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<concept id="GUID-BD8446C5-3ADE-59A6-A13A-A5482D6FC56F" xml:lang="en"><title>Connection
Management</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>This topic introduces the concept of Connection Management and the APIs
needed to perform Connection Management operations. The APIs discussed include <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita"><apiname>RConnection</apiname></xref> and <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita"><apiname>RHostResolver</apiname></xref>. </p>
<p>The RConnection API provides: </p>
<ul>
<li id="GUID-395ABFCE-2A51-5205-B3FF-F85C882AF761"><p>an interface for actively
creating and managing connections </p> </li>
<li id="GUID-C3A61C1A-72DF-5304-9758-F6C298DF93AD"><p>facilities that are
not available when creating connections by other methods. Such facilities
include support for multihoming. </p> </li>
</ul>
<p>Introduced with the <keyword>multihoming</keyword> functionality, which
allows multiple Circuit/Packet Switched Data connections to be active. </p>


<p><b>Implementation </b> </p>
<p>The connection management API is implemented by <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita"><apiname>RConnection</apiname></xref>. </p>
<p> <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita"><apiname>RConnection</apiname></xref> objects are implemented as sub-sessions
to the <xref href="GUID-EF29C1D7-B1E5-370F-AE37-66231A6BE449.dita"><apiname>RSocketServ</apiname></xref>. </p>


<p><b>Connections and subconnections </b> </p>
<p>An RConnection is the handle for an application onto an underlying interface.
(But there may be a number of RConnections per interface). </p>
<p>Technologies such as W-CDMA and later releases of GPRS are capable of establishing
multiple subconnections within a connection. This is supported by the management
interface. </p>
<p>Note that all subconnections within a connection will have certain parameters
in common, such as the Access Point Name in the case of GPRS and WCDMA. However,
each subconnection may have a different Quality-of-Service. </p>


