Jan Kotek's personal website, blog archive, publications, and contact information. Zola 2015-09-25T00:00:00+00:00 https://kotek.net/atom.xml 2015-09-25T00:00:00+00:00 2015-09-25T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_update/

<h1 id="mapdb-2-0-update">MapDB 2.0 update</h1> <p>To begin with, there is a small notification of changes. From now on I am moving the MapDB related posts to a <a rel="external" href="http://www.mapdb.org/blog.html">new blog</a> at mapdb.org. Here is new <a rel="external" href="http://www.mapdb.org/news.xml">RSS</a>. This blog will be used for my interests outside MapDB (most likely it will stay empty).</p>

2015-06-29T00:00:00+00:00 2015-06-29T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_2_beta_1/

<h1 id="mapdb-2-beta-1-is-out">MapDB 2 beta 1 is out</h1> <p>Beta 1 is out. It brings storage format and API freeze into MapDB 2.0 branch. This format and API should be supported for several years to come. Stable MapDB 2.0 will share the same format. Also latter 2.1 release with performance optimizations and long-term support will use the same.</p>

2015-06-16T00:00:00+00:00 2015-06-16T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_20_is_near/

<h1 id="mapdb-2-is-near">MapDB 2 is near</h1> <p>Format and API freeze for MapDB 2.0 is just a few weeks away. I did not write much about the new generation of MapDB (aka JDBM) and it is time to fix that.</p>

2014-07-01T00:00:00+00:00 2014-07-01T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_11_and_unsafe/

<h1 id="mapdb-1-1-and-sun-misc-unsafe">MapDB 1.1 and sun.misc.Unsafe</h1> <p>High performance Java projects usually use <code>sun.misc.Unsafe</code> to directly manipulate memory. It is not officially part of JDK, so it does not work on Dalvik and some other JVMs. Also it might cause JVM to crash in cause of an error, making debugging and user support hard.</p>

2014-05-14T00:00:00+00:00 2014-05-14T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_Roadmap_and_near_future/

<h1 id="mapdb-roadmap-and-near-future">MapDB Roadmap and near future</h1> <p>MapDB 1.0.0, the first stable version, was released last week. Some people tweeted “Christmas came early”. For me it is the culmination of 5 years work. Lets open another chapter and have a look at MapDB in the near future.</p>

2014-01-21T00:00:00+00:00 2014-01-21T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_and_CodeFutures/

<h1 id="codefutures-the-new-mapdb-home">CodeFutures: the new MapDB home</h1> <p><a rel="external" href="http://www.mapdb.org">MapDB</a> was a hobby project for almost 12 years (under the name JDBM). Last year I quit my daily job and started on MapDB full time. The plan was to finish MapDB 1.0 and build a consultancy business around it. I also wanted to work from home and spend more time with my family.</p>

2013-11-06T00:00:00+00:00 2013-11-06T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_1_in_january/

<h1 id="mapdb-1-0-will-be-released-in-january">MapDB 1.0 will be released in January</h1> <p>If you follow me on Github, you may have noticed I started preparations for 1.0 release. Some features were moved <a rel="external" href="https://github.com/jankotek/mapdb/issues?labels=after+1.0">after 1.0</a>, a long manual is <a rel="external" href="https://github.com/jankotek/MapDB/tree/master/src/site/markdown/doc">slowly growing</a> and number of remaining TODOs is shrinking fast.</p>

2013-09-25T00:00:00+00:00 2013-09-25T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_and_the_road_ahead/

<h1 id="mapdb-and-the-road-ahead">MapDB and the road ahead</h1> <p>Five months ago I left my regular job and <a href="/blog/MapDB_Reloaded/">started on MapDB full time</a>. I have been quiet since, so it is time to refresh my plans with MapDB.</p>

2013-07-01T00:00:00+00:00 2013-07-01T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_09_format_support/

<h1 id="mapdb-0-9-format-support">MapDB 0.9 format support</h1> <p>MapDB has currently semi-stable branch 0.9.x. My plan was to keep stable API and storage format. However to support some new features (store size limit, async API) I have to make changes in storage format, which are not backward compatible. Also now I work full-time and project is evolving much faster than I expected.</p>

2013-06-19T00:00:00+00:00 2013-06-19T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_Reloaded/

