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<concept id="GUID-A8130D83-E684-5B6C-BDFE-EB6EE3CD49E8" xml:lang="en"><title>Writing

<li id="GUID-96CBCE79-4F5D-5F87-AC6B-C366346447AB"><p>The <codeph>PrepareDialog()</codeph> function.

This function is called first by the UPS server. It enables the dialog creator

to query other system servers such as AppArc or the SIS registry to retrieve

additional information to display in the dialog. For example it might query

the SIS registry using the client application’s secure id. </p> </li>

<li id="GUID-A439E217-B95B-5B68-8893-BDBD61D694D1"><p>The <codeph>DisplayDialog()</codeph> function.

This function is called second by the UPS server. It displays the prompt,

most commonly through the notification framework. This function also returns

the option selected by the user and, if applicable, the fingerprint for a

new decision record. </p> </li>

</ul> <p>The UPS displays only one prompt at a time so it is possible for

there to be a delay between calling the function to prepare the dialog and

the function to display the dialog. It is also possible for other dialogs

If either function is cancelled, the dialog creator instance is destroyed

without calling further methods. </p> <p>The work split between <codeph>PrepareDialog()</codeph> and <codeph>DisplayDialog()</codeph> described

above is a recommendation, and some of the functionality could be implemented

directly in the notifier implementation. </p> <p>In the example given in this

document, the functionality for dialogs is implemented separately from the

functionality for policy evaluators. This allows multiple policy evaluators

to share common UI code. However, it is possible to deliver policy evaluator

and dialog creator plug-ins in the same DLL. </p> </section>

<section><title>Procedure</title> <p>Dialog creators implement the <codeph>CDialogCreator</codeph> interface.

This section shows how to implement the functions that prepare and display

the user prompt. </p> <ol id="GUID-0F29F8B7-F303-5D42-BB95-A32B1FE13A9A">

<li id="GUID-9FDDAD1F-4B9A-516A-8A00-0C331F38C4CA"><p>Prepare a dialog using

the <xref href="GUID-2308E2F4-A878-3B0A-951B-EFC4908AD9BB.dita"><apiname>PrepareDialog()</apiname></xref> function. </p> </li>

<li id="GUID-45C16A52-A05E-545A-AB3A-967CCA35BB15"><p>Display the dialog using

the <xref href="GUID-E6C3B0F0-43A7-3656-946B-5CFE97DCFC80.dita"><apiname>DisplayDialog()</apiname></xref> function. </p> </li>

</ol> <p>The Dialog Creator plug-in creates a dialog prompt in cases where

no previous decision is found in the decision database. </p> <p><b> Preparing

the dialog</b> </p> <p>The parameters to <codeph>PrepareDialog()</codeph> are

mostly <codeph>const</codeph> pointers and references to the data that has

already been generated by the UPS or policy evaluator. </p> <p>The following

<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

<thead>

<row>

<entry>Parameter</entry>

<entry>Description</entry>

</row>

</thead>

<tbody>

<row>

<entry><p> <codeph>aRequest</codeph>  </p> </entry>

<entry><p>Data that the system server provides to the UPS, including the ClientSid,

ServerSid and ServiceId. </p> </entry>

</row>

<row>

<entry><p> <codeph>aPolicy</codeph>  </p> </entry>

<entry><p>Details of the policy for the service. </p> </entry>

</row>

<row>

<entry><p> <codeph>aFingerprints</codeph>  </p> </entry>

<entry><p>A pointer to the fingerprints array generated by the policy evaluator.

(If the user selects "Always" or “Never”, the dialog creator returns a pointer

to an existing fingerprint object instead of re-generating the fingerprint.) </p> </entry>

</row>

<row>

<entry><p> <codeph>aClientEntity</codeph>  </p> </entry>

<entry><p>Details of client entity (will be null if the client process is

not an execution host or the policy evaluator does not support client entities). </p> </entry>

