<!-- Module User's Guide -->

<chapter>
	<chapterinfo>
	<revhistory>
		<revision>
		<revnumber>$Revision: 1.2 $</revnumber>
		<date>$Date: 2005/10/25 11:19:33 $</date>
		</revision>
	</revhistory>
	</chapterinfo>
	<title>User's Guide</title>

	<section>
	<title>Overview</title>
	<para>
		The module implements a simplified database engine based on text
		files. It can be used by &ser; 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 quickly out of memory. Also, it
		has not implemented all standard database facilities (like order by),
		it includes minimal functionality to work properly (who knows ?!?)
		with &ser;.
	</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.
				NOTE: when you use <emphasis>dbtext</emphasis> in &ser;,
				the	database URL for modules must be the path to the directory
				where the table-files are located, prefixed by 
				<quote>dbtext://</quote>, e.g., 
				<quote>dbtext:///var/dbtext/ser</quote>. If there is no
				<quote>/</quote> after <quote>dbtext://</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>
			</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>
		First line is the definition of the columns. Each column must be
		declared as follows:
			<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 &ser; 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 &ser; 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>
	<section>
	<title>Dependencies</title>
		<section>
			<title>&ser; modules</title>
		<para>
			The next 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>
			The next libraries or applications must be installed before running
			&ser; with this module:
			<itemizedlist>
			<listitem>
				<para>
				<emphasis>none</emphasis>.
				</para>
			</listitem>
			</itemizedlist>
		</para>
		</section>
	</section>
	<section>
	<title>Exported Parameters</title>
		<para>
			<emphasis>None</emphasis>.
	   	</para>
	</section>
	<section>
	<title>Exported Functions</title>
		<para>
			<emphasis>None</emphasis>.
	   	</para>
	</section>
	<section>
		<title>Installation & Running</title>
		<para>
		Compile the module and load it instead of mysql or other DB modules.
		</para>
		<para>
		REMINDER: when you use <emphasis>dbtext</emphasis> in &ser;,
		the	database URL for modules must be the path to the directory
		where the table-files are located, prefixed by
		<quote>dbtext://</quote>, e.g., 
		<quote>dbtext:///var/dbtext/ser</quote>. If there is no <quote>/</quote>
		after <quote>dbtext://</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/ser/modules/dbtext.so"
...
modparam("module_name", "database_URL", "/path/to/dbtext/database")
...
</programlisting>
		</example>
		<section>
			<title>Using dbtext with basic &ser; configuration</title>
		<para>
		Here are the definitions for most important table as well as a basic 
		configuration file to use dbtext with &ser;. The table structures may 
		change in time and you will have to adjust next examples. These are 
		know to work with upcoming &ser; v0.9.0
		</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">
...
&dbtextsercfg;
...
</programlisting>
		</example>
		</section>
	</section>
</chapter>

<!-- Keep this element at the end of the file
Local Variables:
sgml-parent-document: ("dbtext.sgml" "Book" "chapter")
End:
-->