SX Port Daemon User Guide

PortDaemon Functionality

Usage of Port Daemon: These are the commands. Use portDaemonCommand(char *) to transmit them to the port daemon. Two environment variables are scanned: SX_PORTDAEMON_HOST and SX_PORTDAEMON_PORT

REGISTER id host port TRANSIENT|PERMANENT

LOOKUP id

REMOVE id

DUMP

EXIT

The id is a string that can be set by the user. host is a standard hostname like tarkus.pha.jhu.edu port is the port number (somewhere between 1000 10000) The mode given by TRANSIENT specifies to delete the item from the list at lookup, PERMANENT entries have to be removed using REMOVE.

EXIT terminates the daemon, DUMP returns the whole list but this is not handled by portDaemonCommand.

The return message may be the following

REGISTER id hostaddr port mode
LOOKUP id hostaddr port mode
REMOVE id hostaddr port mode
WARNING REGISTER ...
ERROR ...


Usually, the command is returned with the information about the processed port. The WARNING message occurs when an id has been replaced ERROR messages indicate syntax or user errors (host not found, etc)

Example strings:

"REGISTER a1 taltos 2002 TRANSIENT"
--> REGISTER a1 128.220.233.33 2002 TRANSIENT

"REGISTER a2 tarkus 2004 PERMANENT"
--> REGISTER a2 128.220.233.34 2004 PERMANENT

"LOOKUP a2"
--> LOOKUP a2 128.220.233.34 2004 PERMANENT

"LOOKUP a1"
--> LOOKUP a1 128.220.233.33 2002 TRANSIENT

"REGISTER a2 tilos 2005 TRANSIENT"
--> WARNING REGISTER a2 128.220.233.34 2004 PERMANENT was replaced by a2 128.220.233.47 2005 TRANSIENT

"LOOKUP a1"
--> ERROR LOOKUP Id Cannot find id a1: LOOKUP a1



SX PortDaemon functions

readLine

read a line from the RW portal From the portal read a line into _buffer.

For each attempt to read sockfd wait at most timeout seconds. Read at most bufferMaxLenght-1 characters. Add a terminating '\0' at the end of characters read into _buffer.

Return:

-2 when no newline is encountered (before EOF or buffer space runs out).
-3 if timeout forces a return.
-1 read (recv), select calls return an error.
0 o.w.

Bugs:

1. Any data after the '\n' is lost.

Comments:

1. Scheme for infinite timeout is left out. Does not seem essential.

int readLine(const RWSocketPortal& portal, uint16 timeout, char* _buffer, uint16 bufferMaxLength);

portDaemonCommand

This is the public interface function to the portDeamon. Submit a message string (described above) The input message is left as is, the output message will be the returned message (error or ok messages or warnings). If the pointer given to outmsg is 0, we allocate a char string that has to be freed by the user. If you allocate it yourself, use a buffer of at least gMaxMsgSize.

The return values are

0 OK, request complete, msg contains returned string.
1 WARNING, a REGISTER command has replaced an existing entry
2 ERROR, the msg contains an unprocessable string (syntax error) or the LOOKUP has failed (id not found). msg contains detailed error messages: ERROR Cannot understand message (error in input) ERROR LOOKUP Id Cannot find id aaa
-2 The port Deaemon is possibly not running
-1 Unexpected error

int portDaemonCommand (const char *user, const char * passwd, const char *inmsg, char*& _outmsg);

Peter Z. Kunszt, Ani R. Thakar,
Last Modified: October 14, 1999.