</row>

<row>

<entry><p> <codeph>aEvalPrivateData</codeph>  </p> </entry>

<entry><p>Opaque data, which can be any other information for use in the fingerprint

or to be displayed in the dialog. </p> </entry>

</row>

<row>

<entry><p> <codeph>aStatus</codeph>  </p> </entry>

<entry><p>The request status used to contain completion information for the

function. </p> </entry>

</row>

</tbody>

</tgroup>

to the system server except those defined in the UPS policy file. If the dialog

creator returns an option that was not specified in the policy, the request

is rejected and <codeph>EUpsDecNo</codeph> is returned. </p><p>Your implementation

can assume that the pointers remain valid until after <codeph>DisplayDialog()</codeph> has

been called. </p><p>The <codeph>PrepareDialog()</codeph> function sets values. </p><p>The<codeph> DoPrepareDialogL()</codeph> function

prepares the data for the prompt. The DoPrepareDialogL() function is called

through a switch statement, which can be seen in the full code sample at the

end of this. </p> <p><b>Displaying the dialog </b> </p> <p>The <codeph>DisplayDialog()</codeph> function

displays the dialog created by <codeph>PrepareDialog()</codeph>. On completion,

it sets the option selected by the user and the fingerprint value if “Always”

or “Never” was selected. Usually, dialogs are displayed using the notifier

framework, but device creators are free to use other mechanisms. </p> <p>On

completion <codeph>iOptionSelected</codeph> must be set to the option selected

by the user: Yes, No, Session, Always or Never. </p> <ul>

<li id="GUID-C657A459-6ED4-59EF-9A8A-C9FE41AF2DD0"><p>If the user selects

“Always” or “Never”, <codeph>iFingerprint</codeph> must be set to point to

the fingerprint to use for the new decision record. Usually, this would just

point to one of the fingerprints passed to <codeph>PrepareDialog()</codeph>,

but generating a new fingerprint is also permitted. </p> </li>

<li id="GUID-0E2690AB-B44B-5C8B-9365-E09BC3031398"><p>If the decision record

already exists and <codeph>DisplayDialog()</codeph> modifies the value of <codeph>aEvaluatorInfo</codeph>,

the record is updated with the new value. </p> </li>

</ul> <p>In the example at the end of this section, the <codeph>DisplayDialog()</codeph> function

sets values. The <codeph>DoDisplayDialogL()</codeph> function calls the notifier

framework to display the dialogs. The <codeph>DoDisplayDialogL()</codeph> function

is called through a <codeph>switch</codeph> statement, which can be seen in

the full code sample at the end of this section: </p> </section>

<section><title>Example</title> <p>The following code shows an example of

static const TUint KRefDialogCreatorImplementationId = 0x10283694;

static const TUint KRefNotifierImplementationId = 0x1028369B;

CDialogCreator* CRefDialogCreator::CreateDialogCreatorL()

/**

Factory method that instantiates a new dialog creator EComplug-in.

@return A pointer to the new reference dialog creator object.

*/

    {

    CRefDialogCreator* self = new (ELeave)CRefDialogCreator();

    CleanupStack::PushL(self);

    CleanupStack::Pop(self);

    return self;

    }

static const TImplementationProxy ImplementationTable[] = 

    {

    IMPLEMENTATION_PROXY_ENTRY(KRefDialogCreatorImplementationId, CRefDialogCreator::CreateDialogCreatorL)

    };

EXPORT_C const TImplementationProxy* ImplementationGroupProxy(TInt& aTableCount)

/**

Standard EComfactory

*/

    {

    aTableCount = sizeof(ImplementationTable) / sizeof(TImplementationProxy);

    return ImplementationTable;

    }    

CRefDialogCreator::CRefDialogCreator() 

/**

Constructor

*/

    : CDialogCreator(), iPromptResult(), iPromptResultPckg(iPromptResult), iState(EIdle)

    {

    CActiveScheduler::Add(this);    

    }

CRefDialogCreator::~CRefDialogCreator()

/**

Destructor

*/

    {

    Deque();

    delete iPromptData;

    iPromptDataDes.Close();

    iNotifier.Close();

    }

void CRefDialogCreator::ConstructL()

/**

Second phase constructor

*/

    {

    User::LeaveIfError(iNotifier.Connect());

    }

void CRefDialogCreator::DoCancel()

    {

    if (iState == EProcessResult)

