ACE Tutorial 002

#!/bin/sh # This is a shell archive (produced by GNU sharutils 4.2). # To extract the files from this archive, save it to some FILE, remove # everything before the `!/bin/sh' line above, then type `sh FILE'. # # Made on 1999-01-17 14:20 EST by . # Source directory was `/var/home/jcej/projects/ACE_wrappers/docs/tutorials/002'. # # Existing files will *not* be overwritten unless `-c' is specified. # # This shar contains: # length mode name # ------ ---------- ------------------------------------------ # 607 -rw-rw-r-- hdr # 28 -rw-rw-r-- bodies # 1027 -rw-rw-r-- page01.pre # 1819 -rw-rw-r-- page02.pre # 100 -rw-rw-r-- page03.pre # 448 -rw-rw-r-- page04.pre # save_IFS="${IFS}" IFS="${IFS}:" gettext_dir=FAILED locale_dir=FAILED first_param="$1" for dir in $PATH do if test "$gettext_dir" = FAILED && test -f $dir/gettext \ && ($dir/gettext --version >/dev/null 2>&1) then set `$dir/gettext --version 2>&1` if test "$3" = GNU then gettext_dir=$dir fi fi if test "$locale_dir" = FAILED && test -f $dir/shar \ && ($dir/shar --print-text-domain-dir >/dev/null 2>&1) then locale_dir=`$dir/shar --print-text-domain-dir` fi done IFS="$save_IFS" if test "$locale_dir" = FAILED || test "$gettext_dir" = FAILED then echo=echo else TEXTDOMAINDIR=$locale_dir export TEXTDOMAINDIR TEXTDOMAIN=sharutils export TEXTDOMAIN echo="$gettext_dir/gettext -s" fi touch -am 1231235999 $$.touch >/dev/null 2>&1 if test ! -f 1231235999 && test -f $$.touch; then shar_touch=touch else shar_touch=: echo $echo 'WARNING: not restoring timestamps. Consider getting and' $echo "installing GNU \`touch', distributed in GNU File Utilities..." echo fi rm -f 1231235999 $$.touch # if mkdir _sh00205; then $echo 'x -' 'creating lock directory' else $echo 'failed to create lock directory' exit 1 fi # ============= hdr ============== if test -f 'hdr' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'hdr' '(file already exists)' else $echo 'x -' extracting 'hdr' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'hdr' && X X X X X ACE Tutorial 002 X ACE Tutorial 002 X Creating a Better Server X X

SHAR_EOF $shar_touch -am 0117141599 'hdr' && chmod 0664 'hdr' || $echo 'restore of' 'hdr' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'hdr:' 'MD5 check failed' 8a98117995f511d0ed9b699587b5b6a5 hdr SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'hdr'`" test 607 -eq "$shar_count" || $echo 'hdr:' 'original size' '607,' 'current size' "$shar_count!" fi fi # ============= bodies ============== if test -f 'bodies' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'bodies' '(file already exists)' else $echo 'x -' extracting 'bodies' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'bodies' && PAGE=2 server.cpp handler.h SHAR_EOF $shar_touch -am 0117141899 'bodies' && chmod 0664 'bodies' || $echo 'restore of' 'bodies' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'bodies:' 'MD5 check failed' 9ec2171f52b5b973c247ef550fb7b035 bodies SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'bodies'`" test 28 -eq "$shar_count" || $echo 'bodies:' 'original size' '28,' 'current size' "$shar_count!" fi fi # ============= page01.pre ============== if test -f 'page01.pre' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'page01.pre' '(file already exists)' else $echo 'x -' extracting 'page01.pre' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'page01.pre' && X

In this tutorial, we will build a little on what we learned in the first tutorial and add a few extras. In the end, we will have a better server object that is actually simpler and more maintainable than the one we created before.

To begin, let's ask ourselves the same thing we did at the beginning of tutorial 001:

What do you need to create a server?

Something which accepts connections from clients
Something which handles established connections
A main program loop that handles it all

Previously, we created a solution which addressed each one of these questions specifically. At the end of it all, we realized that our only application-specific coding was confined to the handler portion of the program. We hinted that there may be a way to eliminate hand-coding an acceptor each time we want to create a server. Here, we will explore that approach.

