stevenzwu commented on code in PR #12774:
URL: https://github.com/apache/iceberg/pull/12774#discussion_r2376949174


##########
core/src/main/java/org/apache/iceberg/formats/FormatModelRegistry.java:
##########
@@ -0,0 +1,244 @@
+/*
+ * 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.iceberg.data;
+
+import java.util.List;
+import java.util.Map;
+import org.apache.iceberg.ContentFile;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DeleteFile;
+import org.apache.iceberg.FileContent;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.common.DynMethods;
+import org.apache.iceberg.deletes.EqualityDeleteWriter;
+import org.apache.iceberg.deletes.PositionDelete;
+import org.apache.iceberg.deletes.PositionDeleteWriter;
+import org.apache.iceberg.encryption.EncryptedOutputFile;
+import org.apache.iceberg.io.DataWriter;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.FormatModel;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.ReadBuilder;
+import org.apache.iceberg.io.WriteBuilder;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.util.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A registry that manages file-format-specific readers and writers through a 
unified object model
+ * factory interface.
+ *
+ * <p>This registry provides access to {@link ReadBuilder}s for data 
consumption and various writer
+ * builders:
+ *
+ * <ul>
+ *   <li>{@link WriteBuilder} for basic file writing,
+ *   <li>{@link DataWriteBuilder} for data files,
+ *   <li>{@link EqualityDeleteWriteBuilder} for equality deletes,
+ *   <li>{@link PositionDeleteWriteBuilder} for position deletes.
+ * </ul>
+ *
+ * The appropriate builder is selected based on {@link FileFormat} and object 
model name.
+ *
+ * <p>{@link FormatModel} objects are registered through {@link 
#register(FormatModel)} and used for
+ * creating readers and writers. Read builders are returned directly from the 
factory. Write
+ * builders may be wrapped in specialized content file writer implementations 
depending on the
+ * requested builder type.
+ */
+public final class FormatModelRegistry {
+  private static final Logger LOG = 
LoggerFactory.getLogger(FormatModelRegistry.class);
+  // The list of classes which are used for registering the reader and writer 
builders
+  private static final List<String> CLASSES_TO_REGISTER = ImmutableList.of();
+
+  private static final Map<Pair<FileFormat, Class<?>>, FormatModel<?, ?>> 
FORMAT_MODELS =
+      Maps.newConcurrentMap();
+
+  private FormatModelRegistry() {}
+
+  /**
+   * Registers an {@link FormatModel} in this registry.
+   *
+   * <p>The {@link FormatModel} creates readers and writers for a specific 
combinations of file
+   * format (Parquet, ORC, Avro) and object model (for example: "generic", 
"spark", "flink", etc.).
+   * Registering custom factories allows integration of new data processing 
engines for the
+   * supported file formats with Iceberg's file access mechanisms.
+   *
+   * <p>Each factory must be uniquely identified by its combination of file 
format and object model
+   * name. This uniqueness constraint prevents ambiguity when selecting 
factories for read and write
+   * operations.
+   *
+   * @param formatModel the factory implementation to register
+   * @throws IllegalArgumentException if a factory is already registered for 
the combination of
+   *     {@link FormatModel#format()} and {@link FormatModel#type()}
+   */
+  public static void register(FormatModel<?, ?> formatModel) {
+    Pair<FileFormat, Class<?>> key = Pair.of(formatModel.format(), 
formatModel.type());
+    Preconditions.checkArgument(
+        !FORMAT_MODELS.containsKey(key),
+        "Cannot register %s: %s is registered for format=%s model=%s",
+        formatModel.getClass(),
+        FORMAT_MODELS.containsKey(key) ? FORMAT_MODELS.get(key).getClass() : 
null,
+        key.first(),
+        key.second());
+
+    FORMAT_MODELS.put(key, formatModel);
+  }
+
+  @SuppressWarnings("CatchBlockLogException")
+  private static void registerSupportedFormats() {
+    // Uses dynamic methods to call the `register` for the listed classes
+    for (String classToRegister : CLASSES_TO_REGISTER) {
+      try {
+        
DynMethods.builder("register").impl(classToRegister).buildStaticChecked().invoke();
+      } catch (NoSuchMethodException e) {
+        // failing to register a factory is normal and does not require a 
stack trace
+        LOG.info("Unable to register {}: {}", classToRegister, e.getMessage());
+      }
+    }
+  }
+
+  static {
+    registerSupportedFormats();
+  }
+
+  /**
+   * Returns a reader builder for the specified file format and object model.
+   *
