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<chapter id="user">
    <title>The Sip Express Application Server User's Guide</title>

    <section>
      <title>Application Servers</title>

      <section>
        <title>Sip Express Application Server module overview</title>

        <para><acronym>SEAS</acronym> module enables &kamailio; to transfer the
        execution logic control of a sip message to a given external entity,
        called the Application Server. When the &kamailio; script is being
        executed on an incoming SIP message, invocation of the as_relay_t()
        function makes this module send the message along with some
        transaction information to the specified Application Server. The
        Application Server then executes some call-control logic code, and
        tells &kamailio; to take some actions, ie. forward the message
        downstream, or respond to the message with a SIP reply, etc.</para>

        <para>The module acts implements a network protocol acting as the
        interface between &kamailio; internal API and the external Application
        Server entity.</para>

        <para>There's only one relevant function, as_relay_t, exported by this
        module. This function receives as a parameter the name of the
        application server to which the message should be relayed. Every
        message relayed to an Application Server is automatically associated
        to a SIP transaction (a transaction is created for it). Just after the
        message is relayed to the Application Server, the script stops its
        execution on the message, because the control of message-processing is
        now in the Application Server.</para>

        <para>In the context of SEAS module, relaying a message to an App
        Server, is _not_ done in SIP protocol, but in a special protocol by
        means of which the SEAS module and the Application Server communicate
        efficiently and seamlessly. This protocol is specially designed so
        that a message doesn't need to be parsed again once it arrives at the
        Application Server. This protocol carries information regarding the
        internal structure of the SIP message (to avoid reparsing) and also
        information about the associated transaction (recall that invoking
        as_relay_t indirectly calls t_newtran). This way, all the
        SIP-Transaction machinery, and the SIP-Message parsing, is handled at
        the &kamailio; core, while the execution of the Application Logic is
        carried in the Application Server.</para>

        <para>The SEAS module and protocol provide a means by which an
        external entity can utilize &kamailio; as a transaction-stateful
        SIP-stack to act on behalf of it. This means that this external entity
        (which we call the Application Server) is notified whenever a
        SIP-Request enters &kamailio;, and this external entity can then order
        &kamailio; to execute some actions, either replying the request, or
        generating new UAC transactions.</para>

        <para>This version of SEAS works with VozTelecom's WeSIP Application
        Server. This Application Server is a SipServlet JAVA Container.</para>
      </section>

      <section id="ApplicationServer">
        <title>Application Servers</title>

        <para>When &kamailio; starts and SEAS module is loaded, a new process is
        spawn which listens on a server-socket (IP and port are specified as a
        parameter in the config script). From then on, the Application Servers
        can connect to that socket so that &kamailio; can relay messages to them.
        When an Application Server connects to the socket, it sends its name
        through the socket, so every App Server is identified with a name.
        Within the &kamailio; script, invoking as_relay_t() receives a string as
        a parameter, which specifies the name of an application server to
        which the message has to be sent. If that concrete application server
        hasn't already connected to the module, the function returns a
        negative value, otherwise (the Application Server is connected), the
        message is relayed to it.</para>
      </section>

      <section>
        <title>Dependencies</title>

        <section>
          <title>&kamailio; Modules</title>

          <para>SEAS module relies on the Transaction Module (TM module) for
          operation.</para>
        </section>

        <section>
          <title>External Applications</title>

          <para>Using the SEAS module requires to have an Application Server
          running and connected to a particular instance of &kamailio;.</para>

          <para>At the moment, the only Application Server that works with
          SEAS is WeSIP Application Server, which can be downloaded from
          www.wesip.eu, and used freely for non-commercial purposes.</para>
        </section>
      </section>

      <section>
        <title>Parameters</title>

        <section>
          <title><varname>listen_sockets</varname> (string)</title>

          <para>The listen_sockets string tells SEAS where to listen for
          incoming connections of Application Servers. It has the form:
          "ip:port". SEAS will open two server-sockets on that IP, at the
          specified port, and another at port+1. Application Servers must be
          configured to connect to that port.</para>

          <para>In case this parameter is omitted, SEAS listens on the default
          IP which &kamailio; is using, and opens the ports 5080 and 5081 to
          listen for Application Servers.</para>

          <example>
            <title>Set <varname>listen_sockets</varname> parameter</title>

