[jira] [Commented] (METRON-435) Create Stellar REPL

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/METRON-435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15507372#comment-15507372 ] 

ASF GitHub Bot commented on METRON-435:
---------------------------------------

Github user nickwallen commented on a diff in the pull request:

    https://github.com/apache/incubator-metron/pull/262#discussion_r79681676
  
    --- Diff: metron-platform/metron-common/src/main/java/org/apache/metron/common/stellar/shell/StellarExecutor.java ---
    @@ -0,0 +1,130 @@
    +/*
    + *
    + *  Licensed to the Apache Software Foundation (ASF) under one
    + *  or more contributor license agreements.  See the NOTICE file
    + *  distributed with this work for additional information
    + *  regarding copyright ownership.  The ASF licenses this file
    + *  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 "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 org.apache.metron.common.stellar.shell;
    +
    +import com.fasterxml.jackson.core.type.TypeReference;
    +import org.apache.commons.lang.StringUtils;
    +import org.apache.curator.framework.CuratorFramework;
    +import org.apache.metron.common.configuration.ConfigurationsUtils;
    +import org.apache.metron.common.dsl.Context;
    +import org.apache.metron.common.dsl.FunctionResolver;
    +import org.apache.metron.common.dsl.MapVariableResolver;
    +import org.apache.metron.common.dsl.StellarFunctions;
    +import org.apache.metron.common.dsl.VariableResolver;
    +import org.apache.metron.common.stellar.StellarProcessor;
    +import org.apache.metron.common.utils.JSONUtils;
    +
    +import java.io.ByteArrayInputStream;
    +import java.util.Collections;
    +import java.util.HashMap;
    +import java.util.Map;
    +
    +import static org.apache.metron.common.configuration.ConfigurationsUtils.readGlobalConfigBytesFromZookeeper;
    +
    +/**
    + * Executes Stellar expressions and maintains state across multiple invocations.
    + */
    +public class StellarExecutor {
    +
    +  /**
    +   * The variables known by Stellar.
    +   */
    +  private Map<String, Object> variables;
    +
    +  /**
    +   * The function resolver.
    +   */
    +  private FunctionResolver functionResolver ;
    +
    +  /**
    +   * The context
    +   */
    +  private Context context;
    +
    +  public StellarExecutor() throws Exception {
    +    this(null);
    +  }
    +
    +  public StellarExecutor(String zookeeperUrl) throws Exception {
    +    this.variables = new HashMap<>();
    +    this.functionResolver = new StellarFunctions().FUNCTION_RESOLVER();
    +    this.context = getContext(zookeeperUrl);
    +  }
    +
    +  /**
    +   * Creates a Context initialized with configuration stored in Zookeeper.
    +   * @param zookeeperUrl The Zookeeper URL.
    +   */
    +  private Context getContext(String zookeeperUrl) throws Exception {
    +    Context context = Context.EMPTY_CONTEXT();
    +
    +    // load global configuration from zookeeper
    +    if(StringUtils.isNotBlank(zookeeperUrl)) {
    +      try (CuratorFramework client = ConfigurationsUtils.getClient(zookeeperUrl)) {
    +        client.start();
    +
    +        Map<String, Object> global = JSONUtils.INSTANCE.load(
    +                new ByteArrayInputStream(readGlobalConfigBytesFromZookeeper(client)),
    +                new TypeReference<Map<String, Object>>() {
    +                });
    +
    +        context = new Context.Builder()
    +                .with(Context.Capabilities.GLOBAL_CONFIG, () -> global)
    --- End diff --
    
    Added zookeeper client to the Context.


> Create Stellar REPL
> -------------------
>
>                 Key: METRON-435
>                 URL: https://issues.apache.org/jira/browse/METRON-435
>             Project: Metron
>          Issue Type: Improvement
>            Reporter: Nick Allen
>            Assignee: Nick Allen
>
> Create a REPL (Read Eval Print Loop) for the Stellar language that helps in debugging, troubleshooting and learning Stellar. The Stellar DSL (domain specific language) is used to act upon streaming data within Apache Storm. It is difficult to troubleshoot Stellar when it can only be executed within a Storm topology. This REPL is intended to help mitigate that problem by allowing a user to replicate data encountered in production, isolate initialization errors, or understand function resolution problems.



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