LogicApp

Logic Application Configuration

The N2SVCD Logic Application is an extensible, general-purpose application which runs Lua scripts to perform control logic. The scripts can be initiated by various inbound agents, via Lua Services.

Lua scripts running within LogicApp may perform additional actions by calling upon Lua Agents.

This page describes general information about configuring LogicApp. Please refer to the relevant Service or Agent documentation for examples and API specifications for each of the different use-cases.

A sample LogicApp configuration entry is as follows:

<?xml version="1.0" encoding="utf-8"?>
<n2svcd>
  ...
  <applications>
    ...
    <application name="Logic" module="LogicApp">
      <include>
        <lib>../apps/logic/lib</lib>
      </include>
      <parameters>
        <parameter name="trace_level" value="0"/>
        <parameter name="edr_enabled" value="1"/>
        <parameter name="edr_directory" value="/tmp/edr"/>
        <parameter name="default_lua_lib_path" value="../lua/lib/?.lua;../../n2sip/lua/lib/?.lua"/>
        <parameter name="default_smpp_app_name" value="SMPP-Client-Tester"/>
        <parameter name="default_rest_app_name" value="REST-CLIENT"/>
        <parameter name="default_outcall_app_name" value="IVR"/>
      </parameters>
      <config>
        <auto_ids>
          <auto_id key="call_id" length="10" charset="alphanum"/>
        </auto_ids>
        <services>
          <service module="IvrApp::IvrIncallLuaService" libs="../../n2sip/apps/ivr/lib" script_dir="../../n2sip/demo/logic/incall">
            <triggers>
              <trigger called_prefix="800" script_key="800_digit_menu"/>
              <trigger called_prefix="811" script_key="811_rest"/>
              <trigger called_prefix="822" script_key="822_smpp"/>
              <trigger called_prefix="900" script_key="900_mca"/>
            </triggers>
          </service>
          <service module="RestServerApp::RestLuaService" libs="../apps/rest_s/lib" script_dir="../../n2sip/demo/logic/rest"/>
        </services>
        <agents>
          <agent module="RestClientApp::RestLuaAgent" libs="../apps/rest_c/lib"/>
          <agent module="SMPPApp::SMPPLuaAgent" libs="../apps/smpp/lib"/>
          <agent module="IvrApp::IvrOutcallLuaAgent" libs="../../n2sip/apps/ivr/lib"/>
        </agents>
      </config>
    </application>
    ...
  </application>
  ...
</n2svcd>

Configuration Details

The application element attributes for a Logic Application instance may include the below.

For details of the various parameter types used, refer to Common Configuration.

Auto ID Configuration

Automatically generated IDs are a feature available to Lua scripts running within the service logic framework. Each automatic ID must be pre-configured here before it can be used by the service logic scripts.

An auto_id entry within the auto_ids element of the LogicApp configuration has the following attributes:

Each instance of the LogicApp will manage its own auto-incrementing sequences for autoinc IDs. This does mean that when performing load-sharing across multiple logic apps, there is a small but non-zero chance that auto-incrementing IDs will overlap.

Service Configuration

A Lua Service Library handles an inbound message from a Service Application and uses the contents of that message to:

1. Determine which Lua script to execute, and
2. Determine what arguments to supply to that executing Lua script.

When the Lua script completes, the Lua Service Library may send back a final response the originating application.

This section describes the common configuration for adding a Lua Service Library to the Logic Application. For more information on per-Service configuration, please refer to the individual documentation for each Service Library.

A service entry within the services element of the LogicApp configuration has the following attributes:

Many Lua Service Libraries also define additional configuration elements within the service element. For example, Service Libraries which read their Lua scripts from disk will typically define a script_dir attribute. Refer to the per-Service Library documentation for N2SVCD, N2SCP, or N2SIP for details.

Service Global Configuration

Each service may have one or more global definitions configured. Each global may be a simple value such as a string or integer, or may be a complex data structure.

Each global may be defined with:

Service Global Types

The string, integer, and boolean global types are converted directly to their base Lua equivalents. Note that N2SVCD common application Boolean types are used to determine a boolean value. For example, the following service global XML definition:

    <globals>
        <global name="GLOBAL_1" value="0"/>
        <global name="GLOBAL_2" value="0" type="integer"/>
        <global name="GLOBAL_3" value="0" type="boolean"/>
    </globals>

… is equivalent to the following Lua global variable definitions:

GLOBAL_1 = "0"
GLOBAL_2 = 0
GLOBAL_3 = false

For complex global definitions, a hash type is implied when the global has child nodes or when global attributes are present. Hash conversion places each attribute and child in an appropriately-named key. A hash type is also used automatically if an XML node has attributes. In such cases, the value of the node, if any, will be placed under the value key.

