I am looking for a way to evalute continuous queries with memgraph. My goal is to write an application, that notifies a user as soon as an event occurs (e.g. a specific pattern is found). The notification should be a message in a kafka topic. Something like the Neo4J-Kafka-Connector. Currently I found nothing better, than to write a python script that periodically queries the graph. My problem with that is, that I don't want to query the whole graph every time for performance reasons. I could define a timestamp in python and increment it with every query, but this seems very hacky. Is there a better way to solve this issue?
I just tried to connect to Memgraph using Neo4j Kafka Connector.
I’ve created docker-compose.yml:
---
version: "3"
services:
memgraph:
image: "memgraph/memgraph"
hostname: memgraph
ports:
- "7687:7687"
- "7444:7444"
volumes:
- mg_lib:/var/lib/memgraph
- mg_log:/var/log/memgraph
- mg_etc:/etc/memgraph
zookeeper:
image: confluentinc/cp-zookeeper:7.3.0
hostname: zookeeper
container_name: zookeeper
ports:
- "2181:2181"
environment:
ZOOKEEPER_CLIENT_PORT: 2181
ZOOKEEPER_TICK_TIME: 2000
broker:
image: confluentinc/cp-server:7.3.0
hostname: broker
container_name: broker
depends_on:
- zookeeper
ports:
- "9092:9092"
- "9101:9101"
environment:
KAFKA_BROKER_ID: 1
KAFKA_ZOOKEEPER_CONNECT: 'zookeeper:2181'
KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://broker:29092,PLAINTEXT_HOST://localhost:9092
KAFKA_METRIC_REPORTERS: io.confluent.metrics.reporter.ConfluentMetricsReporter
KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS: 0
KAFKA_CONFLUENT_LICENSE_TOPIC_REPLICATION_FACTOR: 1
KAFKA_CONFLUENT_BALANCER_TOPIC_REPLICATION_FACTOR: 1
KAFKA_TRANSACTION_STATE_LOG_MIN_ISR: 1
KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR: 1
KAFKA_JMX_PORT: 9101
KAFKA_JMX_HOSTNAME: localhost
KAFKA_CONFLUENT_SCHEMA_REGISTRY_URL: http://schema-registry:8081
CONFLUENT_METRICS_REPORTER_BOOTSTRAP_SERVERS: broker:29092
CONFLUENT_METRICS_REPORTER_TOPIC_REPLICAS: 1
CONFLUENT_METRICS_ENABLE: 'true'
CONFLUENT_SUPPORT_CUSTOMER_ID: 'anonymous'
schema-registry:
image: confluentinc/cp-schema-registry:7.3.0
hostname: schema-registry
container_name: schema-registry
depends_on:
- broker
ports:
- "8081:8081"
environment:
SCHEMA_REGISTRY_HOST_NAME: schema-registry
SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS: 'broker:29092'
SCHEMA_REGISTRY_LISTENERS: http://0.0.0.0:8081
connect:
image: cnfldemos/cp-server-connect-datagen:0.6.0-7.3.0
hostname: connect
container_name: connect
depends_on:
- broker
- schema-registry
ports:
- "8083:8083"
volumes:
- ./plugins:/tmp/connect-plugins
environment:
CONNECT_BOOTSTRAP_SERVERS: 'broker:29092'
CONNECT_REST_ADVERTISED_HOST_NAME: connect
CONNECT_GROUP_ID: compose-connect-group
CONNECT_CONFIG_STORAGE_TOPIC: docker-connect-configs
CONNECT_CONFIG_STORAGE_REPLICATION_FACTOR: 1
CONNECT_OFFSET_FLUSH_INTERVAL_MS: 10000
CONNECT_OFFSET_STORAGE_TOPIC: docker-connect-offsets
CONNECT_OFFSET_STORAGE_REPLICATION_FACTOR: 1
CONNECT_STATUS_STORAGE_TOPIC: docker-connect-status
CONNECT_STATUS_STORAGE_REPLICATION_FACTOR: 1
CONNECT_KEY_CONVERTER: org.apache.kafka.connect.storage.StringConverter
CONNECT_VALUE_CONVERTER: io.confluent.connect.avro.AvroConverter
CONNECT_VALUE_CONVERTER_SCHEMA_REGISTRY_URL: http://schema-registry:8081
# CLASSPATH required due to CC-2422
CLASSPATH: /usr/share/java/monitoring-interceptors/monitoring-interceptors-7.3.0.jar
