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<concept id="GUID-F43A54C0-E82B-5790-8493-1372D214C642" xml:lang="en"><title>What
are Planes</title><shortdesc>This topic describes the concept of a <i>Plane</i> in the Communications
Framework. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The transmission of data and the management of connections is divided into
separate operations. Symbian platform gives the name <i>Plane</i> to
these operations. The Communications Framework defines three Planes. Each
Plane has a separate role and a separate responsibility. Each Plane matches
a Sockets Server API. </p>
<p>The Planes are called: the Data Plane, the Control Plane and the Management
Plane. </p>
<p>Layers span all three Planes. Code in each Plane operates together to deliver
the required Communications protocol behaviour. </p>
<p>A connection can have a number of subconnections. Subconnections can be
called channels. The concepts of connection and subconnection make it useful
to divide the Control Plane into two parts. The following diagram shows the
concept. The blue arrows indicate dependencies. The vertical dotted lines
indicate the division of Planes. </p>
<fig id="GUID-258000D9-1BC3-5A61-8235-4183D4A759C5">
<title>           Planes in the Communications Framework         </title>
<image href="GUID-3D8FE2A7-E544-51B9-9572-492A3B61377C_d0e76331_href.png" placement="inline"/>
</fig>
<p>The following diagram overlays the Planes with an example series of Layers </p>
<fig id="GUID-1758E53D-2A62-5C4C-93B9-8FE5DE67BBAA">
<title>           Planes and Layers in the Communications Framework      
  </title>
<image href="GUID-47EF98E9-7833-5E94-ADFF-198401463A8C_d0e76342_href.png" placement="inline"/>
</fig>
<ul>
<li id="GUID-45F19CFA-9B96-53B3-9B15-428BB3226BAA"><p> <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-E8250BBE-8529-5C45-BCA3-92A87C013580">Data Plane</xref>  </p> </li>
<li id="GUID-461678D6-3198-55CF-B07E-94F5E1086BAC"><p> <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-CFFC0BC1-FD9D-5F82-8906-2F9E8FCD21F5">Control Plane</xref>  </p> </li>
<li id="GUID-6B98DEAB-F245-5533-A05A-957FADE0C120"><p> <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-2372FF88-FA59-5CDF-9362-1A54F43D8442">Management Plane</xref>  </p> </li>
</ul>
<section id="GUID-E8250BBE-8529-5C45-BCA3-92A87C013580"><title>Data Plane</title> <p>The
Data Plane carries data and uses Communications protocols. The Data Plane
handles conversations with remote peers.The <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-CFFC0BC1-FD9D-5F82-8906-2F9E8FCD21F5">Control
Plane</xref> and the <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-2372FF88-FA59-5CDF-9362-1A54F43D8442">Management
Plane</xref> exist to serve the Data Plane. </p> <p>The Data Plane exists
to minimise interruptions to the flow of data. The Data Plane assigns the
response to interruptions to the Control Plane. Interruptions include: the
start of a new network connection, the management of a timeout and the management
of changes to the status of the network. </p> <p>To make sure that interruptions
cannot interfere with the Data Plane, a thread divide exists between the Data
Plane and the Control/Management Planes. The thread division allows the Communications
Framework to give the Data Plane thread a higher priority than the Control
and Management Plane thread. The difference in thread priorities allows the
Communications Framework to give the task of data transfer the highest priority. </p> <p>The
Communications Framework provides a mechanism to send messages between the
threads. The mechanism is called the <xref href="GUID-4CE10DED-31B2-50B5-9D38-85CE86E8A8DE.dita">Message
Transport</xref>. The Transport sends and delivers the messages asynchronously.
Threads can continue their work until the threads are prepared to process
messages. The Transport always makes sure of the delivery of messages. </p> <p>The
Data Plane corresponds to the Sockets Server API: <xref href="GUID-D4F08503-F1EF-3531-9C3C-4AF24A6255F0.dita"><apiname>RSocket</apiname></xref>. </p> <p>The
following diagram shows the thread divide. </p> <fig id="GUID-A440C4F8-199E-575A-9922-D90059CA69C3">
<title>              Data Plane in the Communications Framework           </title>
<image href="GUID-337FA49D-DE53-5568-9A5C-D6AE3F25E0A6_d0e76412_href.png" placement="inline"/>
</fig> <p><b>Features </b> </p> <p>The Data Plane: </p> <ul>
<li id="GUID-70DDF365-81B9-5D30-BEA1-B338074CF097"><p>exchanges data with
remote peers and uses data transfer protocols </p> </li>
<li id="GUID-E8A426F5-98AD-5BFA-9D8C-820B1656140C"><p>allows any number of
conversations at the same time through many protocols </p> </li>
<li id="GUID-6748E1E2-5FF3-52BC-9FC7-6759F52B59D2"><p>enables the transfer
of data to clients of the protocol stack and from clients of the protocol
stack </p> </li>
<li id="GUID-1073D70B-80FA-55E7-96E9-C9B51A701BC4"><p>enables the transfer
of data to hardware and from hardware </p> </li>
</ul> </section>
<section id="GUID-CFFC0BC1-FD9D-5F82-8906-2F9E8FCD21F5"><title>Control Plane</title> <p>The
Control Plane establishes, maintains and modifies the traffic, or conversations
in the Data Plane. Specifically, the Control Pane establishes, controls, re-binds
and tears down the Communications protocol stack based on commands from the
application and from the Management Plane. </p> <p>The <xref href="GUID-F43A54C0-E82B-5790-8493-1372D214C642.dita#GUID-F43A54C0-E82B-5790-8493-1372D214C642/GUID-E8250BBE-8529-5C45-BCA3-92A87C013580">Data Plane</xref> sends the status of the link and other control information
to the Control Plane. The Control Plane processes the status of the link and
other control information, and allows the Data Plane to give the task of data
transfer the highest priority. </p> <p>A connection can have a number of subconnections.
