Github user ijokarumawak commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2558#discussion_r194971580
--- Diff:
nifi-nar-bundles/nifi-standard-services/nifi-lookup-services-bundle/nifi-lookup-services/src/main/java/org/apache/nifi/lookup/DistributedMapCacheLookupService.java
---
@@ -0,0 +1,127 @@
+/*
+ * 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.nifi.lookup;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnEnabled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.controller.AbstractControllerService;
+import org.apache.nifi.controller.ConfigurationContext;
+import org.apache.nifi.distributed.cache.client.Deserializer;
+import org.apache.nifi.distributed.cache.client.DistributedMapCacheClient;
+import org.apache.nifi.distributed.cache.client.Serializer;
+import
org.apache.nifi.distributed.cache.client.exception.DeserializationException;
+import
org.apache.nifi.distributed.cache.client.exception.SerializationException;
+
+@Tags({"lookup", "enrich", "key", "value", "map", "cache", "distributed"})
+@CapabilityDescription("Allows to choose a distributed map cache client to
retrieve the value associated to a key. "
+ + "The coordinates that are passed to the lookup must contain the key
'key'.")
+public class DistributedMapCacheLookupService extends
AbstractControllerService implements StringLookupService {
+ private static final String KEY = "key";
--- End diff --
LookupAttribute processor loops through dynamic properties to fetch
multiple keys, but it only supports single coordinates.
|Dynamic property name|Dynamic property value|Result|
|------------------------|------------------------|------|
|resultA|`${attributeAKey}`|Lookup cache with `attributeAKey` FlowFile
attribute value and put it to `resultA` attribute|
|resultB|`${attributeBKey}`|Lookup cache with `attributeBKey` FlowFile
attribute value and put it to `resultB` attribute|
Since this LookupService implements StringLookupService, I think it is
correct to require a "key" to fetch the String.
---