If an array is required, it must be indicated by setting the type to array.

As an example of complex global definitions, the following service global XML definition:

    <globals>
        <global name="GLOBAL_4" thing1="1">
            <thing2>
                <thing3 thing4="4"/>
                <thing4>4</thing4>
            </thing2>
        </global>
        <global name="GLOBAL_5" type="hash"/>
        <global name="GLOBAL_6" type="array">
            <item thing1="1" thing2="2"/>
            <item thing1="3" thing2="4">5</item>
            <item>
                <thing1a type="boolean">true</thing1a>
                <thing1b type="boolean" value="true"/>
                <thing1c>true</thing1c>
                <thing1d value="true"/>
                <thing1e type="boolean"/>
                <thing2a type="integer">1</thing2a>
                <thing2b type="integer" value="1"/>
                <thing2c>1</thing2c>
                <thing2d value="1"/>
                <thing2e type="integer"/>
                <thing3a type="string">foo</thing3a>
                <thing3b type="string" value="foo"/>
                <thing3c>foo</thing3c>
                <thing3d value="foo"/>
                <thing3e type="string"/>
            </item>
        </global>
        <global name="GLOBAL_7" type="array"/>
        <global name="GLOBAL_8" thing1="1"/>
    </globals>

… is equivalent to the following Lua global variable definitions:

GLOBAL_4 = {
    thing1 = '1',
    thing2 = {
        thing3 = {
            thing4 = '4'
        },
        thing4 = '4'
    }
}
GLOBAL_5 = {}
GLOBAL_6 = {
    {
        thing1 = '1',
        thing2 = '2'
    },
    {
        thing1 = '3',
        thing2 = '4',
        value = '5'
    },
    {
        thing1a = true,
        thing1b = true,
        thing1c = 'true',
        thing1d = 'true',
        thing1e = false,
        thing2a = 1,
        thing2b = 1,
        thing2c = '1',
        thing2d = '1',
        thing2e = 0,
        thing3a = 'foo',
        thing3b = 'foo',
        thing3c = 'foo',
        thing3d = 'foo',
        thing3e = ''
    }
}
GLOBAL_7 = {}
GLOBAL_8 = {
    thing1 = '1'
}

Note that value is ignored for complex globals.

Service Global Value Types

For any simple global value or complex leaf value, the following value formats can be used:

• ${xxx} to set to the value of the environment variable $xxx.
• xxx to set to the value of the STDOUT output of the shell command xxx.
• If a type is given, set accordingly.
• Otherwise set as string.

If no value is present, the following defaults apply:

• string –> ''
• boolean –> false
• integer –> 0

Node attributes are always treated as strings and cannot be cast using type.

Agent Configuration

A Lua Agent is used to send messages to an AgentApp, typically for the purpose of communicating with external agents. The Lua script execution will suspend while the agent waits for its response.

This section describes the common configuration for adding a Lua Agent to the Logic Application. For more information on per-Agent configuration, please refer to the individual documentation for each Agent Library.

An agent entry within the agents element of the LogicApp configuration has the following attributes:

A Lua Agent typically also requires the configuration of a default_<action>_app_name entry specifying the name of the AgentApp which will receive the messages sent by the Lua Agent. Refer to the per-Agent documentation for details.

Message Handling

In addition to the common Application management messages, the LogicApp uses the following messages:

• DB Messages (DB-REQUEST outbound).

Agent libraries are provided in this package which implement the following messgaes:

• DIAMETER-C Messages (DIAMETER-C-REQUEST outbound).
• REST-C Messages (REST-C-REQUEST outbound).
• SMPP-C Messages (SMPP-C-REQUEST outbound).
• SOAP-C Messages (SOAP-C-REQUEST outbound).
• FOX-C Messages (FOX-C-REQUEST outbound).

Service libraries are provided in this package which support the following messages:

• DIAMETER-C Messages (DIAMETER-C-REQUEST outbound).
• REST-S Messages (REST-S-REQUEST inbound).
• SMPP-S Messages (SMPP-S-REQUEST inbound).
• SOAP-S Messages (SOAP-S-REQUEST inbound).

Also, the ProcessUSSDLuaService library uses these messages for MAP USSD processing:

• TCAP Messages (TCAP-BEGIN inbound).