Subconnections can be called channels. The concepts of connection and subconnection
make it useful to divide the Control Plane into two parts. </p> <p>The Data
Plane corresponds to the Sockets Server APIs: <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita"><apiname>RConnection</apiname></xref> and <xref href="GUID-0AFDA357-EE44-3788-9CAB-162B874134BF.dita"><apiname>RSubConnection</apiname></xref>. </p> <p><b>Features </b> </p> <p>The Control Plane: </p> <ul>
<li id="GUID-EE232AB1-E916-54AB-B658-19B1A3F62B7C"><p>creates the Data Plane </p> </li>
<li id="GUID-F5E545D5-7954-5F20-B8A4-4C9B7F4B06CC"><p>configures the Data
Plane modules from information provided by the client application or the Management
Plane </p> </li>
<li id="GUID-3C4FF301-30D7-5064-BD45-5A05C962E1DE"><p>starts the Data Plane </p> </li>
<li id="GUID-BB2A8489-38D7-5D0B-A272-0C04DDE9B2FF"><p>controls and monitors
the Data Plane: </p> <ul>
<li id="GUID-7D7E7B38-34C4-53F6-A545-774DEEE07403"><p>acts on information
received from the data protocols </p> </li>
<li id="GUID-805AE125-F139-5E65-9912-DCA92926F1EF"><p>notifies the Management
Plane or the client application about changes to the state of the Control
Plane or the Data Plane. </p> </li>
</ul> </li>
<li id="GUID-ACDF9227-7286-5092-AF85-503BA30A2B45"><p>stops the Data Plane </p> </li>
<li id="GUID-54C50C8C-4CFB-5C02-89CE-754EF2F858E2"><p>destroys the Data Plane </p> </li>
<li id="GUID-8FC8ED8A-71DA-546A-8548-D6979B0F8CD7"><p>manages connection session
timers </p> </li>
<li id="GUID-C316844B-3046-599E-967C-085D79F9DA01"><p>manages connection data
channels and their properties </p> </li>
<li id="GUID-7CF74684-F4C8-54FC-9BA0-EA68D081E5AF"><p>handles changes to the
status of the network and handles error reports </p> </li>
</ul> </section>
<section id="GUID-2372FF88-FA59-5CDF-9362-1A54F43D8442"><title>Management
Plane</title> <p>The Management Plane maintains the configuration of the device,
monitors the availability of the network and makes policy decisions for the
Communications Framework. The Management Plane is the main location where
phone creators can customise the behaviour of the Communications protocol
stack. </p> <p>The Management Plane corresponds to the Sockets Server API: <xref href="GUID-55FE59B7-4FA9-3B1A-BD4C-9B7611FE75C2.dita"><apiname>RConnectionServ</apiname></xref>  </p> <p><b>Features </b> </p> <p>The Management Plane: </p> <ul>
<li id="GUID-3FB67172-7DC3-5621-AADB-02AE601D4EAF"><p>selects, constructs
and manages the Communications protocol stack: </p> <ul>
<li id="GUID-003EFE03-849E-5168-AAC3-8CFB6E07436C"><p>selects the correct
protocol stack for a connection based on client and configuration preferences </p> </li>
<li id="GUID-2E1CBE6C-2CCE-51E7-AE9C-F4EFAC0A426B"><p>manages the Control
Plane connections based on the policy set either in the configuration or at
run-time. </p> </li>
</ul> </li>
<li id="GUID-DA0FE037-69DB-586D-8809-C4D5A8D22C67"><p>notifies interested
clients about the state of the Communications protocol stack, for example,
bearer and service availability </p> </li>
<li id="GUID-3B36F963-CCF5-5E75-9486-04CBEF27DFC1"><p>provides an entry point
for third-party plugins to customise and control the Communications protocol
stack </p> </li>
<li id="GUID-D7A39FA9-1C88-5E8E-A566-E030971CCF0A"><p>controls the Communications
protocol stack. This control is based on policy decisions </p> </li>
<li id="GUID-8BBADB62-AB50-5B9D-B0E8-9546488E12DD"><p>communicates with the
Control Plane to influence the behaviour of Control or Data flow operations
in the Communications protocol stack </p> </li>
<li id="GUID-86CAD544-2B60-5713-B8C1-1FB14806FC31"><p>supplies configuration
information to the Layer. </p> </li>
</ul> </section>
</conbody><related-links>
<link href="GUID-61E0CD76-A2E3-5066-84A8-146EECA8ADCD.dita"><linktext>Socket Server</linktext>
</link>
</related-links></concept>