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<!DOCTYPE html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" integrity="sha384-WskhaSGFgHYWDcbwN70/dfYBj47jz9qbsMId/iRN3ewGhXQFZCSftd1LZCfmhktB"
crossorigin="anonymous">
<title>EmbASP</title>
<!-- highlight.js -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.5/styles/default.min.css">
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href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/default.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/highlight.min.js"></script> -->
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<style>
h2 {
padding-top: 55px;
}
.layer {
text-transform: uppercase;
}
.footer {
padding-top: 40px;
padding-bottom: 40px;
margin-top: 40px;
border-top: 1px solid #eee;
}
/* #toTop {
position: fixed;
bottom: 10px;
right: 10px;
cursor: pointer;
display: none;
} */
</style>
<!-- HTML5 shim and Respond.js for IE8 support of HTML5 elements and media queries -->
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<script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
<script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
<![endif]-->
</head>
<body>
<nav class="navbar navbar-expand-lg fixed-top navbar-light bg-light">
<a class="navbar-brand" href="">
<img src="img/EmbASP_Logo.svg" alt="EmbASP logo" height="25" onerror="this.src='img/EmbASP_Logo.png'" />
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent"
aria-expanded="false" aria-label="Toggle navigation">
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</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="#Download">Download</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#Documentation">Documentation</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#CoreTeam">Core Team</a>
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<a class="nav-link" href="#Contacts">Contacts</a>
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<a class="nav-link" href="#License">License</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#Publications">Publications</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#Applications">Applications</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true"
aria-expanded="false">
Previous versions
</a>
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<a class="dropdown-item" href="version_1x.html">Version 1x</a>
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<a class="dropdown-item" href="version_3x.html">Version 3x</a>
<a class="dropdown-item" href="version_4x.html">Version 4x</a>
</div>
</li>
</ul>
</div>
<!-- /.navbar-collapse -->
<span class="navbar-text">
<strong>
<em>EmbASP</em>
</strong>
</span>
</div>
<!-- /.container-fluid -->
</nav>
<div class="container" style="padding-top: 40px">
<div class="page-header">
<!--<h2 style="text-align: center"><img src="img/EmbASP_Logo.png" alt="embASP" height="150" style=" padding-bottom: 0.2cm;" /></h2>-->
<div class="jumbotron jumbotron-fluid">
<div class="container">
<img class="float-right" src="img/EmbASP_Logo.png" alt="EmbASP logo" height="150" onerror="this.src='img/EmbASP_Logo.png'"
/>
<h1 class="display-4">
<em>EmbASP</em>
</h1>
<p class="lead">A framework for the integration (embedding) of Logic Programming in external systems for generic applications.
<br /> It helps developers at designing and implementing complex reasoning tasks by means of solvers on
different platforms.
</p>
<hr class="my-4">
<p>
The framework can be implemented in a object-oriented programming language of choice, easing and guiding the generation of
suitable libraries for the use of specific solvers on selected platforms. We currently provide 3
implementations (in
<a href="https://www.java.com">
<strong>Java</strong>
</a>, in
<a href="https://www.python.org">
<strong>Python</strong>
</a> and in
<a href="https://docs.microsoft.com/dotnet/csharp/language-reference/">
<strong>C#</strong>
</a>) and ready-made libraries for the embedding of the
<em>ASP (Answer Set Programming)</em> solvers
<a href="http://www.dlvsystem.com/dlv">DLV</a>,
<a href="https://potassco.org/clingo">clingo</a> and
<a href="https://www.mat.unical.it/DLV2">DLV2</a> and the
<em>PDDL (Planning Domain Definition Language)</em> cloud solver
<a href="http://solver.planning.domains">Solver.Planning.Domains</a> (SPD) on the Desktop platform and of DLV and SPD on the Mobile (Android™)
one (available only for the Java version).
</p>
<p>
However, the framework has been designed to be easily extensible and adaptable to different solvers and platforms. It is
worth to notice that solvers are invoked in different modes; for instance, SPD is invoked via a remote
connection, while for the other, binaries are effectively embedded and natively executed.