X SHAR_EOF $shar_touch -am 0117141599 'page01.pre' && chmod 0664 'page01.pre' || $echo 'restore of' 'page01.pre' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'page01.pre:' 'MD5 check failed' c5a9075793a200d7b2e49a092ee1ce6c page01.pre SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page01.pre'`" test 1027 -eq "$shar_count" || $echo 'page01.pre:' 'original size' '1027,' 'current size' "$shar_count!" fi fi # ============= page02.pre ============== if test -f 'page02.pre' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'page02.pre' '(file already exists)' else $echo 'x -' extracting 'page02.pre' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'page02.pre' && X

Like Tutorial 1, this is also a rather small program. I'm going to add a couple of new ideas along the way but to make up for it I'm also going to simplify the acceptor a great deal. X

Kirthika's Abstract:

Here, the Logging_Acceptor is an ACE_Acceptor class which is associated with the Logging_Handler and the ACE_SOCK_ACCEPTOR. This will now accept connection requests from the clients on being opened with the reactor instance passed to it.

We also implement a signal to capture CTRL-C [ which generates SIGINT ] using ACE_SigAction and ACE_SignalHandler. This signal can now be used to stop the reactor from handling events.

Then, the reactor is allowed to loop infintely until it is shut down using a ^C, after which both the reactor as well as the acceptor are destroyed.

The Logging_Handler derives from the ACE_Svc_Handler instead of the Event_Handler since the Svc_Handler has inbuilt SOCK_Stream and provides all the calls needed by the reactor. The Svc_Handler has the ability to react to events and communicate to remote tasks using the underlying data stream passed to it.

A timer is scheduled in the reactor which does nothing but simply display how it could be used to provide periodic processing when needed. The ACE_TimeValue is used to set the time period.

Also, optimisations have been made in the form of a separate function for destroying the objects used.

Thus a simpler server has now been built which successfully demonstrates how simple a task, writing a server can become on using the various ACE components judiciously.

We begin by looking at the main (server.cpp) portion program: X

SHAR_EOF $shar_touch -am 0117141899 'page02.pre' && chmod 0664 'page02.pre' || $echo 'restore of' 'page02.pre' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'page02.pre:' 'MD5 check failed' 41fa9b0b5cced9b45407b397a57482ca page02.pre SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page02.pre'`" test 1819 -eq "$shar_count" || $echo 'page02.pre:' 'original size' '1819,' 'current size' "$shar_count!" fi fi # ============= page03.pre ============== if test -f 'page03.pre' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'page03.pre' '(file already exists)' else $echo 'x -' extracting 'page03.pre' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'page03.pre' && X

Now lets take a look at the new Logging_Handler: X

SHAR_EOF $shar_touch -am 0117141899 'page03.pre' && chmod 0664 'page03.pre' || $echo 'restore of' 'page03.pre' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'page03.pre:' 'MD5 check failed' f62bcf39007ec332f581a0849e33fe50 page03.pre SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page03.pre'`" test 100 -eq "$shar_count" || $echo 'page03.pre:' 'original size' '100,' 'current size' "$shar_count!" fi fi # ============= page04.pre ============== if test -f 'page04.pre' && test "$first_param" != -c; then $echo 'x -' SKIPPING 'page04.pre' '(file already exists)' else $echo 'x -' extracting 'page04.pre' '(text)' sed 's/^X//' << 'SHAR_EOF' > 'page04.pre' && X

Well, that's it for the second tutorial. We've found a much easier way to create a server, especially the acceptor part. At the same time, we introduced more functionality and robustness. Not bad for a day's work.

X SHAR_EOF $shar_touch -am 0117142099 'page04.pre' && chmod 0664 'page04.pre' || $echo 'restore of' 'page04.pre' 'failed' if ( md5sum --help 2>&1 | grep 'sage: md5sum \[' ) >/dev/null 2>&1 \ && ( md5sum --version 2>&1 | grep -v 'textutils 1.12' ) >/dev/null; then md5sum -c << SHAR_EOF >/dev/null 2>&1 \ || $echo 'page04.pre:' 'MD5 check failed' b9cf47308b8215298848b4819f6d447c page04.pre SHAR_EOF else shar_count="`LC_ALL= LC_CTYPE= LANG= wc -c < 'page04.pre'`" test 448 -eq "$shar_count" || $echo 'page04.pre:' 'original size' '448,' 'current size' "$shar_count!" fi fi rm -fr _sh00205 exit 0