            <programlisting format="linespecific">
...
modparam("seas", "listen_sockets","127.0.0.1:5080")
...
</programlisting>
          </example>
        </section>
      </section>

      <section>
        <title>Functions</title>

        <section>
          <title><function moreinfo="none">as_relay_t(String
          name)</function></title>

          <para>Creates a new transaction (if it isn't already created) and
          sends the SIP Request and transaction information to the Application
          Server specified in the parameter. Every Application Server
          connected to &kamailio; through the SEAS module, must be identified
          with a different name.</para>

          <para>This function can be used within REQUEST_ROUTE.</para>

          <example>
            <title><function>as_relay_t</function> usage</title>

            <programlisting format="linespecific">
...
if (!as_relay_t("app_server_1")) {
log("Error sending to app server");
t_reply("500","App Server not connected");
}
...
</programlisting>
          </example>

          <section>
            <title>Return value</title>

            <para>In case the Application Server is connected to &kamailio;, the
            function does _not_ return, the Application Server is now in
            charge of processing the request, and it may then reply to the
            request, initiate new transactions, or whatever the application
            being executed wants.</para>

            <para>In case the Application Server identified by the string
            parameter passed to as_relay_t() is not connected to &kamailio;, the
            function returns 0, so that the script can continue processing the
            request.</para>
          </section>
        </section>
      </section>
    </section>

    <section>
      <title>WeSIP Application Server</title>

      <para>At the moment, the only Application Server known to work with SEAS
      is WeSIP. You can download a copy from www.wesip.eu.</para>

      <para>WeSIP is a converged Sip/Http Servlet Container.</para>

      <section>
        <title>The Servlet programming paradigm: Sip/Http Servlets</title>

        <para>Servlets are pieces of code that encapsulate the logic of an
        application. Servlets are deployed into an Application Server.
        Whenever a user requests service, the Application Server processes the
        request, and passes control to the servlet. The servlet then executes
        some logic, may it be a query to a database, the execution of a
        business process, the creation of customized content for the user, or
        whatever the service programmer could imagine. When the servlet
        finishes the execution, it creates a response and gives it back to the
        Application Server, which is in charge of making it reach back to the
        user. The Application Server implements the network protocol, it takes
        care of everything needed for a proper communication between user and
        server, so the servlet doesn&#8217;t have to care about these things. The
        servlet uses a set of resources from the Application Server, such as
        Session management, service routing or chaining, and request/response
        header composition.</para>

        <para>In HttpServlets, a service programmer has to implement a method
        in a JAVA class, which could be called doGet() or doPost(). Whenever
        an HTTP request arrived at the server, one of these functions was
        called with the request as a parameter, so the logic of the
        application was executed over that particular request.</para>

        <para>HttpServlet has been extensively used over the past years, in
        all kinds of business and web services.</para>

        <para>This is how a typical HttpServlet looks like:</para>

        <para><example>
            <title>Typical example of an HttpServlet</title>

            <para><programlisting>public final class Hello extends HttpServlet {
protected void doGet(HttpServletRequest request,HttpServletResponse response)
      throws IOException, ServletException
    {
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
writer.println("&lt;html&gt;");
writer.println("&lt;head&gt;");
writer.println("&lt;title&gt;Sample Application Servlet&lt;/title&gt;");
writer.println("&lt;/head&gt;");
writer.println("&lt;body bgcolor=white&gt;");
writer.println("&lt;table border=\"0\" width=\"100%\"&gt;");
Enumeration names = request.getHeaderNames();
while (names.hasMoreElements()) {
    String name = (String) names.nextElement();
    writer.println("&lt;tr&gt;");
    writer.println("&lt;th align=\"right\"&gt;"+name+":&lt;/th&gt;");
    writer.println("&lt;td&gt;"+request.getHeader(name)+"&lt;/td&gt;");
    writer.println("&lt;/tr&gt;");
}
writer.println("&lt;/table&gt;");
writer.println("&lt;/body&gt;");
writer.println("&lt;/html&gt;");
    }
}</programlisting></para>
          </example></para>

        <para>The successor of HttpServlet for SIP networks, is the SipServlet
        API. Making most of the success of HttpServlet, the SipServlet API
        follows the same programming paradigm, so that SIP application
        programmers can reuse their knowledge in the field.</para>

