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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>

</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>

</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>

</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>