CONNECT_PRODUCER_INTERCEPTOR_CLASSES: "io.confluent.monitoring.clients.interceptor.MonitoringProducerInterceptor"
CONNECT_CONSUMER_INTERCEPTOR_CLASSES: "io.confluent.monitoring.clients.interceptor.MonitoringConsumerInterceptor"
CONNECT_PLUGIN_PATH: "/usr/share/java,/usr/share/confluent-hub-components,/tmp/connect-plugins"
CONNECT_LOG4J_LOGGERS: org.apache.zookeeper=ERROR,org.I0Itec.zkclient=ERROR,org.reflections=ERROR
command:
- bash
- -c
- |
confluent-hub install --no-prompt neo4j/kafka-connect-neo4j:latest
/etc/confluent/docker/run
control-center:
image: confluentinc/cp-enterprise-control-center:7.3.0
hostname: control-center
container_name: control-center
depends_on:
- broker
- schema-registry
- connect
ports:
- "9021:9021"
environment:
CONTROL_CENTER_BOOTSTRAP_SERVERS: 'broker:29092'
CONTROL_CENTER_CONNECT_CONNECT-DEFAULT_CLUSTER: 'connect:8083'
CONTROL_CENTER_KSQL_KSQLDB1_URL: "http://ksqldb-server:8088"
CONTROL_CENTER_KSQL_KSQLDB1_ADVERTISED_URL: "http://localhost:8088"
CONTROL_CENTER_SCHEMA_REGISTRY_URL: "http://schema-registry:8081"
CONTROL_CENTER_REPLICATION_FACTOR: 1
CONTROL_CENTER_INTERNAL_TOPICS_PARTITIONS: 1
CONTROL_CENTER_MONITORING_INTERCEPTOR_TOPIC_PARTITIONS: 1
CONFLUENT_METRICS_TOPIC_REPLICATION: 1
PORT: 9021
volumes:
mg_lib:
mg_log:
mg_etc:
Created nodes with:
CREATE (:TestSource {name: 'john', surname: 'doe', timestamp: localDateTime()});
CREATE (:TestSource {name: 'mary', surname: 'doe', timestamp: localDateTime()});
CREATE (:TestSource {name: 'jack', surname: 'small', timestamp: localDateTime()});
Created source.neo4j.json:
{
"name": "Neo4jSourceConnectorAVRO",
"config": {
"topic": "my-topic",
"connector.class": "streams.kafka.connect.source.Neo4jSourceConnector",
"key.converter": "io.confluent.connect.avro.AvroConverter",
"key.converter.schema.registry.url": "http://schema-registry:8081",
"value.converter": "io.confluent.connect.avro.AvroConverter",
"value.converter.schema.registry.url": "http://schema-registry:8081",
"neo4j.server.uri": "bolt://memgraph:7687",
"neo4j.authentication.basic.username": "",
"neo4j.authentication.basic.password": "",
"neo4j.streaming.poll.interval.msecs": 5000,
"neo4j.streaming.property": "timestamp",
"neo4j.streaming.from": "LAST_COMMITTED",
"neo4j.enforce.schema": true,
"neo4j.source.query": "MATCH (ts:TestSource) RETURN ts.name AS name, ts.surname AS surname, ts.timestamp AS timestamp"
}
}
Created sink.neo4j.json:
{
"name": "Neo4jSinkConnectorAVRO",
"config": {
"topics": "my-topic",
"connector.class": "streams.kafka.connect.sink.Neo4jSinkConnector",
"key.converter": "io.confluent.connect.avro.AvroConverter",
"key.converter.schema.registry.url": "http://schema-registry:8081",
"value.converter": "io.confluent.connect.avro.AvroConverter",
"value.converter.schema.registry.url": "http://schema-registry:8081",
"errors.retry.timeout": "-1",
"errors.retry.delay.max.ms": "1000",
"errors.tolerance": "all",
"errors.log.enable": true,
"errors.log.include.messages": true,
"neo4j.server.uri": "bolt://memgraph:7687",
"neo4j.authentication.basic.username": "",
"neo4j.authentication.basic.password": "",
"neo4j.topic.cypher.my-topic": "MERGE (p:Person{name: event.name, surname: event.surname}) MERGE (f:Family{name: event.surname}) MERGE (p)-[:BELONGS_TO]->(f)"
}
}
Tested with: MATCH (node) RETURN node;
Added new node using CREATE (:TestSource {name: 'Ann', surname: 'Bolin', timestamp: localDateTime()});
Does this help you?