diff --git a/README.md b/README.md
index 939a61a..cc03166 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,10 @@
 ### Installation
 --------
 
-Currently the project contains only one file. Simply add it to your project.
+Currently the project contains only one file. Simply add sysVcom.php to your project. Other files are for testing.
+The global files need to be set correctly for your project. In particular, a file needs to be created which is
+used as the buffer for the SysV system. In practice this is just used as a unique key but it must exist and be
+reachable by both client and server.
 
 The following methods are use to invoke an RPC
 <pre>
diff --git a/listen-ipc.php b/listen-ipc.php
new file mode 100644
index 0000000..cfb4054
--- /dev/null
+++ b/listen-ipc.php
@@ -0,0 +1,23 @@
+<?php
+
+include "sysVcom.php";
+
+//clear the queues at startup - otherwise things can get tricky
+clear_IPC( );
+
+$msgArr = null;
+
+while(true){
+	
+	//get msg
+	$caller_id = IPC_listen( $msgArr );
+
+	//send msg back
+	IPC_reply( $caller_id, $msgArr[$caller_id]['msg'] );
+
+	//done with the message
+	unset( $msgArr[$caller_id] );
+}
+
+	
+?>
diff --git a/listen-rpc.php b/listen-rpc.php
new file mode 100644
index 0000000..6b19038
--- /dev/null
+++ b/listen-rpc.php
@@ -0,0 +1,29 @@
+<?php
+
+include "sysVcom.php";
+
+//clear the queues at startup - otherwise things can get tricky
+clear_IPC( );
+
+$msgArr = null;
+
+while(true){
+	
+	$caller_id = 0;
+	
+	$obj = rpc_listen( $caller_id, $msgArr );
+
+	//print_r( $obj );
+	
+	//do something with the data
+	array_unshift( $obj, "Greetings" );
+
+	//send msg back
+	rpc_reply( $caller_id, $obj );
+
+	//done with the message
+	unset( $msgArr[$caller_id] );
+}
+
+	
+?>
diff --git a/make-ipc.php b/make-ipc.php
new file mode 100644
index 0000000..b2844c4
--- /dev/null
+++ b/make-ipc.php
@@ -0,0 +1,28 @@
+<?php
+
+include "sysVcom.php";
+include "time.php";
+
+/*
+//test a msg larger than queue size
+$data = '';
+$cnt = 1;
+for( $i=0; $i<$g_max_chan; $i++){
+	$data .= $i;
+}*/
+
+$data = 'myFunc,p1,p2';
+$cnt = 50000;
+
+$st_time = (float)getTimeAsString(1733051170);
+for( $i=0; $i<$cnt; $i++){
+	$rtn = IPC( $data );
+}
+$en_time = (float)getTimeAsString(1733051170);
+
+echo "done\n\n";
+echo (($en_time-$st_time)/$cnt) . "\n\n";
+
+// timed on a laptop (1.9GHz, 2-core, 4-threads) at 21uS per IPC call-return
+
+?>
diff --git a/make-rpc.php b/make-rpc.php
new file mode 100644
index 0000000..e685bae
--- /dev/null
+++ b/make-rpc.php
@@ -0,0 +1,26 @@
+<?php
+
+include "sysVcom.php";
+include "time.php";
+
+
+$some_arr = array( 
+	'key_1' => 3.14159,
+	'key_2' => "pony"
+);
+
+$cnt = 10000;
+$st_time = (float)getTimeAsString(1733051170);
+for( $i=0; $i<$cnt; $i++){
+	$obj = rpc( 'myFunct', 34, 4.9e-7, $some_arr );
+}
+//print_r( $obj );
+$en_time = (float)getTimeAsString(1733051170);
+
+echo "done\n\n";
+echo (($en_time-$st_time)/$cnt) . "\n\n";
+
+// timed on a laptop (1.9GHz, 2-core, 4-threads) at 30uS per rpc call-return
+// including a short array object
+
+?>
diff --git a/sysVcom.php b/sysVcom.php
new file mode 100644
index 0000000..c4e1c2d
--- /dev/null
+++ b/sysVcom.php
@@ -0,0 +1,227 @@
+<?php
+
+/**
+ * This file provides a mechanism to allow inter-process communication (IPC) by way of an RPC.
