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kamailio/modules/db_text/doc/db_text_admin.xml

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<?xml version="1.0" encoding='ISO-8859-1'?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
<!-- Include general documentation entities -->
<!ENTITY % docentities SYSTEM "../../../docbook/entities.xml">
%docentities;
]>
<!-- Module User's Guide -->
<chapter xmlns:xi="http://www.w3.org/2001/XInclude">
<title>&adminguide;</title>
<section>
<title>Overview</title>
<para>
The module implements a simplified database engine based on text
files. It can be used by &kamailio; DB interface instead of other
database module (like MySQL).
</para>
<para>
The module is meant for use in demos or small devices that do not
support other DB modules. It keeps everything in memory and if you deal
with large amount of data you may run out of memory quickly. Also, it
does not implement all standard database facilities (like order by),
it includes minimal functionality to work properly (who knows ?!?)
with &kamailio;.
</para>
<para>
NOTE: the timestamp is printed in an integer value from time_t
structure. If you use it in a system that cannot do this conversion,
it will fail (support for such situation is in to-do list).
</para>
<para>
NOTE: even when db_text is in non-caching mode, the module does not write
back to hard drive after changes. In this mode, the module checks if
the corresponding file on disk has changed, and reloads it. The write
to disk happens at &kamailio; shut down.
</para>
<section>
<title>Design of dbtext engine</title>
<para>
The dbtext database system architecture:
<itemizedlist>
<listitem>
<para>
A database is represented by a directory in the local file
system.
</para>
<para>
NOTE: when you use <emphasis>dbtext</emphasis> in &kamailio;,
the database URL for modules must be the path to the directory
where the table-files are located, prefixed by
<quote>text://</quote>, e.g.,
<quote>text:///var/dbtext/ser</quote>. If there is no
<quote>/</quote> after <quote>text://</quote> then
<quote>CFG_DIR/</quote> is inserted at the beginning of the
database path. So, either you provide an absolute path to
database directory or a relative one to <quote>CFG_DIR</quote>
directory.
</para>
<para>
Do not forget that all databases in &kamailio; needs the <quote>version</quote>
table.
</para>
</listitem>
<listitem>
<para>
A table is represented by a text file inside database directory.
</para>
</listitem>
</itemizedlist>
</para>
</section>
<section>
<title>Internal format of a dbtext table</title>
<para>
The first line is the definition of the columns. Each column must be
declared in the following format:
<itemizedlist>
<listitem>
<para>
the name of column must not include white spaces.
</para>
</listitem>
<listitem>
<para>
the format of a column definition is:
<emphasis>name(type,attr)</emphasis>.
</para>
</listitem>
<listitem>
<para>
between two column definitions must be a white space, e.g.,
<quote>first_name(str) last_name(str)</quote>.
</para>
</listitem>
<listitem>
<para>
the type of a column can be:
<itemizedlist>
<listitem>
<para>
<emphasis>int</emphasis> - integer numbers.
</para>
</listitem>
<listitem>
<para>
<emphasis>double</emphasis> - real numbers with two
decimals.
</para>
</listitem>
<listitem>
<para>
<emphasis>str</emphasis> - strings with maximum size of 4KB.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
a column can have one of the attributes:
<itemizedlist>
<listitem>
<para>
<emphasis>auto</emphasis> - only for 'int' columns,
the maximum value in that column is incremented and stored
in this field if it is not provided in queries.
</para>
</listitem>
<listitem>
<para>
<emphasis>null</emphasis> - accept null values in column
fields.
</para>
</listitem>
<listitem>
<para>
if no attribute is set, the fields of the column cannot have
null value.
</para>
</listitem>
</itemizedlist>
</para>
</listitem>
<listitem>
<para>
each other line is a row with data. The line ends with
<quote>\n</quote>.
</para>
</listitem>
<listitem>
<para>
the fields are separated by <quote>:</quote>.
</para>
</listitem>
<listitem>
<para>
no value between two ':' (or between ':' and start/end of a row)
means <quote>null</quote> value.
</para>
</listitem>
<listitem>
<para>
next characters must be escaped in strings: <quote>\n</quote>,
<quote>\r</quote>, <quote>\t</quote>, <quote>:</quote>.
</para>
</listitem>
<listitem>
<para>
<emphasis>0</emphasis> -- the zero value must be escaped too.
</para>
</listitem>
</itemizedlist>
</para>
<example>
<title>Sample of a dbtext table</title>
<programlisting format="linespecific">
...
id(int,auto) name(str) flag(double) desc(str,null)
1:nick:0.34:a\tgood\: friend
2:cole:-3.75:colleague
3:bob:2.50:
...
</programlisting>
</example>
<example>
<title>Minimal &kamailio; location dbtext table definition</title>
<programlisting format="linespecific">
...
username(str) contact(str) expires(int) q(double) callid(str) cseq(int)
...
