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<div class="section" lang="en">
<div class="titlepage">
<div><div><h2 class="title" style="clear: both">
<a name="id2457752"></a>4.Running the examples</h2></div></div>
<div></div>
</div>
<div class="toc"><dl>
<dt><span class="section"><a href="ar01s04.html#id2457818">4.1. Start the Naming Service (omniNames)</a></span></dt>
<dt><span class="section"><a href="ar01s04.html#id2457838">4.2. Start the omniEvents daemon
(omniEvents)</a></span></dt>
<dt><span class="section"><a href="ar01s04.html#id2457986">4.3. Create an Event Channel
(eventc)</a></span></dt>
<dt><span class="section"><a href="ar01s04.html#id2458093">4.4. Run one or more example suppliers/consumers</a></span></dt>
</dl></div>
<p>The examples programs (<span><b class="command">eventc</b></span>,
<span><b class="command">pushsupp</b></span>, <span><b class="command">pushcons</b></span>,
<span><b class="command">pullsupp</b></span>, <span><b class="command">pullcons</b></span>) are also
available as Python and Java. Look in
<tt class="filename">examples/python/*</tt> and
<tt class="filename">examples/java/*</tt>.</p>
<p>In these examples, we run omniEvents from the command line. A real
installation would probably use a system service, as mentioned in the
<a href="ar01s02.html" title="2.Build and Installation">installation</a> section.</p>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="id2457818"></a>4.1.Start the Naming Service (omniNames)</h3></div></div>
<div></div>
</div>
<p>You must start the naming service (<span><b class="command">omniNames</b></span>) as
the examples make use of the naming service to locate the event channel
factory. Please refer to the omniORB documentation for information on how
to set up the naming service.</p>
</div>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="id2457838"></a>4.2.Start the omniEvents daemon
(<a href="re01.html" title="omniEvents">omniEvents</a>)</h3></div></div>
<div></div>
</div>
<p><span><b class="command">omniEvents</b></span> implements an Event Channel Factory
server which clients can use to create Event Channels. The factory
registers itself with the Naming Service to enable clients to locate
it.</p>
<p>Before you start, you may need to set the environment variable
<tt class="literal">OMNIORB_CONFIG</tt> to contain the full path name of the
file <tt class="filename">omniORB.cfg</tt>. The default is
<tt class="filename">/etc/omniORB.cfg</tt>. For example:</p>
<pre class="programlisting">% OMNIORB_CONFIG=/wib/wob/omniORB.cfg; export OMNIORB_CONFIG</pre>
<p>Start omniEvents by running the executable. The binary is in
<tt class="filename">PREFIX/sbin</tt> (if you used the <span><b class="command">configure
--prefix</b></span> parameter), or in
<tt class="filename">/usr/local/sbin</tt> (by default). Once the service is
correctly started up, it automatically backgrounds itself (Unix
only).</p>
<div class="example">
<a name="id2457918"></a><p class="title"><b>Example2.Startup from the command-line.</b></p>
<pre class="programlisting">% omniEvents -l $HOME
%</pre>
</div>
<p>omniEvents supports the following options:</p>
<pre class="literallayout"> cold start syntax: src/omniEvents [-pPORT] [-aENDPOINT] [OPTIONS]
warm start syntax: src/omniEvents [OPTIONS]
COLD START OPTIONS:
-p PORT configure server port [11169]
-a ENDPOINT set alternate endPoint for failover
OPTIONS:
-l PATH full path to data directory* [/var/lib/omniEvents]
-P PIDFILE keep track of running instance in PIDFILE.
-N ID factory naming service id ["EventChannelFactory"]
-f Stay in the foreground.
-t FILE Send trace messages to FILE instead of syslog.
-v print the IOR of the new EventChannelFactory.
-V display version
-h display this help text
*You can also set the environment variable OMNIEVENTS_LOGDIR
to specify the directory where the data files are kept.</pre>
<p>The options provided allow you to override the default name used
to register the Event Channel Factory with the Naming Service.</p>
<p>omniEvents supports persistent channels by writing all state
changes to a file. This persistency datafile is stored in
<tt class="filename">/var/lib/omniEvents/</tt> by default. Use the
<tt class="option">-l</tt> option or the <tt class="literal">OMNIEVENTS_LOGDIR</tt>
environment variable to override the default.</p>
</div>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="id2457986"></a>4.3.Create an Event Channel
(<a href="re03.html" title="eventc">eventc</a>)</h3></div></div>
<div></div>
</div>
<p><span><b class="command">eventc</b></span> resolves the factory name with the
Naming Service and then contacts the factory to request an Event
Channel. The Event Channel is created within the the omniEvents
process.</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>You can by-pass the factory completely and instantiate the event
channel directly within your own process by linking your application
directly with the omniEvents shared libraries. The
<tt class="filename">src/main.cc</tt> file is a good starting point to
find out how.</p>
</div>
<p>eventc then registers the created Event Channel with the Naming
Service, and exits.</p>
<p>eventc has the following options:</p>
<pre class="literallayout"> syntax: tools/eventc OPTIONS [FACTORY_URI]
FACTORY_URI: The factory may be specified as a URI.
This may be an IOR, or a corbaloc::: or corbaname::: URI.