        <para>SipServlet API works the same way as HttpServlet: an Application
        Server implements a SIP Stack and executes all the complex protocol
        logic. It receives and pre-processes the requests from the network,
        and at the right moment, passes control to the servlet doXxx() method,
        where the programmer implemented the application logic. Depending on
        what kind of SIP Message it was, a method or another will be executed.
        For example, if an INVITE is received, the doInvite() method will be
        invoked in the servlet.</para>

        <para>The application can then access all the parts of the request and
        do its work. When the service has been executed, it passes control
        back to the Application Server with a response, so that it can be
        forwarded to the user, and the service be satisfied.</para>

        <para>Sip Servlets can be used to implement basic SIP network
        functionalities (such as Proxy or Registrar servers), but their true
        power emerges in the implementation of value-added services, which
        greatly surpasses the basic service functionality of plain SIP
        servers.</para>

        <para>Examples of value-added services, are Virtual PBX or IPCentrex,
        Attended call forwarding, Instant Messaging, etc.</para>

        <para>This is the appearance a typical SipServlet:</para>

        <para><example>
            <title>Typical Sip Servlet Example</title>

            <para><programlisting>public class ProxyServlet extends SipServlet {
    protected void doInvite(SipServletRequest req) throws
ServletException, IOException
    {
        if (req.isInitial()) {
            Proxy proxy = req.getProxy();
            proxy.setRecordRoute(false);
            proxy.setParallel(parallel);
            proxy.setSupervised(supervised);
            SipURI rrURI = proxy.getRecordRouteURI();
            rrURI.setParameter("foo", "bar");
            req.setContent("Method is INVITE", "text/plain");
            proxy.proxyTo(uris);
        } else {
            log("re-INVITE");
        }
    }
    protected void doAck(SipServletRequest req) throws
ServletException, IOException
    {
        log("doAck " + req.getRequestURI());
        if (req.isInitial()) {
            throw new ServletException("unexpectedly got initial ACK");</programlisting></para>
          </example>The servlet programming API is event-ridden: every time a
        request comes into the Application Server (may it be an Http or SIP
        one), the specific servlet is executed and the service provided within
        it.</para>

        <para>It is a very straightforward way of programming services, and
        the Servlet API provides very easy and powerful means to access
        information about the SIP-session or Http-session, about the request
        or response, about the state of the dialog, or whatever it is
        needed.</para>

        <para>The application programmer has a rich framework of resources
        that allow him to focus only on the service logic, without having to
        worry about the underlying protocol specifics (SIP or HTTP).</para>

          <figure>
            <title>SipServlet UML diagram</title>

            <mediaobject>
              <imageobject>
				  <imagedata fileref="./images/image024.png"/>
              </imageobject>
            </mediaobject>
		</figure>
		<para>The Servlet programming language is JAVA, which offers a
        wide spectrum of programming API&#8217;s dealing with all kinds of
        techniques, tools and resources, which also are available seamlessly
        from the Servlet context.</para>

        <para>This makes the SipServlet API very desirable for all kinds
        application developers.</para>

        <para>SipServlet allows a rapid SIP application development and
        deployment, and also provides a reliable and secure framework of
        service execution (the JAVA sandbox and the Application Server
        execution environment).</para>

        <section>
          <title>Converged Http/Sip Servlet Containers</title>

          <para>SipServlets achieve the most of it when they can be deployed
          along with HttpServlets, in the same Application Server (also known
          as Servlet Container). This environment truly realizes the power of
          converged voice/data networks: Http protocol represents one of the
          most powerful data transmission protocols used in modern networks
          (think of the SOAP web-services protocol), and SIP is the protocol
          of choice in most of the modern and future voice over IP (VoIP)
          networks for the signaling part. So an Application Server capable of
          combining and leveraging the power of these two APIs will be the
          most successful.</para>

          <para>Convergence of SIP and HTTP protocols into the same
          Application Server offers, amongst others, the following key
          advantages:</para>

          <para>-It doesn&#8217;t require to have 2 different servers (Http and Sip)
          so it relieves from maintenance problems, and eases user and
          configuration provisioning.</para>

          <para>-It offers great convenience to the application programmer to
          have all the classes related to the different protocols handled
          within the same code.</para>

