<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE task

  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-60EE22AA-402D-4FC2-9AD1-B3AEF822E8DC" xml:lang="en"><title>Receiving

Channel Data based on Conditions</title><shortdesc>Conditional listening enables you to receive sensor data feeds

based on a specific condition. For example, you can choose to receive sensor

feeds that are only movement specific.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

<prereq id="GUID-A4F41A1D-D093-418E-BA65-30C36DA0B0DA">       <p>Before listening

for channel data, you must <xref href="GUID-4B709839-8EEF-4AD2-9868-9AF0176B1E5B.dita#GUID-4B709839-8EEF-4AD2-9868-9AF0176B1E5B/GUID-FBBD3A8B-F240-4DC0-B516-3A51FDD86A88">open

the sensor channel</xref>.</p>      </prereq>

<steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-10-1-9-1-1-8-1-4-1-5-1-10-1-3-2">

<step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-10-1-9-1-1-8-1-4-1-5-1-10-1-3-2-1"><cmd>Create channel condition

items using <parmname>CSensrvChannelCondition</parmname> constructor. These

conditions can be used to filter the sensor data feeds.</cmd>

<stepxmp><codeblock xml:space="preserve">//Comparison values needed for condition

...

TInt firstNumber=45;

HBufC8 *firstBufNumber=NULL;

InetProtTextUtils::ConvertIntToDescriptorL(firstNumber,firstBufNumber);

CleanupStack::PushL(firstBufNumber);

TInt secondNumber=150;

HBufC8 *secondBufNumber=NULL;

InetProtTextUtils::ConvertIntToDescriptorL(secondNumber,secondBufNumber);

CleanupStack::PushL(secondBufNumber);

//Creates a SingleLimit Condition with a GreaterThan operator

CSensrvChannelCondition *firstCondition = CSensrvChannelCondition::NewL(ESensrvSingleLimitCondition,ESensrvOperatorGreaterThan,1,*firstBufNumber);

//Creates a SingleLimit Condition with a LessThan operator

CSensrvChannelCondition *secondCondition = CSensrvChannelCondition::NewL(ESensrvSingleLimitCondition,ESensrvOperatorLessThan,2,*secondBufNumber);</codeblock></stepxmp>

</step>

<step id="GUID-A94F1F87-9CD4-45E9-9FDA-B53E26C8F92D"><cmd>Create a channel

condition set using <parmname>CSensrvChannelConditionSet</parmname> constructor.

Add the condition items to the condition set using the <xref href="GUID-AF4BAE05-7111-3DF7-964D-C8A49D8F3D08.dita#GUID-AF4BAE05-7111-3DF7-964D-C8A49D8F3D08/GUID-84740BEB-2E6E-38E6-822B-9F6E4A55DF7D"><apiname>CSensrvChannelConditionSet::AddConditionL()</apiname></xref> function.</cmd>

<stepxmp><codeblock xml:space="preserve">//Creates a ConditionSet with ConditionType OR 

    CSensrvChannelConditionSet *ConditionSet=CSensrvChannelConditionSet::NewLC(ESensrvAndConditionSet);

    //Add channel1 and channel2 to conditonset

    ConditionSet->AddChannelConditionL(firstCondition);

    ConditionSet-&gt;AddChannelConditionL(secondCondition);</codeblock></stepxmp>

</step>

<step id="GUID-E51A9E16-67C8-43AB-BBEF-99411A3EEE0F"><cmd>Add the condition

set to the required channel using the <xref href="GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844.dita#GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844/GUID-006A659E-72F1-3D5D-8476-952619E3BA2F"><apiname>CSensrvChannel::AddConditionL()</apiname></xref> function.</cmd>

<stepxmp><codeblock xml:space="preserve">CSensrvChannel* channel;

channel->AddConditionL(*ConditionSet);   

</codeblock></stepxmp>

</step>

<step id="GUID-47EED068-A9C7-4DCF-AF03-3803CECAE7C8"><cmd>Create a condition

listener implementation for the <parmname>MSensrvChannelConditionListener</parmname> interface,

which listens for sensor data feeds based on <parmname>CSensrvChannelConditionSet</parmname>.</cmd>

<stepxmp><codeblock xml:space="preserve">class ConditionListener:public MSensrvChannelConditionListener

    {

    public:

        void ConditionMet(CSensrvChannel &aChannel, CSensrvChannelConditionSet &aChannelConditionSet, TDesC8 &avalue)

        {

        ...

         //Implementation

        }

    void ConditionError(CSensrvChannel &aChannel, TSensrvErrorSeverity aError)

        {

        ...

         //Implementation

        }

    void GetChannelConditionListenerInterfaceL(TUid aInterfaceUid, TAny *&aInterface)

        {

        ...

         //Implementation

        }

    };</codeblock></stepxmp>

</step>

<step id="GUID-196F04E0-2A98-4479-8165-9A803823E6AD"><cmd>Start conditional

listening by passing an instance of the condition listener implementation,

using the <xref href="GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844.dita#GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844/GUID-4CA77329-E958-3568-B34D-1086AA34A334"><apiname>CSensrvChannel::StartConditionListeningL()</apiname></xref> function.</cmd>

<stepxmp><codeblock xml:space="preserve">//Instance of the condition listener implementation

ConditionListener conditionListener;   

...

channel->StartConditionListeningL(conditionListener,1,1);

...</codeblock></stepxmp>

</step>

<step id="GUID-93BD0200-C12B-4AB1-9D23-F11AC54D39E6"><cmd>Once you get the

required sensor data feeds from the sensor channel based on the conditions

set, you can stop conditional listening using the <xref href="GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844.dita#GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844/GUID-78F64EA2-2901-3304-B4AE-B865D18772E8"><apiname>CSensrvChannel::StopConditionListening()</apiname></xref> function.</cmd>

<stepxmp><codeblock xml:space="preserve">channel-&gt;StopConditionListening();

</codeblock></stepxmp>

</step>

</steps>

<postreq id="GUID-40C4B810-AD44-4A28-8C29-8A08E914970D"><p>End the session

with the sensor channel using the <xref href="GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844.dita#GUID-22DC917F-D833-3531-AB2D-A6E2D52EF844/GUID-0B8F50A6-2CA1-316A-82AB-AA026005E810"><apiname>CSensrvChannel::CloseChannel()</apiname></xref> function.</p></postreq>