Module httpclient

This module implements a simple HTTP client that can be used to retrieve webpages/other data.

Note: This module is not ideal, connection is not kept alive so sites with many redirects are expensive. As such in the future this module may change, and the current procedures will be deprecated.

Retrieving a website

This example uses HTTP GET to retrieve http://google.com

echo(getContent("http://google.com"))

Using HTTP POST

This example demonstrates the usage of the W3 HTML Validator, it uses multipart/form-data as the Content-Type to send the HTML to the server.

var headers: string = "Content-Type: multipart/form-data; boundary=xyz\c\L"
var body: string = "--xyz\c\L"
# soap 1.2 output
body.add("Content-Disposition: form-data; name=\"output\"\c\L")
body.add("\c\Lsoap12\c\L")

# html
body.add("--xyz\c\L")
body.add("Content-Disposition: form-data; name=\"uploaded_file\";" &
         " filename=\"test.html\"\c\L")
body.add("Content-Type: text/html\c\L")
body.add("\c\L<html><head></head><body><p>test</p></body></html>\c\L")
body.add("--xyz--")

echo(postContent("http://validator.w3.org/check", headers, body))

SSL/TLS support

This requires the OpenSSL library, fortunately it's widely used and installed on many operating systems. httpclient will use SSL automatically if you give any of the functions a url with the https schema, for example: https://github.com/, you also have to compile with ssl defined like so: nimrod c -d:ssl ....

Timeouts

Currently all functions support an optional timeout, by default the timeout is set to -1 which means that the function will never time out. The timeout is measured in miliseconds, once it is set any call on a socket which may block will be susceptible to this timeout, however please remember that the function as a whole can take longer than the specified timeout, only individual internal calls on the socket are affected. In practice this means that as long as the server is sending data an exception will not be raised, if however data does not reach client within the specified timeout an ETimeout exception will then be raised.

Proxy

A proxy can be specified as a param to any of these procedures, the newProxy constructor should be used for this purpose. However, currently only basic authentication is supported.

Types

TResponse = tuple[version: string, status: string, headers: PStringTable, 
                  body: string]
PProxy = ref object 
  url*: TUrl
  auth*: string

EInvalidProtocol = object of ESynch
exception that is raised when server does not conform to the implemented protocol 
EHttpRequestErr = object of ESynch
Thrown in the getContent proc and postContent proc, when the server returns an error 
THttpMethod = enum 
  httpHEAD, ## Asks for the response identical to the one that would
            ## correspond to a GET request, but without the response
            ## body.
  httpGET,                    ## Retrieves the specified resource.
  httpPOST, ## Submits data to be processed to the identified 
            ## resource. The data is included in the body of the 
            ## request.
  httpPUT,                    ## Uploads a representation of the specified resource.
  httpDELETE,                 ## Deletes the specified resource.
  httpTRACE, ## Echoes back the received request, so that a client 
             ## can see what intermediate servers are adding or
             ## changing in the request.
  httpOPTIONS, ## Returns the HTTP methods that the server supports 
               ## for specified address.
  httpCONNECT ## Converts the request connection to a transparent 
              ## TCP/IP tunnel, usually used for proxies.
the requested HttpMethod

Consts

defUserAgent = "Nimrod httpclient/0.1"

Procs

proc newProxy(url: string; auth = ""): PProxy {.raises: [], tags: [].}
Constructs a new TProxy object. 
proc request(url: string; httpMethod = httpGET; extraHeaders = ""; body = ""; 
             sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
             userAgent = defUserAgent; proxy: PProxy = nil): TResponse {.raises: [
    EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, EInvalidProtocol, 
    E_Base], tags: [FReadIO, FWriteIO, FTime].}

Requests url with the specified httpMethod.
Extra headers can be specified and must be seperated by \c\L
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

proc get(url: string; extraHeaders = ""; maxRedirects = 5; 
         sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
         userAgent = defUserAgent; proxy: PProxy = nil): TResponse {.raises: [
    EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, EInvalidProtocol, 
    E_Base], tags: [FReadIO, FWriteIO, FTime].}

GETs the url and returns a TResponse object
This proc also handles redirection
Extra headers can be specified and must be separated by \c\L.
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

proc getContent(url: string; extraHeaders = ""; maxRedirects = 5; 
                sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
                userAgent = defUserAgent; proxy: PProxy = nil): string {.raises: [
    EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, EInvalidProtocol, 
    E_Base, EHttpRequestErr], tags: [FReadIO, FWriteIO, FTime].}

GETs the body and returns it as a string.
Raises exceptions for the status codes 4xx and 5xx
Extra headers can be specified and must be separated by \c\L.
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

proc post(url: string; extraHeaders = ""; body = ""; maxRedirects = 5; 
          sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
          userAgent = defUserAgent; proxy: PProxy = nil): TResponse {.raises: [
    EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, EInvalidProtocol, 
    E_Base], tags: [FReadIO, FWriteIO, FTime].}

POSTs body to the url and returns a TResponse object.
This proc adds the necessary Content-Length header.
This proc also handles redirection.
Extra headers can be specified and must be separated by \c\L.
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

proc postContent(url: string; extraHeaders = ""; body = ""; maxRedirects = 5; 
                 sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
                 userAgent = defUserAgent; proxy: PProxy = nil): string {.raises: [
    EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, EInvalidProtocol, 
    E_Base, EHttpRequestErr], tags: [FReadIO, FWriteIO, FTime].}

POSTs body to url and returns the response's body as a string
Raises exceptions for the status codes 4xx and 5xx
Extra headers can be specified and must be separated by \c\L.
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

proc downloadFile(url: string; outputFilename: string; 
                  sslContext: PSSLContext = defaultSSLContext; timeout = - 1; 
                  userAgent = defUserAgent; proxy: PProxy = nil) {.raises: [
    EOutOfMemory, EIO, EHttpRequestErr, EOverflow, EInvalidValue, EOS, ETimeout, 
    EInvalidProtocol, E_Base], tags: [FWriteIO, FReadIO, FTime].}

Downloads url and saves it to outputFilename
An optional timeout can be specified in miliseconds, if reading from the

server takes longer than specified an ETimeout exception will be raised.

Generated: 2014-03-11 21:26:45 UTC