+ * 
+ * It uses the System V architecture which was meant to have been superceeded by POSIX. However,
+ * I found some issues with POSIX around non-blocking behaviour and timeouts. This may have been
+ * the PHP inplementation and I have intentions to revisit this later. For the time being, SysV
+ * is works exactly as you would expect. 
+ * 
+ * Given the issues around the message length, I will not even try to use the serialisation. There
+ * is no way to know what size the resultant serialised message will be. There are errors occurring
+ * when the message length is not even halve of that specified by the value at /proc/sys/kernel/msgmnb
+ * 
+ */
+ 
+$g_procName = 'BU-commander';
+//posix_mkfifo( $g_procName, 0644 );
+
+//max msg length - this fails on Mint-21. Trial and error gives a max size of 8182.
+//$g_max_chan = file_get_contents('/proc/sys/kernel/msgmnb');
+$g_max_chan = 8182;
+
+// If the receive bytes is not larger than what was sent, the rcv will fail with code 7. Making it 10 bytes
+// larger was not enough but 100 was emough. I mean, go figure ???
+$g_max_rcv = $g_max_chan+100;
+
+$g_max_data = $g_max_chan - 2;	//we use the first 2 bytes for msg chunks
+$g_k_caller = ftok( $g_procName, 'A');		//caller
+$g_k_reply = ftok( $g_procName, 'B');		//reply
+
+
+//************************************************************************************************************************
+// The following functions all relate to making an RPC.
+// They use the php serialize() to send objects across the process boundary
+
+function rpc( $funcName, ...$params ){
+	array_unshift( $params, $funcName);
+	return unserialize( IPC( serialize( $params ) ) );
+}
+
+function rpc_listen( &$caller_id, &$msgArr, $bBlock = true ){
+	$caller_id = IPC_listen( $msgArr, $bBlock );
+	return unserialize( $msgArr[$caller_id]['msg'] );
+}
+
+function rpc_reply( $caller_id, $obj ){
+	IPC_reply( $caller_id, serialize($obj) );
+}
+
+
+//************************************************************************************************************************
+//
+// All functions fast this point relate to sending and recieving of a single message as a string without the concept
+// of a function or parameters.
+//
+
+function clear_IPC( ){
+
+	global $g_k_caller;
+	global $g_k_reply;
+
+	$q_caller = msg_get_queue($g_k_caller);
+	msg_remove_queue($q_caller);
+	
+	$q_reply = msg_get_queue($g_k_reply);
+	msg_remove_queue($q_reply);
+	
+}
+
+/**
+ * Turns out that the largest premissible queue size is found at  /proc/sys/kernel/msgmnb
+ * On my system this is 16384 bytes.
+ * 
+ * Rather than increase this, it will be easier to split the messages into chunks.
+ * 
+*/
+function IPC( $str_data ){
+	
+	global $procName;
+	global $g_k_caller;
+	global $g_k_reply;
+	global $g_max_data;
+	global $g_max_rcv;
+
+	$q_caller = msg_get_queue($g_k_caller);
+	$q_reply = msg_get_queue($g_k_reply);
+	$pid = getmypid();
+
+	IPC_send( $q_caller, $pid, $str_data );
+	
+	$msgArr = null;
+	IPC_rcv( $q_reply, $pid, $msgArr );
+	
+	return $msgArr[$pid]['msg'];
+
+}
+
+/**
+ * Listens to the caller queue and collects messages from all calling processes and populates the
+ * given array indexed by the ID of the message rcvd.
+ * 
+ * As soon as a message is complete, the procid will be returned. The array may also contain partially filled
+ * message from other IDs so the caller should check the contents of msgArr before deleting. This method is
+ * designed to be called by an RPC serving process.
+ * 
+ * Note that there may still be other procids still sending but returning as soon as possible ensures that
+ * no one caller can hog the channel.
+ */
+function IPC_listen( &$msgArr, $bBlock = true ){
+	
+	global $g_k_caller;
+
+	$q_caller = msg_get_queue($g_k_caller);	
+	return IPC_rcv( $q_caller, 0, $msgArr, $bBlock );
+
+}
+
+/**
+ * Server replies to an RPC request.
