A Sample Message Filter Script

The following annotated MSPL script filters incoming SIP responses and attempts to select the best endpoint for each message based on the endpoint ID (EPID).

<?xml version="1.0">
<lc:applicationManifest
 lc:appUri="https://www.contoso.com/DefaultRoutingScript"
 xmlns:lc="https://schemas.microsoft.com/lcs/2006/05">
<lc:requestFilter methodNames="INVITE,MESSAGE,INFO,REFER,ACK,BYE,OTHER"
                        strictRoute="false"
                        registrarGenerated="true"
                        domainSupported="true"/ >
<lc:responseFilter reasonCodes="NONE" />
<lc:proxyByDefault action="true" />
<lc:scriptOnly />
<lc:splScript><![CDATA[
    //
    // This script handles default routing of requests to Lync Server.  It
    // looks up all the registered endpoints for the To: user@host and tries
    // to pick the best endpoint to route to based on:
    //  EPID
    //
    // Endpoints with no presence or an availability less than 100, or
    // no routing information (for example, set presence without
    // register) are not considered.
    //

    Log( "Debugr", 1, "we have a request - ", sipRequest.Method );

    //
    // Build the user@host from the To: header.
    //
    toUri = GetUri( sipRequest.To );
    toUserAtHost = Concatenate( GetUserName( toUri ), "@", GetHostName( toUri ) );

    //
    // Determine whether this request is already asking for a specific EPID
    // via a parameter in the To: header.
    //
    requestEPID = GetParameterValue( sipRequest.To, "EPID" );

    //
    // Now loop over all the endpoints for the To: user@host.
    //
    bestEPID = "";
    bestAgeOfPresence = 0x7FFFFFFF;
    bestAvailability = 0;
    bestActivity = 0;
    bestContactInfo = "";
    Log( "Debugr", 1, "EPID - ", requestEPID );
    Log( "Debugr", 1, "toUserAtHost - ", toUserAtHost );
    foreach (dbEndpoint in QueryEndpoints( toUserAtHost, true )) {
        Log( "Debugr", 1, "    endpoint.EPID - ", dbEndpoint.EPID );
        Log( "Debugr", 1, "    endpoint.ContactInfo - ", dbEndpoint.ContactInfo );

        //
        // First, determine whether this endpoint supports the method in the request.
        //
        if (!SupportsMethod( sipRequest.Method, dbEndpoint.StandardMethods, dbEndpoint.ExtraMethods )) {
            //
            // Skip this endpoint because it cannot handle the method on this request.
            //
            Log( "Debugr", 1, "        * skipped because of method" );
            continue;
            }

        if (requestEPID != "") {
            if (requestEPID == dbEndpoint.EPID) {
                //
                // The request is already targeted at a specific EPID that can handle the method,
                // so use this endpoint.
                //
                Log( "Debugr", 1, "        * matched EPID" );
                bestContactInfo = dbEndpoint.ContactInfo;
                break;
            }
            else {
                //
                // The request is targeted at a specific EPID, but does not match this endpoint.
                // Skip this endpoint.
                //
                Log( "Debugr", 1, "        * skipped because of EPID" );
                continue;
            }
        }


        bestEPID = dbEndpoint.EPID;
        bestContactInfo = dbEndpoint.ContactInfo;
        Log( "Debugr", 1, "        *** new best contact" );
        }


    //
    // See if an endpoint to proxy to was found.
    //
    if (bestContactInfo == "") {
        /* Uncomment this block of code and the two assignments to sawAtLeastOneEndpoint
           above if you want to run a UAC application before this one and have this code
           route your messages to the correct home server.
        if (!sawAtLeastOneEndpoint) {
            homeServer = QueryHomeServer( toUserAtHost );
            if (!EqualString( homeServer, FQDN, true )) {
                Log( "Debugr", 1, toUserAtHost, " is homed on ", homeServer );
                newRequestUri = Concatenate( sipRequest.RequestUri, ";maddr=", homeServer );
                Log( "Debugr", 1, "Request is being routed to ", newRequestUri );
                AddHeader( "MS-LBVIA", FQDN );
                ProxyRequest( newRequestUri );
                return;
            }
        }
        */
        Log( "Debugr", 1, "Responding 480 - temporarily unavailable as no suitable endpoint found" );
        Respond( 480, "Temporarily Unavailable" );
    }
    else {
        if (requestEPID == "") {
            Log( "Debugr", 1, "Adding missing EPID '", bestEPID, "' to To header" );
            SetParameterValue( "To", "epid", bestEPID );
            }

        Log( "Debugr", 1, "Proxying request to - ", bestContactInfo );
        ProxyRequest( bestContactInfo );
        }

    return;
]]></lc:splScript>
</lc:applicationManifest>