For example: corbaloc::localhost:11169/omniEvents
OPTIONS: DEFAULT:
-n channel name ["EventChannel"]
-N factory name (if URI is not specified) ["EventChannelFactory"]
-c override default CyclePeriod_ns of new channel (nanoseconds)
-i set the InsName of new channel, to enable access via corbaloc
-p override default MaxNumProxies of new channel
-q override default MaxQueueLength of new channel
-R override default PullRetryPeriod_ms for new channel (milliseconds)
-t set an event type filter, FilterId=<RepositoryId>
-v print the IOR of the new EventChannel to standard output.
-h display this help text
OLD OPTIONS: (only used by omniEvents v2.4 and earlier)
-m override default MaxEventsPerConsumer for new channel</pre>
<p>The options provided allow you to override the default name used
to register the Event Channel Factory and the created Event Channel with
the Naming Service.</p>
<p>eventc starts silently unless it encounters any problems or if you
turn tracing on by supplying the omniORB specific option
<tt class="option">-ORBtraceLevel 20</tt>. eventc terminates once the event
channel has been created:</p>
<pre class="programlisting">% eventc
%</pre>
</div>
<div class="section" lang="en">
<div class="titlepage">
<div><div><h3 class="title">
<a name="id2458093"></a>4.4.Run one or more example suppliers/consumers</h3></div></div>
<div></div>
</div>
<p>There are four example clients: <span><b class="command">pushsupp</b></span>,
<span><b class="command">pushcons</b></span>, <span><b class="command">pullsupp</b></span> and
<span><b class="command">pullcons</b></span>. When run, each supplier and consumer
contacts the Naming Service to obtain a reference to the Event Channel
created in step 2 above. They then connect themselves to the channel and
do their bits. The data sent through the channel is always of type
<tt class="literal">long</tt> in the examples.</p>
<p>As per <span><b class="command">eventc</b></span>, you can override the default
name used to register the channel in the naming service. The
<tt class="option">-d</tt> option is used to exercise the disconnect
functionality provided by the channel.</p>
<pre class="literallayout"> syntax: examples/pushsupp OPTIONS [CHANNEL_URI]
CHANNEL_URI: The event channel may be specified as a URI.
This may be an IOR, or a corbaloc::: or corbaname::: URI.
OPTIONS: DEFAULT:
-d NUM disconnect after sending NUM events [0 - never disconnect]
-r connect using a nil reference
-s SECS sleep SECS seconds after disconnecting [0]
-n NAME channel name (if URI is not specified) ["EventChannel"]
-h display this help text
syntax: examples/pushcons OPTIONS [CHANNEL_URI]
CHANNEL_URI: The event channel may be specified as a URI.
This may be an IOR, or a corbaloc::: or corbaname::: URI.
OPTIONS: DEFAULT:
-d NUM disconnect after receiving NUM events [0 - never disconnect]
-s SECS sleep SECS seconds after disconnecting [0]
-n NAME channel name (if URI is not specified) ["EventChannel"]
-h display this help text
syntax: examples/pullsupp OPTIONS [CHANNEL_URI]
CHANNEL_URI: The event channel may be specified as a URI.
This may be an IOR, or a corbaloc::: or corbaname::: URI.
OPTIONS: DEFAULT:
-d NUM disconnect after sending NUM events [0 - never disconnect]
-s SECS sleep SECS seconds after disconnecting [0]
-n NAME channel name (if URI is not specified) ["EventChannel"]
-h display this help text
syntax: examples/pullcons OPTIONS [CHANNEL_URI]
CHANNEL_URI: The event channel may be specified as a URI.
This may be an IOR, or a corbaloc::: or corbaname::: URI.
OPTIONS: DEFAULT:
-t enable try_pull mode
-r connect using a nil reference
-d NUM disconnect after receiving NUM events [0 - never disconnect]
-s SECS sleep SECS seconds after disconnecting [0]
-n NAME channel name (if URI is not specified) ["EventChannel"]
-h display this help text</pre>
<p>The <tt class="option">-t</tt> option in pullcons causes the pull
consumer to issue non-blocking <tt class="literal">try_pull()</tt> invocations
rather than blocking <tt class="literal">pull()</tt>s.</p>
<div class="example">
<a name="id2458214"></a><p class="title"><b>Example3.Here is what to expect during a typical session</b></p>
<pre class="programlisting"> % examples/pushsupp
Looking for EventChannel
Obtained SupplierAdmin.
Obtained ProxyPushConsumer.
Connected Push Supplier.
Push Supplier: push() called. Data : 0
Push Supplier: push() called. Data : 1
Push Supplier: push() called. Data : 2
Push Supplier: push() called. Data : 3
Push Supplier: push() called. Data : 4
Push Supplier: push() called. Data : 5
...
% examples/pushcons
Obtained ConsumerAdmin.
Obtained ProxyPushSupplier.
Connected Push Consumer.
Push Consumer: push() called. Data : 0
Push Consumer: push() called. Data : 1
Push Consumer: push() called. Data : 2
Push Consumer: push() called. Data : 3
Push Consumer: push() called. Data : 4
Push Consumer: push() called. Data : 5
Push Consumer: push() called. Data : 6
...</pre>
</div>
<p>Pull consumers cause the event channel to poll every pull supplier
connected when they request an event (using <tt class="literal">pull()</tt>,
not <tt class="literal">try_pull()</tt>) until an event enters the event
channel (which could come from a push supplier).</p>
<p>In order to prevent the Event Channel from consuming excessive
<span class="acronym">CPU</span> when polling for events the <tt class="option">-r</tt>
option of eventc can be used to specify a pull retry period
<span class="acronym">QOS</span> parameter. This parameter represents a timeout in
seconds to wait for before each poll cycle. This parameter defaults to 1
second.</p>
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