Chapter 211. OPC UA Client Component

Available as of Camel version 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.

NameDescriptionDefaultType

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

211.1. 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.

211.2. 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:

211.2.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

endpointUri

Required The OPC UA server endpoint

 

String

211.2.2. Query Parameters (24 parameters):

NameDescriptionDefaultType

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

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 options 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

211.2.3. 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:

KeyTypeDescription

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

211.2.4. 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.

211.3. See Also

  • Configuring Camel
  • Component
  • Endpoint
  • Getting Started