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Send a custom command to the remote host.
Syntax
object.Command( Command, Resource,
[Parameters], [Options] )
Remarks
The Command method sends a command to the remote host and
processes the result code sent back in response to that command.
This method can be used to send custom commands to a server to take
advantage of features or capabilities that may not be supported
internally by the control.
- Command
- A string which specifies the command to send. There are a
number of standard commands which may be used, and there are
extended commands which depend on the type of server that the
client is connected to. Consult the protocol standard and/or the
technical reference documentation for the server to determine what
commands may be issued by a client application. An example of some
common HTTP commands are:
| Command |
Description |
| GET |
Return the contents of the specified resource.
This command is recognized by all servers. |
| HEAD |
Return only header information for the
specified resource. This command is recognized by servers that
support at least version 1.0 of the protocol. |
| POST |
Post data to the specified resource. This
command is recognized by servers that support at least version 1.0
of the protocol. |
| PUT |
Create or replace the specified resource on the
server. This command is recognized by servers that support at least
version 1.0 of the protocol. Not all servers support this
command. |
| DELETE |
Delete the specified resource from the server.
This command is recognized by servers that support at least version
1.1 of the protocol. Not all servers support this command. |
- Resource
- A string which specifies the resource that the command is to be
performed upon. The resource may be a file, such as an HTML
document or an image, or it may be a script used to process data
submitted by the client. Note that this argument specifies the name
of the resource only, not a complete URL.
- Parameters
- An optional string or byte array which specifies one or more
parameters to be sent along with the command. The parameter data is
encoded according to the encoding type specified by the
Encoding property. If the resource does not require any
parameters, this argument should be omitted. Note that it is
possible to pass binary data by specifying an array of bytes rather
than a string as the argument.
- Options
- A numeric value which specifies one or more options. Currently
this argument is reserved and should either be omitted, or a value
of zero should always be used.
Not all servers support all of the listed commands, and some
commands may require specific changes to the server configuration.
In particular, the PUT and DELETE commands typically require that
configuration changes be made by the site administrator. All
servers will support the use of the GET command, and all servers
that support at least version 1.0 of the protocol will support the
POST command.
The Parameters argument is used to pass additional
information to the server when a resource is requested. This is
most commonly used to provide information to scripts, similar to
how arguments are used when executing a program from the command
line. Unless the POST command is being executed, the data in the
buffer will automatically be encoded using the current encoding
mechanism specified for the client. By default, the data is URL
encoded, which means that any spaces and non-printable characters
are converted to printable characters before submitted to the
server. The type of encoding that is performed can be changed by
setting the Encoding property. Although the default encoding
is appropriate for most applications, those that submit XML
formatted data may need to change the encoding type.
Only one request may be in progress at one time for each client
session. Use the CloseFile method to terminate the request
after all of the data has been read from the server.
Return Value
A value of zero is returned if the command was successful.
Otherwise, a non-zero error code is returned which indicates the
cause of the failure. To determine the result code returned by the
server in response to the command, read the value of the
ResultCode property.
See Also
Encoding Property,
ResultCode Property,
ResultString Property,
OnCommand Event
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