+   * <p>The returned {@link ReadBuilder} provides a fluent interface for 
configuring how data is
+   * read from the input file and converted to the output objects. The builder 
supports
+   * configuration options like schema projection, predicate pushdown, batch 
size and encryption.
+   *
+   * @param format the file format (Parquet, Avro, ORC) that determines the 
parsing implementation
+   * @param type the output type
+   * @param inputFile source file to read data from
+   * @param <D> the type of data records the reader will produce
+   * @return a configured reader builder for the specified format and object 
model
+   */
+  public static <D, S> ReadBuilder<D, S> readBuilder(
+      FileFormat format, Class<D> type, InputFile inputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    return factory.readBuilder(inputFile);
+  }
+
+  /**
+   * Returns a writer builder for appending data to the specified output file.
+   *
+   * <p>The returned builder produces a {@link FileAppender} that accepts 
records defined by the
+   * specified object model and persists them using the given file format. 
Data is written to the
+   * output file, but this basic writer does not collect or return {@link 
ContentFile} metadata.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured writer builder for creating the appender
+   */
+  public static <D, S> WriteBuilder<D, S> writeBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    return 
factory.writeBuilder(outputFile.encryptingOutputFile()).content(FileContent.DATA);
+  }
+
+  /**
+   * Returns a writer builder for generating a {@link DataFile}.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the provided file format. Unlike basic 
writers, this writer
+   * collects file metadata during the writing process and generates a {@link 
DataFile} that can be
+   * used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured data write builder for creating a {@link DataWriter}
+   */
+  public static <D, S> DataWriteBuilder<D, S> dataWriteBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    WriteBuilder<D, S> writeBuilder =
+        
factory.writeBuilder(outputFile.encryptingOutputFile()).content(FileContent.DATA);
+    return ContentFileWriteBuilderImpl.forDataFile(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  /**
+   * Creates a writer builder for generating a {@link DeleteFile} with 
equality deletes.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the given file format. The writer persists 
equality delete
+   * records that identify rows to be deleted based on the configured equality 
fields, producing a
+   * {@link DeleteFile} that can be used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured delete write builder for creating an {@link 
EqualityDeleteWriter}
+   */
+  public static <D, S> EqualityDeleteWriteBuilder<D, S> 
equalityDeleteWriteBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    WriteBuilder<D, S> writeBuilder =
+        factory
+            .writeBuilder(outputFile.encryptingOutputFile())
+            .content(FileContent.EQUALITY_DELETES);
+    return ContentFileWriteBuilderImpl.forEqualityDelete(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  /**
+   * Creates a writer builder for generating a {@link DeleteFile} with 
position-based deletes.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the given file format. The writer accepts 
{@link PositionDelete}
+   * records that identify rows to be deleted by file path and position, 
producing a {@link
+   * DeleteFile} that can be used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param outputFile destination for the written data
+   * @return a configured delete write builder for creating a {@link 
PositionDeleteWriter}
+   */
+  public static PositionDeleteWriteBuilder positionDeleteWriteBuilder(
+      FileFormat format, EncryptedOutputFile outputFile) {
+    FormatModel<PositionDelete<?>, Object> factory = 
factoryForPositionDelete(format);
+    WriteBuilder<PositionDelete<?>, Object> writeBuilder =
+        factory
+            .writeBuilder(outputFile.encryptingOutputFile())
+            .content(FileContent.POSITION_DELETES);
+    return ContentFileWriteBuilderImpl.forPositionDelete(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <D, S> FormatModel<D, S> factoryFor(FileFormat format, 
Class<D> type) {
+    return ((FormatModel<D, S>) FORMAT_MODELS.get(Pair.of(format, type)));
+  }
+
+  @SuppressWarnings("unchecked")
+  private static FormatModel<PositionDelete<?>, Object> 
factoryForPositionDelete(
+      FileFormat format) {
+    // Registry should use Pair<FileFormat, Class<?>> as key, so use 
PositionDelete.class