<h1 id="mapdb-reloaded">MapDB Reloaded</h1> <p>Last month I wrote about <a href="/blog/MapDB_Future/">the future of MapDB</a>. It was not very optimistic. MapDB is my hobby project and the time I could give it is severely limited. This led to some absurd situations: despite having a very fast db-engine I would not publish any performance benchmarks. I also discouraged possible users so I would not have to deal with support emails.</p>

2013-04-23T00:00:00+00:00 2013-04-23T00:00:00+00:00 Unknown https://kotek.net/blog/MapDB_Future/

<h1 id="mapdb-future">MapDB Future</h1> <p>MapDB 0.9.x was released a few weeks ago. Now that the project enters <i>usable alpha phase</i>, is time to talk about the future.</p>

2012-11-12T00:00:00+00:00 2012-11-12T00:00:00+00:00 Unknown https://kotek.net/blog/3G_map/

<h1 id="3-billion-items-in-java-map-with-16-gb-ram">3 billion items in Java Map with 16 GB RAM</h1> <p>One rainy evening I meditated about memory managment in Java and how effectively Java collections utilise memory. I made simple experiment, how much entries can I insert into Java Map with 16 GB of RAM?</p>

2012-11-03T00:00:00+00:00 2012-11-03T00:00:00+00:00 Unknown https://kotek.net/blog/JDBM4_renamed_to_MapDB/

<h1 id="jdbm4-renamed-to-mapdb">JDBM4 renamed to MapDB</h1> <p>‘JDBM’ (Java Database Manager) name has long history. Original ‘DBM’ (Database Manager) has been introduced in seventies. Java version started in 2001 and first stable version was introduced in 2005. Until 2012 it has dozen forks including JDBM2,3,4 and ApacheDS.</p>

2012-09-16T00:00:00+00:00 2012-09-16T00:00:00+00:00 Unknown https://kotek.net/blog/JDBM4_now_open_for_public/

<h1 id="jdbm4-now-open-for-public">JDBM4 now open for public</h1> <p>After 4 months of development <a rel="external" href="https://github.com/jankotek/JDBM4">JDBM4</a> is now stable enough for the first public testing. Now is good time for any early adopters or possible contributors to take JDBM4 for a quick spin.</p>

2012-06-08T00:00:00+00:00 2012-06-08T00:00:00+00:00 Unknown https://kotek.net/blog/announcing_JDBM4/

<h1 id="announcing-jdbm4">Announcing JDBM4</h1> <p>The JDBM3 project has been quiet for the last few weeks, but a lot has happened in between. I talked about JDBM3 at the Geecon conference in front of 50 people. I also met a handful of JDBM users. Results were not very encouraging. JDBM3 is very fast, but it is synchronized on single-big lock and does not scale well with concurrent access on multi core CPUs. And for most people this can be a deal breaker.</p>

2012-02-16T00:00:00+00:00 2012-02-16T00:00:00+00:00 Unknown https://kotek.net/blog/kotlin_pre-pre-pre_alpha_survival_guide/

<h1 id="kotlin-pre-pre-pre-alpha-survival-guide">Kotlin pre-pre-pre alpha survival guide</h1> <p>Jetbrains recently open-sourced Kotlin, so you may want to take it for a quick spin. Here are a few tips and workarounds. I worked with Kotlin last few weeks as volunteer tester, I am not connected with Jetbrains.</p>

2012-01-18T00:00:00+00:00 2012-01-18T00:00:00+00:00 Unknown https://kotek.net/blog/jdbm_3.0_alpha_1_released/

<h1 id="jdbm-3-0-alpha-1-released">JDBM 3.0 alpha 1 released</h1> <p>I am proud to announce first alpha of JDBM3. JDBM is embedded Java key value database with more than 10 years of history. It provides java collections (maps, sets and lists) backed up by disk storage. And it has unbeatable performance and simplicity.</p>

2011-11-01T00:00:00+00:00 2011-11-01T00:00:00+00:00 Unknown https://kotek.net/blog/pixy2_updated/

<h1 id="pixy2-updated">Pixy2 updated</h1> <p>Pixy 2 System is an astronomical image examination and object identification application. It process raw images and makes basic corrections. It can also identify asteroids, comets and find variable stars. It was developed by Seiichi Yoshida, I took liberty and updated it a bit.</p>

2011-10-23T00:00:00+00:00 2011-10-23T00:00:00+00:00 Unknown https://kotek.net/blog/jdbm_3_is_coming/