+ */
+function IPC_reply( $caller_id, $str_data ){
+	global $g_k_reply;
+	$q_reply = msg_get_queue($g_k_reply);	
+	IPC_send( $q_reply, $caller_id, $str_data );
+}
+
+/**
+ * Receives a complete message from the queue. $rqd_msg_id may be zero to get
+ * any message or >0 for a specific message ID.
+ */
+function IPC_rcv( $queue, $rqd_msg_id, &$msgArr, $bBlock = true ){
+
+	$message = '';
+	$received_message_type = 0;
+	
+	while(true){
+				
+		global $g_max_rcv;
+
+		$flags = 0;
+		if(!$bBlock){
+			$flags = MSG_IPC_NOWAIT;
+		}
+		if( FALSE === msg_receive( $queue, $rqd_msg_id, $received_message_type, $g_max_rcv, $message, true, $flags, $error_code ) ){
+			if(!$bBlock && $error_code==MSG_ENOMSG){
+				return 0;
+			}
+			//code 7 when g_max_rcv is too small
+			throw new Exception("Failed to rcv message err = $error_code");	
+		}
+		
+		//echo "Got msg part " . substr( $message, 0, 20 ) . "\n\n";
+		
+		$d_meta = substr( $message, 0, 2 );
+		$message = substr( $message, 2 );
+	
+		if( $msgArr!=null && array_key_exists( $received_message_type, $msgArr) ){
+			$msgArr[ $received_message_type ]['msg'] .= $message;
+			
+		}else{
+			$msgArr=array();
+			$msgArr[ $received_message_type ] = array( 'final' => false, 'msg' => $message );
+		}
+
+		if($d_meta=='f:'){
+			// final message part
+			$msgArr[ $received_message_type ]['final'] = true;
+			break;
+		}
+					
+	}
+
+	return $received_message_type;
+
+}
+
+
+/**
+ * Send a data string of any length.
+ * 
+ * */
+function IPC_send( $queue, $caller_id, $str_data ){
+	
+	//print_r( msg_stat_queue($queue) );
+	
+	global $procName;
+	global $g_k_caller;
+	global $g_k_reply;
+	global $g_max_data;
+
+	$d_meta = null;
+	$chunk_cnt = 0;
+
+	if( strlen($str_data) > $g_max_data ){
+		//split the data into chunks
+		$chunk_cnt = intdiv( strlen($str_data), $g_max_data );
+		$d_meta = "p:";	//partial data - many calls
+	}
+
+	$str_chunk = null;
+	while( $chunk_cnt>=0 ){
+
+		if($chunk_cnt>0){
+			$str_chunk = substr( $str_data, 0, $g_max_data );
+			$str_data = substr( $str_data, $g_max_data );
+		}else{
+			$d_meta = "f:";	//'final' part of data
+			$str_chunk = $str_data;
+		}
+
+		//echo "send($caller_id) len = ".strlen($d_meta.$str_chunk)."\n";
+		
+		$error_code = 0;
+		if( FALSE === msg_send( $queue, $caller_id, $d_meta.$str_chunk, true, true, $error_code ) ){
+			//code 22 when the message is too large
+			throw new Exception("Failed to send message err = $error_code");
+		}
+		$chunk_cnt--;
+		if($chunk_cnt==0){
+			$d_meta = "f:";	//final data chunk
+		}
+	}
+	
+}
+
+?>
diff --git a/time.php b/time.php
new file mode 100644
index 0000000..644a8cd
--- /dev/null
+++ b/time.php
@@ -0,0 +1,18 @@
+<?php
+
+/**
+ * This returns a string for the current time. You cannot convert directly into a float because
+ * it is too large. So you can adjust the epoch to something else if desired by setting adj.
+ * 
+ * For example, set adj = 1733011200 to set the epoch to Sunday 1st of December 2024 12:00:00 AM
+ * 
+ * To use the full string values, you have the option of using the BC Math Functions.
+ * https://www.php.net/manual/en/ref.bc.php
+ * 
+ */
+function getTimeAsString( int $adj=0 ){
+	$str_time_arr = explode(' ', microtime() );       // string(21) "0.89115400 1283846202"
+	return ((int)$str_time_arr[1]-$adj) . substr($str_time_arr[0],1);
+}
+
+?>