UNIXNetworkStream

UNIXNetworkStream Class

UNIXNetworkStream and its subclasses define instance and class variables and methods to communicate over UNIX domain sockets between processes and programs operating on the same machine.

As a type of interprocess communication, UNIX domain sockets are more flexible than named pipes - programs create and manage one or more sets of reader and writer objects independently of each other.

The section UNIXNetworkStreamReader describes the methods and instance data for creating and managing reader objects See UNIXNetworkStreamReader, and the section UNIXNetworkStreamWriter describes the details of writer objects See UNIXNetworkStreamWriter.

Class Variables

socketPrefix

A String that defaults to the machine-specific directory name where the system stores its temporary files (e.g., /tmp, /var/tmp, etc.).

Instance Variables

sock

An Integer that contains the file handle number the receiver’s socket.

socketBaseName

A String that contains the base name of the socket’s path name. The string may contain escape characters. Refer to the makeSocketPath method, below.

socketPath

A String that contains the fully qualified path name of a program’s UNIX domain socket.

Instance Methods

closeSocket (void)

Shuts down the receiver’s socket (defined in the sock instance variable) and deletes the socket’s file entry (which is defined in the socketPath instance variable), if present.

makeSocketPath (String basename)

Constructs a fully qualified socket path from basename and the prefix given by socketPrefix (described above). If basename contains the characters ‘$$’, the method replaces the character with the program’s process ID.

After constructing the fully qualified name, the method fills in the receiver’s socketBaseName and socketPath instance variables, and returns the value of the socketPath instance variable.

The small program here constructs and prints the file pathname of a program’s UNIX socket, which includes the process ID of the program.

int main () {
  UNIXNetworkStream new un;
  String new sockName;

  sockName = "myprogsocket.$$";

  un makeSocketPath sockName;
  printf ("%s\n", un socketPath);
}

removeSocket (void)

Deletes the socket’s file entry by its name, which is defined by makeSocketPath, above.