</programlisting>
</example>
<example>
<title>Minimal &kamailio; subscriber dbtext table example</title>
<programlisting format="linespecific">
...
username(str) password(str) ha1(str) domain(str) ha1b(str)
suser:supasswd:xxx:alpha.org:xxx
...
</programlisting>
</example>
</section>
<section>
<title>Existing limitations</title>
<para>This database interface does not support data insertion with
default values. All such values specified in the database template
are ignored. So its advisable to specify all data for a column at
insertion operations.
</para>
</section>
</section>
<section>
<title>Dependencies</title>
<section>
<title>&kamailio; modules</title>
<para>
These modules must be loaded before this module:
<itemizedlist>
<listitem>
<para>
<emphasis>none</emphasis>.
</para>
</listitem>
</itemizedlist>
</para>
</section>
<section>
<title>External libraries or applications</title>
<para>
These libraries or applications must be installed before running
&kamailio; with this module:
<itemizedlist>
<listitem>
<para>
<emphasis>none</emphasis>.
</para>
</listitem>
</itemizedlist>
</para>
</section>
</section>
<section>
<title>Parameters</title>
<para>
<emphasis>None</emphasis>.
</para>
<section>
<title><varname>db_mode</varname> (integer)</title>
<para>
Set caching mode (0) or non-caching mode (1). In caching mode, data
is loaded at startup. In non-caching mode, the module check every time
a table is requested whether the corresponding file on disk has
changed, and if yes, will re-load the table from file.
</para>
<para>
<emphasis>
Default value is <quote>0</quote>.
</emphasis>
</para>
<example>
<title>Set <varname>db_mode</varname> parameter</title>
<programlisting format="linespecific">
...
modparam("db_text", "db_mode", 1)
...
</programlisting>
</example>
</section>
</section>
<section>
<title>Exported RPC Functions</title>
<section>
<title>
<function moreinfo="none">db_text.dump</function>
</title>
<para>Write back to hard drive all modified tables.</para>
<para>Name: <emphasis>db_text.dump</emphasis></para>
<para>Parameters: <emphasis>none</emphasis></para>
<para>RPC Command Format:</para>
<programlisting format="linespecific">
kamcmd db_text.dump
</programlisting>
</section>
</section>
<section>
<title>Installation and Running</title>
<para>
Compile the module and load it instead of mysql or other DB modules.
</para>
<para>
REMINDER: when you use <emphasis>text</emphasis> in &kamailio;,
the database URL for modules must be the path to the directory
where the table-files are located, prefixed by
<quote>text://</quote>, e.g.,
<quote>text:///var/dbtext/ser</quote>. If there is no <quote>/</quote>
after <quote>text://</quote> then <quote>CFG_DIR/</quote> is inserted
at the beginning of the database path. So, either you provide an
absolute path to database directory or a relative one to
<quote>CFG_DIR</quote> directory.
</para>
<example>
<title>Load the dbtext module</title>
<programlisting format="linespecific">
...
loadmodule "/path/to/kamailio/modules_k/db_text.so"
...
modparam("module_name", "db_url", "text:///path/to/dbtext/database")
...
</programlisting>
</example>
<section>
<title>Using db_text with a basic &kamailio; configuration</title>
<para>
Here are definitions for the most important tables as well as a basic
configuration file to use db_text with &kamailio;. The table structures
may change in time and you will have to adjust these examples. Check the
source code directory <quote>utils/kamctl/dbtxt/kamailio</quote> for
current definitions.
</para>
<para>
You have to populate the table 'subscriber' by hand with user profiles
in order to have authentication. To use with the given configuration
file, the table files must be placed in the '/tmp/serdb' directory.
</para>
<example>
<title>Definition of 'subscriber' table (one line)</title>
<programlisting format="linespecific">
...
username(str) domain(str) password(str) first_name(str) last_name(str) phone(str) email_address(str) datetime_created(int) datetime_modified(int) confirmation(str) flag(str) sendnotification(str) greeting(str) ha1(str) ha1b(str) perms(str) allow_find(str) timezone(str,null) rpid(str,null)
...
</programlisting>
</example>
<example>
<title>Definition of 'location' and 'aliases' tables (one line)</title>
<programlisting format="linespecific">
...
username(str) domain(str,null) contact(str,null) received(str) expires(int,null) q(double,null) callid(str,null) cseq(int,null) last_modified(str) flags(int) user_agent(str) socket(str)
...
</programlisting>
</example>
<example>
<title>Definition of 'version' table and sample records</title>
<programlisting format="linespecific">
...
table_name(str) table_version(int)
subscriber:3
location:6
aliases:6
...
</programlisting>
</example>
<example>
<title>Configuration file</title>
<programlisting format="linespecific">
...
<xi:include href="db_text.cfg" parse="text"/>
...
</programlisting>
</example>
</section>
</section>
</chapter>