhether to make a deep clone.
Other async:
AsyncQueue,
Async,
HttpRequest
## Not run:
# pass in requests via ...
req1 <- HttpRequest$new(
url = "https://httpbin.org/get",
opts = list(verbose = TRUE),
headers = list(foo = "bar")
)$get()
req2 <- HttpRequest$new(url = "https://httpbin.org/post")$post()
# Create an AsyncVaried object
out <- AsyncVaried$new(req1, req2)
# before you make requests, the methods return empty objects
out$status()
out$status_code()
out$content()
out$times()
out$parse()
out$responses()
# make requests
out$request()
# access various parts
## http status objects
out$status()
## status codes
out$status_code()
## content (raw data)
out$content()
## times
out$times()
## parsed content
out$parse()
## response objects
out$responses()
# use $verb() method to select http verb
method <- "post"
req1 <- HttpRequest$new(
url = "https://httpbin.org/post",
opts = list(verbose = TRUE),
headers = list(foo = "bar")
)$verb(method)
req2 <- HttpRequest$new(url = "https://httpbin.org/post")$verb(method)
out <- AsyncVaried$new(req1, req2)
out
out$request()
out$responses()
# pass in requests in a list via .list param
reqlist <- list(
HttpRequest$new(url = "https://httpbin.org/get")$get(),
HttpRequest$new(url = "https://httpbin.org/post")$post(),
HttpRequest$new(url = "https://httpbin.org/put")$put(),
HttpRequest$new(url = "https://httpbin.org/delete")$delete(),
HttpRequest$new(url = "https://httpbin.org/get?g=5")$get(),
HttpRequest$new(
url = "https://httpbin.org/post")$post(body = list(y = 9)),
HttpRequest$new(
url = "https://httpbin.org/get")$get(query = list(hello = "world"))
)
out <- AsyncVaried$new(.list = reqlist)
out$request()
out$status()
out$status_code()
out$content()
out$times()
out$parse()
# using auth with async
url <- "https://httpbin.org/basic-auth/user/passwd"
auth <- auth(user = "user", pwd = "passwd")
reqlist <- list(
HttpRequest$new(url = url, auth = auth)$get(),
HttpRequest$new(url = url, auth = auth)$get(query = list(a=5)),
HttpRequest$new(url = url, auth = auth)$get(query = list(b=3))
)
out <- AsyncVaried$new(.list = reqlist)
out$request()
out$status()
out$parse()
# failure behavior
## e.g. when a URL doesn't exist, a timeout, etc.
reqlist <- list(
HttpRequest$new(url = "http://stuffthings.gvb")$get(),
HttpRequest$new(url = "https://httpbin.org")$head(),
HttpRequest$new(url = "https://httpbin.org",
opts = list(timeout_ms = 10))$head()
)
(tmp <- AsyncVaried$new(.list = reqlist))
tmp$request()
tmp$responses()
tmp$parse("UTF-8")
# access intemediate redirect headers
dois <- c("10.7202/1045307ar", "10.1242/jeb.088898", "10.1121/1.3383963")
reqlist <- list(
HttpRequest$new(url = paste0("https://doi.org/", dois[1]))$get(),
HttpRequest$new(url = paste0("https://doi.org/", dois[2]))$get(),
HttpRequest$new(url = paste0("https://doi.org/", dois[3]))$get()
)
tmp <- AsyncVaried$new(.list = reqlist)
tmp$request()
tmp
lapply(tmp$responses(), "[[", "response_headers_all")
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.