          <para>-As it eases development of interactive and multimedia
          services, realizing the power of well-known web-services and
          intermixing them with new voice services.</para>

          <para>These are some simple, but suggestive examples of services
          that could be developed within a converged Http/Sip servlet:</para>

          <para>-IP Centrex: through the use of the Web-interface, users could
          have a layout of the office in a web page, and see what phones were
          ringing at a given moment, so they could pick-up a call ringing in
          another phone in their own desktop. Or they could forward a call to
          another party by clicking on the web page and selecting which of the
          office phones it had to be transferred to.</para>

          <para>-Voicemail: users could upload an audio file to the server
          through a web-page, to be used as the automatic answering message,
          and then also download their voicemail through the web-page, or
          organize the messages and remove the old ones.</para>

          <para>-Instant Messaging: users could continue a voice call by
          starting or joining a new Instant Messaging session carried over a
          web-page.</para>

          <para>-Click-to-dial: users could initiate SIP sessions only by
          clicking a link on a web page, without the need of the Web-Browser
          being SIP-aware nor needing even a SIP phone: the server could
          handle all the logic so the user who clicked could receive a call
          from the server&#8217;s SIP network.</para>
        </section>
      </section>

      <section>
        <title>Configuring WeSIP to work with SEAS</title>

        <para>The WeSIP Application Server configuration file is based on the
        Apache Tomcat configuration system: It is an XML-formatted file, in
        which the different components of the server are specified.</para>

        <para>The default config file that comes with the WeSIP distribution
        package should be suitable for most of the deployment
        configurations.</para>

        <para/>

        <section>
          <title>Server</title>

          <para>The topmost element in the XML configuration file is the
          "server" which has 2 xml attributes, called "port" and "shutdown".
          The former specifies a port on which the WeSIP AS will listen for
          the shutdown command, and the latter is the magic word that will
          make the server shutdown.</para>

          <example>
            <title>Server</title>

            <para><programlisting>&lt;Server port="8005" shutdown="SHUTDOWN" &gt;</programlisting></para>
          </example>

          <para>if you send the magic word "SHUTDOWN" to the port 8005 of the
          localhost, the server will stop cleanly.</para>

          <para/>
        </section>

        <section>
          <title>Service</title>

          <para>Nested within the Server element, must be a "Service" element,
          with an attribute called "name" which specifies the name for the
          service. This attribute is not very relevant, you can call it
          whatever you like.</para>

          <example>
            <title>Service</title>

            <para>&lt;Service name="WeSIP-Standalone"&gt;</para>
          </example>

          <para>Within the Service element must be two or more elements: the
          connectors and the engines. A connector is the instance that will
          receive messages from the network. You can specify HTTP connectors
          and/or SIP connectors. Every connector needs an attribute called
          "className" which specifies which class will be responsible for
          receiving the messages from the network. For HTTP connectors, the
          classname must be "org.apache.catalina.connector.http.HttpConnector"
          and for SIP connectors
          "com.voztele.sipservlet.connector.SipConnector".</para>
        </section>

        <section>
          <title>Connector</title>

          <para>The SIP Connector uses 4 attributes:</para>

          <para><programlisting>className="com.voztele.sipservlet.connector.SipConnector"</programlisting></para>

          <para>specifies the classname of the connector.</para>

          <para><programlisting>minProcessors="5"</programlisting></para>

          <para>specifies the minimum number of SIPprocessor instances (and
          threads in the pool) to process incoming SIP messages. More
          processors should allow more load to be processed. This is the
          minimum number of instances, even if they are spare and not
          working.</para>

          <para><programlisting>maxProcessors="10"</programlisting></para>

          <para>specifies the maximum number of SIP processors used (a
          negative value specifies that there is no limit).</para>

          <para><programlisting>addresses="localhost:5060"</programlisting></para>

          <para>Specifies the SIP address and port in which the Application
          Server from which the Application Server will process the SIP
          messages. This address is where &kamailio; listens for the messages, so
          in fact, &kamailio; is listening on them, but &kamailio; passes the
          messages to WeSIP, so WeSIP must be aware of this IP/port.</para>

          <warning>
            <para>this attribute MUST match one of the listening points
            declared within &kamailio; in the "listen" parameters.</para>

