# &adminguide;

## Overview

The matrix module can be used to arbitrary lookup operations over an array. One possible use-case is to define which routing tree should be used depending on the preferred carrier of the source number and the carrier id of the destination number.

The matrix cells are read from a database and can be reloaded using a FIFO command.

You do not have to define all matrix cells. The matrix can be sparse.

Currently, the implementation is designed for a small number of columns (they are stored in a linked list). This does not scale well and has to be replaced by more an efficient data data structure when needed.

## Dependencies

### &kamailio; Modules

The module depends on the following modules (in other words the listed modules must be loaded before this module):

- none

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- none

## Parameters

### `db_url` (string)

The URL for the database connection.

Default value is &defaultrodb;.

#### Set `db_url` parameter

    ...
    modparam("matrix", "db_url", "&defaultrodb;")
    ...

### `matrix_table` (string)

The name of the table containing the matrix data.

Default value is matrix.

#### Set `matrix_table` parameter

    ...
    modparam("matrix", "matrix_table", "matrix")
    ...

### `matrix_first_col` (string)

The name of the column containing the first row in the matrix.

Default value is first.

#### Set `matrix_first_col` parameter

    ...
    modparam("matrix", "matrix_first_col", "first")
    ...

### `matrix_second_col` (string)

The name of the column containing the second row in the matrix.

Default value is second.

#### Set `matrix_second_col` parameter

    ...
    modparam("matrix", "matrix_second_col", "second")
    ...

### `matrix_res_col` (string)

The name of the column containing the result ID to be used.

Default value is res.

#### Set `matrix_res_col` parameter

    ...
    modparam("matrix", "matrix_res_col", "res")
    ...

## Functions

### `matrix (string first, string second, string dstavp)`

Looks up the desired result ID in the matrix for the given column and value and saves the result in dstavp. Returns false if the cell is not defined or when an error occurred.

Pseudo-variables or AVPs can be used for first and second.

#### `matrix` usage

    ...
    if (!matrix("$avp(first)", "$avp(second)", "$avp(route_tree)"))
      $avp(route_tree) = $avp(frst); # default routing as defined for source number
    }
    cr_route("$avp(route_tree)", "$rd", "$rU", "$rU", "call_id");
    ...

## RPC Commands

### `matrix.reload`

Reloads the internal matrix representation from the database. This is necessary after entries in the database have been changed.

#### `matrix.reload` usage

    ...
    &kamctl; rpc matrix.reload
    ...

## Installation and Running

### Database setup

Before running &kamailio; with matrix, you have to set up the database table where the module will read the matrix data. For that, if the table was not created by the installation script or you choose to install everything by yourself you can use the matrix-create.sql SQL script in the database directories in the kamailio/scripts folder as template. Database, table, and column names can be set with module parameters so they can be changed. You can also find the complete database documentation on the project webpage, &kamailiodbdocs;.

#### Example database content - matrix table

    ...
    +---------+--------------+---------+
    |  first  |    second    |   res   |
    +---------+--------------+---------+
    |       1 |            9 |       2 |
    |       2 |           69 |       1 |
    |       2 |           13 |       3 |
    +---------+--------------+---------+
    ...