<p><b>Guidelines for use </b> </p>
<p> <codeph>RConnection</codeph> s need to be opened on an existing socket
server session, <xref href="GUID-EF29C1D7-B1E5-370F-AE37-66231A6BE449.dita"><apiname>RSocketServ</apiname></xref>. </p>
<p>In the API as a whole, there is an important distinction made between an <codeph>RConnection</codeph> object
which has been newly opened on an socket server session but not yet associated
with an underlying interface on the server, and one which is opened and associated.
There are certain operations that require a <codeph>RConnection</codeph> object
to be in the associated state to work successfully. The <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita#GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD/GUID-CB62E838-A380-309C-8B08-1F804EDB4387"><apiname>RConnection::Start()</apiname></xref> and <xref href="GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD.dita#GUID-BED8A733-2ED7-31AD-A911-C1F4707C67FD/GUID-EAB8B0B1-0F5B-31E5-BFD6-B3AE1181868E"><apiname>RConnection::Attach()</apiname></xref> methods
are used to associate an <codeph>RConnection</codeph> object with an interface. </p>
<p>There is no restriction on the number of <codeph>RConnection</codeph> objects
per socket server session. It is also possible for several <codeph>RConnection</codeph> objects
to refer to the same underlying interface. For example, several applications,
each with its own socket server session and <codeph>RConnection</codeph> object,
could refer to the same underlying interface. It is also technically possible
for the said <codeph>RConnection</codeph> objects to be on the same socket
server session, though this may be somewhat redundant. </p>
<p>Rather like <xref href="GUID-D4F08503-F1EF-3531-9C3C-4AF24A6255F0.dita"><apiname>RSocket</apiname></xref> /<xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita"><apiname>RHostResolver</apiname></xref> objects,
an individual <codeph>RConnection</codeph> object is not designed to be used
by multiple clients simultaneously (i.e. have multiple requests outstanding
on it from different clients). </p>
<p>Although <codeph>RConnection</codeph> objects are automatically closed
when the corresponding socket server session is closed, appropriate use of <codeph>CleanupClosePushL(RConnection&amp;)</codeph> is
more likely to ensure proper operation. </p>
<p> <xref href="GUID-D4F08503-F1EF-3531-9C3C-4AF24A6255F0.dita"><apiname>RSocket</apiname></xref> and <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita"><apiname>RHostResolver</apiname></xref> objects
can be associated with an <codeph>RConnection</codeph> object. In this case,
data will flow over the same underlying interface as the <codeph>RConnection</codeph> to
which they have been associated. For this to work, the <codeph>RSocket/RHostResolver/RConnection</codeph> objects
must all be on the same socket server session, and the <codeph>RConnection</codeph> object
must have been previously opened and active (i.e. associated with an underlying
interface). </p>
<section id="GUID-83D1E933-6A85-40C0-A9D0-7F465953DAFB"><title>Connection Management functionality</title> <p> <codeph>RConnection</codeph> provides
clients with the following functionality: </p> <ul>
<li id="GUID-882DB251-213D-58BF-9398-9ADC68341298"><p>Opening and closing
the connection </p> </li>
<li id="GUID-E20078EE-FE93-5452-877B-C3F7985142FD"><p>Starting a connection,
which means associating it with a new underlying interface </p> </li>
<li id="GUID-FBBB3514-280E-5989-AC76-B81DD8CAC8B8"><p>Attaching the <codeph>RConnection</codeph> instance
to an existing interface </p> </li>
<li id="GUID-BB58A700-B58C-5C26-BD67-688EE0CF55C2"><p>Stopping the connection,
which means disassociating it from the underlying interface </p> </li>
<li id="GUID-A74BD98D-F3A7-5FE4-9F74-60AC2E1FBB78"><p>Obtaining progress information
and notification during connection start-up </p> <p>This is useful because
the process of dialling an ISP, logging in and starting network protocols
can be quite lengthy, taking up to a minute in some cases. In addition, the
application can get the last error which occurred in setting up the connection. </p> <p> </p> </li>
<li id="GUID-9AAABE2A-3FB0-5B63-948F-2B3112683B0C"><p>Notifying when subconnections
come up and go down </p> </li>
<li id="GUID-418DFF66-415A-510D-AB86-1090EE0DC6B8"><p>Notifying when there
is a service change for the connection </p> </li>
<li id="GUID-CF7D3A21-0A1F-537B-AF50-4EDDBB931557"><p>Notifying when a given
amount of data has been sent or received on a connection or subconnection </p> </li>
<li id="GUID-E192532A-F857-5869-B5E0-D657AAFC8290"><p>Reading CommDB fields
specific to an active connection </p> </li>
<li id="GUID-1A83A7BD-FA23-5F4F-8D28-A0A24481DB9F"><p>Collecting statistical
information on the network connection and subconnections. A UI component can
display the collected statistical information in order to allow the user to
examine the status of connections. The information that can be gathered is
the following: </p> <ul>
<li id="GUID-AF90F93C-DA10-539F-842A-34337C51427F"><p>All available internet
access point names and internet access point 'friendly' names as appropriate
for each network (GPRS/UMTS) connection </p> </li>
<li id="GUID-66B29945-C319-5E56-ABCA-301188643CDB"><p>Enumerating the currently
active connections and subconnections </p> </li>
<li id="GUID-8E888149-A79D-5608-9875-9753CEE59EE9"><p>The current status of
all network connections e.g. active/suspended </p> </li>
<li id="GUID-B1125663-747F-5F8C-927F-94AB17482FE5"><p>The amount of data (in
bytes) transferred uplink and downlink by the network connection and subconnections </p> </li>
<li id="GUID-E00B23A4-E91B-54E7-9AE1-429E19C520AB"><p>The amount of time each
network connection has been active (in seconds) </p> </li>
<li id="GUID-7AC5AC0D-9147-52A5-A427-B5D798D9A119"><p>The current status of
the connection and subconnections with respect to data transfer, i.e. active/inactive </p> </li>
<li id="GUID-AD4C0A7A-E48E-513F-806A-40934415D42B"><p>The Quality of Service
profile associated with each Packet Data Protocol (GPRS/UMTS) context, e.g.
low/medium/high </p> </li>
</ul> </li>
</ul> </section>
</conbody><related-links>
<link href="GUID-5CFC075C-8F53-5E1B-A111-C6F4567DFD1E.dita"><linktext>RConnection
API Summary                 Reference</linktext></link>
</related-links></concept>