Sinking topic data from Java producer to Mongodb

Question

I produce data with java and sink it to Kafka topic after that I want this data to get sank to MongoDB. When I send the data as JSON via JAVA it won't store into MongoDB because of this error.

[2020-08-15 18:42:19,164] ERROR WorkerSinkTask{id=Kafka_ops-0} Task threw an uncaught and unrecoverable exception. Task is being killed and will not recover until manually restarted. Error: JSON reader was expecting a value but found 'siqdj'. (org.apache.kafka.connect.runtime.WorkerSinkTask)
org.bson.json.JsonParseException: JSON reader was expecting a value but found 'siqdj'.
        at org.bson.json.JsonReader.readBsonType(JsonReader.java:270)
        at org.bson.AbstractBsonReader.verifyBSONType(AbstractBsonReader.java:680)
        at org.bson.AbstractBsonReader.checkPreconditions(AbstractBsonReader.java:722)
        at org.bson.AbstractBsonReader.readStartDocument(AbstractBsonReader.java:450)
        at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:81)
        at org.bson.BsonDocument.parse(BsonDocument.java:62)
        at com.mongodb.kafka.connect.sink.converter.JsonRawStringRecordConverter.convert(JsonRawStringRecordConverter.java:34)
        at com.mongodb.kafka.connect.sink.converter.SinkConverter.convert(SinkConverter.java:44)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$buildWriteModel$6(MongoSinkTask.java:229)
        at java.util.ArrayList.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.buildWriteModel(MongoSinkTask.java:228)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.processSinkRecords(MongoSinkTask.java:169)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$put$2(MongoSinkTask.java:117)
        at java.util.ArrayList.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$put$3(MongoSinkTask.java:116)
        at java.util.HashMap.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.put(MongoSinkTask.java:114)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:560)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:323)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:226)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:198)
        at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:185)
        at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:235)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
[2020-08-15 18:42:19,166] ERROR WorkerSinkTask{id=Kafka_ops-0} Task threw an uncaught and unrecoverable exception (org.apache.kafka.connect.runtime.WorkerTask)
org.apache.kafka.connect.errors.ConnectException: Exiting WorkerSinkTask due to unrecoverable exception.
        at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:588)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:323)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:226)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:198)
        at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:185)
        at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:235)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Caused by: org.bson.json.JsonParseException: JSON reader was expecting a value but found 'siqdj'.
        at org.bson.json.JsonReader.readBsonType(JsonReader.java:270)
        at org.bson.AbstractBsonReader.verifyBSONType(AbstractBsonReader.java:680)
        at org.bson.AbstractBsonReader.checkPreconditions(AbstractBsonReader.java:722)
        at org.bson.AbstractBsonReader.readStartDocument(AbstractBsonReader.java:450)
        at org.bson.codecs.BsonDocumentCodec.decode(BsonDocumentCodec.java:81)
        at org.bson.BsonDocument.parse(BsonDocument.java:62)
        at com.mongodb.kafka.connect.sink.converter.JsonRawStringRecordConverter.convert(JsonRawStringRecordConverter.java:34)
        at com.mongodb.kafka.connect.sink.converter.SinkConverter.convert(SinkConverter.java:44)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$buildWriteModel$6(MongoSinkTask.java:229)
        at java.util.ArrayList.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.buildWriteModel(MongoSinkTask.java:228)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.processSinkRecords(MongoSinkTask.java:169)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$put$2(MongoSinkTask.java:117)
        at java.util.ArrayList.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.lambda$put$3(MongoSinkTask.java:116)
        at java.util.HashMap.forEach(Unknown Source)
        at com.mongodb.kafka.connect.sink.MongoSinkTask.put(MongoSinkTask.java:114)
        at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:560)
        ... 10 more

Here is the data I send via my java program in the Kafka consumer.

{"name":"This is a test","dept":"siqdj","studentId":1}
{"name":"This is another","dept":"siqdj","studentId":2}

Each line represents a record

Here are my config files

connect-standalone.properties

bootstrap.servers=localhost:9092

# The converters specify the format of data in Kafka and how to translate it into Connect data. Every Connect user will
# need to configure these based on the format they want their data in when loaded from or stored into Kafka
key.converter=org.apache.kafka.connect.storage.StringConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
# Converter-specific settings can be passed in by prefixing the Converter's setting with the converter we want to apply
# it to
key.converter.schemas.enable=false
value.converter.schemas.enable=false

offset.storage.file.filename=/tmp/connect.offsets
# Flush much faster than normal, which is useful for testing/debugging
offset.flush.interval.ms=10000
plugin.path=/plugins

MongoSinkConnector.properties

name=Kafka_ops
connector.class=com.mongodb.kafka.connect.MongoSinkConnector
tasks.max=1
topics=TestTopic4
connection.uri=mongodb://mongo1:27017,mongo2:27017,mongo3:27017
database=student_kafka
collection=students
key.converter=org.apache.kafka.connect.storage.StringConverter
key.converter.schemas.enable=false
value.converter=org.apache.kafka.connect.json.JsonConverter
value.converter.schemas.enable=false

Answer 1

Tariq - I am no expert in this topic. But I have tried a similar thing with JDBC sink adapter with Oracle database.

The data format you are sending to the topic does not seems right to me. Hence, you may be getting the error. Since you are using the JsonConverter, each row in the topic should be in the following format for the sink adapter to parse and write to a data store. Currently your data does not have schema in the payload. Hence the error.

Please pass the below to the topic and see if it sinks to MongoDB.

{
    "schema": {
        "type": "struct",
        "fields": [
            {
                "type": "string",
                "optional": false,
                "field": "name"
            },
            {
                "type": "string",
                "optional": true,
                "field": "dept"
            },
            {
                "type": "int64",
                "optional": true,
                "field": "studentId"
            }
        ],
        "optional": false,
        "name": "YOUR_TABLE_NAME"
    },
    "payload": {
        "name": "This is a test",
        "dept": "siqdj",
        "studentId": 1
    }
}