Command: open

Syntax

open <channel> {,<mode>}

Description

Open a system input/output channel for communication. This includes opening communication channels to Fire translator Services (i.e. not database services) running on a web server.

Parameters

• <channel>
  A channel identifier. If the identifier does not exist, it will be created using current scope rules. If it is unassigned, it will be given the value of the next free system channel.

• <mode>
  One of the following values:

• r
  Channel to be opened in read-only mode.

• w
  Channel to be opened in write-only mode.

• rw
  Channel to be opened in read/write mode.

• a
  Channel to be opened in write-only append mode.

If omitted, r is assumed.

Mode a is valid only for text file channels.

Switches

• -at=<atable>
  An atable to be searched within callback procedures for this channel. This means that any identifiers within <atable> referenced in a callback do not have to be prefixed by ~<atable>. This cannot be the local atable.

• -c
  If <channel> is already open, get confirmation from the operator before it is closed and reopened. If the file to be written (w mode) already exists, get confirmation before it is overwritten.

• -del=<string>
  Use <string> as the delimiting character(s) between fields when reading from or writing to the channel. For read channels, <string> may be a one or two character string, containing a delimiting character and optionally a space to indicate that white space is also permitted. For write channels, <string> may be any sequence of characters. If no delimiter is set for a channel, then ', ' (command and/or space) is used when reading from the channel, and a space is used when writing to the channel.

• -f=<file>
  The name of a text file to be opened on <channel>.

• -ip=<string>
  The name of a host and port number to open a communications channel to. The process to which the socket is connected must communicate in text packets, each terminated with a \n character. The value of the parameter should be a string value indicating a host IP address or name and a port number, in the form host:n. The socket must be a STREAM (TCP/IP) socket.

• -li=<port>
  Listen for a connection on a port number. When a caller connects, the channel is available for binary communication with the caller using the Fire Hose protocol. The socket will be a STREAM (TCP/IP) socket. Passing a <port> of 0 will grab a free one. The port grabbed can be subsequently accessed via the channel.name attribute.

• -p=<string>
  The name of an external process to be opened on <channel>.

• -req=<string>
  The url of a remote eim data transfer service running on a web server.

• -s=<string>
  The name of an external data transfer server process to be opened on <channel>. This will then run in eim client/server mode.

• -tim=<num>
  A timeout, in seconds, to wait for a connection to and subsequent responses from a server process or communications socket. If not specified, the timeout is 60 seconds. A value of 0 indicates no timeout, i.e. blocking reads, and is not advised.

• -uof=<string>
  The name of an external filter process to be opened on <channel>.

Notes

The system numeric free_channel may be used to request an unused channel number.

The <mode> parameter is ignored for both data transfer server and filter process channels, which always use w.

Examples

Open a file for reading.

open chan1,-f=test.dat

Open a file for writing.

open chan2, w, -f=outs

Open a process for reading on the next free channel.

channel myc
open myc, -p='ls -l'

Open a server process on the next free channel.

open myc, -s='dxf_server'

Open a connection to a socket.

open myc,-ip='manta:4999'

Open a connection to a Translation Service running on a Web Server.

open ch,-req='http://www.my_web_server.com/xmarc/Broker?service=ACAD_SERVICE'

Open a listener connection.

open myc, -li=3101

See Also