| <html><head><META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>3.3.3. Handling of conflicts</title><link href="style.css" rel="stylesheet" type="text/css"><meta content="DocBook XSL Stylesheets V1.72.0" name="generator"><link rel="start" href="index.html" title="The VIATRA2 Model Transformation Framework"><link rel="up" href="sec_GTRuleBehaviour.html" title="3.3. Behavioural Specification of Graph Transformation Rules"><link rel="prev" href="sec_PostconditionSpec.html" title="3.3.2. Complete behavioral specification of postcondition patterns"><link rel="next" href="sec_InvokeGTRule.html" title="3.4. Invocation of Graph Transformation Rules"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table summary="Navigation header" width="100%"><tr><th align="center" colspan="3">3.3.3. Handling of conflicts</th></tr><tr><td align="left" width="20%"><a accesskey="p" href="sec_PostconditionSpec.html">Prev</a> </td><th align="center" width="60%">3.3. Behavioural Specification of Graph Transformation Rules</th><td align="right" width="20%"> <a accesskey="n" href="sec_InvokeGTRule.html">Next</a></td></tr></table><hr></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="sec_ConflictHandling"></a>3.3.3. Handling of conflicts</h4></div></div></div><p> | |
| If conflicting behavior is defined for a model element in the effect set, then | |
| it is a run-time exception, and the execution is terminated. Conflicts and | |
| ambiguities arise between the following elementary operations: | |
| </p><div class="itemizedlist"><ul type="disc"><li><p> | |
| <code class="computeroutput">keep(X)</code> | |
| and | |
| <code class="computeroutput">deleteEntity(X)</code> | |
| or | |
| <code class="computeroutput">deleteRelation(R)</code> | |
| (delete-use conflict) | |
| </p></li><li><p> | |
| <code class="computeroutput">newRelation(R, A, B)</code> | |
| and | |
| <code class="computeroutput">deleteEntity(A)</code> | |
| or | |
| <code class="computeroutput">deleteEntity(B)</code> | |
| (or | |
| <code class="computeroutput">deleteRelation(A)</code> | |
| or | |
| <code class="computeroutput">deleteRelation(B)</code> | |
| ) (create-delete conflict) | |
| </p></li><li><p> | |
| <code class="computeroutput">move(X, A)</code> | |
| and | |
| <code class="computeroutput">move(X,B)</code> | |
| if | |
| <code class="computeroutput">A B</code> | |
| </p></li><li><p> | |
| <code class="computeroutput">setFrom(R,A)</code> | |
| and | |
| <code class="computeroutput">setFrom(R,B)</code> | |
| if | |
| <code class="computeroutput">A B</code> | |
| </p></li><li><p> | |
| <code class="computeroutput">setTo(R,A)</code> | |
| and | |
| <code class="computeroutput">setTo(R,B)</code> | |
| if | |
| <code class="computeroutput">A B</code> | |
| </p></li><li><p> | |
| <code class="computeroutput">newEntity(X)</code> | |
| and no | |
| <code class="computeroutput">move(X,A)</code> | |
| in the effect set (thus when creating an entity, it should be assigned to a parent entity) | |
| </p></li></ul></div><p> | |
| It is also a run-time exception if a constraint in the <span class="emphasis"><em>check set</em></span> is | |
| violated after resolving the postcondition pattern. Here constraint violation is | |
| caused in the following cases: | |
| </p><div class="itemizedlist"><ul type="disc"><li><p> | |
| <code class="computeroutput">move(X, A)</code> | |
| and | |
| <code class="computeroutput">descendantOf(X,B)</code> | |
| if | |
| <code class="computeroutput">A</code> | |
| is not a descendant of | |
| <code class="computeroutput">B</code> | |
| </p></li><li><p> | |
| <code class="computeroutput">newInstanceOf(X,A)</code> | |
| and | |
| <code class="computeroutput">instanceOf(X,B)</code> | |
| if | |
| <code class="computeroutput">A B</code> | |
| </p></li></ul></div><p> | |
| Note that the pattern matching phase and the model manipulation phase (i.e | |
| handling of precondition and postcondition patterns, respectively) are separate | |
| phases, and a conflict only arises if the model manipulation part contains | |
| ambiguous modifications. | |
| </p><div class="highlights"><a name="def_GTRuleBehaviour_Remark"></a><p><b>Remark. </b> | |
| In theory, the effect set and check set is passed to the action part of a GT | |
| rule to enable the detection of conflicts between the postcondition pattern | |
| and ASM model manipulation rules in the action part. However, this is not | |
| checked in the current release. | |
| Furthermore, since transaction handling is also not part of the current | |
| release, not all conflicts are guaranteed to be detected by the | |
| engine at run-time. | |
| However, as a main rule of thumb, non-deleting GT rules invoked by a | |
| <a href="def_ForallRule.html" title="4.3.7. Forall Rule">forall rule</a> are deterministic and free of undetectable | |
| conflicts (by their construction) already in the current release. | |
| </p></div><p> | |
| <a href="sec_ConflictHandling.html#tab:VTCL_EntManipBehav" title="Table 2.1. Behavior table for entity manipulation">Table 2.1, “Behavior table for entity manipulation”</a> and <a href="sec_ConflictHandling.html#tab:VTCL_RelManipBehav" title="Table 2.2. Behavior table for relation manipulation (both the source A and target B are entities)">Table 2.2, “Behavior table for relation manipulation (both the source A and target B are entities)”</a> | |
| below summarizes how model manipulation can be carried out by the | |
| postcondition. | |
| </p><p> | |