        {

        iNotifier.CancelNotifier(TUid::Uid(KRefNotifierImplementationId));

        }

    if (iClientStatus)

        {

        User::RequestComplete(iClientStatus, KErrCancel);

        }

    }

TInt CRefDialogCreator::RunError(TInt aError)

    {

    if (iClientStatus)

        {

        User::RequestComplete(iClientStatus, aError);

        }

    return KErrNone;

    }

void CRefDialogCreator::RunL()

    {

    User::LeaveIfError(iStatus.Int());

    switch (iState)

        {

        case EPrepareDialog:

            DoPrepareDialogL();

            break;

        case EDisplayDialog:

            DoDisplayDialogL();

            break;

        case EProcessResult:

            DoProcessResultL();

            break;

        default:

            ASSERT(EFalse);            

        }

    }

void CRefDialogCreator::DoPrepareDialogL()

    {

    iPromptData = CPromptData::NewL();

    // Only one state at the moment but more should be

    // added for long running operators e.g. querying the SIS registry

    // or resolving the client entity.

    // Get the vendor name for the client process

    // Server / Service localized names generated in notifier plug-in. 

    // Different dialog text is displayed depending on whether the client application

    // is signed.

    // N.B. Protected SID is assumed to be signed or included at ROM build.

    // Use the options specified by the policy

    // Add the descriptions of the fingerprints. This could be used

    // to allow the user to grant access to all destinations 

    // or a single destination.

    for (TInt i = 0; i < count; ++i)

        {

        CleanupStack::Pop(description);

        }

    User::RequestComplete(iClientStatus, KErrNone);

    // DisplayDialog is invoked by the UPS, this just verifies 

    // that PrepareDialog was called first.

    iState = EDisplayDialog;

    }

void CRefDialogCreator::DoDisplayDialogL()

/**

Uses the notifier framework to display the dialog.

*/

    {

    // Externalize the prompt data to a descriptor

    RNullWriteStream ns;

    ns << *iPromptData;

    ns.CommitL();

    iPromptDataDes.CreateL(ns.BytesWritten());

    RDesWriteStream ws;    

    ws.Open(iPromptDataDes);

    ws << *iPromptData;

    ws.CommitL();    

    iNotifier.StartNotifierAndGetResponse(iStatus, TUid::Uid(KRefNotifierImplementationId),

        iPromptDataDes, iPromptResultPckg);

    SetActive();

    iState = EProcessResult;

    }

void CRefDialogCreator::DoProcessResultL()

/**

Processes the result returned by the notifier.

*/

    {

    if (iPromptResult.iSelected == CPolicy::EAlways ||

        iPromptResult.iSelected == CPolicy::ENever)

        {

        // The Always or Never option was selected so return the fingerprint 

        // for the new decision record.

        // 

        // In this implementation a copy of the original fingerprint is returned. However,

        // it is permitted to return a different fingerprint e.g. a modifier description.        

            {

            *iFingerprint = (*iFingerprints)[iPromptResult.iDestination];

            }

        else

            {

            ASSERT(EFalse);    // should never happen, unless the notifier has errors.

            }

        }            

    *iOptionSelected =    iPromptResult.iSelected;

    iState = EIdle;

    User::RequestComplete(iClientStatus, KErrNone);        

    }

void CRefDialogCreator::ResolveVendorNameL(const TVendorId& aVid)

/**

Looks up the localized vendor name for the client process and writes

Typically, this would be resolved from the SIS registry or a lookup table.

@param aVid    The vendor id of the client process.

*/

    {

        {

        // already obtained vendor name from SIS registry

        return;

        }

    if (aVid.iId == 0x70000001)

        {

        _LIT(KSymbian, "Symbian Foundation");

        }

    else 

        {

        _LIT(KUnknown, "Unknown vendor");

        }

    }

void CRefDialogCreator::ResolveClientNameL(const TSecureId& aSid)

/**

Generates a human readable name for the client process. In order of 

preference the following data is returned

- The AppArc caption name.

- The localized package name that owns this SID.

- A value from a lookup table.

- The filename for the client process executable.

@param aSid    The secure id of the client process.