</p>
</div>
</div>
<div class="alert alert-info" role="alert">
NOTE: this is the official site of versions
<strong>5</strong> of the EmbASP Framework. If you are looking for an older version, please check the last item in
the top menu.</a>
</div>
</div>
<div class="row">
<div class="col">
<h2 id="Download">Download
<a href="https://github.com/DeMaCS-UNICAL/EmbASP">
<img src="img/GitHub-Mark-120px-plus.png" alt="GitHub" height="40" />
</a>
</h2>
<!-- <div>
<h3 id="release">Latest release version</h3>
<div>To use the specialized library on Desktop, a JAR file, an wheel file and a DLL have been released.</div>
<div>To use the specialized library on Mobile (Android), an AAR file has been released.</div>
<div>You can download their last stable versions <a href="https://github.com/DeMaCS-UNICAL/EmbASP/releases">here</a>.</div>
</div> -->
<div>
<h3>Development Version</h3> You can find the current development version
<a href="https://github.com/DeMaCS-UNICAL/EmbASP">on GitHub</a>
</div>
</div>
</div>
<div class="row">
<div class="col">
<h2 id="Documentation">Documentation</h2>
<!-- Nav tabs -->
<ul class="nav nav-pills nav-justified" id="myTab" role="tablist">
<li class="nav-item">
<a class="nav-link active" href="#architecture" aria-controls="architecture" role="tab" data-toggle="tab" aria-selected="true">Abstract Architecture</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#implementations" aria-controls="implementations" role="tab" data-toggle="tab" aria-selected="false">Implementations</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#examples" aria-controls="examples" role="tab" data-toggle="tab" aria-selected="false">Examples</a>
</li>
</ul>
<!-- Tab panes -->
<div class="tab-content" style="padding-top: 15px">
<div role="tabpanel" class="tab-pane fade show active" id="architecture">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Architecture Description</h3>
</div>
<div class="card-body">
<p>
The general architecture of EmbASP is depicted in the following figure: it is intended as an abstract framework to be implemented
in some object-oriented programming language.
</p>
<p>
In addition, this architecture can be specialized for different platforms, logic languages and solvers.
</p>
<p>
The figure also reports general dependencies among the main modules.
</p>
<figure style="padding-bottom: 1em">
<img class="img-fluid mx-auto d-block" src="img/architecture_v3.svg" alt="Abstract Architecture" onerror="this.src='img/architecture_v3.png'">
<figcaption class="text-center">
Abstract Architecture of the framework.
<br /> Blocks overshadowed in white depict the abstract components of the framework, while
dark-grey blocks represent the modules more closely related to the proposed specialization.
</figcaption>
</figure>
<p>
The framework architecture has been designed by means of four modules:
<code class="layer">Core</code>,
<code class="layer">Platforms</code>,
<code class="layer">Languages</code>, and
<code class="layer">Systems</code>. In the following, we denote with "solver" a logic-based system that is meant to be
used by external application with the help of EmbASP.
</p>
<h4>Core Module</h4>
<p>The
<code class="layer">Core</code> module defines the basic components of the Framework.</p>
<p>
The
<code>Handler</code> component mediates the communication between the Framework and the user that can provide
it with the input program(s) via the component
<code>InputProgram</code>, along with any desired solver's option(s) via the component
<code>OptionDescriptor</code>. A
<code>Service</code> component is meant for managing the chosen solver executions.
</p>
<p>
Two different execution modes can be made available: synchronous or asynchronous. While in the synchronous mode any call
to the execution of the solver is
<em>blocking</em> (i.e., the caller waits until the reasoning task is completed), in asynchronous
mode the call is non-blocking: a
<code>Callback</code> component notifies the caller once the reasoning task is completed. The result of the
execution (i.e., the output of the logic system) is handled by the
<code>Output</code> component, in both modes.</p>
<h4>Platforms Module</h4>
<p>
The
<code class="layer">Platforms</code> module is meant for containing what is platform-dependent; in particular, the
<code>Handler</code> and
<code>Service</code> components from the
<code class="layer">Core</code> module that should be adapted according to the platform at hand, since they take care
of practically launching solvers.
</p>
<h4>Languages Module</h4>
<p>
The
<code class="layer">Languages</code> module defines specific facilities for each supported logic language.