| </p><div class="table"><a name="tab:VTCL_EntManipBehav"></a><p class="title"><b>Table 2.1. Behavior table for entity manipulation</b></p><div class="table-contents"><table summary="Behavior table for entity manipulation" border="1"><colgroup><col><col><col></colgroup><thead><tr><th><span class="strong"><strong>Effect</strong></span></th><th><span class="strong"><strong>Pattern body (Post)</strong></span></th><th><span class="strong"><strong>Pattern parameters (Post)</strong></span></th><th><span class="strong"><strong>Further Conditions on X</strong></span></th><th><span class="strong"><strong>Conditions on M</strong></span></th><th><span class="strong"><strong>Side effects</strong></span></th></tr></thead><tbody><tr><td><span class="strong"><strong>Leaves entity X unchanged</strong></span></td><td>entity(X) in M; </td><td>X is a ground parameter of Post </td><td>The parent of X is (already) M prior to rule application </td><td>M is bound to an entity </td><td>None </td></tr><tr><td><span class="strong"><strong>Moves entity X to new parent M</strong></span></td><td>entity(X) in M; </td><td>X is a ground parameter of Post </td><td>The parent of X is not M prior to rule application </td><td>M is bound to an entity or entity M is to be created by Post </td><td>None </td></tr><tr><td><span class="strong"><strong>Creates new entity X with M as parent</strong></span></td><td>entity(X) in M; </td><td>X is <span class="emphasis"><em>not</em></span> a parameter of Post, or if so, it is <span class="emphasis"><em>not</em></span> ground </td><td>None </td><td>M is either bound to an entity or entity M is to be created by Post </td><td>None </td></tr><tr><td><span class="emphasis"><em>move_content</em></span> <span class="strong"><strong>Deletes entity X (with semantics)</strong></span></td><td>X does not appear in pattern body </td><td>X is a ground parameter of Post </td><td>X is bound to an entity </td><td>None </td><td>delete(X) ASM rule is called with move_contents semantics, i.e. all incoming and outgoing relations and relationships are also deleted, but the children of X are preserved </td></tr></tbody></table></div><p></p></div><br class="table-break"><div class="table"><a name="tab:VTCL_RelManipBehav"></a><p class="title"><b>Table 2.2. Behavior table for relation manipulation (both the source A and target B are entities)</b></p><div class="table-contents"><table summary="Behavior table for relation manipulation (both the source A and target B are entities)" border="1"><colgroup><col><col><col></colgroup><thead><tr><th><span class="strong"><strong>Effect</strong></span></th><th><span class="strong"><strong>Pattern body (Post)</strong></span></th><th><span class="strong"><strong>Pattern parameters (Post)</strong></span></th><th><span class="strong"><strong>Further Conditions on R</strong></span></th><th><span class="strong"><strong>Conditions on source (A) and target (B)</strong></span></th><th><span class="strong"><strong>Side effects</strong></span></th></tr></thead><tbody><tr><td><span class="strong"><strong>Leaves relation R unchanged</strong></span></td><td>relation(R, A, B); </td><td>R is a ground parameter of Post </td><td>A and B is (already) the source and target of R prior to rule application </td><td>(1) A and B are ground variables, (2) none of them is to be deleted by Post </td><td>None </td></tr><tr><td><span class="strong"><strong>Redirects relation R to lead out from A (setFrom)</strong></span></td><td>relation(R, A, B); </td><td>R is a ground parameter of Post </td><td>A is not the source of R prior to rule application </td><td>(1) A and B are ground variables, or (2) they are created by Post, (3) none of them is to be deleted by Post </td><td>If the type of R is an aggregation, then B is moved to the new parent A </td></tr><tr><td><span class="strong"><strong>Redirects relation R to lead into B (setTo)</strong></span></td><td>relation(R, A, B); </td><td>R is a ground parameter of Post </td><td>B is not the target of R prior to rule application </td><td>(1) A and B are ground variables, or (2) they are created by Post, (3) none of them is to be deleted by Post </td><td>If the type of R is an aggregation, then B is moved to parent A </td></tr><tr><td><span class="strong"><strong>Creates relation R with A as source and B as target</strong></span></td><td>relation(R, A, B); </td><td>R is <span class="emphasis"><em>not</em></span> a parameter of Post, or if so, it is <span class="emphasis"><em>not</em></span> ground </td><td>None </td><td>(1) A and B are ground variables, or (2) they are created by Post, (3) none of them is to be deleted by Post </td><td>If the type of R is an aggregation, then B is moved to parent A </td></tr><tr><td><span class="strong"><strong>Deletes relation R</strong></span></td><td>R does not appear in pattern body </td><td>R is a ground parameter of Post </td><td>R is bound to a relation </td><td>None </td><td>None, i.e. B is not moved from A </td></tr></tbody></table></div><p></p></div><br class="table-break"></div><div class="navfooter"><hr><table summary="Navigation footer" width="100%"><tr><td align="left" width="40%"><a accesskey="p" href="sec_PostconditionSpec.html">Prev</a> </td><td align="center" width="20%"><a accesskey="u" href="sec_GTRuleBehaviour.html">Up</a></td><td align="right" width="40%"> <a accesskey="n" href="sec_InvokeGTRule.html">Next</a></td></tr><tr><td valign="top" align="left" width="40%">3.3.2. 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