<h1 id="jdbm-3-is-coming">JDBM 3 is coming</h1> <p>A few weeks ago I started work on <a rel="external" href="https://github.com/jankotek/jdbm3">JDBM 3 at github</a>. Main goal is to improve simplicity and performance. JDBM3 is packed with new features and changes. Difference from JDBM2 is even bigger than between JDBM1 and JDBM2. But there is still policy ‘no test left behind’, so we should enjoy great stability similar to previous releases.</p>

2011-07-06T00:00:00+00:00 2011-07-06T00:00:00+00:00 Unknown https://kotek.net/blog/scala_problems/

<h1 id="scala-problems">scala problems</h1> <p>I love Scala, it lifted my capabilities and made me incredible productive. But after 18 months I found a few problems.</p>

2011-04-12T00:00:00+00:00 2011-04-12T00:00:00+00:00 Unknown https://kotek.net/blog/galway_sky_atlas_1st_edition/

<h1 id="galway-sky-atlas-1st-edition">Galway Sky Atlas 1st edition</h1> <p>I am pleased to announce first edition of <a rel="external" href="https://picasaweb.google.com/105883183836974264111/GalwaySkyAtlas1stEdition">Galway Sky Atlas</a>. It is an opensource community free a beer atlas. It coverts 200000 stars down to 10.5 magnitudes. It also contains 10000 objects from <a rel="external" href="http://www.saguaroastro.org/content/downloads.htm">SAC deep sky database</a>. Atlas comes on 473 charts with same layout as first edition of Uranometria.</p>

2011-03-29T00:00:00+00:00 2011-03-29T00:00:00+00:00 Unknown https://kotek.net/blog/quick_look_at_upcoming_parallel_collections_in_scala_2.9/

<h1 id="quick-look-at-upcoming-parallel-collections-in-scala-2-9">Quick look at upcoming Parallel Collections in Scala 2.9</h1> <p>Scala 2.9 should be released “in weeks”, so I took recent snapshot for quick spin, to see how it work with my open-source project. Upgrade was easy, nothing compared to 2.7. Just replacing scalac and scala-lib jar files. I encountered three minor problems:</p>

2011-01-16T00:00:00+00:00 2011-01-16T00:00:00+00:00 Unknown https://kotek.net/blog/jdbm_2.1_and_beyond/

<h1 id="jdbm-2-1-and-beyond">JDBM 2.1 and beyond</h1> <p>JDBM 2.0 was released just a few weeks ago, now is time to start working on new version. JDBM 2.1 will bring fixes and performance improvements, but keeping file format and API compatible with 2.0.</p>

2010-12-20T00:00:00+00:00 2010-12-20T00:00:00+00:00 Unknown https://kotek.net/blog/enumeration_problem_at_scala_2.8.1/

<h1 id="enumeration-problem-at-scala-2-8-1">Enumeration problem at Scala 2.8.1</h1> <p>Scala is great language and I love it. But sometimes one can found strange stuff in there. A few weeks ago I updated Scala library in my project from 2.8.0 to 2.8.1. There were a few minor issues. But also one really big one. It took me a few hours to find reason why my tests are failing.</p>

2010-12-19T00:00:00+00:00 2010-12-19T00:00:00+00:00 Unknown https://kotek.net/blog/jdbm2_released/

<h1 id="jdbm2-released">JDBM2 released</h1> <p>I am proud to announce stable release of <a rel="external" href="http://googlecode.com/p/jdbm2">JDBM2</a> key-value database. It is similar to BerkleyDB Java Edition, but is free as beer and under Apache 2 license. JDBM2 provides ‘java.util.Map’ stored on disk.</p>

2010-11-28T00:00:00+00:00 2010-11-28T00:00:00+00:00 Unknown https://kotek.net/blog/junit3_scala_testcase/

<h1 id="junit3-scala-testcase">JUnit3 Scala TestCase</h1> <p>There is number of new testing framework for Java and Scala. For example JUnit4, TestNG, Spec, ScalaTest… I never liked annotation driven test cases or ‘story driven tests’. So I wrote my own TestCase which works with JUnit3 and can use some Scala features.</p>

2010-11-11T00:00:00+00:00 2010-11-11T00:00:00+00:00 Unknown https://kotek.net/blog/swingutilities.invokeandwait_with_return_value/

<h1 id="swingutilities-invokeandwait-with-return-value">SwingUtilities.invokeAndWait with return value</h1> <p>Threading in Swing is tricky. In many cases it is necessary to make a calculation on EDT thread and receive result back. For example components should not be created outside of EDT, or values should be accessed in thread safe way.</p>

