exceptionfactory commented on code in PR #10013:
URL: https://github.com/apache/nifi/pull/10013#discussion_r2222946299


##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {
+                response.getOutputStream().write("Content size is too large to 
display.".getBytes());
+                return;
+            }
+
+            Configuration conf = new Configuration();
+            conf.setBoolean("parquet.avro.readInt96AsFixed", true);
+
+            final InputFile inputFile = new NifiParquetInputFile(new 
ByteArrayInputStream(data), data.length);
+            final ParquetReader<GenericRecord> reader = 
AvroParquetReader.<GenericRecord>builder(inputFile)
+                    .withConf(conf)
+                    .build();
+
+            //Get each column per record and save it to corresponding column 
list
+            GenericRecord record;
+            Gson gson = new GsonBuilder().setPrettyPrinting().create();
+            boolean firstRecord = true;
+
+            while ((record = reader.read()) != null) {
+                if (firstRecord) {
+                    firstRecord = false;
+                } else {
+                    response.getOutputStream().write(",\n".getBytes());
+                }
+
+                
response.getOutputStream().write(gson.toJson(JsonParser.parseString(record.toString())).getBytes());

Review Comment:
   It should be possible to write directly to the output stream, instead of 
creating a string and then writing it to the stream.



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {
+                response.getOutputStream().write("Content size is too large to 
display.".getBytes());
+                return;
+            }
+
+            Configuration conf = new Configuration();
+            conf.setBoolean("parquet.avro.readInt96AsFixed", true);
+
+            final InputFile inputFile = new NifiParquetInputFile(new 
ByteArrayInputStream(data), data.length);
+            final ParquetReader<GenericRecord> reader = 
AvroParquetReader.<GenericRecord>builder(inputFile)
+                    .withConf(conf)
+                    .build();
+
+            //Get each column per record and save it to corresponding column 
list
+            GenericRecord record;
+            Gson gson = new GsonBuilder().setPrettyPrinting().create();

Review Comment:
   Gson should be avoided in general, and Jackson is preferred.



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB

Review Comment:
   This can be declared as a static variable.



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {
+                response.getOutputStream().write("Content size is too large to 
display.".getBytes());
+                return;
+            }
+
+            Configuration conf = new Configuration();
+            conf.setBoolean("parquet.avro.readInt96AsFixed", true);

Review Comment:
   Is there a reason for this property setting? It should be commented if 
needed as to the reason.



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {
+                response.getOutputStream().write("Content size is too large to 
display.".getBytes());
+                return;
+            }
+
+            Configuration conf = new Configuration();
+            conf.setBoolean("parquet.avro.readInt96AsFixed", true);
+
+            final InputFile inputFile = new NifiParquetInputFile(new 
ByteArrayInputStream(data), data.length);
+            final ParquetReader<GenericRecord> reader = 
AvroParquetReader.<GenericRecord>builder(inputFile)
+                    .withConf(conf)
+                    .build();
+
+            //Get each column per record and save it to corresponding column 
list
+            GenericRecord record;
+            Gson gson = new GsonBuilder().setPrettyPrinting().create();
+            boolean firstRecord = true;
+
+            while ((record = reader.read()) != null) {
+                if (firstRecord) {
+                    firstRecord = false;
+                } else {
+                    response.getOutputStream().write(",\n".getBytes());
+                }
+
+                
response.getOutputStream().write(gson.toJson(JsonParser.parseString(record.toString())).getBytes());
+            }
+        } catch (final Throwable t) {
+            logger.warn("Unable to format FlowFile content", t);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Unable 
to format FlowFile content");
+        }
+    }
+
+    private byte[] getInputStreamBytes(final InputStream inputStream, long 
maxBytes) throws IOException {

Review Comment:
   This method can be refactored to use a ByteArrayOutputStream and transferTo, 
avoiding the intermediate List of byte arrays.



