Neo4j

Since Camel 4.10

Only producer is supported

The Neo4j component provides support for Neo4j graph database.

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-neo4j</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

neo4j:name[?options]

Where name is the database name.

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

At the component level, you set general and shared configurations that are, then, inherited by the endpoints. It is the highest configuration level.

For example, a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre-configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

You can configure components using:

  • the Component DSL.

  • in a configuration file (application.properties, *.yaml files, etc).

  • directly in the Java code.

Configuring Endpoint Options

You usually spend more time setting up endpoints because they have many options. These options help you customize what you want the endpoint to do. The options are also categorized into whether the endpoint is used as a consumer (from), as a producer (to), or both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders.

Property placeholders provide a few benefits:

  • They help prevent using hardcoded urls, port numbers, sensitive information, and other settings.

  • They allow externalizing the configuration from the code.

  • They help the code to become more flexible and reusable.

The following two sections list all the options, firstly for the component followed by the endpoint.

Component Options

The Neo4j component supports 19 options, which are listed below.

Name Description Default Type

alias (producer)

Node alias.

String

configuration (producer)

The configuration;.

Neo4jConfiguration

databaseUrl (producer)

Url for connecting to Neo database.

String

detachRelationship (producer)

Detach a relationship - set true if want to delete a node and detach its relationships to other nodes at same time.

false

boolean

dimension (producer)

Dimension of Vector Index.

Integer

label (producer)

Node Label.

String

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

maxResults (producer)

Maximum results for Vector Similarity search.

3

int

minScore (producer)

Minimum score for Vector Similarity search.

0

double

query (producer)

Cypher Query.

String

similarityFunction (producer)

Similarity Function of Vector Index.

Enum values:

  • cosine

  • euclidean

cosine

Neo4jSimilarityFunction

vectorIndexName (producer)

Vector Index Name.

String

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

driver (advanced)

Autowired Advanced - Driver.

Driver

kerberosAuthTicket (security)

Kerberos Authentication encoded base64 ticket.

String

password (security)

Basic authentication database password.

String

realm (security)

Basic authentication database realm.

String

token (security)

Bearer authentication database realm.

String

username (security)

Basic authentication database user.

String

Endpoint Options

The Neo4j endpoint is configured using URI syntax:

neo4j:name

With the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

name (producer)

Required The database name.

String

Query Parameters (17 parameters)

Name Description Default Type

alias (producer)

Node alias.

String

databaseUrl (producer)

Url for connecting to Neo database.

String

detachRelationship (producer)

Detach a relationship - set true if want to delete a node and detach its relationships to other nodes at same time.

false

boolean

dimension (producer)

Dimension of Vector Index.

Integer

label (producer)

Node Label.

String

maxResults (producer)

Maximum results for Vector Similarity search.

3

int

minScore (producer)

Minimum score for Vector Similarity search.

0

double

query (producer)

Cypher Query.

String

similarityFunction (producer)

Similarity Function of Vector Index.

Enum values:

  • cosine

  • euclidean

cosine

Neo4jSimilarityFunction

vectorIndexName (producer)

Vector Index Name.

String

lazyStartProducer (producer (advanced))

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

driver (advanced)

Autowired Advanced - Driver.

Driver

kerberosAuthTicket (security)

Kerberos Authentication encoded base64 ticket.

String

password (security)

Basic authentication database password.

String

realm (security)

Basic authentication database realm.

String

token (security)

Bearer authentication database realm.

String

username (security)

Basic authentication database user.

String

Message Headers

The Neo4j component supports 12 message header(s), which is/are listed below:

Name Description Default Type

CamelNeo4jOperation (producer)

Constant: OPERATION

The operation to be performed.

Enum values:

  • CREATE_NODE

  • DELETE_NODE

  • RETRIEVE_NODES

  • RETRIEVE_NODES_AND_UPDATE_WITH_CYPHER_QUERY

  • ADD_OR_DELETE_NODE_WITH_CYPHER_QUERY

  • CREATE_VECTOR_INDEX

  • DROP_VECTOR_INDEX

  • CREATE_VECTOR

  • VECTOR_SIMILARITY_SEARCH

String

CamelNeo4jMatchProperties (producer)

Constant: MATCH_PROPERTIES

MATCH properties for the generated MATCH query. Needed only if we are matching properties and values. Example: \{name: 'Alice'}.

String

CamelNeo4jQueryResult (producer)

Constant: QUERY_RESULT

Query Result.

String

CamelNeo4jQueryResultNodesCreated (producer)

Constant: QUERY_RESULT_NODES_CREATED

Query Number of nodes created.

Long

CamelNeo4jQueryResultNodesDeleted (producer)

Constant: QUERY_RESULT_NODES_DELETED

Query Number of nodes deleted.

Long

CamelNeo4jQueryResultContainsUpdates (producer)

Constant: QUERY_RESULT_CONTAINS_UPDATES

Query executed contains update.