</p>
<p>
The generic
<code>Mapper</code> component is conceived as an utility for managing input and output via objects, if the
programming language at hand permits it.
</p>
<p>
The sub-module ASP comprises components such as
<code>ASPInputProgram</code> that adapts
<code>InputProgram</code> to the ASP case, while
<code>AnswerSet</code> and
<code>AnswerSets</code> represent the
<code>Output</code> for ASP. Moreover the
<code>ASPMapper</code> allow the management of ASP input facts and answer sets via objects.
</p>
<p>
Similarly, the sub-module PDDL includes
<code>PDDLInputProgram</code>,
<code>Action</code>,
<code>Plan</code> and
<code>PDDLMapper</code>.
</p>
<h4>Systems Module</h4>
<p>
The
<code class="layer">Systems</code> module defines what is system-dependent; in particular, the
<code>InputProgram</code>,
<code>Output</code> and
<code>OptionDescriptor</code> components from the
<code class="layer">Core</code> module should be adapted in order to effectively interact with the solver at hand.
</p>
</div>
</div>
</div>
<div role="tabpanel" class="tab-pane fade" id="implementations">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Implementations</h3>
</div>
<div class="card-body">
<!-- Nav tabs -->
<ul class="nav nav-pills nav-justified" role="tablist">
<li class="nav-item">
<a class="nav-link active" href="#implementation_java" aria-controls="implementation_java" role="tab" data-toggle="tab" aria-selected="true">Java implementation</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#implementation_python" aria-controls="implementation_python" role="tab" data-toggle="tab" aria-selected="false">Python implementation</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#implementation_csharp" aria-controls="implementation_csharp" role="tab" data-toggle="tab" aria-selected="false">C# implementation</a>
</li>
</ul>
<!-- Tab panes -->
<div class="tab-content" style="padding-top: 15px">
<div role="tabpanel" class="tab-pane fade show active" id="implementation_java">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Implementation Description</h3>
</div>
<div class="card-body">
<p>
As mentioned above, we provide a
<a href="https://www.oracle.com/java">Java</a> implementation of the EmbASP framework.
</p>
<p>
The following figure provides some details about classes and interfaces of the implementation.
</p>
<figure style="padding-bottom: 1em">
<img class="img-fluid mx-auto d-block" src="img/class_diagram_v3.svg" alt="Simplified Class Diagram" onerror="this.src='img/class_diagram_v3.png'">
<figcaption class="text-center">
Simplified class diagram of the provided Java implementation of EmbASP.
</figcaption>
</figure>
<h4>Core module implementation</h4>
<p>
Each component in the
<code class="layer">Core</code> module has been implemented by means of an homonymous class or interface.
</p>
<p>
In particular, the
<code>Handler</code> class collects
<code>InputProgram</code> and
<code>OptionDescriptor</code> objects communicated by the user.
</p>
<p>
For what the asynchronous mode is concerned, the class
<code>Service</code> depends from the interface
<code>Callback</code>, since once the reasoning service has terminated, the result of the
computation is returned back via a class
<code>Callback</code>.
</p>
<h4>Platforms module implementation</h4>
<p>
In order to support a new platform, the
<code>Handler</code> and
<code>Service</code> components must be adapted.
</p>
<p>
As for the Android platform, we developed an
<code>AndroidHandler</code> that handles the execution of an
<code>AndroidService</code>, which provides facilities to manage the execution of a solver on the
Android platform.
</p>
<p>
Similarly, for the desktop platform we developed a
<code>DesktopHandler</code> and a
<code>DesktopService</code>, which generalizes the usage of a solver on the desktop platform, allowing
both synchronous and asynchronous execution modes.
</p>
<h4>Languages module implementation</h4>
<p>
This module includes specific classes for the management of input and output to ASP and PDDL solvers.
</p>
<p>
The
<code>Mapper</code> component of the
<code class="layer">Languages</code> module is implemented via a
<code>Mapper</code> class, that allows to translate input and output into Java objects.
Such translations are guided by
<a href="https://docs.oracle.com/javase/tutorial/java/annotations">Java Annotations</a>, a form of metadata that mark Java code and provide
information that is not part of the program itself: they have no direct
effect on the operation of the code they annotate.
