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<concept id="GUID-E18592CD-223D-5B50-AF40-1AC7267BAB8C" xml:lang="en"><title>Watcher

Framework Overview</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This section provides an overview of the functionality and the architecture

of the Watcher Framework component. </p>

<section><title>Purpose</title> <p>The Watcher Framework is a lightweight

framework used to launch watchers. </p> <p>Watcher processes are launched

when a device starts and execute until the device is switched-off. They watch

for incoming messages and handle them as appropriate. For example an SMS Watcher

waits for incoming SMS messages and delivers them to the Message Store. </p> </section>

<section><title>Architecture</title> <p>The Watcher Framework consists of

an executable, <filepath>watcher.exe</filepath>, that is started when the

device boots. The start method depends on the UI family. The framework automatically

loads each watcher plug-in DLL in <filepath>z:\system\libs\watchers</filepath>. </p> <p> <b>Note:</b> The

Watcher Framework loads plug-ins only from ROM. </p> <p>Because the watchers

are started during system start-up it is important that they start quickly. </p> <p>After

the watcher framework has constructed all the watchers it starts an active

scheduler which remains active while the phone is switched on. </p> <p>The

watcher executable is has the capabilities necessary for write-access to the <b>Messaging

Outbox </b> folder. For instance, to update a delivery report, it may require

an entry in the Outbox to be updated. </p> <fig id="GUID-B1A76302-6F78-50A1-B5CF-B7FB670A4477">

<title>              Watcher Framework architecture            </title>

<image href="GUID-C4945844-643F-5479-AA2C-61C35817555A_d0e499797_href.jpg" placement="inline"/>

</fig> <p>A watcher plug-in typically make requests to another subsystem such

that they are completed when an external event (an SMS) being received occurs.

When a watcher has completed processing the request it waits for the next

event. </p> </section>

<section><title>API summary</title> <p>The <xref href="GUID-2C666512-BA5C-31FC-A226-9C5449A73711.dita"><apiname>CWatcherLog</apiname></xref> class

logs the watcher operations. </p> </section>

<section><title>Limitation</title> <p>Support for starting and stopping watchers

dynamically is not provided. This limitation makes watchers unsuitable for

operations such as listening for messages transported through infrared (IR)

because the IR port is not normally active. </p> </section>

</conbody><related-links>

<link href="GUID-96C1C892-890E-5FA1-AEE2-DB6BA2AD0A1D.dita"><linktext>WAP

                Stack</linktext></link>

</related-links></concept>