pdt_devel.sgml

用来作为linux中SIP SERVER,完成VOIP网络电话中服务器的功能

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<chapter>
    <chapterinfo>
	<revhistory>
	    <revision>
		<revnumber>$Revision: 1.1 $</revnumber>
		<date>$Date: 2003/07/24 17:57:40 $</date>
	    </revision>
	</revhistory>
    </chapterinfo>
    <title>Developer's Guide</title>
    <para>
	The module registers also a function that works with the fifo server ( get_domaincode ).
	That will provide support for a web user interface which will be used by admins to register
	new domains and by simple users to find the code for a domain.
    </para>
    <para>
	Registered domains are stored in a database and in tables in share memory. The database is
	kept consistent with the tables in memory. When a new domain is registered the information
	goes first in the database and only than in tables in share memory.
    </para>
    <para>
	Data in share memory is kept in hashtables to have fast searches. Searches are 
	possible for domains, but also for codes. Searches for codes are necessary more 
	often, every time when a message that needs to be translated passes through &ser;
	Searches for domains are requested by the user interface only.
    </para>
    <para>
	Through the web interface a normal user can find the code for a domain and a privileged user
	(i.e., admins) can register new domains too. The web interface also encounters problems of
	mutual exclusion. Any user of the interface posts a request to the fifo server and waits his
	response in a file. The file must be unique per user to avoid interfering responses for
	different simultaneous user. That problem is solved using session per user offered by the
	<acronym>PHP</acronym> language.
    </para>
</chapter>

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