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {

Review Comment:
   This can be simplified:
   ```suggestion
               if (data.length == 0) {
   ```



##########
nifi-extension-bundles/nifi-parquet-bundle/nifi-parquet-content-viewer/src/main/java/org/apache/parquet/web/controller/ParquetContentViewerController.java:
##########
@@ -0,0 +1,167 @@
+/*
+ * 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.parquet.web.controller;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParser;
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.http.HttpServlet;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.nifi.authorization.AccessDeniedException;
+import org.apache.nifi.web.ContentAccess;
+import org.apache.nifi.web.ContentRequestContext;
+import org.apache.nifi.web.DownloadableContent;
+import org.apache.nifi.web.HttpServletContentRequestContext;
+import org.apache.nifi.web.ResourceNotFoundException;
+import org.apache.parquet.avro.AvroParquetReader;
+import org.apache.parquet.hadoop.ParquetReader;
+import org.apache.parquet.io.InputFile;
+import org.apache.nifi.parquet.shared.NifiParquetInputFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.util.ArrayList;
+import java.util.List;
+
+public class ParquetContentViewerController extends HttpServlet {
+    private static final Logger logger = 
LoggerFactory.getLogger(ParquetContentViewerController.class);
+
+    @Override
+    public void doGet(final HttpServletRequest request, final 
HttpServletResponse response) throws IOException {
+        final ContentRequestContext requestContext = new 
HttpServletContentRequestContext(request);
+
+        final ServletContext servletContext = request.getServletContext();
+        final ContentAccess contentAccess = (ContentAccess) 
servletContext.getAttribute("nifi-content-access");
+        // get the content
+        final DownloadableContent downloadableContent;
+        try {
+            downloadableContent = contentAccess.getContent(requestContext);
+        } catch (final ResourceNotFoundException e) {
+            logger.warn("Content not found", e);
+            response.sendError(HttpURLConnection.HTTP_NOT_FOUND, "Content not 
found");
+            return;
+        } catch (final AccessDeniedException e) {
+            logger.warn("Content access denied", e);
+            response.sendError(HttpURLConnection.HTTP_FORBIDDEN, "Content 
access denied");
+            return;
+        } catch (final Exception e) {
+            logger.warn("Content retrieval failed", e);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Content 
retrieval failed");
+            return;
+        }
+
+        response.setStatus(HttpServletResponse.SC_OK);
+
+        final boolean formatted = 
Boolean.parseBoolean(request.getParameter("formatted"));
+        if (!formatted) {
+            final InputStream contentStream = downloadableContent.getContent();
+            contentStream.transferTo(response.getOutputStream());
+            return;
+        }
+
+        // allow the user to drive the data type but fall back to the content 
type if necessary
+        String displayName = request.getParameter("mimeTypeDisplayName");
+        if (displayName == null) {
+            displayName = downloadableContent.getType();
+        }
+
+        if (displayName == null || !(displayName.equals("parquet") || 
displayName.equals("application/vnd.apache.parquet"))) {
+            response.sendError(HttpURLConnection.HTTP_BAD_REQUEST, "Unknown 
content type");
+            return;
+        }
+
+        try {
+            //Convert InputStream to a seekable InputStream
+            long maxBytes = 1024 * 1024 * 2; //10MB
+            byte[] data = 
getInputStreamBytes(downloadableContent.getContent(), maxBytes);
+
+            if (data.length < 1) {
+                response.getOutputStream().write("Content size is too large to 
display.".getBytes());
+                return;
+            }
+
+            Configuration conf = new Configuration();
+            conf.setBoolean("parquet.avro.readInt96AsFixed", true);
+
+            final InputFile inputFile = new NifiParquetInputFile(new 
ByteArrayInputStream(data), data.length);
+            final ParquetReader<GenericRecord> reader = 
AvroParquetReader.<GenericRecord>builder(inputFile)
+                    .withConf(conf)
+                    .build();
+
+            //Get each column per record and save it to corresponding column 
list
+            GenericRecord record;
+            Gson gson = new GsonBuilder().setPrettyPrinting().create();
+            boolean firstRecord = true;
+
+            while ((record = reader.read()) != null) {
+                if (firstRecord) {
+                    firstRecord = false;
+                } else {
+                    response.getOutputStream().write(",\n".getBytes());
+                }
+
+                
response.getOutputStream().write(gson.toJson(JsonParser.parseString(record.toString())).getBytes());
+            }
+        } catch (final Throwable t) {
+            logger.warn("Unable to format FlowFile content", t);
+            response.sendError(HttpURLConnection.HTTP_INTERNAL_ERROR, "Unable 
to format FlowFile content");
+        }
+    }
+
+    private byte[] getInputStreamBytes(final InputStream inputStream, long 
maxBytes) throws IOException {
+        final int bufferSize = 8 * 1024; //8KB

Review Comment:
   This can be set to a static variable.



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