Review Comment:
   nit: this comment seems unnecessary



##########
core/src/main/java/org/apache/iceberg/formats/FormatModelRegistry.java:
##########
@@ -0,0 +1,260 @@
+/*
+ * 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.iceberg.formats;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import org.apache.iceberg.ContentFile;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DeleteFile;
+import org.apache.iceberg.FileContent;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.common.DynMethods;
+import org.apache.iceberg.deletes.EqualityDeleteWriter;
+import org.apache.iceberg.deletes.PositionDelete;
+import org.apache.iceberg.deletes.PositionDeleteWriter;
+import org.apache.iceberg.encryption.EncryptedOutputFile;
+import org.apache.iceberg.io.DataWriter;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.InputFile;
+import 
org.apache.iceberg.relocated.com.google.common.annotations.VisibleForTesting;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.util.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A registry that manages file-format-specific readers and writers through a 
unified object model
+ * factory interface.
+ *
+ * <p>This registry provides access to {@link ReadBuilder}s for data 
consumption and various writer
+ * builders:
+ *
+ * <ul>
+ *   <li>{@link WriteBuilder} for basic file writing,
+ *   <li>{@link DataWriteBuilder} for data files,
+ *   <li>{@link EqualityDeleteWriteBuilder} for equality deletes,
+ *   <li>{@link PositionDeleteWriteBuilder} for position deletes.
+ * </ul>
+ *
+ * The appropriate builder is selected based on {@link FileFormat} and object 
model name.
+ *
+ * <p>{@link FormatModel} objects are registered through {@link 
#register(FormatModel)} and used for
+ * creating readers and writers. Read builders are returned directly from the 
factory. Write
+ * builders may be wrapped in specialized content file writer implementations 
depending on the
+ * requested builder type.
+ */
+public final class FormatModelRegistry {
+  private static final Logger LOG = 
LoggerFactory.getLogger(FormatModelRegistry.class);
+  // The list of classes which are used for registering the reader and writer 
builders
+  private static final List<String> CLASSES_TO_REGISTER = ImmutableList.of();
+
+  private static final Map<Pair<FileFormat, Class<?>>, FormatModel<?, ?>> 
MODELS =
+      Maps.newConcurrentMap();
+
+  private FormatModelRegistry() {}
+
+  /**
+   * Registers an {@link FormatModel} in this registry.
+   *
+   * <p>The {@link FormatModel} creates readers and writers for a specific 
combinations of file
+   * format (Parquet, ORC, Avro) and object model (for example: "generic", 
"spark", "flink", etc.).
+   * Registering custom factories allows integration of new data processing 
engines for the
+   * supported file formats with Iceberg's file access mechanisms.
+   *
+   * <p>Each factory must be uniquely identified by its combination of file 
format and object model
+   * name. This uniqueness constraint prevents ambiguity when selecting 
factories for read and write
+   * operations.
+   *
+   * @param formatModel the factory implementation to register
+   * @throws IllegalArgumentException if a factory is already registered for 
the combination of
+   *     {@link FormatModel#format()} and {@link FormatModel#type()}
+   */
+  public static void register(FormatModel<?, ?> formatModel) {
+    Pair<FileFormat, Class<?>> key = Pair.of(formatModel.format(), 
formatModel.type());
+
+    FormatModel<?, ?> existing = MODELS.get(key);
+    Preconditions.checkArgument(
+        existing == null || checkFormatModelEquals(existing, formatModel),
+        "Cannot register %s: %s is registered for format=%s type=%s 
schemaType=%s",
+        formatModel.getClass(),
+        existing == null ? null : existing.getClass(),
+        key.first(),
+        key.second(),
+        existing == null ? null : existing.schemaType());
+
+    MODELS.put(key, formatModel);
+  }
+
+  private static boolean checkFormatModelEquals(
+      FormatModel<?, ?> model1, FormatModel<?, ?> model2) {
+    return Objects.equals(model1.getClass().getName(), 
model2.getClass().getName())

Review Comment:
   if we are going to check class name, we probably should use fully qualified 
`getCanonicalName`.
   
   I guess we can't use the equality comparison if they are loaded from 
different class loaders?
   ```
   model1.getClass() == model2.getClass()
   ```
   
   Also if the fully qualified class names match, is it necessarily to check 
the fields?



