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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>5. Read/write master-capable backends</title><link rel="stylesheet" href="docbook.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="PowerDNS manual" /><link rel="up" href="backend-writers-guide.html" title="Appendix C. Backend writers' guide" /><link rel="prev" href="rw-backends.html" title="4. Read/write slave-capable backends" /><link rel="next" href="compiling-powerdns.html" title="Appendix D. Compiling PowerDNS" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">5. Read/write master-capable backends</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="rw-backends.html">Prev</a> </td><th width="60%" align="center">Appendix C. Backend writers' guide</th><td width="20%" align="right"> <a accesskey="n" href="compiling-powerdns.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="5. Read/write master-capable backends"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="master-backends"></a>5. Read/write master-capable backends</h2></div></div></div><p>
In order to be a useful master for a domain, notifies must be sent out whenever a domain is changed. Periodically, PDNS
queries backends for domains that may have changed, and sends out notifications for slave nameservers.
</p><p>
In order to do so, PDNS calls the <code class="function">getUpdatedMasters()</code> method. Like the <code class="function">getUnfreshSlaveInfos()</code>
function mentioned above, this should add changed domain names to the vector passed.
</p><p>
The following excerpt from the DNSBackend shows the relevant functions:
</p><p>
</p><pre class="programlisting">
class DNSBackend {
public:
/* ... */
virtual void getUpdatedMasters(vector<DomainInfo>* domains);
virtual void setNotified(uint32_t id, uint32_t serial);
/* ... */
}
</pre><p>
</p><p>
These functions all have a default implementation that returns false - which explains that these methods can be omitted in simple backends.
Furthermore, unlike with simple backends, a slave capable backend must make sure that the 'DNSBackend *db' field of the SOAData record is filled
out correctly - it is used to determine which backend will house this zone.
</p><div class="variablelist"><dl><dt><span class="term">void getUpdatedMasters(vector<DomainInfo>* domains)</span></dt><dd><p>
When called, the backend should examine its list of master domains and add any changed ones to the DomainInfo vector
</p></dd><dt><span class="term">bool setNotified(uint32_t domain_id, uint32_t serial)</span></dt><dd><p>
Indicate that notifications have been queued for this domain and that it need not be considered 'updated' anymore
</p></dd></dl></div><p>
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