Java tutorial
/** * Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com) * * 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 com.linkedin.pinot.common.utils; import com.google.common.base.Preconditions; import com.linkedin.pinot.common.data.FieldSpec; import com.linkedin.pinot.common.data.Schema; import java.io.IOException; import java.net.URL; import java.util.concurrent.TimeUnit; import javax.annotation.Nonnull; import javax.annotation.Nullable; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.methods.DeleteMethod; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod; import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity; import org.apache.commons.httpclient.methods.multipart.Part; import org.apache.commons.httpclient.methods.multipart.StringPart; import org.apache.commons.httpclient.params.HttpMethodParams; import org.apache.helix.ZNRecord; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Utility class which contains {@link Schema} related operations. */ public class SchemaUtils { private static final Logger LOGGER = LoggerFactory.getLogger(SchemaUtils.class); private static final HttpClient HTTP_CLIENT = new HttpClient(); private SchemaUtils() { } /** * Fetch {@link Schema} from a {@link ZNRecord}. */ public static Schema fromZNRecord(@Nonnull ZNRecord record) throws IOException { String schemaJSON = record.getSimpleField("schemaJSON"); return Schema.fromString(schemaJSON); } /** * Wrap {@link Schema} into a {@link ZNRecord}. */ public static ZNRecord toZNRecord(@Nonnull Schema schema) throws IllegalArgumentException, IllegalAccessException { ZNRecord record = new ZNRecord(schema.getSchemaName()); record.setSimpleField("schemaJSON", schema.getJSONSchema()); return record; } /** * Given host, port and schema name, send a http GET request to download the {@link Schema}. * * @return schema on success. * <P><code>null</code> on failure. */ public static @Nullable Schema getSchema(@Nonnull String host, int port, @Nonnull String schemaName) { Preconditions.checkNotNull(host); Preconditions.checkNotNull(schemaName); try { URL url = new URL("http", host, port, "/schemas/" + schemaName); GetMethod httpGet = new GetMethod(url.toString()); try { int responseCode = HTTP_CLIENT.executeMethod(httpGet); String response = httpGet.getResponseBodyAsString(); if (responseCode >= 400) { // File not find error code. if (responseCode == 404) { LOGGER.info("Cannot find schema: {} from host: {}, port: {}", schemaName, host, port); } else { LOGGER.warn("Got error response code: {}, response: {}", responseCode, response); } return null; } return Schema.fromString(response); } finally { httpGet.releaseConnection(); } } catch (Exception e) { LOGGER.error("Caught exception while getting the schema: {} from host: {}, port: {}", schemaName, host, port, e); return null; } } /** * Given host, port and schema, send a http POST request to upload the {@link Schema}. * * @return <code>true</code> on success. * <P><code>false</code> on failure. */ public static boolean postSchema(@Nonnull String host, int port, @Nonnull Schema schema) { Preconditions.checkNotNull(host); Preconditions.checkNotNull(schema); try { URL url = new URL("http", host, port, "/schemas"); PostMethod httpPost = new PostMethod(url.toString()); try { Part[] parts = { new StringPart(schema.getSchemaName(), schema.toString()) }; MultipartRequestEntity requestEntity = new MultipartRequestEntity(parts, new HttpMethodParams()); httpPost.setRequestEntity(requestEntity); int responseCode = HTTP_CLIENT.executeMethod(httpPost); if (responseCode >= 400) { String response = httpPost.getResponseBodyAsString(); LOGGER.warn("Got error response code: {}, response: {}", responseCode, response); return false; } return true; } finally { httpPost.releaseConnection(); } } catch (Exception e) { LOGGER.error("Caught exception while posting the schema: {} to host: {}, port: {}", schema.getSchemaName(), host, port, e); return false; } } /** * Given host, port and schema name, send a http DELETE request to delete the {@link Schema}. * * @return <code>true</code> on success. * <P><code>false</code> on failure. */ public static boolean deleteSchema(@Nonnull String host, int port, @Nonnull String schemaName) { Preconditions.checkNotNull(host); Preconditions.checkNotNull(schemaName); try { URL url = new URL("http", host, port, "/schemas/" + schemaName); DeleteMethod httpDelete = new DeleteMethod(url.toString()); try { int responseCode = HTTP_CLIENT.executeMethod(httpDelete); if (responseCode >= 400) { String response = httpDelete.getResponseBodyAsString(); LOGGER.warn("Got error response code: {}, response: {}", responseCode, response); return false; } return true; } finally { httpDelete.releaseConnection(); } } catch (Exception e) { LOGGER.error("Caught exception while getting the schema: {} from host: {}, port: {}", schemaName, host, port, e); return false; } } /** * Compare two schemas ignoring their version number. * * @return <code>true</code> if two schemas equal to each other. * <p><code>false</code>if two schemas do not equal to each other. */ public static boolean equalsIgnoreVersion(@Nonnull Schema schema1, @Nonnull Schema schema2) { Preconditions.checkNotNull(schema1); Preconditions.checkNotNull(schema2); return schema1.getSchemaName().equals(schema2.getSchemaName()) && schema1.getFieldSpecMap().equals(schema2.getFieldSpecMap()); } /** * An example on how to use this utility class. */ public static void main(String[] args) { Schema schema = new Schema.SchemaBuilder().setSchemaName("testSchema") .addSingleValueDimension("dimension", FieldSpec.DataType.DOUBLE) .addMetric("metric", FieldSpec.DataType.INT).addTime("time", TimeUnit.DAYS, FieldSpec.DataType.INT) .build(); System.out.println(postSchema("localhost", 8100, schema)); Schema fetchedSchema = getSchema("localhost", 8100, "testSchema"); Preconditions.checkNotNull(fetchedSchema); System.out.println(fetchedSchema); System.out.println(equalsIgnoreVersion(schema, fetchedSchema)); System.out.println(deleteSchema("localhost", 8100, "testSchema")); } }