OPC UA Client

Since Camel 2.19

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

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>

The OPC UA Client component supports 6 options, which are listed below.

Name Description Default Type

defaultConfiguration (common)

All default options for client

MiloClientConfiguration

applicationName (common)

Default application name

String

applicationUri (common)

Default application URI

String

productUri (common)

Default product URI

String

reconnectTimeout (common)

Default reconnect timeout

Long

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

URI format

The URI syntax of the endpoint is:

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

If the server does not use a path, then it is possible to simply omit it:

milo-client:tcp://[user:password@]host:port?node=RAW(nsu=urn:foo:bar;s=item-1)

If no user credentials are provided the client will switch to anonymous mode.

URI options

All configuration options in the group client are applicable to the shared client instance. Endpoints will share client instances for each endpoint URI. So the first time a request for that endpoint URI is made, the options of the client group are applied. All further instances will be ignored.

If you need alternate options for the same endpoint URI it is possible though to set the clientId option which will by added internally to the endpoint URI in order to select a different shared connection instance. In other words, shared connections located by the combination of endpoint URI and client id.

The OPC UA Client endpoint is configured using URI syntax:

milo-client:endpointUri

with the following path and query parameters:

Path Parameters (1 parameters):

Name Description Default Type

endpointUri

Required The OPC UA server endpoint

String

Query Parameters (27 parameters):

Name Description Default Type

clientId (common)

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

String

defaultAwaitWrites (common)

Default await setting for writes

false

boolean

discoveryEndpointSuffix (common)

A suffix for endpoint URI when discovering

String

discoveryEndpointUri (common)

An alternative discovery URI

String

method (common)

The method definition (see Method ID)

ExpandedNodeId

node (common)

The node definition (see Node ID)

ExpandedNodeId

samplingInterval (common)

The sampling interval in milliseconds

Double

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange.

ExchangePattern

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

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

URL

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

requestTimeout (client)

Request timeout in milliseconds

Long

sessionName (client)

Session name

String

sessionTimeout (client)

Session timeout in milliseconds

Long

Spring Boot Auto-Configuration

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

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

The component supports 24 options, which are listed below.

Name Description Default Type

camel.component.milo-client.application-name

Default application name

String

camel.component.milo-client.application-uri

Default application URI

String

camel.component.milo-client.default-configuration.allowed-security-policies

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

Set

camel.component.milo-client.default-configuration.application-name

The application name

Apache Camel adapter for Eclipse Milo

String

camel.component.milo-client.default-configuration.application-uri

The application URI

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

String

camel.component.milo-client.default-configuration.channel-lifetime

Channel lifetime in milliseconds

Long

camel.component.milo-client.default-configuration.client-id

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

String

camel.component.milo-client.default-configuration.discovery-endpoint-suffix

A suffix for endpoint URI when discovering

String

camel.component.milo-client.default-configuration.discovery-endpoint-uri

An alternative discovery URI

String

camel.component.milo-client.default-configuration.key-alias

The name of the key in the keystore file

String

camel.component.milo-client.default-configuration.key-password

The key password

String

camel.component.milo-client.default-configuration.key-store-password

The keystore password

String

camel.component.milo-client.default-configuration.key-store-type

The key store type

String

camel.component.milo-client.default-configuration.max-pending-publish-requests

The maximum number of pending publish requests

Long

camel.component.milo-client.default-configuration.max-response-message-size

The maximum number of bytes a response message may have

Long

camel.component.milo-client.default-configuration.override-host

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

false

Boolean

camel.component.milo-client.default-configuration.product-uri

The product URI

http://camel.apache.org/EclipseMilo

String

camel.component.milo-client.default-configuration.request-timeout

Request timeout in milliseconds

Long

camel.component.milo-client.default-configuration.session-name

Session name

String

camel.component.milo-client.default-configuration.session-timeout

Session timeout in milliseconds

Long

camel.component.milo-client.enabled

Enable milo-client component

true

Boolean

camel.component.milo-client.product-uri

Default product URI

String

camel.component.milo-client.reconnect-timeout

Default reconnect timeout

Long

camel.component.milo-client.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

Discovery

If the server uses a dedicated discovery endpoint (e.g. /discovery), which may support different (less secure) security policies, then you can make use of this via the parameter discoveryEndpointSuffix, which will be appended to the endpointUri. Or by using an explicit discoveryEndpointUri.

Overriding the host name

The client uses the host information from the endpoint information, queried from the server. However in some situations this endpoint URI might be different, and wrong from the point of view of the connecting client (e.g. an internal hostname).

In this case it is possible to set the parameter overrideHost to true, which will take the discovered endpoint information, but override the host information with the value of the original URI.

Node ID

In order to define a target node a namespace and node id is required. In previous versions this was possible by specifying nodeId and either namespaceUri or namespaceIndex. However this only allowed for using string based node IDs. And while this configuration is still possible, the newer one is preferred.

The new approach is to specify a full namespace+node ID in the format ns=1;i=1 which also allows to use the other node ID formats (like numeric, GUID/UUID or opaque). If the node parameter is used the older ones must not be used. The syntax of this node format is a set of key=value pairs delimited by a semi-colon (;).

Exactly one namespace and one node id key must be used. See the following table for possible keys:

Key Type Description

ns

namespace

Numeric namespace index

nsu

namespace

Namespace URI

s

node

String node ID

i

node

Numeric node ID

g

node

GUID/UUID node ID

b

node

Base64 encoded string for opaque node ID

As the values generated by the syntax cannot be transparently encoded into a URI parameter value, it is necessary to escape them. However Camel allows to wrap the actual value inside RAW(…), which makes escaping unnecessary. For example:

milo-client:tcp://user:password@localhost:12345?node=RAW(nsu=http://foo.bar;s=foo/bar)

Method ID

It is possible to perform methods calls on OPC UA nodes. If the parameter method is set to the Node ID of a method call (the node ID must be set to the parent object in this case), then a method call will be performed instead of a write operation.

Input parameters are taken from the body:

  • If the body is null, then an empty Variant[] will be used

  • If the body is a Variant[], then it will be used as is

  • If the body is a Variant, then it will be wrapped in a Variant[] array

  • Otherwise the body will be converted into a Variant and wrapped in an array of Variant[]

Security policies

When setting the allowing security policies is it possible to use the well known OPC UA URIs (e.g. http://opcfoundation.org/UA/SecurityPolicy#Basic128Rsa15) or to use the Milo enum literals (e.g. None). Specifying an unknown security policy URI or enum is an error.

The known security policy URIs and enum literals are can be seen here: SecurityPolicy.java

Note: In any case security policies are considered case sensitive.

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