HTTP Control

Properties Methods Events Configuration Settings Errors

The HTTP Component can be used to retrieve documents from the World Wide Web.

Syntax

HTTP

Remarks

The HTTP Control implements a standard HTTP client through a simple plug-and-play interface as defined in RFCs 1945 and 2616 .

The control contains a number of properties that map directly to HTTP request headers. Files are received through events: Transfer for contents, and Header for HTTP headers. The StartTransfer and EndTransfer events are fired at the beginning and end of transmission.

To receive a document call the Get method with the URL parameter. Data can be POST-ed to the HTTP server by assigning it to the PostData property and then calling the Post method.

The PUT method is also supported. You should specify the User and Password properties or alternatively the Authorization and call the Put method with the specified URL. The AttachedFile will be sent to the server.

The HTTP Control supports the HTTP Basic authentication scheme through the User and Password properties. Other authentication schemes can be implemented by using the AuthScheme property.

Property List

The following is the full list of the properties of the control with short descriptions. Click on the links for further details.


Accept	A list of acceptable MIME types for the request.
AllowHTTPCompression	Enables HTTP compression for receiving data.
AttachedFile	A file to append to PostData if the POST or PUT methods are used.
Authorization	The Authorization string to be sent to the server.
AuthScheme	The authentication scheme to use when server authorization is required.
Connected	Shows whether the component is connected.
ContentType	Content type for posts and puts.
CookieCount	The number of records in the Cookie arrays.
CookieDomain	The domain of a received cookie.
CookieExpiration	This property contains an expiration time for the cookie (if provided by the server).
CookieName	The name of the cookie.
CookiePath	This property contains a path name to limit the cookie to (if provided by the server).
CookieSecure	This property contains the security flag of the received cookie.
CookieValue	This property contains the value of the cookie.
FirewallAutoDetect	This property tells the component whether or not to automatically detect and use firewall system settings, if available.
FirewallType	This property determines the type of firewall to connect through.
FirewallHost	This property contains the name or IP address of firewall (optional).
FirewallPassword	This property contains a password if authentication is to be used when connecting through the firewall.
FirewallPort	This property contains the TCP port for the firewall Host .
FirewallUser	This property contains a user name if authentication is to be used connecting through a firewall.
FollowRedirects	Determines what happens when the server issues a redirect.
From	The email address of the HTTP agent (optional).
HTTPMethod	The HTTP method used for the request.
Idle	The current status of the component.
IfModifiedSince	A date determining the maximum age of the desired document.
LocalFile	The path to a local file for downloading. If the file exists, it is overwritten.
LocalHost	The name of the local host or user-assigned IP interface through which connections are initiated or accepted.
OtherHeaders	Other headers as determined by the user (optional).
ParsedHeaderCount	The number of records in the ParsedHeader arrays.
ParsedHeaderField	This property contains the name of the HTTP header (same case as it is delivered).
ParsedHeaderValue	This property contains the header contents.
Password	A password if authentication is to be used.
PostData	The data to post with the URL if the POST method is used.
Pragma	A browser/server specific header line (optional).
ProxyAuthScheme	This property is used to tell the component which type of authorization to perform when connecting to the proxy.
ProxyAutoDetect	This property tells the component whether or not to automatically detect and use proxy system settings, if available.
ProxyPassword	This property contains a password if authentication is to be used for the proxy.
ProxyPort	This property contains the TCP port for the proxy Server (default 80).
ProxyServer	If a proxy Server is given, then the HTTP request is sent to the proxy instead of the server otherwise specified.
ProxyUser	This property contains a user name, if authentication is to be used for the proxy.
Range	The byte-range to be sent to the server.
Referer	Referer URL/document (optional).
StatusLine	The first line of the last server response.
Timeout	A timeout for the component.
TransferredData	The contents of the last response from the server.
TransferredDataLimit	The maximum of data to be transferred.
TransferredHeaders	The full set of headers as received from the server.
URL	The URL to fetch.
URLPath	The path for the URL.
URLPort	The port for the URL.
URLScheme	The scheme for the URL.
URLServer	The server for the URL.
User	A user name if authentication is to be used.

Method List

The following is the full list of the methods of the control with short descriptions. Click on the links for further details.


