OPC UA Browser

Since Camel 3.15

Only producer is supported

The Milo Client component provides access to OPC UA servers using the Eclipse Milo™ implementation.

Java 11+: This component requires Java 11+ at runtime.

This component uses Eclipse Milo 1.0.5. When migrating from earlier versions, be aware that the Milo API has undergone significant changes in the 1.0.x series.

Maven users will need to add the following dependency to their pom.xml for this component:

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

URI format

The URI syntax of the endpoint is:

milo-browse:opc.tcp://[user:password@]host:port/path/to/service?node=RAW(nsu=urn:foo:bar;s=item-1)

Please refer to the Milo Client component for further details about the construction of the URI.

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 OPC UA Browser component supports 24 options, which are listed below.

Name Description Default Type

clientId (producer)

A virtual client id to force the creation of a new connection instance.

String

configuration (producer)

All default options for client configurations.

MiloClientConfiguration

discoveryEndpointSuffix (producer)

A suffix for endpoint URI when discovering.

String

discoveryEndpointUri (producer)

An alternative discovery URI.

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

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

allowedSecurityPolicies (client)

A set of allowed security policy URIs. Default is to accept all and use the highest.

String

applicationName (client)

The application name.

Apache Camel adapter for Eclipse Milo

String

applicationUri (client)

The application URI.

http://camel.apache.org/EclipseMilo/Client

String

channelLifetime (client)

Channel lifetime in milliseconds.

Long

keyAlias (client)

The name of the key in the keystore file.

String

keyPassword (client)

The key password.

String

keyStorePassword (client)

The keystore password.

String

keyStoreType (client)

The key store type.

String

keyStoreUrl (client)

The URL where the key should be loaded from.

String

maxPendingPublishRequests (client)

The maximum number of pending publish requests.

Long

maxResponseMessageSize (client)

The maximum number of bytes a response message may have.

Long

miloClientConnectionManager (client)

Autowired Instance for managing client connections.

MiloClientConnectionManager

overrideHost (client)

Override the server reported endpoint host with the host from the endpoint URI.

false

boolean

productUri (client)

The product URI.

http://camel.apache.org/EclipseMilo

String

requestedPublishingInterval (client)

The requested publishing interval in milliseconds.

1_000.0

Double

requestTimeout (client)

Request timeout in milliseconds.

Long

sessionName (client)

Session name.

String

sessionTimeout (client)

Session timeout in milliseconds.

Long

Endpoint Options

The OPC UA Browser endpoint is configured using URI syntax:

milo-browse:endpointUri

With the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

endpointUri (producer)

Required The OPC UA server endpoint.

String

Query Parameters (29 parameters)

Name Description Default Type

clientId (producer)

A virtual client id to force the creation of a new connection instance.

String

depth (producer)

When browsing recursively into sub-types, what’s the maximum search depth for diving into the tree. Default value notice: Maximum depth for browsing recursively (only if recursive = true).

3

int

direction (producer)

The direction to browse (forward, inverse, …​). Default value notice: The direction to browse; see org.eclipse.milo.opcua.stack.core.types.enumerated.BrowseDirection.

Enum values:

  • Forward

  • Inverse

  • Both

Forward

BrowseDirection

discoveryEndpointSuffix (producer)

A suffix for endpoint URI when discovering.

String

discoveryEndpointUri (producer)

An alternative discovery URI.

String

filter (producer)

Filter out node ids to limit browsing. Default value notice: Regular filter expression matching node ids.

None

String

includeSubTypes (producer)

Whether to include sub-types for browsing; only applicable for non-recursive browsing.

true

boolean

maxNodeIdsPerRequest (producer)

The maximum number node ids requested per server call. Default value notice: Maximum number of node ids requested per browse call (applies to browsing sub-types only; only if recursive = true).

10

int

node (producer)

The node definition (see Node ID). Default value notice: Root folder as per OPC-UA spec.

ns=0;id=84

String

nodeClasses (producer)

The mask indicating the node classes of interest in browsing. Default value notice: Comma-separated node class list; see org.eclipse.milo.opcua.stack.core.types.enumerated.NodeClass.

Variable,Object,DataType

String

recursive (producer)

Whether to browse recursively into sub-types, ignores includeSubTypes setting as it’s implied to be set to true. Default value notice: Whether to recursively browse sub-types: truefalse.

false

boolean

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

allowedSecurityPolicies (client)

A set of allowed security policy URIs. Default is to accept all and use the highest.

String

applicationName (client)

The application name.

Apache Camel adapter for Eclipse Milo

String

applicationUri (client)

The application URI.

http://camel.apache.org/EclipseMilo/Client

String

channelLifetime (client)

Channel lifetime in milliseconds.

Long

keyAlias (client)

The name of the key in the keystore file.

String

keyPassword (client)

The key password.

String

keyStorePassword (client)

The keystore password.

String

keyStoreType (client)

The key store type.

String

keyStoreUrl (client)

The URL where the key should be loaded from.

String

maxPendingPublishRequests (client)

The maximum number of pending publish requests.

Long

maxResponseMessageSize (client)

The maximum number of bytes a response message may have.

Long

overrideHost (client)

Override the server reported endpoint host with the host from the endpoint URI.

false

boolean

productUri (client)

The product URI.

http://camel.apache.org/EclipseMilo

String

requestedPublishingInterval (client)

The requested publishing interval in milliseconds.

1_000.0

Double

requestTimeout (client)

Request timeout in milliseconds.

Long

sessionName (client)

Session name.

String

sessionTimeout (client)

Session timeout in milliseconds.

Long

Message Headers

The OPC UA Browser component supports 1 message header(s), which is/are listed below:

Name Description Default Type

CamelMiloNodeIds (producer)

Constant: HEADER_NODE_IDS

The node ids.

List

Client

The browse component shares the same base options like the Camel Milo Client component, e.g. concerning topics like discovery, security policies, the construction of node ids, etc.

Please refer to the documentation of the Camel Milo Client component for further details.

Browsing

The main use of this component is to be able to determine the nodes values to be retrieved or to be written by first browsing the node tree of the OPC-UA server, e.g. to avoid hard-coding a significant number of node ids within the configuration of Camel routes. The component is designed to work in conjunction with the Camel Milo Client component as illustrated in the following example:

from("direct:start")

    // Browse sub tree
    .setHeader("CamelMiloNodeIds", constant(Arrays.asList("ns=1;s=folder-id")))
    .enrich("milo-browse:opc.tcp://localhost:4334", (oldExchange, newExchange) -> newExchange)

    // Filter specific ids
    .filter(...)

        // Retrieve the values for the nodes of interest
        .enrich("milo-client:opc.tcp://localhost:4334", (oldExchange, newExchange) -> newExchange)

Recursion

Dependent to the OPC-UA server there it might be required to browse a hierarchy of nodes. Be aware that this is potentially a very expensive operation.

Milo 1.0.5 Migration Notes

With Milo 1.0.5, the browse API remains largely compatible, but shares the same security-related changes as the client and server components. Please refer to the Milo Client documentation for details on security configuration changes.

Unresolved include directive in modules/ROOT/pages/milo-browse-component.adoc - include::spring-boot:partial$starter.adoc[]