</p>
<p>
In our setting, we make use of such feature so that it is possible to translate facts into strings and vice-versa via two
custom annotations, defined according to the following syntax:
</p>
<ul>
<li>
<code>@Id (string_name)</code>: the target must be a class, and defines the predicate name (in
the ASP case) and the action name (in the PDDL case) the class is
mapped to;
</li>
<li>
<code>@Param (integer_position)</code>: the target must be a field of a class annotated via
<code>@Id</code>, and defines the term (and its position) in the atom (in the ASP
case) and in the action (in the PDDL case) the field is mapped to.
</li>
</ul>
<p>
By means of the Java Reflection mechanisms, annotations are examined at runtime, and taken into account to properly define
the translation.
</p>
<p>
If the classes intended for the translation are not annotated or not correctly annotated, an exception is raised.
</p>
<p>
In addition to the
<code>Mapper</code>, this module features two sub-modules which are more strictly related
to ASP and PDDL.
</p>
<h4>Systems Module Implementation</h4>
<p>
The classes
<code>DLVAnswerSets</code>,
<code>ClingoAnswerSets</code>,
<code>DLV2AnswerSets</code> and
<code>SPDPlan</code> implement specific extensions of the
<code>AnswerSets</code> or
<code>Plan</code> classes, in charge of manipulating the output of the respective solvers.
</p>
<p>
Moreover, this module can contain classes extending
<code>OptionDescriptor</code> to implement specific options of the solver at hand.
</p>
</div>
</div>
<div class="card card-primary" id="javadoc">
<div class="card-header">
<h3 class="card-title">Javadoc</h3>
</div>
<div class="card-body">
<p>
The Javadoc documentation is available
<a href="javadoc/index.html">here</a>.
</p>
<p>
For an offline usage, you can download it
<a href="javadoc-embasp.zip">here</a>.
</p>
</div>
</div>
<div class="card card-primary" id="class-diagram">
<div class="card-header">
<h3 class="card-title">Class Diagram</h3>
</div>
<div class="card-body">
A complete UML Class Diagram is available
<a href="img/complete_class_diagram2.png">here</a>.
</div>
</div>
</div>
<div role="tabpanel" class="tab-pane fade" id="implementation_python">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Implementation Description</h3>
</div>
<div class="card-body">
<p>
As mentioned above, we provide a
<a href="https://www.python.org/">Python</a> implementation of the EmbASP framework.
</p>
<p>
The following figure provides some details about classes and interfaces of the implementation.
</p>
<figure style="padding-bottom: 1em">
<img class="img-fluid mx-auto d-block" src="img/class_diagram_python.png" alt="Simplified Class Diagram" onerror="this.src='img/class_diagram_v3.png'">
<figcaption class="text-center">
Simplified class diagram of the provided Python implementation of EmbASP.
</figcaption>
</figure>
<h4>Core module implementation</h4>
<p>
Each component in the
<code class="layer">Core</code> module has been implemented by means of an abstract class or generic
classes that will specialize in the following packages.
</p>
<p>
In particular, the
<code>Handler</code> class collects
<code>InputProgram</code> and
<code>OptionDescriptor</code> objects communicated by the user.
</p>
<p>
For what the asynchronous mode is concerned, the class
<code>Service</code> depends from the interface
<code>Callback</code>, since once the reasoning service has terminated, the result of the
computation is returned back via a class
<code>Callback</code>.
</p>
<h4>Platforms module implementation</h4>
<p>
In order to support a new platform, the
<code>Handler</code> and
<code>Service</code> components must be adapted.
</p>
<p>
For the desktop platform we developed a
<code>DesktopHandler</code> and a
<code>DesktopService</code>, which generalizes the usage of a solver on the desktop platform, allowing
both synchronous and asynchronous execution modes.
</p>
<h4>Languages module implementation</h4>
<p>
This module includes specific classes for the management of input and output to ASP and PDDL solvers.
</p>
<p>
The
<code>Mapper</code> component of the
<code class="layer">Languages</code> module is implemented via a
<code>Mapper</code> class, that allows to translate input and output into Python objects.
Such translations are guided by
<code>Predicate</code> abstract class, also present in the module.