Boolean

CamelNeo4jQueryResultRelationshipsCreated (producer)

Constant: QUERY_RESULT_RELATIONSHIPS_CREATED

Query executed number of relationships created.

Long

CamelNeo4jQueryResultRelationshipsDeleted (producer)

Constant: QUERY_RESULT_RELATIONSHIPS_DELETED

Query executed number of relationships deleted.

Long

CamelNeo4jQueryResultRetrieveSize (producer)

Constant: QUERY_RETRIEVE_SIZE

Number of nodes retrieved.

Long

CamelNeo4jQueryResultListNeo4jNodes (producer)

Constant: QUERY_RETRIEVE_LIST_NEO4J_NODES

Query execution time in Milliseconds.

Long

CamelNeo4jVectorEmbeddingId (producer)

Constant: VECTOR_ID

Vector Id for the embedding.

String

CamelNeo4jLabel (producer)

Constant: LABEL

Label for the Node - used when inserting from Embeddings.

String

Spring Boot Auto-Configuration

When using neo4j with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-neo4j-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 20 options, which are listed below.

Name Description Default Type

camel.component.neo4j.alias

Node alias.

String

camel.component.neo4j.autowired-enabled

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

Boolean

camel.component.neo4j.configuration

The configuration;. The option is a org.apache.camel.component.neo4j.Neo4jConfiguration type.

Neo4jConfiguration

camel.component.neo4j.database-url

Url for connecting to Neo database.

String

camel.component.neo4j.detach-relationship

Detach a relationship - set true if want to delete a node and detach its relationships to other nodes at same time.

false

Boolean

camel.component.neo4j.dimension

Dimension of Vector Index.

Integer

camel.component.neo4j.driver

Advanced - Driver. The option is a org.neo4j.driver.Driver type.

Driver

camel.component.neo4j.enabled

Whether to enable auto configuration of the neo4j component. This is enabled by default.

Boolean

camel.component.neo4j.kerberos-auth-ticket

Kerberos Authentication encoded base64 ticket.

String

camel.component.neo4j.label

Node Label.

String

camel.component.neo4j.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean

camel.component.neo4j.max-results

Maximum results for Vector Similarity search.

3

Integer

camel.component.neo4j.min-score

Minimum score for Vector Similarity search.

Double

camel.component.neo4j.password

Basic authentication database password.

String

camel.component.neo4j.query

Cypher Query.

String

camel.component.neo4j.realm

Basic authentication database realm.

String

camel.component.neo4j.similarity-function

Similarity Function of Vector Index.

cosine

Neo4jSimilarityFunction

camel.component.neo4j.token

Bearer authentication database realm.

String

camel.component.neo4j.username

Basic authentication database user.

String

camel.component.neo4j.vector-index-name

Vector Index Name.

String

Graph database usage - simple operations

Create a Node

To create a node in a database named test, define the body as a string containing the JSON body. Use the operation CREATE_NODE. The URI endpoint should contain also specify the label and the alias.

Example:
        var body = "{name: 'Alice', email: 'alice@example.com', age: 30}";

        Exchange result = fluentTemplate.to("neo4j:test?alias=u1&label=User")
                .withBodyAs(body, String.class)
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.CREATE_NODE)
                .request(Exchange.class);

Create a Node with properties

To create a node in a database named test with properties, define the body as a Map containing the properties and values. Use the operation CREATE_NODE. The URI endpoint should contain also specify the label and the alias.

Example:
        Map<String, Object> params = Map.of(
                "name", "Bob",
                "email", "bob@example.com",
                "age", 25);

        Exchange result = fluentTemplate.to("neo4j:test?alias=u2&label=User")
                .withBodyAs(params, Map.class)
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.CREATE_NODE)
                .request(Exchange.class);

Retrieve Node

To retrieve a node in a database named test. Define the header MATCH_PROPERTIES as a string containing the match query. Use the operation RETRIEVE_NODES. The URI endpoint should also specify the label and the alias. The response is a List of Map<String, Object>. Each map represents the list of properties of a single node.

Example:
        Exchange result = fluentTemplate.to("neo4j:test?alias=u&label=User")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.RETRIEVE_NODES)
                .withHeader(Neo4j.Headers.MATCH_PROPERTIES, "{name: 'Alice'}")
                .request(Exchange.class);

To retrieve all nodes with label=User, use the same request without specifying any MATCH_PROPERTIES.

Example:
        Exchange result = fluentTemplate.to("neo4j:test?alias=u&label=User")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.RETRIEVE_NODES)
                .request(Exchange.class);

Delete Node

To delete a node in a database named test. Define the header MATCH_PROPERTIES as a string containing the match query. Use the operation DELETE_NODE. The URI endpoint should also specify the label and the alias.

Example:
        Exchange result = fluentTemplate.to("neo4j:test?alias=u&label=User")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.DELETE_NODE)
                .withHeader(Neo4j.Headers.MATCH_PROPERTIES, "{name: 'Alice'}")
                .request(Exchange.class);

Delete Node with relationships

If a node has relationships, it won’t be deleted unless we either delete the relationships or delete it with detached relationships. To delete a node with detached relationships, set the option detachRelationship to true.

