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<concept id="GUID-CED041C8-D68D-55D1-957E-1A48EEFFF851" xml:lang="en"><title>Inquiring

about Remote Devices</title><shortdesc>Describes how to inquire about remote devices.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>Now that you have decided on the best method of selecting a remote device

you will need to go through the process. For the purposes of this tutorial

we will assume you are going to allow the program to determine the remote

device with which to connect. </p>

<section id="GUID-2AE00E8E-3DC5-4AB3-9B85-5953BDC873BF"><title>How to inquire about remote devices</title> <p>Each Bluetooth

device has a 48-bit unique address built into its hardware. A basic inquiry

for devices in range returns zero or more of these addresses. </p> <p>As well

as an address, a Bluetooth device has a text name suitable for display to

users. If you want to display a list of available devices to the user, you

will also need to obtain these names. </p> <p>The address and the name inquiries

can occur simultaneously, if the underlying hardware supports this. Otherwise,

the address inquiry must finish before the name request can be issued over

the air. </p> <p>Address and name inquiries are performed through the generic

Symbian platform sockets class <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita"><apiname>RHostResolver</apiname></xref>.

A specialist Bluetooth sockets address class, <xref href="GUID-0ECE42E1-5E04-3BFB-BA17-F8036510798D.dita"><apiname>TInquirySockAddr</apiname></xref>,

which encapsulates Bluetooth address, Inquiry Access Code, and service and

device classes, is provided for use with such inquiries. </p> <p><b> Basic

Procedure</b> </p> <p>To inquire for the addresses of remote devices, take

the following steps: </p> <ol id="GUID-B794CB43-DF26-5C9E-BABC-95E614B8225F">

<li id="GUID-20EDA9A2-9C57-55E2-B36D-117CFF923D49"><p>Connect to the Sockets

Server (<xref href="GUID-EF29C1D7-B1E5-370F-AE37-66231A6BE449.dita"><apiname>RSocketServ</apiname></xref>), and then select the protocol to be

used using <xref href="GUID-EF29C1D7-B1E5-370F-AE37-66231A6BE449.dita#GUID-EF29C1D7-B1E5-370F-AE37-66231A6BE449/GUID-95B5BAA3-5A01-37F3-9C81-C5E71530B3B7"><apiname>RSocketServ::FindProtocol()</apiname></xref>. Address and name

queries are supplied by the stack's BTLinkManager protocol layer, so select

this. </p> </li>

<li id="GUID-30F19EEC-CB83-53D4-99E6-84C68A2DED9C"><p>Create and initialise

an <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita"><apiname>RHostResolver</apiname></xref> object. </p> </li>

<li id="GUID-B2FD4AE2-A5DE-5EB4-A135-CDA502364550"><p>Set the <codeph>TInquirySockAddr</codeph> parameter

for the inquiry: for address inquiries, the <xref href="GUID-75438E00-D211-3C94-A47D-61C5644A667D.dita"><apiname>KHostResInquiry</apiname></xref> flag

must be set through <xref href="GUID-0ECE42E1-5E04-3BFB-BA17-F8036510798D.dita#GUID-0ECE42E1-5E04-3BFB-BA17-F8036510798D/GUID-E4E83FA5-3102-3CE8-8796-A70C017D4FC7"><apiname>TInquirySockAddr::SetAction()</apiname></xref>. </p> <p>The

query can then be started with <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita#GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD/GUID-B210BAF2-1D26-3F5A-8EBE-EF5B460A69E1"><apiname>RHostResolver::GetByAddress()</apiname></xref>. </p> </li>

<li id="GUID-85980345-3E1A-5E10-A9F0-547DECBE52BB"><p>When <codeph>GetByAddress()</codeph> completes,

it fills in a <xref href="GUID-C625E339-6726-3FB9-8F8A-F4DB0CAC15FF.dita"><apiname>TNameEntry</apiname></xref> object with the address and class

of the first device found (or is undefined if no device was found). </p> </li>

<li id="GUID-B2FE92B6-989A-5A9F-92CB-9759587C31F8"><p>To get all the devices

discovered, call <xref href="GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD.dita#GUID-B16CAD6D-85B1-3482-AAC0-9BADEDB6ABDD/GUID-B64AB6BA-6D1D-30EB-88EF-381B52939F3D"><apiname>RHostResolver::Next()</apiname></xref> repeatedly until <codeph>KErrHostResNoMoreResults</codeph> is

returned. </p> </li>

</ol> <p><b>Getting

the addresses of remote devices</b> </p> <p>The following example shows how

to start a remote device address inquiry. </p> <ol id="GUID-A31D5876-7EE5-56B6-8F5A-7B8986C55349">

<li id="GUID-B6BCA711-BBC7-52C0-9B7A-F128031346ED"><p>Connect to the socket

server </p> <codeblock id="GUID-9E81DC37-FFC5-5427-BC01-54DFD82ED929" xml:space="preserve">RSocketServ socketServ;

socketServ.Connect();

TProtocolDesc pInfo;

_LIT(KL2Cap, "BTLinkManager");

User::LeaveIfError(socketServ.FindProtocol(KL2Cap,pInfo));</codeblock> </li>

<li id="GUID-48A0FDB1-BB15-5759-8AC1-F837513B423A"><p>Create and initialise

an <codeph>RHostResolver</codeph>  </p> <codeblock id="GUID-221037A8-6A39-5C27-A0DD-2A2BD14E5A7F" xml:space="preserve">RHostResolver hr;