</p>
<p>
To make possible translate facts into strings and vice versa, the classes that want to represent a predicate, must extend
the abstract class
<code>Predicate</code>, and must be implemented by including the following code:
</p>
<ul>
<li>
<code>predicateName="string_name"</code>: must be entered as a class field and must contain the predicate
name (in the ASP case) or the action name (in the PDDL case) to map;
</li>
<li>
<code>[("class_field_name_1", int), ("class_field_name_2"), ...]</code>: Is a list that must be passed to super in the constructor, and
must contain so many tuples how many are the class field, containing
the field name, sorted by the position of the terms they represent,
and optionally the keyword
<code>int</code> if the field represents an integer.
</li>
</ul>
<p>
Thanks to the structure of the
<code>Predicate</code> class, this information is passed to the
<code>Mapper</code> class, to correctly perform the translation mechanism.
</p>
<p>
If the classes intended for the translation are not constructed correctly in this way, an exception is raised.
</p>
<p>
In addition to the
<code>Mapper</code>, this module features two sub-modules which are more strictly related
to ASP and PDDL.
</p>
<h4>Systems Module Implementation</h4>
<p>
The classes
<code>DLVAnswerSets</code>,
<code>ClingoAnswerSets</code>,
<code>DLV2AnswerSets</code> and
<code>SPDPlan</code> implement specific extensions of the
<code>AnswerSets</code> or
<code>Plan</code> classes, in charge of manipulating the output of the respective solvers.
</p>
<p>
Moreover, this module can contain classes extending
<code>OptionDescriptor</code> to implement specific options of the solver at hand.
</p>
</div>
</div>
</div>
<div role="tabpanel" class="tab-pane fade" id="implementation_csharp">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Implementation Description</h3>
</div>
<div class="card-body">
In development
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div role="tabpanel" class="tab-pane fade" id="examples">
<div class="card card-primary" id="arch-desc">
<div class="card-header">
<h3 class="card-title">Examples</h3>
</div>
<div class="card-body">
<!-- Nav tabs -->
<ul class="nav nav-pills nav-justified" role="tablist">
<li class="nav-item">
<a class="nav-link active" href="#android_example" aria-controls="android_example" role="tab" data-toggle="tab" aria-selected="true">Example DLV on Android</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#desktop_example" aria-controls="desktop_example" role="tab" data-toggle="tab" aria-selected="false">Example SPD on Desktop</a>
</li>
</ul>
<!-- Tab panes -->
<div class="tab-content" style="padding-top: 15px">
<div role="tabpanel" class="tab-pane fade show active" id="android_example">
<div class="card card-primary" id="getting-started">
<div class="card-header">
<h3 class="card-title">Getting Started</h3>
</div>
<div class="card-body">
<mark>This example is available only in Java due to the restrictions of the Android
mobile operating system.
</mark>
<h4>How to import the framework on Android Studio</h4>
<p>In order to use the framework in your applications you have to import it
as module on Android Studio.
</p>
<ol>
<li>Import the framework module:
<ol>
<li>Download the framework last released
<a href="#release">module</a>.
</li>
<li>In the project view, right-click on your project
<b>New > Module</b>.
</li>
<li>Select
<b>Import .JAR/.AAR Package</b>.
</li>
<li>Select the directory in which the module has been downloaded.
</li>
</ol>
</li>
<li>Set the dependency:
<ol>
<li>In the Android Studio menu:
<b>File > Project Structure
</b>.
</li>
<li>Select your project module (by default called
<b>app</b>).
</li>
<li>In the
<b>Dependencies Tab</b> add as
<b>Module Dependency
</b> the previously imported framework.
</li>
</ol>
</li>
</ol>
</div>
</div>
<div class="card card-primary" id="setting-up">
<div class="card-header">
<h3 class="card-title">Using EmbASP</h3>
</div>
<div class="card-body">
<p>
In the following, we describe an the actual usage of the framework by means of a running example; as a use case, we will
develop a simple Android application for solving Sudoku puzzles.
</p>
<p>
The complete code of this example is freely available
<a href="files/EmbASP_Android_Sudoku.zip">here</a>. Please note that the zip file contains an Android Studio (version
2.3) project and uses the version 3.1.0 of EmbASP.
