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https://issues.apache.org/jira/browse/NIFI-3682?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15976670#comment-15976670
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ASF GitHub Bot commented on NIFI-3682:
--------------------------------------
Github user markap14 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1682#discussion_r112450731
--- Diff:
nifi-nar-bundles/nifi-standard-services/nifi-record-serialization-services-bundle/nifi-record-serialization-services/src/main/java/org/apache/nifi/schema/access/HortonworksEncodedSchemaReferenceStrategy.java
---
@@ -0,0 +1,60 @@
+/*
+ * 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.schema.access;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+
+import org.apache.nifi.controller.ConfigurationContext;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.schemaregistry.services.SchemaRegistry;
+import org.apache.nifi.serialization.record.RecordSchema;
+import org.apache.nifi.stream.io.StreamUtils;
+
+public class HortonworksEncodedSchemaReferenceStrategy implements
SchemaAccessStrategy {
--- End diff --
I found the pattern used by looking at source code, since the Schema
Registry is open source. I can look for documentation that spells this out. In
my mind, I would steer clear of calling it something like
IdentifierVersionSchemaReferenceStrategy for a few reasons. Firstly, it's quite
wordy (though I guess mine is too) :) Secondly, the first byte of the pattern
is a 'protocol' value that tells us how to interpret the rest of the bytes, how
many bytes there are, etc. If the Hwx Schema Registry changes their
serialization format - for instance, by adding new fields beyond identifier and
version, or if they decide that the current format is too verbose and remove
the version (assuming that a unique identifier would be given to each
'version') then this strategy can be updated to take advantage of that. If we
went the route of IdentifierVersionSchemaReferenceStrategy, then we would need
yet another strategy and it may be difficult for the user to know which one
they need. Finally, it is not obvious from such a name why it would be used
whereas a name like HortonworksEncodedSchemaReferenceStrategy makes it clear to
users of the Hwx Schema Registry, I think, that this is compatible with the
serializers & deserializers available there.
> Add "Schema Access Strategy" to Record Readers and Writers
> ----------------------------------------------------------
>
> Key: NIFI-3682
> URL: https://issues.apache.org/jira/browse/NIFI-3682
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Extensions
> Reporter: Mark Payne
> Assignee: Mark Payne
> Fix For: 1.2.0
>
>
> Currently the record readers are mostly configured with a Schema Registry
> service and the name of the schema. We should instead allow user to choose
> one of several strategies for determining the schema: Schema Registry +
> schema.name attribute, Schema Registry + identifier and version embedded at
> start of record/stream, avro.schema attribute, embedded schema for cases like
> Avro where the schema can be embedded in the content itself.
> On the writer side, we should also expose these options in order to convey
> the schema information to others.
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