| Description: | Sends HTTP requests to an HTTP server |
| Returns: |
A reference to itself so that you can monitor for completion. See also pResponse in the comments. |
Usage:  |
Script Only. |
| Function Groups: | Stream and Buffer |
| Related to: | |
| Format: |
\System.HTTPClient.HTTPSend(URL, pResponse[, Username, Password, ExtraHeaders, Action, MessageBody, ContentType, TimeLimit, NConcurrent, KeepAlive, MessageOnly, MaxSendRate ]) |
| Parameters: |
| URL |
| Full URL |
| pResponse |
| [OUT] Pointer set to a response structure when request completes |
| Username |
| Username for basic authentication |
| Password |
| Password for basic authentication |
| ExtraHeaders |
| Dictionary of extra HTTP headers where the dictionary key is used as the header name and its value as the header value |
| Action |
| Typically "POST" or "GET"; default GET |
| MessageBody |
| The "payload" of the HTTP message |
| ContentType |
| Meaningful only if MessageBody is valid; default "text/xml; charset="UTF-8"" |
| TimeLimit |
| Time in seconds to wait for response; default 60 |
| NConcurrent |
| Number of concurrent keep-alive connections to maintain per server-port; default 1 |
| KeepAlive |
| TRUE to keep the connection alive; default TRUE |
| MessageOnly |
| TRUE to just send the message body; default FALSE |
| MaxSendRate |
| Optional numeric. the maximum number of requests to send per second to the host. Defaults to an unlimited rate if not specified. (See comments) |
| Comments: |
Note that HTTPSend is part of the HTTPClient library and therefore must be used in the form, \System.HTTPClient.HTTPSend(...
The response structure contains the following fields: ReturnCode The response code. See following notes. Body The response body Headers A dictionary of response headers ErrorText Supplementary error text beyond ReturnCode
The ReturnCode will either be a standard HTTP status code, such as 200 for success, or one of the following: -1: Connection timed out -2: Response timed out -3: Invalid (non-HTTP) response -4: Incomplete response -5: Unsupported transfer-encoding -6: Missing parameters
Related properties in Setup.INI: HTTPClientKeepAliveTime - The length of time to maintain an inactive HTTP connection marked as "keepalive". Default is 15 seconds. HTTPMaxDeflatedDataSize - An integer that specifies the max size of a payload to decompress. If the payload is bigger than this size it will be truncated. Defaults to 65536 bytes. There is risk when changing this setting: If it is too large, and a bad payload is received, it could cause VTScada to allocate a buffer of the max size. Most users should not need to change this property.
MaxSendRate is the maximum number of requests to send per second to the host. It defaults to an unlimited rate. This is necessary for situations where a host may reject a client if it has received more than X requests per second from that client. By setting MaxSendRate, HTTPClient throttles the rate at which it sends messages. |