</p>
<p>
The framework features a annotation-guided mapping, offered by the
<i>ASPMapper</i> component, for two-way translations between strings recognizable
by ASP solvers and objects in the programming language at hand, directly
employable within applications. By means of this feature, the ASP-based
aspects can be separated from the Java coding: the programmer doesn't
even necessarily need to be aware of ASP.
</p>
<p>
Let us think of a user that designed (or has been given) a proper logic program
<i>P</i> to solve a sudoku puzzle and has also an initial schema. We assume
that the initial schema is well-formed i.e. the complete schema solution
exists and is unique. A possible program
<i>P</i> is embedded in the complete example, that, coupled with a set of
facts
<i>F</i> representing the given initial schema, allows to obtain the only
admissible solution.
</p>
<p>
By means of the annotation-guided mapping, the initial schema can be expressed in forms of Java objects. To this extent,
we define the class
<i>Cell</i>, aimed at representing the single cell of the sudoku schema,
as follows:
</p>
<pre><code class="language-java">
@Id("cell")
public class Cell {
@Param(0)
private int row;
@Param(1)
private int column;
@Param(2)
private int value;
[...]
}
</code></pre>
<p>
It is worth noticing how the class has been annotated by two custom annotations, defined according to the following syntax:
</p>
<ul>
<li>
<i>@Id(string_name)</i>: the target must be a class, and defines the
predicate name the class is mapped to;
</li>
<li>
<i>@Param(integer_position)</i>: the target must be a field of a class
annotated via @Id, and defines the term (and its position) in the
ASP atom the field is mapped to.
</li>
</ul>
<p>
Thanks to these annotations the
<i>ASPMapper</i> class will be able to map
<i>Cell</i> objects into strings properly recognizable from the ASP solver
as logic facts of the form
<i>cell(Row,Column,Value)</i>. At this point, we can create an
<a href="https://developer.android.com/reference/android/app/Activity.html">Android Activity Component</a>, and start deploying our sudoku application:
</p>
<pre><code class="language-java">
public class MainActivity extends AppCompatActivity {
[...]
private Handler handler;
@Override
protected void onCreate(Bundle bundle) {
handler = new AndroidHandler(getApplicationContext(), DLVAndroidService.class);
[...]
}
public void onClick(final View view){
startReasoning();
[...]
}
public void startReasoning() {
InputProgram inputProgram = new InputProgram();
for (int i = 0; i < 9; i++){
for (int j = 0; j < 9; j++)
try {
if(sudokuMatrix[i][j]!=0) {
inputProgram.addObjectInput(new Cell(i, j, sudokuMatrix[i][j]));
}
} catch (Exception e) {
// Handle Exception
}
}
handler.addProgram(inputProgram);
String sudokuEncoding = getEncodingFromResources();
handler.addProgram(new InputProgram(sudokuEncoding));
Callback callback = new MyCallback();
handler.startAsync(callback);
}
}
</code></pre>
<p>
The class contains an
<i>Handler</i> instance as field, that is initialized when the
<i>Activity</i> is created as an
<i>AndroidHandler</i>. Required parameters include the
<i>Android Context</i> (an Android utility, needed to start an Android Service
Component) and the type of
<i>AndroidService</i> to use, in our case a
<i>DLVAndroidService</i>.
</p>
<p>
In addiction, in order to represent an initial sudoku schema, the class features a matrix of integers as another field where
position
<i> (i,j) </i> contains the value of cell
<i> (i,j) </i> in the initial schema; cells initially empty are represented
by positions containing zero.
</p>
<p>
The method
<i>startReasoning</i> is in charge of actually managing the reasoning: in
our case, it is invoked in response to a click event that is generated
when the user asks for the solution. It is firstly created an
<i>InputProgram</i> object that is filled with
<i>Cell</i> objects representing the initial schema, which is then provided
to the handler; then it is provided with the sudoku encoding. It could
be loaded, for instance, by means of an utility function that retrieves
it from the
<a href="http://developer.android.com/guide/topics/resources">Android Resources folder</a>, which, within Android applications, is
typically meant for containing images, sounds, files and resources in
general.
