cache.html

---
layout: main
title: Talares | Cache
---
<article>

  <h1>Cache</h1>
  <hr>

  <p>
    Talares does not use a caching library of it's own. In stead it leaves supplying a cache implementation up to the
    user. This is done by creating an instance of one of the caches residing in <strong>org.talares.cache</strong> for
    Java and <strong>org.talares.api.cache</strong> for Scala. Talares will leverage this instance to apply the chosen
    caching strategy.
  </p>

  <p>
    Specific caching strategies can be chosen by supplying an instance of the corresponding class. The different
    strategies are described below.
  </p>

  <article id="no-cache">

    <h2>No cache</h2>

    <p>
      When no cache instance or an instance of NoCache is provided, the 'no cache' strategy is chosen. As the name
      implies this strategy will not cache results retrieved from the webservice.
    </p>

  </article>

  <article id="simple-cache">

    <h2>Simple cache</h2>

    <p>
      The 'simple cache' strategy uses the supplied cache implementation to store results retrieved from the webservice.
      It does not supply any additional logic of it's own. Therefore the configuration of the supplied cache instance,
      like time to live, is honored.
    </p>

  </article>

  <article id="auto-update-cache">

    <h2>Auto update cache</h2>

    <p>
      When the 'auto update cache' strategy is activated, cached values will be updated using an asynchronous process.
      This allows for clients to always be served a value from cache while also ensuring that these values are up to
      date.
    </p>

    <p>
      A few configuration steps are needed to make this work. First of all the configuration of the cache implementation
      supplied by the user will have to be modified to accommodate the auto update cache behaviour. For instance a short
      TTL might cause cached values to be evicted before the library has a chance to update them.
    </p>

    <p>
      Furthermore, users will have to decide the frequency with which to update the cached values. This can be done in
      the <em>application.conf</em> file using the key <strong>talares.cache.refreshratio</strong>. The value specified
      there represents the number of times a cached item should be allowed to be accessed before an update task is 
      triggered. 
      It is advised to increase this value to an adequate number for high traffic environments. The result of an
      incrementation of this value might be that some clients receive slightly outdated content, but the load that is
      relieved from the webservice will be significant.
    </p>

  </article>

</article>