Virtual Machine Identifier aka CorrelationId

If for any reason you want to create a UNIQUE Id across all Java virtual machines. VMIDs (Virtual Machine ID) are used by the distributed garbage collector to identify client VMs.
This is my humble implementation :)
public static final String CORRELATION_ID_TOKEN_SEP = ":"; private static final Integer MAX_CORRELATION_ID_LEN = 100; private static String host=""; static{ try{ host = getHostName(InetAddress.getLocalHost().getHostName()); }catch(Exception e){ host="unknown"; } } /** * <p>Generates unique Id for each Tx based on java.rmi.dgc.VMID().toString() to populate guid parameter</p> * * @see java.rmi.dgc.VMID.toString() * * @param guid the String to parse, may be null * @param appName * * @return uniqueId for this Tx */ public static String generateCorrelationId(String guid, String appName){ StringBuffer sb = new StringBuffer(MAX_CORRELATION_ID_LEN); sb.append(guid).append(CORRELATION_ID_TOKEN_SEP); sb.append(host).append(CORRELATION_ID_TOKEN_SEP).append(appName); String s = sb.toString().trim(); return (s.length()>MAX_CORRELATION_ID_LEN)? s.substring(0, MAX_CORRELATION_ID_LEN-1):s; } /** * <p>Returns the host name from the Fully Qualified Domain Name (FQDN)</p> * * @param fqdn Fully Qualified Domain Name * * @return Host name */ public static String getHostName(String fqdn){ String host = StringUtils.trim(fqdn); if(host.length()>0){ int loc = host.indexOf('.'); if(loc>-1) host = host.substring(0, loc); } return host; }