URLRead

sends a request to a URL and reads back the response, returning it as a response object.

sends a request to a URL built from an association of components and metadata elements.

sends a request specified by a symbolic HTTPRequest object.

URLRead[req,"elem"]

returns only the element elem from the response.

URLRead[req,{"elem₁","elem₂",…}]

returns an association of the values of the elements elem_i.

URLRead[{req₁,req₂,…},…]

sends the requests req_i in parallel, giving a list of the results obtained.

Details and Options

In URLRead[url], url can be a string, a URL object, or a cloud object.
The URL can also be specified by giving the following components in an association:

	"Scheme"	URL scheme
	"User"	user information
	"Domain"	domain name or host
	"Port"	port number (as an integer)
	"Path"	path list or string
	"Query"	query string or list of parameter-value pairs

The following additional entries can also be included in the association, as in HTTPRequest:

Method	"GET"	method to use for the HTTP request
"Body"	""	contents of message body to be sent
"ContentType"	Automatic	content-type header for the request
"Username"	""	username to use for the request
"Password"	""	password to use for the request
"Cookies"	Automatic	cookies to send to the server
"UserAgent"	Automatic	user agent string to send
"Headers"	{}	list of headers to be sent to the server

	"string"	string to be sent literally
	ByteArray[…]	byte array to be sent literally
	{b₁,b₂,b₃,…}	list of bytes to be sent literally
	{"par₁""val₁","par₂""val₂",…}	list of parameters and values to be sent URL encoded
	{"par₁"{"val₁₁",…},…}	list with multiple values associated with a single parameter
	<\|"key₁"val₁,"key₂"val₂,…\|>	alternative form for list of parameters and values
	{"par₁"File[…],"par₂"File[…],…}	files to be sent with multipart encoding
	{"par₁"assoc₁,…}	multipart encoding with detailed specifications for each part

Detailed specifications for each part in a multipart encoding are given as an association with the following elements:
"Content" the content, as a string, byte array, file object, etc.

"Name" the name to assign to the part

"MIMEType" the MIME type to assign to the part
The setting "Cookies"->Automatic specifies that cookies from $Cookies for the domain corresponding to url should be sent. "Cookies" can also give an explicit list of associations representing cookies. "Cookies"->None specifies that no cookies should be sent.
The default "UserAgent" is typically "Wolfram HTTP Client xxxx", where xxxx is a version number.
The setting for "Headers" can be a list of rules or an association.
In URLRead[req,elem], the following elements can be used:

	"Body"	body of the response as a string
	"BodyByteArray"	raw body of the response as a byte array
	"BodyBytes"	raw body of the response as a list of byte values
	"Headers"	list of headers received in the response
	"Cookies"	list of cookies received in the response
	"ContentType"	content type header
	"StatusCode"	status code returned by the server
	"StatusCodeDescription"	plain text description of status code
	"Stream"	stream object to read the response body
	{elem₁,elem₂,…}	an association of the elements elem_i
	Automatic	symbolic HTTPResponse object
	All	an association of all elements

Authentication	None	authentication information to send
CharacterEncoding	Automatic	character encoding for strings sent
CookieFunction	Automatic	function to apply to each cookie received
FollowRedirects	True	whether to follow HTTP redirects
Interactive	True	whether to allow interactive authentication dialogs
TimeConstraint	Infinity	time to wait for a response
VerifySecurityCertificates	True	whether to verify SSL security certificates

The setting CharacterEncoding->"enc" specifies that all strings that appear in the request should be encoded using the encoding enc before being sent to the server.
The setting CharacterEncoding->None specifies that no change should be made to strings before sending them to the server.
With CharacterEncoding->Automatic, the encoding is taken from the "ContentType" element if this is specified; otherwise, the encoding is "UTF8".
TimeConstraint->t allows a maximum of t seconds for connection to the URL and reading from it.
TimeConstraint-><|"Connecting"->t_c,"Reading"->t_r|> specifies separate timeouts for connecting to the URL and reading from it.