            <para>For example in &kamailioconfig;:<programlisting>listen = tcp:localhost:5060
listen = udp:localhost:5060</programlisting></para>
          </warning>

          <para>Within the SIP Connector element there must be an
          ExtraProperties element, containing nested Property elements. Each
          property element specifies a parameter for the SIP Stack. Each
          property is specified by a key and a value. The most significant
          keys are:</para>

          <itemizedlist>
            <listitem>
              <para>com.voztele.javax.sip.SER_ADDRESS</para>

              <para>This specifies the IP and port in which the &kamailio; is
              listening for Application Servers to connect and register. This
              specifies the IP and port in which the &kamailio; is listening for
              Application Servers to connect and register.</para>

              <para><warning>
                  <para>This needs to match the
                  <varname>listen_sockets</varname> seas module parameter
                  within the &kamailio; configuration file. Ie.:</para>

                  <para><programlisting>modparam("seas", "listen_sockets","127.0.0.1:5080") </programlisting></para>
                </warning></para>
            </listitem>

            <listitem>
              <para>javax.sip.STACK_NAME</para>

              <para>Specifies the name identifying this instance of the
              Application Server.</para>

              <para><warning>
                  <para>This is the name you will set in the &kamailio;
                  configuration script when you invoke the WeSIP Application
                  Server, by calling the as_relay_t function. This is the name
                  you pass as the parameter of the function. If you have
                  different WeSIP instances all connecting to the same
                  &kamailio;, they must each one have a different STACK_NAME",
                  and within &kamailio; you can call each of them by invoking
                  as_relay_t() with a different name. Example:</para>

                  <para><programlisting>&lt;Property key="javax.sip.STACK_NAME" value="app_server_one" /&gt;</programlisting></para>
                </warning></para>
            </listitem>

            <listitem>
              <para>com.voztele.javax.sip.THREAD_POOL_SIZE (integer)</para>

              <para>Specifies the number of threads there must be in the pool
              to process incoming SIP messages. If unspecified, the default
              is "infinity".</para>
            </listitem>

            <listitem>
              <para>com.voztele.javax.sip.SPIRAL_HDR</para>

              <para>This property tells WeSIP and SEAS that every SipRequest
              and UAC transaction generated from WeSIP, must spiral through
              SER, and will be added a special Header called "X-WeSIP-SPIRAL:
              true" this will make all the outgoing messages pass again
              through the &kamailio; script, so that they can be accounted or
              whatever the configurator wants. For example, the configuration
              script could go:</para>

              <para><programlisting>route{
        if(is_present_hf("X-WeSIP-SPIRAL")){
 /* account, log, register, or whatever */
                t_relay();
        }else{
                as_relay_t("app_server_1");
        }
}</programlisting></para>
            </listitem>
          </itemizedlist>

          <para/>
        </section>

        <section>
          <title>Engine</title>

          <para>The Engine must also be nested within the Server element,
          along with the Connectors. It must have a "name" attribute with
          whatever name you feel like. It needs to have another attribute
          called "defaultHost" which will be the default host to which to pass
          the incoming request (in HTTP/1.0 the requests don&#8217;t have a Host
          header, so they will be passed to this default host, in SIP, this
          attribute doesn&#8217;t have a meaning.). In order to have this Engine
          handling also SIP messages, the "className" attribute of the Engine
          <emphasis>must be
          "com.voztele.sipservlet.core.ConvergedEngine".</emphasis></para>

          <para>Within the Engine, there can be one or more Hosts, each one
          specified within a "Host" element nested in the engine.</para>
        </section>

        <section>
          <title>Mapper</title>

          <para>A mapper is used to map an incoming request to one or another
          SIP or HTTP host. In case it is a SIP request, the mapping is done
          based on the sip.xml deployment descriptor rules. The classname of
          the SIP mapper MUST BE
          "com.voztele.sipservlet.core.EngineSipMapper". The "mapper" element
          must also have a "protocol" attribute, specifying which protocol
          this mapper handles. In<emphasis> case of the SIP mapper it must be
          "SIP/2.0". The HTTP mapper's classname must be
          "org.apache.catalina.core.StandardEngineMapper" and the protocol
          attribute "HTTP/1.1"</emphasis></para>
        </section>

