HTTP Client protocol
The HTTP (HyperText Transfer Protocol) Client protocol driver provides an HTTP interface that is highly programmable. HTTP transmits messages to and from remote web servers or other web-enabled applications.
The HTTP Client protocol has a
option that is used for recurring events.HTTP client proxy support
HTTP Clients (for example, web browsers) are often required to use what is called a proxy server for requesting documents. When a proxy server is employed, all HTTP requests are sent directly to the proxy server by the client. The proxy server then forwards the requests to the appropriate HTTP server.
In this model, the only server that the HTTP Client connects to directly is the proxy server. This is in contrast to the traditional model, where requests are made to the HTTP servers directly by the client.
Typical applications are:
- To share a single Internet connection. Only the proxy server must have Internet access. All other computers that use the single Internet connection must only be on the LAN. In this way, they can send requests to the proxy server running on the machine with the Internet connection.
- To provide increased security by requiring that only one computer, the one with the proxy server, has access to the Internet through a firewall.
- To locally cache web pages for increased performance.
- To control access to certain web sites. This is content filtering.
To configure the proxy server, you can specify these from the dialog box:
- The host name or IP address of the proxy server.
- The port number on which the proxy server is listening.
- A user name and password to support proxy authentication. This is optional.
Proxy server configuration
Points to remember when using the proxy server:
- If neither the host name/IP nor port for the proxy is specified, then the proxy feature is inactive. HTTP requests are made directly to the target HTTP servers.
- If a host name is supplied, then that host is used to proxy all requests.
- If no port is supplied, then 8080 on the proxy server machine is used by default.
- If a port is supplied, but not a host, then the proxy server is assumed to be listening at the specified port on hostname.
This configuration information is stored in the NetConfig configuration file and specified as arguments to the httpget, httpput, and httppost commands as follows:
{PROXY {USER username} {PASS password} {HOST proxyServerMachine} {PORT proxyServerPort} }
PROXY
is a container key that is a list of proxy
configuration options:
-
USER username
is the user name that the connection uses to authenticate the user to the proxy server.If the proxy server is not authenticating, then this field is still sent, but is ignored by the proxy server.
-
PASS password
is the password associated with the user name.If the proxy server is not authenticating, then this field is still sent, but is ignored by the proxy server.
-
HOST proxyServerMachine
is the host name of the computer on which the proxy server is running. -
PORT proxyServerPort
is the IP port on which the proxy server listens for connections.