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First, you need to decide if you want to place the operator in a new OSGi bundle or in an existing one. Independently of that, the operator must be placed in a bundle ending with logicaloperator if it should be integrated automatically.
To create your own logical operator you need to extend AbstractLogicalOperator (which implements ILogicalOperator). For convenience reasons there are base implementations for operators with single input (UnaryLogicalOp) and binary input (BinaryLogicalOp). As a naming convention, the class name should end with AO (for algebra operator).
This class must provide (at least) two constructors and the clone method. The default constructor is required as instances of logical operators are created by newInstance(). Clone must call the copy constructor and the copy constructor must call the super copy constructor! If at runtime an error like "has no owner" is called, in most cases this is because of the missing call to the super copy constructor.
Finally, the class needs setters and getters for the parameter it should keep.
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/**********************************************************************************
* Copyright 2011 The Odysseus Team
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.uniol.inf.is.odysseus.core.server.logicaloperator;
import java.util.List;
import de.uniol.inf.is.odysseus.core.predicate.IPredicate;
import de.uniol.inf.is.odysseus.core.server.logicaloperator.annotations.LogicalOperator;
import de.uniol.inf.is.odysseus.core.server.logicaloperator.annotations.Parameter;
import de.uniol.inf.is.odysseus.core.server.logicaloperator.builder.PredicateParameter;
@LogicalOperator(name="ROUTE", minInputPorts=1, maxInputPorts=1)
public class RouteAO extends UnaryLogicalOp {
private static final long serialVersionUID = -8015847502104587689L;
public RouteAO(){
super();
}
public RouteAO(RouteAO routeAO){
super(routeAO);
}
@Override
@Parameter(type=PredicateParameter.class, isList=true)
public void setPredicates(List<IPredicate<?>> predicates) {
super.setPredicates(predicates);
}
@Override
public AbstractLogicalOperator clone() {
return new RouteAO(this);
}
} |
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