##########
core/src/main/java/org/apache/iceberg/formats/ContentFileWriteBuilderImpl.java:
##########
@@ -0,0 +1,336 @@
+/*
+ * 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.iceberg.data;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.Metrics;
+import org.apache.iceberg.MetricsConfig;
+import org.apache.iceberg.PartitionSpec;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.SortOrder;
+import org.apache.iceberg.StructLike;
+import org.apache.iceberg.deletes.EqualityDeleteWriter;
+import org.apache.iceberg.deletes.PositionDelete;
+import org.apache.iceberg.deletes.PositionDeleteWriter;
+import org.apache.iceberg.encryption.EncryptionKeyMetadata;
+import org.apache.iceberg.io.DataWriter;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.WriteBuilder;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+
+/**
+ * An internal implementation that handles all {@link ContentFileWriteBuilder} 
interface variants.
+ *
+ * <p>This unified implementation serves as a backend for multiple specialized 
content writers:
+ *
+ * <ul>
+ *   <li>{@link DataWriteBuilder} for creating data files
+ *   <li>{@link EqualityDeleteWriteBuilder} for creating equality delete files
+ *   <li>{@link PositionDeleteWriteBuilder} for creating position delete files
+ * </ul>
+ *
+ * <p>The implementation delegates to a format-specific {@link WriteBuilder} 
while enriching it with
+ * content-specific functionality. When building a writer, the implementation 
configures the
+ * underlying builder and calls its {@link WriteBuilder#build()} method to 
create the appropriate
+ * specialized writer for the requested content type.
+ *
+ * @param <B> the concrete builder type for method chaining
+ * @param <S> the type of the schema for the input data
+ * @param <D> the type of data records the writer will accept
+ */
+@SuppressWarnings("unchecked")
+abstract class ContentFileWriteBuilderImpl<B extends 
ContentFileWriteBuilder<B, S>, D, S>
+    implements ContentFileWriteBuilder<B, S> {
+  private final WriteBuilder<D, S> writeBuilder;
+  private final String location;
+  private final FileFormat format;
+  private PartitionSpec spec = null;
+  private StructLike partition = null;
+  private EncryptionKeyMetadata keyMetadata = null;
+  private SortOrder sortOrder = null;
+
+  static <D, S> DataWriteBuilder<D, S> forDataFile(
+      WriteBuilder<D, S> writeBuilder, String location, FileFormat format) {
+    return new DataFileWriteBuilder<>(writeBuilder, location, format);
+  }
+
+  static <D, S> EqualityDeleteWriteBuilder<D, S> forEqualityDelete(
+      WriteBuilder<D, S> writeBuilder, String location, FileFormat format) {
+    return new EqualityDeleteFileWriteBuilder<>(writeBuilder, location, 
format);
+  }
+
+  static <D, S> PositionDeleteWriteBuilder<D, S> forPositionDelete(
+      WriteBuilder<PositionDelete<D>, S> writeBuilder, String location, 
FileFormat format) {
+    return new PositionDeleteFileWriteBuilder<>(writeBuilder, location, 
format);
+  }
+
+  private ContentFileWriteBuilderImpl(
+      WriteBuilder<D, S> writeBuilder, String location, FileFormat format) {
+    this.writeBuilder = writeBuilder;
+    this.location = location;
+    this.format = format;
+  }
+
+  @Override
+  public B set(String property, String value) {
+    writeBuilder.set(property, value);
+    return self();
+  }
+
+  @Override
+  public B meta(String property, String value) {
+    writeBuilder.meta(property, value);
+    return self();
+  }
+
+  @Override
+  public B metricsConfig(MetricsConfig metricsConfig) {
+    writeBuilder.metricsConfig(metricsConfig);
+    return self();
+  }
+
+  @Override
+  public B overwrite() {
+    writeBuilder.overwrite();
+    return self();
+  }
+
+  @Override
+  public B fileEncryptionKey(ByteBuffer encryptionKey) {
+    writeBuilder.fileEncryptionKey(encryptionKey);
+    return self();
+  }
+
+  @Override
+  public B fileAADPrefix(ByteBuffer aadPrefix) {
+    writeBuilder.fileAADPrefix(aadPrefix);
+    return self();
+  }
+
+  @Override
+  public B spec(PartitionSpec newSpec) {
+    this.spec = newSpec;
+    return self();
+  }
+
+  @Override
+  public B partition(StructLike newPartition) {
+    this.partition = newPartition;
+    return self();
+  }
+
+  @Override
+  public B keyMetadata(EncryptionKeyMetadata newKeyMetadata) {
+    this.keyMetadata = newKeyMetadata;
+    return self();
+  }
+
+  @Override
+  public B sortOrder(SortOrder newSortOrder) {
+    this.sortOrder = newSortOrder;
+    return self();
+  }
+
+  private static class DataFileWriteBuilder<D, S>

Review Comment:
   close this thread since most think it is good to keep builders as interfaces.



