org.apache.iotdb.pipe.api.PipeSource Maven / Gradle / Ivy
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* to you 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
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*/
package org.apache.iotdb.pipe.api;
import org.apache.iotdb.pipe.api.customizer.configuration.PipeSourceRuntimeConfiguration;
import org.apache.iotdb.pipe.api.customizer.parameter.PipeParameterValidator;
import org.apache.iotdb.pipe.api.customizer.parameter.PipeParameters;
import org.apache.iotdb.pipe.api.event.Event;
/**
* PipeSource
*
* {@link PipeSource} is responsible for capturing {@link Event}s from sources.
*
*
Various data sources can be supported by implementing different {@link PipeSource} classes.
*
*
The lifecycle of a {@link PipeSource} is as follows:
*
*
* - When a collaboration task is created, the KV pairs of `WITH EXTRACTOR` clause in SQL are
* parsed and the validation method {@link PipeSource#validate(PipeParameterValidator)} will
* be called to validate the {@link PipeParameters}.
*
- Before the collaboration task starts, the method {@link
* PipeSource#customize(PipeParameters, PipeSourceRuntimeConfiguration)} will be called to
* configure the runtime behavior of the {@link PipeSource}.
*
- Then the method {@link PipeSource#start()} will be called to start the {@link PipeSource}.
*
- While the collaboration task is in progress, the method {@link PipeSource#supply()} will be
* called to capture {@link Event}s from sources and then the {@link Event}s will be passed to
* the {@link PipeProcessor}.
*
- The method {@link PipeSource#close()} will be called when the collaboration task is
* cancelled (the `DROP PIPE` command is executed).
*
*/
public interface PipeSource extends PipeExtractor {
/**
* This method is mainly used to validate {@link PipeParameters} and it is executed before {@link
* PipeSource#customize(PipeParameters, PipeSourceRuntimeConfiguration)} is called.
*
* @param validator the validator used to validate {@link PipeParameters}
* @throws Exception if any {@link PipeParameters} is invalid
*/
void validate(PipeParameterValidator validator) throws Exception;
/**
* This method is mainly used to customize {@link PipeSource}. In this method, the user can do the
* following things:
*
*
* - Use {@link PipeParameters} to parse key-value pair attributes entered by the user.
*
- Set the running configurations in {@link PipeSourceRuntimeConfiguration}.
*
*
* This method is called after the method {@link PipeSource#validate(PipeParameterValidator)}
* is called.
*
* @param parameters used to parse the input {@link PipeParameters} entered by the user
* @param configuration used to set the required properties of the running {@link PipeSource}
* @throws Exception the user can throw errors if necessary
*/
void customize(PipeParameters parameters, PipeSourceRuntimeConfiguration configuration)
throws Exception;
/**
* Start the {@link PipeSource}. After this method is called, {@link Event}s should be ready to be
* supplied by {@link PipeSource#supply()}. This method is called after {@link
* PipeSource#customize(PipeParameters, PipeSourceRuntimeConfiguration)} is called.
*
* @throws Exception the user can throw errors if necessary
*/
void start() throws Exception;
/**
* Supply single {@link Event} from the {@link PipeSource} and the caller will send the {@link
* Event} to the {@link PipeProcessor}. This method is called after {@link PipeSource#start()} is
* called.
*
* @return the {@link Event} to be supplied. the {@link Event} may be {@code null} if the {@link
* PipeSource} has no more {@link Event}s at the moment, but the {@link PipeSource} is still
* running for more {@link Event}s.
* @throws Exception the user can throw errors if necessary
*/
Event supply() throws Exception;
}