*/

    {

    TBool found = EFalse;

    // Although the client name from AppArc takes precedance the SIS

    // registry is always invoked in order to retrieve the vendor name

    found |= ResolveClientNameFromSisRegistryL(aSid);

    found |= ResolveClientNameFromAppArcL(aSid);

    // A lookup that maps secure-ids to application names could

    // be used here.

    // Fall back to the filename of the client process

    // The original thread may have exited so the process handle is used instead.

    // because the client-side object e.g. RSocket may be shared between threads.

    // If the process has exited then it's o.k. to leave.

    if (! found)

        {            

        RProcess clientProcess;

        CleanupClosePushL(clientProcess);

        CleanupStack::PopAndDestroy(&clientProcess); 

        }

    }

TBool CRefDialogCreator::ResolveClientNameFromAppArcL(const TSecureId& aSid)

/**

Gets the caption name for the application from AppArc (if available).

@param    aSid    The secure id of the client process.

@return            ETrue if a match was found in apparc; otherwise, EFalse is returned.

*/

    {

    TBool found(EFalse);

    RApaLsSession apa;

    CleanupClosePushL(apa);    

    TInt err = apa.Connect();

    if (err == KErrNone)

        {        

        TApaAppInfo* info = new(ELeave) TApaAppInfo();

        CleanupStack::PushL(info);

        err = apa.GetAppInfo(*info, TUid::Uid(aSid));

        if (err == KErrNone)

            {

            found = ETrue;

            }

        else if (err != KErrNotFound)

            {

            User::Leave(err);

            }    

        CleanupStack::PopAndDestroy(info); 

        }

    else if (err != KErrNotFound)

        {

        // If the connection to apparc failed with KErrNotFound

        // then the error is ignored becase we assume the dialog

        // creator was invoked from text-shell

        User::Leave(err);

        }

    CleanupStack::PopAndDestroy(&apa);

    return found;

    }

TBool CRefDialogCreator::ResolveClientNameFromSisRegistryL(const TSecureId& aSid)

/**

Retrieves the client and vendor information from the SIS registry.

@param aSid        The secure-id of the client application to lookup in the registry.

@return            ETrue, if the lookup was successful; otherwise, EFalse is returned.

*/

    {

    TBool found(EFalse);

    Swi::RSisRegistrySession r;

    User::LeaveIfError(r.Connect());

    CleanupClosePushL(r);

    Swi::CSisRegistryPackage* p(0);

    TRAPD(err, p = r.SidToPackageL(TUid::Uid(aSid.iId)));

    if (err == KErrNone)

        {

        found = ETrue;

        delete p;

        }

    CleanupStack::PopAndDestroy(&r);

    return found;

    }

// From CDialogCreator

void CRefDialogCreator::PrepareDialog(

    const UserPromptService::CPromptRequest& aRequest, const CPolicy& aPolicy,            

    const TAny* aEvalPrivateData, TRequestStatus& aStatus)

    {

    aStatus = KRequestPending;

    iClientStatus = &aStatus;

    iRequest = &aRequest;

    iPolicy = &aPolicy;

    iFingerprints = &aFingerprints;

    iEvalPrivateData = aEvalPrivateData;

    (void) aClientEntity;

    // Kick off dialog creator state machine

    iState = EPrepareDialog;

    iStatus = KRequestPending;

    TRequestStatus* status = &iStatus;

    SetActive();

    User::RequestComplete(status, KErrNone);

    }

void CRefDialogCreator::DisplayDialog(CPolicy::TOptions& aOptions, const CFingerprint*& aFingerprint,

        TUint& aEvaluatorInfo, TRequestStatus& aStatus)

    {    

    aStatus = KRequestPending;

    iClientStatus = &aStatus;

    iOptionSelected = &aOptions;

    iFingerprint = &aFingerprint;

    aFingerprint = 0;

    iEvaluatorInfo = &aEvaluatorInfo;

    iClientStatus = &aStatus;

    // Start state machine

    ASSERT(iState == EDisplayDialog); // PrepareDialog should have been called first

    iStatus = KRequestPending;

    TRequestStatus* status = &iStatus;

    SetActive();

    User::RequestComplete(status, KErrNone);

    }

</codeblock> </section>