<h2class="blog-post-title">DurationParameter and other minor changes: Release 1.0.0-RC4</h2>
<pclass="blog-post-meta">October 9, 2014 by <ahref="#">Robert</a></p>
<p>New <i>DurationParameter</i> and additional minor changes: Release of 1.0.0-RC4 which can be downloaded on the <ahref="downloads.html">download</a> page.</p>
<hr>
<p>While implementing a use case in a Strolch based application it was detected that an essential parameter type was missing, the <i>DurationParameter</i>. This parameter currently stores the value as a long in memory and serializes to <ahref="http://en.wikipedia.org/wiki/ISO_8601#Durations">ISO8601</a>. As soon as we move Strolch to Java8, we will change this to use the <i>Period</i> class in the new Java8 date and time API.</p>
<p>In addition to the new parameter, a couple of other changes were made:</p>
<pclass="blog-post-meta">August 24, 2014 by <ahref="#">Robert</a></p>
<p>Important feature <i>Database Initialization</i> added: Release of 1.0.0-RC3 which can be downloaded on the <ahref="downloads.html">download</a> page.</p>
<hr>
<p>When living <i>continuous integration</i> and <i>continuous delivery</i>, it is vital that things like database migrations and initialization are performed in a controlled, but automatic way.</p>
<p>A Strolch-based application is using the PostgreSQL persistence layer. The implementation understands the concepts of migration, and validating the database schema, but currently a mechanism to automatically initialize the database with a minimal set of data was missing.</p>
<p>Migrating a database for Strolch is mostly a one time thing. The object model in Strolch is quite static, so there is seldom a need to migrate the database. Domain specific changes, i.e. new Resources, or adding Parameters to Resources, is not a schema change. Thus, instead of going the way other frameworks go, e.g. Ruby on Rails, we built the data initialization right into the <i>PersistenceHandler</i>.</p>
<p>Now if the PostgreSQL <i>PersistenceHandler</i> creates the schema, then it might also initialize the minimal set of data. For this to work, the <i>PersistenceHandler</i> checks if the flags <i>allowSchemaCreation</i>, <i>allowSchemaDrop</i> and <i>allowDbInitOnSchemaCreate</i>. If those flags are enabled, and the schema was created during initialization, then the database is also initialized with the contents of the XML file configured under key <i>dataStoreFile</i> of the relevant <i>Realm</i>.</p>
<p>The database initialization is done as a system user action which must have the name <i>db_initializer</i>. This is another fail-safe, so that on a production system, this user can simply be deleted.</p>
<p>So, Strolch 1.0.0-RC3 is out the door, go ahead and <ahref="downloads.html">try it out</a>.</p>
<p>Scratch that RC1, here is the brand new 1.0.0-RC2 which can be downloaded on the <ahref="downloads.html">download</a> page.</p>
<hr>
<p>So, as expected there were a few bugs, for instance the Strolch tutorial apps didn't start, so now i fixed those and released an RC2. Go <ahref="downloads.html">get it</a> and give it a try!</p>
<p>With the Go-Live of a Strolch-based application around the corner, it is time to release Version 1.0.0 of Strolch. To this affect we have now released version 1.0.0-RC1 which can be downloaded on the <ahref="downloads.html">download</a> page.</p>
<p>Strolch as a component based software agent has been two years in the making. The concepts in Strolch have been taken from a proprietary planning, scheduling and controlling software agent, which was, and is been, used in industrial automation, logistics and production. Strolch was created to bring the concepts, which were working well for small teams to go-live with large projects in short to medium time-frames to the open source world.</p>
<p>Strolch was completely rewritten using the key concepts of a parameterized object model and a component based agent but remembering which clutches the original implementation had, thus trying to eradicate those without bringing in new ones. It might not be perfect in version 1.0.0, but it is a starting point form which to carry on from.</p>
<h3>Features</h3>
<p>Strolch isn't feature complete by a long shot, but it sure has got many features which make it useable in a concrete project, thus making sure it is not vaporware =)</p>
<p>The following is a list of key features, many of which were driven by concrete project requirements:</p>
<li>Integrated authentication and authorization to validate user privileges using <ahref="https://github.com/eitchnet/ch.eitchnet.privilege">Privilege</a></li>
<li>Ready to use <ahref="http://en.wikipedia.org/wiki/Observer_pattern">Observer</a> pattern</li>
<li>(currently) Read-only <ahref="http://en.wikipedia.org/wiki/Restful">REST</a> API to access the agent model remotely</li>
<li>Basic components required to <ahref="https://github.com/eitchnet/ch.eitchnet.utils/tree/master/src/main/java/ch/eitchnet/communication">communicate</a> with external devices using TCP/IP</li>
<p>With the light weight implementation, where there are basically no third party libraries required for the normal runtime, Strolch has a minimal foot print which allows it to run on small devices for instance a <ahref="http://beagleboard.org/Products/BeagleBone+Black">BeagleBone Black</a>. Using the in-memory mode, it is an easy feat to set up test environments with little to no further requirements than the JVM.</p>
<p>So what is planned for the future? Although Strolch has quite a few interesting features, it is by no way feature complete. The greatest wish is for Strolch to become a community driven platform, so many new features will arise in the future, but at least one major future feature which will be tackled in the near future and will certainly drive the next major release is a planning and scheduling engine using a <ahref="http://en.wikipedia.org/wiki/Gantt_chart">Gantt</a> chart to visualize the schedule.</p>
<p>The planning engine will use the timed values on Resources extensively to create a planning engine on which Workflows can be placed and allowing to detect violations and bottlenecks.</p>
<p>An extension of the planning of the scheduling engine will allow more than just placing Workflows on Resources, but actually searching groups of Resources for a time slot of when to place tasks. This will allow to use capacity constraints to plan and schedule workflows using different algorithms, and respecting calendars etc.</p>
<p>Further time will be spent on giving Strolch it's own UI. Currently the idea is to use <ahref="http://www.polymer-project.org/">Google's Polymer</a> to implement the UI, thus creating reusable widgets that can be used in projects.</p>
<p>So, now the important part is for new users to start using Strolch for their own projects. Go ahead, check out the
<ahref="downloads.html">Downloads</a> page for the latest release and then checkout the two tutorial applications to get yourself up to speed!</p>
<p>Don't hesitate to send us feedback or questions, we will be delighted to help you get your Strolch-based application up and running, or provide feedback to your concerns!</p>
<p>Strolch is an open source component based software agent written in Java and can be compared, in a light sense, with the Java EE stack: Strolch takes care of persistence, implements Services for use cases, Commands as re-usable algorithms and has a parameterized data model.</p>