##########
core/src/main/java/org/apache/iceberg/formats/FormatModelRegistry.java:
##########
@@ -0,0 +1,244 @@
+/*
+ * 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.iceberg.data;
+
+import java.util.List;
+import java.util.Map;
+import org.apache.iceberg.ContentFile;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DeleteFile;
+import org.apache.iceberg.FileContent;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.common.DynMethods;
+import org.apache.iceberg.deletes.EqualityDeleteWriter;
+import org.apache.iceberg.deletes.PositionDelete;
+import org.apache.iceberg.deletes.PositionDeleteWriter;
+import org.apache.iceberg.encryption.EncryptedOutputFile;
+import org.apache.iceberg.io.DataWriter;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.FormatModel;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.ReadBuilder;
+import org.apache.iceberg.io.WriteBuilder;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.util.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A registry that manages file-format-specific readers and writers through a 
unified object model
+ * factory interface.
+ *
+ * <p>This registry provides access to {@link ReadBuilder}s for data 
consumption and various writer
+ * builders:
+ *
+ * <ul>
+ *   <li>{@link WriteBuilder} for basic file writing,
+ *   <li>{@link DataWriteBuilder} for data files,
+ *   <li>{@link EqualityDeleteWriteBuilder} for equality deletes,
+ *   <li>{@link PositionDeleteWriteBuilder} for position deletes.
+ * </ul>
+ *
+ * The appropriate builder is selected based on {@link FileFormat} and object 
model name.
+ *
+ * <p>{@link FormatModel} objects are registered through {@link 
#register(FormatModel)} and used for
+ * creating readers and writers. Read builders are returned directly from the 
factory. Write
+ * builders may be wrapped in specialized content file writer implementations 
depending on the
+ * requested builder type.
+ */
+public final class FormatModelRegistry {
+  private static final Logger LOG = 
LoggerFactory.getLogger(FormatModelRegistry.class);
+  // The list of classes which are used for registering the reader and writer 
builders
+  private static final List<String> CLASSES_TO_REGISTER = ImmutableList.of();
+
+  private static final Map<Pair<FileFormat, Class<?>>, FormatModel<?, ?>> 
FORMAT_MODELS =
+      Maps.newConcurrentMap();
+
+  private FormatModelRegistry() {}
+
+  /**
+   * Registers an {@link FormatModel} in this registry.
+   *
+   * <p>The {@link FormatModel} creates readers and writers for a specific 
combinations of file
+   * format (Parquet, ORC, Avro) and object model (for example: "generic", 
"spark", "flink", etc.).
+   * Registering custom factories allows integration of new data processing 
engines for the
+   * supported file formats with Iceberg's file access mechanisms.
+   *
+   * <p>Each factory must be uniquely identified by its combination of file 
format and object model
+   * name. This uniqueness constraint prevents ambiguity when selecting 
factories for read and write
+   * operations.
+   *
+   * @param formatModel the factory implementation to register
+   * @throws IllegalArgumentException if a factory is already registered for 
the combination of
+   *     {@link FormatModel#format()} and {@link FormatModel#type()}
+   */
+  public static void register(FormatModel<?, ?> formatModel) {
+    Pair<FileFormat, Class<?>> key = Pair.of(formatModel.format(), 
formatModel.type());
+    Preconditions.checkArgument(
+        !FORMAT_MODELS.containsKey(key),
+        "Cannot register %s: %s is registered for format=%s model=%s",
+        formatModel.getClass(),
+        FORMAT_MODELS.containsKey(key) ? FORMAT_MODELS.get(key).getClass() : 
null,
+        key.first(),
+        key.second());
+
+    FORMAT_MODELS.put(key, formatModel);
+  }
+
+  @SuppressWarnings("CatchBlockLogException")
+  private static void registerSupportedFormats() {
+    // Uses dynamic methods to call the `register` for the listed classes
+    for (String classToRegister : CLASSES_TO_REGISTER) {
+      try {
+        
DynMethods.builder("register").impl(classToRegister).buildStaticChecked().invoke();
+      } catch (NoSuchMethodException e) {
+        // failing to register a factory is normal and does not require a 
stack trace
+        LOG.info("Unable to register {}: {}", classToRegister, e.getMessage());
+      }
+    }
+  }
+
+  static {
+    registerSupportedFormats();
+  }
+
+  /**
+   * Returns a reader builder for the specified file format and object model.
+   *
+   * <p>The returned {@link ReadBuilder} provides a fluent interface for 
configuring how data is
+   * read from the input file and converted to the output objects. The builder 