Example:
        Exchange result = fluentTemplate.to("neo4j:test?alias=u&label=User&detachRelationship=true")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.DELETE_NODE)
                .withHeader(Neo4j.Headers.MATCH_PROPERTIES, "{name: 'Alice'}")
                .request(Exchange.class);

Graph database usage - use Cypher Queries

Create / Delete Nodes with a Cypher query

To create or delete nodes with a Cypher query in a database named test, set the Cypher query in the body. Use the operation ADD_OR_DELETE_NODE_WITH_CYPHER_QUERY. The operation can be used too to create multiple nodes and relationships between nodes.

Example creating a node:
        var cypherQuery = "CREATE (u3:User {name: 'Charlie', email: 'charlie@example.com', age: 35})";
        Exchange result = fluentTemplate.to("neo4j:test")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.ADD_OR_DELETE_NODE_WITH_CYPHER_QUERY)
                .withBodyAs(cypherQuery, String.class)
                .request(Exchange.class);
Example deleting a node:
        var cypherQuery = "MATCH (u:User {name: 'Bob'}) DELETE u";
        Exchange result = fluentTemplate.to("neo4j:test")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.ADD_OR_DELETE_NODE_WITH_CYPHER_QUERY)
                .withBodyAs(cypherQuery, String.class)
                .request(Exchange.class);

Retrieve / Update nodes with a Cypher query

To retrieve or update nodes with Cypher Query in a database named test, set the Cypher query in the body. Use the operation RETRIEVE_NODES_AND_UPDATE_WITH_CYPHER_QUERY.

The operation is the same as ADD_OR_DELETE_NODE_WITH_CYPHER_QUERY, except that it returns a list of retrieved or updated nodes represented as Map<String, Object>.

Example updating a node:
         var cypherQuery = "MATCH " +
                          "(u:User {name: 'Ethan'})" +
                          "SET u.age=41 " +
                          "RETURN u";

         Exchange result = fluentTemplate.to("neo4j:test")
                .withBodyAs(cypherQuery, String.class)
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.RETRIEVE_NODES_AND_UPDATE_WITH_CYPHER_QUERY)
                .request(Exchange.class);

Vector database embeddings usage

Create a vector index

To use Neo4j as a Vector database, we must create first a vector index for a label.

To create a vector index in a database named test, use the operation CREATE_VECTOR_INDEX. The URI endpoint should also specify the label, the alias, the vector index name and the dimension of embeddings.

Example:
         Exchange result = fluentTemplate.to("neo4j:test?vectorIndexName=movieIdx&alias=m&label=Movie&dimension=2")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.CREATE_VECTOR_INDEX)
                .request(Exchange.class);

Drop a vector index

To drop a vector index in a database named test, use the operation DROP_VECTOR_INDEX. The URI endpoint should contain also specify the vector index name.

Example:
         Exchange result = fluentTemplate.to("neo4j:test?vectorIndexName=movieIdx")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.DROP_VECTOR_INDEX)
                .request(Exchange.class);

Create a vector

To create a vector in a database named test, use the operation CREATE_VECTOR. The URI endpoint should also specify the label, the alias and the vector index name.

Camel Neo4j will create the node and store the vector as an embedding property.

Example:
         Exchange result = fluentTemplate.to("neo4j:test?vectorIndexName=movieIdx&label=Movie&alias=m")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.CREATE_VECTOR)
                .withHeader(Neo4j.Headers.VECTOR_ID, testData.getId())
                .withBody(List.of(0.8f, 0.6f))
                .request(Exchange.class);

Similarity search

To perform a similarity search using vectors in a database named test, use the operation VECTOR_SIMILARITY_SEARCH. The URI endpoint should also specify the label, the alias and the vector index name.

Example:
         Exchange result = fluentTemplate.to("neo4j:test?vectorIndexName=movieIdx&label=Movie&alias=m")
                .withHeader(Neo4j.Headers.OPERATION, Neo4Operation.CREATE_VECTOR)
                .withHeader(Neo4j.Headers.VECTOR_ID, testData.getId())
                .withBody(List.of(0.75f, 0.65f))
                .request(Exchange.class);

Generate Embeddings with Langchain4j-embeddings

You can generate embeddings with an Embedding Models using the camel Lancghain4j Embeddings components. Camel Neo4j introduces a DataType neo4j:embeddings that automates the transformations of the Lancghain4j embeddings to Neo4j vectors.

Example of a camel Route that create embeddings with Camel Langchain4j Embeddings
         from("direct:in")
            .to("langchain4j-embeddings:test")
            .setHeader(Neo4j.Headers.OPERATION).constant(Neo4Operation.CREATE_VECTOR)
            .setHeader(Neo4j.Headers.LABEL).constant("Test")
            .transform(new DataType("neo4j:embeddings"))
            .to("neo4j:test");
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