class TWebFile: public TFile

 Create a Web file object. A web file is the same as a read-only
 TFile except that it is being read via a HTTP server. The url
 argument must be of the form: http://host.dom.ain/file.root.
 The opt can be "NOPROXY", to bypass any set "http_proxy" shell
 variable. The proxy can be specified as (in sh, or equivalent csh):
   export http_proxy=http://pcsalo.cern.ch:3128
 The proxy can also be specified via the static method TWebFile::SetProxy().
 Basic authentication (AuthType Basic) is supported. The user name and
 passwd can be specified in the url like this:
   http://username:mypasswd@pcsalo.cern.ch/files/aap.root
 If the file specified in the URL does not exist or is not accessible
 the kZombie bit will be set in the TWebFile object. Use IsZombie()
 to see if the file is accessible. The preferred interface to this
 constructor is via TFile::Open().

 Create a Web file object. A web file is the same as a read-only
 TFile except that it is being read via a HTTP server. Make sure url
 is a valid TUrl object.
 The opt can be "NOPROXY", to bypass any set "http_proxy" shell
 variable. The proxy can be specified as (in sh, or equivalent csh):
   export http_proxy=http://pcsalo.cern.ch:3128
 The proxy can also be specified via the static method TWebFile::SetProxy().
 Basic authentication (AuthType Basic) is supported. The user name and
 passwd can be specified in the url like this:
   http://username:mypasswd@pcsalo.cern.ch/files/aap.root
 If the file specified in the URL does not exist or is not accessible
 the kZombie bit will be set in the TWebFile object. Use IsZombie()
 to see if the file is accessible.

 Cleanup.

 Initialize a TWebFile object.

 Set GET command for use by ReadBuffer(s)10(), handle redirection if
 needed. Give full URL so Apache's virtual hosts solution works.

 Check if shell var "http_proxy" has been set and should be used.

 A TWebFile that has been correctly constructed is always considered open.

 Reopen a file with a different access mode, like from READ to
 UPDATE or from NEW, CREATE, RECREATE, UPDATE to READ. Thus the
 mode argument can be either "READ" or "UPDATE". The method returns
 0 in case the mode was successfully modified, 1 in case the mode
 did not change (was already as requested or wrong input arguments)
 and -1 in case of failure, in which case the file cannot be used
 anymore. A TWebFile cannot be reopened in update mode.

 Read specified byte range from remote file via HTTP daemon. This
 routine connects to the remote host, sends the request and returns
 the buffer. Returns kTRUE in case of error.

 Read specified byte range from remote file via HTTP daemon. This
 routine connects to the remote host, sends the request and returns
 the buffer. Returns kTRUE in case of error.

 Read specified byte range from remote file via HTTP 1.0 daemon (without
 mod-root installed). This routine connects to the remote host, sends the
 request and returns the buffer. Returns kTRUE in case of error.

 Read specified byte ranges from remote file via HTTP daemon.
 Reads the nbuf blocks described in arrays pos and len,
 where pos[i] is the seek position of block i of length len[i].
 Note that for nbuf=1, this call is equivalent to TFile::ReafBuffer
 This function is overloaded by TNetFile, TWebFile, etc.
 Returns kTRUE in case of failure.

 Read specified byte ranges from remote file via HTTP 1.0 daemon (without
 mod-root installed). Read the nbuf blocks described in arrays pos and len,
 where pos[i] is the seek position of block i of length len[i].
 Note that for nbuf=1, this call is equivalent to TFile::ReafBuffer
 This function is overloaded by TNetFile, TWebFile, etc.
 Returns kTRUE in case of failure.

 Read request from web server. Returns -1 in case of error,
 0 in case of success.

 Read multiple byte range request from web server.
 Uses HTTP 1.0 daemon wihtout mod-root.
 Returns -2 in case file does not exist, -1 in case
 of error and 0 in case of success.

 Set position from where to start reading.

 Return maximum file size.

 Get the HTTP header. Depending on the return code we can see if
 the file exists and if the server uses mod_root.
 Returns -1 in case of an error, -2 in case the file does not exists,
 -3 in case HEAD is not supported (dCache HTTP door) and
 0 in case of success.

 Read a line from the socket. Reads at most one less than the number of
 characters specified by maxsize. Reading stops when a newline character
 is found, The newline (\n) and cr (\r), if any, are removed.
 Returns -1 in case of error, or the number of characters read (>= 0)
 otherwise.

 Read a hunk of data from the socket, up until a terminator. The hunk is
 limited by whatever the TERMINATOR callback chooses as its
 terminator. For example, if terminator stops at newline, the hunk
 will consist of a line of data; if terminator stops at two
 newlines, it can be used to read the head of an HTTP response.
 Upon determining the boundary, the function returns the data (up to
 the terminator) in hunk.

 In case of read error, -1 is returned. In case of having read some
 data, but encountering EOF before seeing the terminator, the data
 that has been read is returned, but it will (obviously) not contain the
 terminator.

 The TERMINATOR function is called with three arguments: the
 beginning of the data read so far, the beginning of the current
 block of peeked-at data, and the length of the current block.
 Depending on its needs, the function is free to choose whether to
 analyze all data or just the newly arrived data. If TERMINATOR
 returns 0, it means that the terminator has not been seen.
 Otherwise it should return a pointer to the character immediately
 following the terminator.

 The idea is to be able to read a line of input, or otherwise a hunk
 of text, such as the head of an HTTP request, without crossing the
 boundary, so that the next call to RecvRaw() etc. reads the data
 after the hunk. To achieve that, this function does the following:

 1. Peek at incoming data.

 2. Determine whether the peeked data, along with the previously
    read data, includes the terminator.

 3a. If yes, read the data until the end of the terminator, and
     exit.

 3b. If no, read the peeked data and goto 1.

 The function is careful to assume as little as possible about the
 implementation of peeking.  For example, every peek is followed by
 a read. If the read returns a different amount of data, the
 process is retried until all data arrives safely.

 Reads at most one less than the number of characters specified by maxsize.

 Determine whether [START, PEEKED + PEEKLEN) contains an HTTP new
 line [\r]\n. If so, return the pointer to the position after the line,
 otherwise return 0. This is used as callback to GetHunk(). The data
 between START and PEEKED has been read and cannot be "unread"; the
 data after PEEKED has only been peeked.

 Return basic authentication scheme, to be added to the request.

 Static method setting global proxy URL.

 Static method returning the global proxy URL.

 Process the HTTP header in the argument. This method is intended to be
 overwritten by subclasses that exploit the information contained in the
 HTTP headers.