App Config (TCP/UDP)

Overview

Serveral Application types implement UDP or TCP/SCTP connectivity based on the TcpApp base class. In addition to the common Application configuration parameters and their application-specific attributes, all of these Applications typically require UDP/TCP/SCTP configuration as indicated here.

<?xml version="1.0" encoding="utf-8"?>
<n2svcd>
  ...
  <applications>
    ...
    <application name="(name)" module="(module)">
      <include><lib>/path/to/library</lib></include>
      <parameters>
        <!-- application-specific parameters -->
        ...
        <!-- TCP/UDP application parameters (server example) -->
        <parameter name="listen_queue" value="20"/>
        <parameter name="local_hosts" value="192.168.10.10"/>
        <parameter name="local_port" value="8118"/>
        <parameter name="local_timeout" value="5"/>
        ...
        <!-- TCP/UDP application parameters (client example, identical) -->
        <parameter name="num_client_connections" value="5"/>
        <parameter name="local_hosts" value="192.168.10.10"/>
        <parameter name="remote_hosts" value="192.168.10.44"/>
        <parameter name="remote_port" value="8080"/>
        <parameter name="reconnect_interval" value="60"/>
        <parameter name="backlog_timeout" value="2"/>
        <parameter name="server_timeout" value="5"/>
        ...
        <!-- TCP application parameters (client example, disparate) -->
        <parameter name="local_hosts" value="192.168.10.10"/>
        <parameter name="remote_hosts" value="prod-prim.telco.com"/>
        <parameter name="reconnect_interval" value="60"/>
        <parameter name="backlog_timeout" value="2"/>
        <parameter name="server_timeout" value="5"/>
        ...
        <!-- SSL configuration for a simple SSL-encrypted server -->
        <parameter name="ssl" value="yes"/>
        <parameter name="ssl.SSL_cert_file" value="../etc/ssl/localhost.crt"/>
        <parameter name="ssl.SSL_key_file" value="../etc/ssl/localhost.key"/>
        ...
        <!-- SSL configuration for a simple SSL-encrypted client using self-generated CA -->
        <parameter name="ssl" value="yes"/>
        <parameter name="ssl.SSL_ca_file" value="../etc/ssl/localhost.crt"/>
      </parameters>
      <config>
        <client_connections>
          <client_connection remote_port="8080"/>
          <client_connection remote_port="8081"/>
          <client_connection remote_port="8082"/>
          <client_connection remote_port="8080"
            remote_hosts="prod-sec.telco.com" local_hosts="192.168.11.10" priority="2"/>
        </client_connections>
      </config>     
    </application>
    ...
  </application>
  ...
</n2svcd>

The following applications are UDP-only. They bind to a local UDP port and use that to send and receive messages via UDP datagrams.

• DnsClientApp
• DnsServerApp
• RadiusApp

The following applications are TCP/SCTP server-mode only. They accept inbound socket requests.

• RestServerApp
• SoapServerApp

The following applications are TCP/SCTP client-mode only. They perform outbound socket connects.

• RestClientApp
• SoapClientApp
• FoxApp
• MmlClientApp

The following applications are TCP/SCTP and can support either client-mode or server-mode (but not mixed).

Applications which can operate in either mode will use the socket_mode parameter to specify if this configuration is for either the TCP/SCTP server or TCP/SCTP client mode. They may not use both at once.

• DiameterApp
• SMPPApp

Note that the terms “client” and “server” in this context apply purely to the TCP/SCTP establishment mode at the socket level, i.e. a “client” will perform a socket “connect” and a “server” will perform a socket “listen”/“accept”.

This does not relate to the mechanism for sending the high-level messaging. For example, a DiameterApp may act as a “client” at the socket level, but then may act as a “server” in the sense that it accepts and processes inbound Diameter Requests and returns Diameter response.

Configuration Details

The application element attributes for all TCP Application instances are as below. For details of the various parameter types used, refer to Common Configuration.

TCP Client Connection

In the simplest case, a TCP Client application will create a single client connection, or will create multiple identical client connections. In that case the parameters mechanism will suffice.

However, there are cases where an TCP Client application wishes to connect to disparate remote hosts and/or ports. In this case the config.client_connections element must be configured to define two or more client_connection elements.

A client_connection entry within the config.client_connections element of a TCP Client application has the following attributes:

Note that the num_client_connections parameter is incompatible with config.client_connections.

Some applications (e.g. FoxApp) may also have the option to load TCP client connection information from other sources, e.g. from a database.