supports
+   * configuration options like schema projection, predicate pushdown, batch 
size and encryption.
+   *
+   * @param format the file format (Parquet, Avro, ORC) that determines the 
parsing implementation
+   * @param type the output type
+   * @param inputFile source file to read data from
+   * @param <D> the type of data records the reader will produce
+   * @return a configured reader builder for the specified format and object 
model
+   */
+  public static <D, S> ReadBuilder<D, S> readBuilder(
+      FileFormat format, Class<D> type, InputFile inputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    return factory.readBuilder(inputFile);
+  }
+
+  /**
+   * Returns a writer builder for appending data to the specified output file.
+   *
+   * <p>The returned builder produces a {@link FileAppender} that accepts 
records defined by the
+   * specified object model and persists them using the given file format. 
Data is written to the
+   * output file, but this basic writer does not collect or return {@link 
ContentFile} metadata.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured writer builder for creating the appender
+   */
+  public static <D, S> WriteBuilder<D, S> writeBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    return 
factory.writeBuilder(outputFile.encryptingOutputFile()).content(FileContent.DATA);
+  }
+
+  /**
+   * Returns a writer builder for generating a {@link DataFile}.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the provided file format. Unlike basic 
writers, this writer
+   * collects file metadata during the writing process and generates a {@link 
DataFile} that can be
+   * used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured data write builder for creating a {@link DataWriter}
+   */
+  public static <D, S> DataWriteBuilder<D, S> dataWriteBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    WriteBuilder<D, S> writeBuilder =
+        
factory.writeBuilder(outputFile.encryptingOutputFile()).content(FileContent.DATA);
+    return ContentFileWriteBuilderImpl.forDataFile(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  /**
+   * Creates a writer builder for generating a {@link DeleteFile} with 
equality deletes.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the given file format. The writer persists 
equality delete
+   * records that identify rows to be deleted based on the configured equality 
fields, producing a
+   * {@link DeleteFile} that can be used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param type the input type
+   * @param outputFile destination for the written data
+   * @param <D> the type of data records the writer will accept
+   * @return a configured delete write builder for creating an {@link 
EqualityDeleteWriter}
+   */
+  public static <D, S> EqualityDeleteWriteBuilder<D, S> 
equalityDeleteWriteBuilder(
+      FileFormat format, Class<D> type, EncryptedOutputFile outputFile) {
+    FormatModel<D, S> factory = factoryFor(format, type);
+    WriteBuilder<D, S> writeBuilder =
+        factory
+            .writeBuilder(outputFile.encryptingOutputFile())
+            .content(FileContent.EQUALITY_DELETES);
+    return ContentFileWriteBuilderImpl.forEqualityDelete(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  /**
+   * Creates a writer builder for generating a {@link DeleteFile} with 
position-based deletes.
+   *
+   * <p>The returned builder produces a writer that accepts records defined by 
the specified object
+   * model and persists them using the given file format. The writer accepts 
{@link PositionDelete}
+   * records that identify rows to be deleted by file path and position, 
producing a {@link
+   * DeleteFile} that can be used for table operations.
+   *
+   * @param format the file format used for writing
+   * @param outputFile destination for the written data
+   * @return a configured delete write builder for creating a {@link 
PositionDeleteWriter}
+   */
+  public static PositionDeleteWriteBuilder positionDeleteWriteBuilder(
+      FileFormat format, EncryptedOutputFile outputFile) {
+    FormatModel<PositionDelete<?>, Object> factory = 
factoryForPositionDelete(format);
+    WriteBuilder<PositionDelete<?>, Object> writeBuilder =
+        factory
+            .writeBuilder(outputFile.encryptingOutputFile())
+            .content(FileContent.POSITION_DELETES);
+    return ContentFileWriteBuilderImpl.forPositionDelete(
+        writeBuilder, outputFile.encryptingOutputFile().location(), format);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <D, S> FormatModel<D, S> factoryFor(FileFormat format, 
Class<D> type) {