2009-11-30T00:00:00+00:00 2009-11-30T00:00:00+00:00 Unknown https://kotek.net/blog/rangeset_and_huge_datasets/

<h1 id="rangeset-and-huge-datasets">RangeSet and huge datasets</h1> <p>Most of collections does not use memory efficiently. But there is simple compression trick to store virtually unlimited data sets. And there are practical implementations.</p>

2009-11-30T00:00:00+00:00 2009-11-30T00:00:00+00:00 Unknown https://kotek.net/blog/using_ant_and_javac_without_installation/

<h1 id="using-ant-and-javac-without-installation">Using Ant and Javac without installation</h1> <p>Installing Ant and JDK can be pain. This post shows howto make Ant Java compiler part of your project. So it does not require installation. Only one external dependency needed to make build will be JRE. This setup makes it also much easier for new comers to start on project</p>

2009-11-07T00:00:00+00:00 2009-11-07T00:00:00+00:00 Unknown https://kotek.net/blog/piccolo_and_svg/

<h1 id="piccolo-and-svg">Piccolo and SVG</h1> <p>I was thinking how to improve symbols on map. Star clusters, nebulas etc have complicated signs and it is difficult to draw them with plain Java2d. I decided to use SVG vector graphic to draw those symbols. Using vector editor is way way easier then coding in Java2d.</p>

2009-06-09T00:00:00+00:00 2009-06-09T00:00:00+00:00 Unknown https://kotek.net/blog/more_realistic_view_on_groovy/

<h1 id="more-realistic-view-on-groovy">More realistic view on Groovy</h1> <p>Realistic evaluation of Groovy based on half year usage in hobby projects.</p>

2009-02-05T00:00:00+00:00 2009-02-05T00:00:00+00:00 Unknown https://kotek.net/blog/pixy2/

<h1 id="pixy2">Pixy2</h1> <p>I am not sure if you know <a rel="external" href="http://www.aerith.net/misao/pixy/index.html">Pixy2</a>. It is very good program for making photometry on CCD image. It can also identify starts on CCD image. But Pixy2 depends on external XML parser and does not start with JRE 1.6 (internal XML parser).</p>

2009-01-17T00:00:00+00:00 2009-01-17T00:00:00+00:00 Unknown https://kotek.net/blog/label_layout_algorithm/

<h1 id="label-layout-algorithm">Label layout algorithm</h1> <p>One of most common problems in astro cartography are labels. There is many objects on map and many of them have an label. In highly concentrated areas (galaxy clusters, Saggitarius) it is hard to place label without overlaping with other objects and labels.</p>

2008-09-05T00:00:00+00:00 2008-09-05T00:00:00+00:00 Unknown https://kotek.net/blog/writing_fast_nio_webserver/

<h1 id="writing-fast-nio-webserver">Writing fast NIO webserver</h1> <p>I wrote fast and simple <a href="/down/asynchttpd-m2.zip">web server</a> using New I/O and Kilim microthreads. No locks, no blocking, no channel selector. With a few optimization tricks, it is probably fastest webserver written in Java.</p>

2007-09-17T00:00:00+00:00 2007-09-17T00:00:00+00:00 Unknown https://kotek.net/blog/spring_and_memento_pattern/

<h1 id="spring-and-memento-pattern">Spring and memento pattern</h1> <p><a rel="external" href="http://en.wikipedia.org/wiki/Memento_pattern">Memento pattern</a> is common way howto save and restore object state. It is used in many applications including Eclipse and Netbeans. Implementation in OpenCoeli is easy to use, Spring friendly and very simple.</p>

2007-08-21T00:00:00+00:00 2007-08-21T00:00:00+00:00 Unknown https://kotek.net/blog/spring_bean_name_resolver/

<h1 id="spring-bean-name-resolver">Spring bean name resolver</h1> <p>OpenCoeli is heavily using Spring IOC framework. It is great, but is missing one feature: inverse bean name resolver. Why it is good to know bean name? For example for configuration, if you inject different bean you just need to save bean name. Also it can be very useful for logging.</p>

2007-07-30T00:00:00+00:00 2007-07-30T00:00:00+00:00 Unknown https://kotek.net/blog/astronomy_and_gis/

<h1 id="astronomy-and-gis">Astronomy and GIS</h1> <p>There is entire engineering discipline called <a rel="external" href="http://en.wikipedia.org/wiki/Geographic_information_system">Geographic information system</a>, it is all about how to draw maps and present various informations on Earth’s surface. About GIS was written many books.</p>