        <section>
          <title>Realm</title>

          <para>The authentication in HTTP is performed in Apache-Tomcat
          through Realms. The memory realm is (textual copy from the
          Apache-Tomcat javadoc"): "Simple implementation of Realm that reads
          an XML file to configure the valid users, passwords, and
          roles."</para>

          <para>The classname must be
          "org.apache.catalina.realm.MemoryRealm"</para>

          <para>A "pathname" attribute can be specified to tell the Realm
          which file contains the usernames, passwords and roles. If not
          specified, it is "conf/wesip-users.xml"</para>
        </section>

        <section>
          <title>Host</title>

          <para>A Host represents a VirtualHost in HTTP/1.1 servers, so the
          requests will be dispatched to one or another virtual host depending
          on the Host: header. In SIP this doesn't make much sense, because
          there's no such Host: header, and virtual hosting is not done in
          this way. Every host must have a "name" attribute which specifies
          the name of the virtual host, it must also have a "nameSip"
          attribute which MUST MATCH the IP or hostname _and_ port" specified
          in &kamailio; listen parameters and in the Sip Connector the hostname
          and the port must be separated with an underscore. for example:
          nameSip="localhost_5060" or nameSip="192.168.1.1_5060" The next
          important attribute that must have the Host element is "appBase"
          which declares the directory where the WEB and SIP applications
          reside. It usually is a directory called apps in the directory from
          which the server runs. The attribute "unpackWARs" says the WeSIP
          Application Server to unpack the Web or Sip Application Archives
          (.war or .sar extensions) found inside the appBase directory. It
          should usually be set to "true". The "port" attribute specifies the
          port where this host is going to receive SIP messages . This only
          has to do with the SIP protocol, not with HTTP. It must be the same
          as the port specified in &kamailio; parameter "listen_sockets" (for the
          seas module). The "autoDeploy" attribute tells the host to monitor
          the "appBase" directory for new application archives (.sar or .war)
          so they can automatically be deployed. This parameter should be set
          to "true". The "className" used for the Host _must_be_
          "com.voztele.sipservlet.core.ConvergedHost"</para>
        </section>

        <section>
          <title>Mapper</title>

          <para>Hosts must also have a nested Mapper element, but when the
          mapper is inside a Host (and not in an Engine) the classnames must
          be "com.voztele.sipservlet.core.SipHostMapper" for the "SIP/2.0"
          protocol and "org.apache.catalina.core.HttpHostMapper" for the
          "HTTP/1.1" protocol. (2 mappers must be nested inside the
          Host).</para>
        </section>
      </section>

      <section>
        <title>Configuration Examples</title>

        <para>In general, you can configure WeSIP to work with your &kamailio; in
        two ways: have 2 &kamailio; instances, the first acting as
        Proxy/Registrar/Redirect and the second cooperating with WeSIP to act
        as the Application Server. This is the preferred deployment layout, as
        the first &kamailio; works as usual, and the requests that need special
        services are relayed to another &kamailio; which acts on behalf of the
        WeSIP AS. This configuration profile distributes load (call-routing
        logic in one instance, and Application Services in the other), and is
        also more fault-tolerant. On the other hand, you can have all your
        call-routing logic and Application Server on the same &kamailio;, having
        one script handle all the logic, and then invoking the App Server at
        any point.</para>

        <para/>

        <section>
          <title>&kamailioconfig; in standalone</title>

          <para><programlisting>debug=3            # debug level (cmd line: -dddddddddd)
fork=yes
log_stderror=no    # (cmd line: -E)
check_via=no    # (cmd. line: -v)
dns=no          # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
port=5060
children=4
loadmodule "/usr/local/lib/kamailio/modules/sl.so"
loadmodule "/usr/local/lib/kamailio/modules/tm.so"
loadmodule "/usr/local/lib/kamailio/modules/rr.so"
loadmodule "/usr/local/lib/kamailio/modules/maxfwd.so"
loadmodule "/usr/local/lib/kamailio/modules/usrloc.so"
loadmodule "/usr/local/lib/kamailio/modules/registrar.so"
loadmodule "/usr/local/lib/kamailio/modules/textops.so"
loadmodule "/usr/local/lib/kamailio/modules/seas.so"