</p>
<p>
At this point, the reasoning process can start; since for Android we provide only the asynchronous execution mode, a callback
object is in charge of fetching the output when the ASP system has done.
</p>
<p>
Finally, once the computation is over, from within the callback function the output can be retrieved directly in form of
Java objects. For instance, in our case an inner class
<i>MyCallback</i> implements the interface
<i>Callback</i>:</p>
<pre><code class="language-java">
private class MyCallback implements Callback {
@Override
public void callback(Output o) {
if(!(o instanceof AnswerSets))
return;
AnswerSets answerSets=(AnswerSets)o;
if(answerSets.getAnswersets().isEmpty())
return;
AnswerSet as = answerSets.getAnswersets().get(0);
try {
for(Object obj:as.getAtoms()) {
Cell cell = (Cell) obj;
sudokuMatrix[cell.getRow()][cell.getColumn()] = cell.getValue();
}
} catch (Exception e) {
// Handle Exception
}
displaySolution();
}
}
</code></pre>
</div>
</div>
</div>
<div role="tabpanel" class="tab-pane fade" id="desktop_example">
<div class="card card-primary" id="getting-started">
<div class="card-header">
<h3 class="card-title">Getting Started</h3>
</div>
<div class="card-body">
<div class="row">
<div class="col col-md-6">
<h4>Java version</h4>
<p>
The framework is released as JAR file to be used on a Desktop platform, therefore it can be easily imported and used in any
Java project.
</p>
<p>
The SPD solver is invoked via an HTTP connection using JSON files as data interchange format. In order to manage them, the
framework needs the
<a href="https://cliftonlabs.github.io/json-simple">json-simple library</a> (you can download the JAR and include
directly in your project or you can use Gradle or Maven)
</p>
<!--<p>
It's worth noticing that in order to use the ASP solvers (DLV, clingo and DLV2) on a Desktop platform, the binaries for the
specific machine must be download in advance.
</p>-->
</div>
<div class="col col-md-6">
<h4>Python version</h4>
<p>
The framework is released as EGG file to be used on a Desktop platform, it can be easily installed in a Python installation.
</p>
<p>
The framework is stand alone and does not need any library for its operation, except for a Python installation.
</p>
</div>
</div>
</div>
</div>
<div class="card card-primary" id="setting-up">
<div class="card-header">
<h3 class="card-title">Using EmbASP</h3>
</div>
<div class="card-body">
<p>
In the following, we describe an the actual usage of the framework by means of a running example; as a use case, we will
develop a simple Desktop application to solve the blocks-world problem.
</p>
<p>
The complete code of this example is freely available
<a href="files/EmbASP_Desktop_Blocksworld.zip">here</a>. Please note that the zip file contains an Eclipse (Neon) project
and uses the version 3.1.0 of EmbASP.
</p>
<figure style="padding-bottom: 1em">
<img class="img-fluid mx-auto d-block" src="img/blocks-world.svg" alt="blocks-world configuration" onerror="this.src='img/blocks-world.png'">
<figcaption class="text-center">
Sample configuration for blocks-world.
</figcaption>
</figure>
<p>
We will make use of the annotation-guided mapping, in order to retrieve the actions constituting a PDDL plan via Java objects.
To this purpose, the following classes are intended to represent possible
actions that a blocks-world solution plan can feature:
</p>
<div class="row">
<div class="col col-md-6">
<h4>Java version</h4>
<pre><code class="language-java">
@Id("pick-up")
public class PickUp {
@Param(0)
private String block;
[...]
}
</code></pre>
<pre><code class="language-java">
@Id("put-down")
public class PutDown {
@Param(0)
private String block;
[...]
}
</code></pre>
<pre><code class="language-java">
@Id("stack")
public class Stack {
@Param(0)
private String block1;
@Param(1)
private String block2;
[...]
}
</code></pre>
<pre><code class="language-java">
@Id("unstack")
public class Unstack {
@Param(0)
private String block1;
@Param(1)
private String block2;
[...]
}
</code></pre>
</div>
<div class="col col-md-6">
<h4>Python version</h4>
<pre><code class="language-python">
class PickUp(Predicate):
predicateName="pick-up"
def __init__(self, block=None):
super(PickUp, self).__init__([("block")])
self.block = block
[...]