AddCookie	Adds a cookie and the corresponding value to the outgoing request headers.
Config	Sets or retrieves a configuration setting .
Delete	Deletes an object on the server.
DoEvents	Processes events from the internal message queue.
Get	Fetch the document using the HTTP GET method.
Head	Fetches the document headers using the HTTP HEAD method.
Interrupt	Interrupt the current method.
Post	Posts data to the HTTP server using the HTTP POST method.
Put	Sends data to the HTTP server using the HTTP PUT method.
ResetHeaders	Resets all HTTP Headers, Cookies, LocalFile , and AttachedFile .

Event List

The following is the full list of the events fired by the control with short descriptions. Click on the links for further details.


Connected	Fired immediately after a connection completes (or fails).
ConnectionStatus	Fired to indicate changes in connection state.
Disconnected	Fired when a connection is closed.
EndTransfer	Fired when a document finishes transferring.
Error	Information about errors during data delivery.
Header	Fired every time a header line comes in.
Redirect	Fired when a redirection is received from the server.
SetCookie	Fired for every cookie set by the server.
StartTransfer	Fired when a document starts transferring (after the headers).
Status	Fired when the HTTP status line is received from the server.
Transfer	Fired while a document transfers (delivers document).

Configuration Settings

The following is a list of configuration settings for the control with short descriptions. Click on the links for further details.


AcceptEncoding	Used to tell the server which types of content encodings the client supports.
AllowHTTPCompression	This property enables HTTP compression for receiving data.
AllowIdenticalRedirectURL	Allow redirects to the same URL.
Append	Whether to append data to LocalFile.
Authorization	The Authorization string to be sent to the server.
BytesTransferred	Contains the number of bytes transferred in the response data.
EncodeURL	If set to true the URL will be encoded by the component.
FollowRedirects	Determines what happens when the server issues a redirect.
GetOn302Redirect	If set to true the component will perform a GET on the new location.
HTTPVersion	The version of HTTP used by the component.
IfModifiedSince	A date determining the maximum age of the desired document.
KeepAlive	Determines whether the HTTP connection is closed after completion of the request.
MaxRedirectAttempts	Limits the number of redirects that are followed in a request.
OtherHeaders	Other headers as determined by the user (optional).
ProxyAuthorization	The authorization string to be sent to the proxy server.
ProxyAuthScheme	The authorization scheme to be used for the proxy.
ProxyPassword	A password if authentication is to be used for the proxy.
ProxyPort	Port for the proxy server (default 80).
ProxyServer	Name or IP address of a proxy server (optional).
ProxyUser	A user name if authentication is to be used for the proxy.
TransferredDataLimit	The maximum number of incoming bytes to be stored by the component.
TransferredHeaders	The full set of headers as received from the server.
UseChunkedEncoding	Enables or Disables HTTP chunked encoding for transfers.
ChunkSize	Specifies the chunk size in bytes when using chunked encoding.
UserAgent	Information about the user agent (browser).
KerberosSPN	The Service Principal Name for the Kerberos Domain Controller.
ConnectionTimeout	Sets a separate timeout value for establishing a connection.
FirewallAutoDetect	Tells the component whether or not to automatically detect and use firewall system settings, if available.
FirewallHost	Name or IP address of firewall (optional).
FirewallPassword	Password to be used if authentication is to be used when connecting through the firewall.
FirewallPort	The TCP port for the FirewallHost;.
FirewallType	Determines the type of firewall to connect through.
FirewallUser	A user name if authentication is to be used connecting through a firewall.
KeepAliveTime	The inactivity time in milliseconds before a TCP keep-alive packet is sent.
KeepAliveInterval	The retry interval, in milliseconds, to be used when a TCP keep-alive packet is sent and no response is received.
Linger	When set to True, connections are terminated gracefully.
LingerTime	Time in seconds to have the connection linger.
LocalHost	The name of the local host through which connections are initiated or accepted.
LocalPort	The TCP port in the local host where the component binds.
MaxLineLength	The maximum amount of data to accumulate when no EOL is found.
MaxTransferRate	The transfer rate limit in bytes per second.
RecordLength	The length of received data records.
TCPKeepAlive	Determines whether or not the keep alive socket option is enabled.
UseIPv6	Whether to use IPv6.
TcpNoDelay	Whether or not to delay when sending packets.
AbsoluteTimeout	Determines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallData	Used to send extra data to the firewall.
InBufferSize	The size in bytes of the incoming queue of the socket.
OutBufferSize	The size in bytes of the outgoing queue of the socket.
CodePage	The system code page used for Unicode to Multibyte translations.