modparam("usrloc", "db_mode",   0)
modparam("rr", "enable_full_lr", 1)
modparam("seas", "listen_sockets", "127.0.0.1:5080");

route{
       if (!mf_process_maxfwd_header("10")) {
               sl_send_reply("483","Too Many Hops");
               exit;
       };
       if (msg:len &gt;=  2048 ) {
               sl_send_reply("513", "Message too big");
               exit;
       };
       if (!method=="REGISTER")
               record_route();
       if (loose_route()) {
               append_hf("P-hint: rr-enforced\r\n");
               route(1);
       };
       if (uri==myself) {
               if (method=="REGISTER") {
                       save("location");
                       exit;
               };
               lookup("aliases");
               if (!uri==myself) {
                       append_hf("P-hint: outbound alias\r\n");
                       route(1);
               };
               if (!lookup("location")) {
                       sl_send_reply("404", "Not Found");
                       exit;
               };
               append_hf("P-hint: usrloc applied\r\n");
       };
       route(1);
}
route[1] {
                if(!as_relay_t("app_server_one")){
                       t_reply("500","Application Server error");
               }
}</programlisting></para>
        </section>

        <section>
          <title>&kamailioconfig; working as WeSIP front-end</title>

          <para><programlisting>debug=9            # debug level (cmd line: -dddddddddd)
fork=yes
log_stderror=yes    # (cmd line: -E)

check_via=no    # (cmd. line: -v)
dns=no          # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
port=5060
children=4

reply_to_via=1
listen = tcp:localhost:5060
listen = udp:localhost:5060

mpath="/home/elias/src/sipservlet/seas"

loadmodule "modules/tm/tm.so"
loadmodule "modules/seas/seas.so"

modparam("seas", "listen_sockets","127.0.0.1:5080")

route{
                if(!as_relay_t("app_server_1")){
                        t_reply("500","Application Server error");
                }

}</programlisting></para>
        </section>

        <section>
          <title>Server.xml</title>

          <para><programlisting>&lt;Server port="8005" shutdown="SHUTDOWN" debug="0"&gt;
  &lt;Service name="WeSIP-Standalone"&gt;
    &lt;Connector className="org.apache.catalina.connector.http.HttpConnector"
        port="8080" minProcessors="5" maxProcessors="75"
        enableLookups="true" address="localhost" acceptCount="10" debug="10" /&gt;
        &lt;Connector className="com.voztele.sipservlet.connector.SipConnector"
        minProcessors="5" maxProcessors="75"
        addresses="localhost:5060" &gt;
               &lt;ExtraProperties&gt;
                       &lt;Property key="com.voztele.javax.sip.SER_ADDRESS" value="127.0.0.1:5080" /&gt;
                       &lt;Property key="javax.sip.STACK_NAME" value="app_server_one" /&gt;
                       &lt;Property key="com.voztele.javax.sip.THREAD_POOL_SIZE" value="10" /&gt;
               &lt;/ExtraProperties&gt;
       &lt;/Connector&gt;
    &lt;Engine name="Standalone" defaultHost="localhost" debug="10"
       className="com.voztele.sipservlet.core.ConvergedEngine"&gt;

        &lt;Logger className="org.apache.catalina.logger.SystemOutLogger"
           timestamp="true"/&gt;
        &lt;Mapper className="org.apache.catalina.core.StandardEngineMapper" protocol="HTTP/1.1"/&gt;
        &lt;Mapper className="com.voztele.sipservlet.core.EngineSipMapper" protocol="SIP/2.0"/&gt;
        &lt;Realm  className="org.apache.catalina.realm.MemoryRealm" /&gt;
        &lt;Host name="localhost" nameSip="localhost_5060" debug="10" appBase="webapps" unpackWARs="true"
        port="5060" autoDeploy="true" className="com.voztele.sipservlet.core.ConvergedHost"&gt;
               &lt;Mapper className="com.voztele.sipservlet.core.SipHostMapper" protocol="SIP/2.0"/&gt;
               &lt;Mapper className="org.apache.catalina.core.HttpHostMapper" protocol="HTTP/1.1"/&gt;
     &lt;/Host&gt;
  &lt;/Engine&gt;
&lt;/Service&gt;
&lt;/Server&gt;</programlisting></para>
        </section>
      </section>
    </section>
  </chapter>