User::LeaveIfError(hr.Open(socketServ,pInfo.iAddrFamily,pInfo.iProtocol));</codeblock> </li>

<li id="GUID-4A5D7DFC-FDFE-5D87-8DAB-A1BE59EFF806"><p>Set up a discovery query

and start it </p> <codeblock id="GUID-DA8F9430-CDE6-5663-9DED-D897B134DEEF" xml:space="preserve">TInquirySockAddr addr;

TNameEntry entry;

addr.SetIAC(KGIAC);

addr.SetAction(KHostResInquiry);

TRequestStatus status;

hr.GetByAddress(addr, entry, status);

User::WaitForRequest(status);</codeblock> </li>

<li id="GUID-9835B54E-E6D2-5FD5-8E7C-1374177F2D8A"><p>Process the information

returned in <codeph>entry</codeph>  </p> <codeblock id="GUID-766A738A-2F2F-5570-964B-196FA45BA601" xml:space="preserve">...</codeblock> </li>

</ol> <p><b>Notes:</b> </p> <ul>

<li id="GUID-71BF7F7E-AD6E-5715-B9A5-BAE7488B9B80"><p> <xref href="GUID-0ECE42E1-5E04-3BFB-BA17-F8036510798D.dita#GUID-0ECE42E1-5E04-3BFB-BA17-F8036510798D/GUID-B8F50B34-789B-3ADE-8D1E-04B59394BC2A"><apiname>TInquirySockAddr::SetIAC()</apiname></xref> sets

the Bluetooth Inquiry Access Code. For more information, see <xref href="http://www.bluetooth.org/assigned-numbers/" scope="external">Bluetooth Assigned Numbers</xref>. </p> </li>

<li id="GUID-B55A03AB-3F37-5377-80E6-5F94045A4C5F"><p>The host resolver caches

the results of inquiries so that devices that are no longer present may appear

in the list of results. This does not cause any additional complications,

as it is always possible for a device to go out of range between when it is

discovered and when a connection to it is made. </p> </li>

<li id="GUID-51CA2D0D-6A75-537F-A040-EA47D00DFEE0"><p>Communications API calls

are typically asynchronous (indicated by a <xref href="GUID-E0B34F3E-D4C4-3232-B8B1-7DB35B454646.dita"><apiname>TRequestStatus</apiname></xref> parameter

in the call). It is recommended that such calls are encapsulated in active

objects, as explained in <xref href="GUID-B507490F-6BD3-5DF5-97E4-EFDFEA2B4EDD.dita">Using

Asynchronous Programming</xref>. </p> </li>

</ul> <p><b>Getting

the name of a remote device</b> </p> <p>The name of a remote device can be

queried for by taking the same steps as for an address query, but setting

the action flag of a <codeph>TInquirySockAddr</codeph> to <xref href="GUID-8B748089-6177-3C64-8F54-C2F6E1C364F4.dita"><apiname>KHostResName</apiname></xref>.

The name is returned in the <codeph>iName</codeph> member accessed through

the <codeph>TNameEntry</codeph>. </p> <p><b>Example </b> </p> <codeblock id="GUID-F670B724-E96C-5077-9317-4A6F27CBFF67" xml:space="preserve">// Now do name inquiry

addr.SetAction(KHostResName);

hr.GetByAddress(addr, entry, stat);

User::WaitForRequest(stat);

TPtrC deviceName;

if (stat == KErrNone)

     deviceName.Set(entry().iName);</codeblock> <p><b>Notes </b> </p> <ul>

<li id="GUID-DB873994-76A6-5FE2-8B8D-00E0FD815DF2"><p>To do a simultaneous

address and name inquiry, use <codeph>SetAction(KHostResName|KHostResInquiry)</codeph>. </p> </li>

<li id="GUID-5823E26F-BFE7-5745-A208-C51DECF21D14"><p> <codeph>RHostResolver::GetByName()</codeph> is

not supported </p> </li>

</ul> </section>

<section id="GUID-4425B269-2649-4A3C-81A4-17AB3733CF1C"><title>Where Next?</title> <p>This tutorial set takes you through

all the steps involved in setting up and communicating over a Bluetooth connection. </p> <ul>

<li id="GUID-78BDF706-7245-5D78-AB1D-8DB1352CFEAF"><p> <xref href="GUID-301488F8-B6D8-569A-B05E-19B740FE4C00.dita">Selecting

a Remote Device</xref>  </p> </li>

<li id="GUID-65BD97CF-9CD6-5050-9B96-4B22124C7E0F"><p> <b>Inquiring About

Remote Devices</b> - This document </p> </li>

<li id="GUID-2418982B-074A-561F-AF89-C0A233F7C593"><p> <xref href="GUID-A13494B9-C1E4-506A-B236-8AE0A6D6D557.dita">Inquiring

About Services on a Remote Device</xref>  </p> </li>

<li id="GUID-3E09B7DF-5BD7-5FC7-9C09-245421BCA730"><p> <xref href="GUID-A24D2CEF-88C9-5C63-A14D-85EFFBEF3C92.dita">Connecting

and Transferring Data to a Remote Device</xref>  </p> </li>

<li id="GUID-9AF0CBD6-3762-5724-82EF-88348D246CA1"><p> <xref href="GUID-4F0C4B9D-AA42-59C4-900A-7045FEAAF2F4.dita">Using

security on outgoing sockets</xref>  </p> </li>

</ul> </section>

</conbody></concept>