+
+<div id="outline-container-sec-4-4" class="outline-3">
+<h3 id="sec-4-4"><span class="section-number-3">4.4</span> Layered architecture</h3>
+<div class="outline-text-3" id="text-4-4">
+<dl class="org-dl">
+<dt> layer 1 </dt><dd>disk / block storage / partition
+</dd>
+
+<dt> layer 2 </dt><dd>key/value storage. Keys are unique and are dictated by
+storage engine. Value is arbitrary but limited size byte
+array. This layer is responsible for handling disk
+defragmentation and consistency in case of crash
+recovery.
+</dd>
+
+<dt> layer 3 </dt><dd>key/value storage. Keys are content hashes. Values are
+arbitrary but limited size content byte arrays. This
+layer effectively implements content addressable
+storage. Content addressible storage enables GIT-like
+behavior (possibility for competing branches, retaining
+history, transparent deduplication)
+</dd>
+
+<dt> layer 4 </dt><dd>Implements arbitrary dimensional multiverse.
+</dd>
+
+<dt> layer 5 </dt><dd>Distributed computation engine.
+</dd>
+</dl>
+</div>
+</div>
+</div>
+<div id="outline-container-sec-5" class="outline-2">
+<h2 id="sec-5"><span class="section-number-2">5</span> Current status</h2>
+<div class="outline-text-2" id="text-5">
+<ul class="org-ul">
+<li>More or less defined <a href="#sec-2">Vision / goal</a>.
+</li>
+
+<li>Collected some <a href="#sec-3-1">ideas</a>.
+</li>
+
+<li>Implemented very simple persistent key-value map.
+<ul class="org-ul">
+<li>Long term goal is to use it as a backing storage engine and
+implement more advanced features on top of this.
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+
+<div id="outline-container-sec-6" class="outline-2">
+<h2 id="sec-6"><span class="section-number-2">6</span> See also</h2>
+<div class="outline-text-2" id="text-6">
+<p>
+Interesting or competing projects with good ideas:
+</p>
+
+<ul class="org-ul">
+<li>GRAKN.AI
+<ul class="org-ul">
+<li>database in the form of a knowledge graph that uses machine
+reasoning to simplify data processing challenges for AI
+applications. <a href="https://grakn.ai/">https://grakn.ai/</a>
+</li>
+</ul>
+</li>
+
+<li>Magma
+<ul class="org-ul">
+<li>multi-user object database for Squeak
+<a href="http://wiki.squeak.org/squeak/2665">http://wiki.squeak.org/squeak/2665</a>
+</li>
+</ul>
+</li>
+
+<li>Gemstone/S
+<ul class="org-ul">
+<li>Completely distributed smalltalk based computing
+system. <a href="http://esug.org/data/ESUG2015/3%20wednesday/1100-1130%20SQL%20Queries%20on%20Smalltalk%20Objects/SQL%20Queries%20in%20Smalltalk%20(James%20Foster)">http://esug.org/data/ESUG2015/3%20wednesday/1100-1130%20SQL%20Queries%20on%20Smalltalk%20Objects/SQL%20Queries%20in%20Smalltalk%20(James%20Foster)</a>.pdf
+</li>
+</ul>
+</li>
+
+<li>TAOS
+<ul class="org-ul">
+<li>Completely distributed operating system/virtual machine:
+<a href="http://www.uruk.org/emu/Taos.html">http://www.uruk.org/emu/Taos.html</a>
+</li>
+</ul>
+</li>
+</ul>
+</div>
+</div>
+</div><div class="col-md-3"><nav id="table-of-contents">
+<div id="text-table-of-contents" class="bs-docs-sidebar">
+<ul class="nav">
+<li><a href="#sec-1">1. General</a>
+<ul class="nav">
+<li><a href="#sec-1-1">1.1. Source code</a></li>
+</ul>
+</li>
+<li><a href="#sec-2">2. Vision / goal</a></li>
+<li><a href="#sec-3">3. Inspiration</a>
+<ul class="nav">
+<li><a href="#sec-3-1">3.1. Brain</a></li>
+</ul>
+</li>
+<li><a href="#sec-4">4. Ideas</a>
+<ul class="nav">
+<li><a href="#sec-4-1">4.1. Distributed computation and data storage</a></li>
+<li><a href="#sec-4-2">4.2. Mapping of hyperspace to traditional object-oriented model</a></li>
+<li><a href="#sec-4-3">4.3. Handling of relations</a></li>
+<li><a href="#sec-4-4">4.4. Layered architecture</a></li>
+</ul>
+</li>
+<li><a href="#sec-5">5. Current status</a></li>
+<li><a href="#sec-6">6. See also</a></li>
+</ul>