"The networking words are quite general and work with " { $emphasis "address specifiers" } " rather than concrete concepts such as host names. There are four types of address specifiers."
"While the " { $link inet } " addressing specifier is capable of performing name lookups when passed to " { $link <client> } ", sometimes it is necessary to look up a host name without making a connection:"
"The " { $vocab-link "io.servers.connection" } " library defines high-level wrappers around " { $link <server> } " which makes it easy to listen for IPv4, IPv6 and secure socket connections simultaneously, perform logging, and optionally only allow connections from the loopback interface."
{ { $link local } " - Unix domain datagram sockets on Unix systems" }
{ { $link inet4 } " - a TCP/IP connection to an IPv4 address and port number; no name lookup is performed" }
{ { $link inet6 } " - a TCP/IP connection to an IPv6 address and port number; no name lookup is performed" }
}
"The " { $link inet } " address specifier is not supported by the " { $link send } " word because a single host name can resolve to any number of IPv4 or IPv6 addresses, therefore there is no way to know which address should be used. Applications should call " { $link resolve-host } " then use some kind of strategy to pick the correct address (for example, by sending a packet to each one and waiting for a response, or always assuming IPv4).";
ARTICLE: "network-streams""Networking"
"Factor supports connection-oriented and packet-oriented communication over a variety of protocols:"
{ $class-description "Local address specifier for Unix domain sockets on Unix systems. The " { $snippet "path" } " slot holds the path name of the socket. New instances are created by calling " { $link <local> } "." }
{ $class-description "Host name/port number specifier for TCP/IP and UDP/IP connections. The " { $snippet "host" } " and " { $snippet "port" } " slots hold the host name and port name or number, respectively. New instances are created by calling " { $link <inet> } "." }
"This address specifier is only supported by " { $link <client> } ", which calls " { $link resolve-host } " to obtain a list of IP addresses associated with the host name, and attempts a connection to each one in turn until one succeeds. Other network words do not accept this address specifier, and " { $link resolve-host } " must be called directly; it is then up to the application to pick the correct address from the (possibly several) addresses associated to the host name."
{ $class-description "IPv4 address/port number specifier for TCP/IP and UDP/IP connections. The " { $snippet "host" } " and " { $snippet "port" } " slots hold the IPv4 address and port number, respectively. New instances are created by calling " { $link <inet4> } "." }
{ $notes "Most applications do not operate on IPv4 addresses directly, and instead should use the " { $link inet } " address specifier, or call " { $link resolve-host } "." }
{ $class-description "IPv6 address/port number specifier for TCP/IP and UDP/IP connections. The " { $snippet "host" } " and " { $snippet "port" } " slots hold the IPv6 address and port number, respectively. New instances are created by calling " { $link <inet6> } "." }
{ $notes "Most applications do not operate on IPv6 addresses directly, and instead should use the " { $link inet } " address specifier, or call " { $link resolve-host } "." }
{ $description "Opens a network connection and outputs a bidirectional stream using the given encoding, together with the local address the socket was bound to." }
{ $description "Opens a network connection and calls the quotation in a new dynamic scope with " { $link input-stream } " and " { $link output-stream } " rebound to the network streams. The local address the socket is connected to is stored in the " { $link local-address } " variable, and the remote address is stored in the " { $link remote-address } " variable." }
"To start a TCP/IP server which listens for connections from any host, use an address specifier returned by the following code, where 1234 is the desired port number:"
"To start a server which listens for connections from the loopback interface only, use an address specifier returned by the following code, where 1234 is the desired port number:"
"Since " { $link resolve-host } " can return multiple address specifiers, your server code must listen on them all to work properly. The " { $vocab-link "io.servers.connection" } " vocabulary can be used to help with this."
"To start a TCP/IP server which listens for connections on a randomly-assigned port, set the port number in the address specifier to 0, and then read the " { $snippet "addr" } " slot of the server instance to obtain the actual port number it is listening on:"
{ $description "Waits for a connection to a server socket created by " { $link <server> } ", and outputs a bidirectional stream when the connection has been established. The encoding of this stream is the one that was passed to the server constructor." }
"To accept UDP/IP packets from the loopback interface only, use an address specifier returned by the following code, where 1234 is the desired port number:"
"Since " { $link resolve-host } " can return multiple address specifiers, your code must create a datagram socket for each one and co-ordinate packet sending accordingly."