Review Comment:
   The two `factoryFor` methods should throw illegal argument exception for not 
supported file format and row type.
   
   In the uber PR, I can see the registry can fail silently for class not found 
exception. Maybe the error msg here could also explain some possible reasons, 
like the relevant classes (Orc) are not loaded.



##########
core/src/main/java/org/apache/iceberg/formats/FormatModelRegistry.java:
##########
@@ -0,0 +1,242 @@
+/*
+ * 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.iceberg.data;
+
+import java.util.List;
+import java.util.Map;
+import org.apache.iceberg.ContentFile;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DeleteFile;
+import org.apache.iceberg.FileContent;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.common.DynMethods;
+import org.apache.iceberg.deletes.EqualityDeleteWriter;
+import org.apache.iceberg.deletes.PositionDelete;
+import org.apache.iceberg.deletes.PositionDeleteWriter;
+import org.apache.iceberg.encryption.EncryptedOutputFile;
+import org.apache.iceberg.io.DataWriter;
+import org.apache.iceberg.io.FileAppender;
+import org.apache.iceberg.io.FormatModel;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.ReadBuilder;
+import org.apache.iceberg.io.WriteBuilder;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.iceberg.util.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A registry that manages file-format-specific readers and writers through a 
unified object model
+ * factory interface.
+ *
+ * <p>This registry provides access to {@link ReadBuilder}s for data 
consumption and various writer
+ * builders:
+ *
+ * <ul>
+ *   <li>{@link WriteBuilder} for basic file writing,
+ *   <li>{@link DataWriteBuilder} for data files,
+ *   <li>{@link EqualityDeleteWriteBuilder} for equality deletes,
+ *   <li>{@link PositionDeleteWriteBuilder} for position deletes.
+ * </ul>
+ *
+ * The appropriate builder is selected based on {@link FileFormat} and object 
model name.
+ *
+ * <p>{@link FormatModel} objects are registered through {@link 
#register(FormatModel)} and used for
+ * creating readers and writers. Read builders are returned directly from the 
factory. Write
+ * builders may be wrapped in specialized content file writer implementations 
depending on the
+ * requested builder type.
+ */
+public final class FormatModelRegistry {
+  private static final Logger LOG = 
LoggerFactory.getLogger(FormatModelRegistry.class);
+  // The list of classes which are used for registering the reader and writer 
builders
+  private static final List<String> CLASSES_TO_REGISTER = ImmutableList.of();
+
+  private static final Map<Pair<FileFormat, Class<?>>, FormatModel<?, ?>> 
FORMAT_MODELS =
+      Maps.newConcurrentMap();
+
+  private FormatModelRegistry() {}
+
+  /**
+   * Registers an {@link FormatModel} in this registry.
+   *
+   * <p>The {@link FormatModel} creates readers and writers for a specific 
combinations of file
+   * format (Parquet, ORC, Avro) and object model (for example: "generic", 
"spark", "flink", etc.).
+   * Registering custom factories allows integration of new data processing 
engines for the
+   * supported file formats with Iceberg's file access mechanisms.
+   *
+   * <p>Each factory must be uniquely identified by its combination of file 
format and object model
+   * name. This uniqueness constraint prevents ambiguity when selecting 
factories for read and write
+   * operations.
+   *
+   * @param formatModel the factory implementation to register
+   * @throws IllegalArgumentException if a factory is already registered for 
the combination of
+   *     {@link FormatModel#format()} and {@link FormatModel#type()} ()}
+   */
+  public static void register(FormatModel<?, ?> formatModel) {
+    Pair<FileFormat, Class<?>> key = Pair.of(formatModel.format(), 
formatModel.type());
+    Preconditions.checkArgument(

Review Comment:
   closing old thread as code is updated to fail re-registering for a different 
format model class



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