Chapter 377. XQuery Component Available as of Camel version 1.0 Camel supports XQuery to allow an Expression or Predicate to be used in the DSL or Xml Configuration . For example you could use XQuery to create an Predicate in a Message Filter or as an Expression for a Recipient List. 377.1. Options The XQuery component supports 4 options, which are listed below. Name Description Default Type moduleURIResolver (advanced) To use the custom ModuleURIResolver ModuleURIResolver configuration (advanced) To use a custom Saxon configuration Configuration configurationProperties (advanced) To set custom Saxon configuration properties Map 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 The XQuery endpoint is configured using URI syntax: with the following path and query parameters: 377.1.1. Path Parameters (1 parameters): Name Description Default Type resourceUri Required The name of the template to load from classpath or file system String 377.1.2. Query Parameters (31 parameters): Name Description Default Type allowStAX (common) Whether to allow using StAX mode false boolean headerName (common) To use a Camel Message header as the input source instead of Message body. String namespacePrefixes (common) Allows to control which namespace prefixes to use for a set of namespace mappings Map resultsFormat (common) What output result to use DOM ResultFormat resultType (common) What output result to use defined as a class Class stripsAllWhiteSpace (common) Whether to strip all whitespaces true boolean 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 sendEmptyMessageWhenIdle (consumer) If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead. 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 pollStrategy (consumer) A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel. PollingConsumerPoll Strategy configuration (advanced) To use a custom Saxon configuration Configuration configurationProperties (advanced) To set custom Saxon configuration properties Map moduleURIResolver (advanced) To use the custom ModuleURIResolver ModuleURIResolver parameters (advanced) Additional parameters Map properties (advanced) Properties to configure the serialization parameters Properties staticQueryContext (advanced) To use a custom Saxon StaticQueryContext StaticQueryContext synchronous (advanced) Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). false boolean backoffErrorThreshold (scheduler) The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in. int backoffIdleThreshold (scheduler) The number of subsequent idle polls that should happen before the backoffMultipler should kick-in. int backoffMultiplier (scheduler) To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured. int delay (scheduler) Milliseconds before the poll. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour). 500 long greedy (scheduler) If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the run polled 1 or more messages. false boolean initialDelay (scheduler) Milliseconds before the first poll starts. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour). 1000 long runLoggingLevel (scheduler) The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that. TRACE LoggingLevel scheduledExecutorService (scheduler) Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool. ScheduledExecutor Service scheduler (scheduler) To use a cron scheduler from either camel-spring or camel-quartz2 component none ScheduledPollConsumer Scheduler schedulerProperties (scheduler) To configure additional properties when using a custom scheduler or any of the Quartz2, Spring based scheduler. Map startScheduler (scheduler) Whether the scheduler should be auto started. true boolean timeUnit (scheduler) Time unit for initialDelay and delay options. MILLISECONDS TimeUnit useFixedDelay (scheduler) Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details. true boolean 377.2. Spring Boot Auto-Configuration The component supports 8 options, which are listed below. Name Description Default Type camel.component.xquery.configuration To use a custom Saxon configuration. The option is a net.sf.saxon.Configuration type. String camel.component.xquery.configuration-properties To set custom Saxon configuration properties Map camel.component.xquery.enabled Enable xquery component true Boolean camel.component.xquery.module-u-r-i-resolver To use the custom ModuleURIResolver. The option is a net.sf.saxon.lib.ModuleURIResolver type. String camel.component.xquery.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 camel.language.xquery.enabled Enable xquery language true Boolean camel.language.xquery.trim Whether to trim the value to remove leading and trailing whitespaces and line breaks true Boolean camel.language.xquery.type Sets the class name of the result type (type from output) The default result type is NodeSet String 377.3. Examples from("queue:foo").filter(). xquery("//foo"). to("queue:bar") You can also use functions inside your query, in which case you need an explicit type conversion (or you will get a org.w3c.dom.DOMException: HIERARCHY_REQUEST_ERR) by passing the Class as a second argument to the xquery() method. from("direct:start"). recipientList().xquery("concat('mock:foo.', /person/@city)", String.class); 377.4. Variables The IN message body will be set as the contextItem . Besides this these Variables is also added as parameters: Variable Type Description exchange Exchange The current Exchange in.body Object The In message's body out.body Object The OUT message's body (if any) in.headers.* Object You can access the value of exchange.in.headers with key foo by using the variable which name is in.headers.foo out.headers.* Object You can access the value of exchange.out.headers with key foo by using the variable which name is out.headers.foo variable key name Object Any exchange.properties and exchange.in.headers and any additional parameters set using setParameters(Map) . These parameters is added with they own key name, for instance if there is an IN header with the key name foo then its added as foo . 377.5. Using XML configuration If you prefer to configure your routes in your Spring XML file then you can use XPath expressions as follows <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:foo="http://example.com/person" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"> <camelContext id="camel" xmlns="http://activemq.apache.org/camel/schema/spring"> <route> <from uri="activemq:MyQueue"/> <filter> <xquery>/foo:person[@name='James']</xquery> <to uri="mqseries:SomeOtherQueue"/> </filter> </route> </camelContext> </beans> Notice how we can reuse the namespace prefixes, foo in this case, in the XPath expression for easier namespace based XQuery expressions! When you use functions in your XQuery expression you need an explicit type conversion which is done in the xml configuration via the @type attribute: <xquery type="java.lang.String">concat('mock:foo.', /person/@city)</xquery> 377.6. Using XQuery as transformation We can do a message translation using transform or setBody in the route, as shown below: from("direct:start"). transform().xquery("/people/person"); Notice that xquery will use DOMResult by default, so if we want to grab the value of the person node, using text() we need to tell xquery to use String as result type, as shown: from("direct:start"). transform().xquery("/people/person/text()", String.class); 377.7. Using XQuery as an endpoint Sometimes an XQuery expression can be quite large; it can essentally be used for Templating. So you may want to use an XQuery Endpoint so you can route using XQuery templates. The following example shows how to take a message of an ActiveMQ queue (MyQueue) and transform it using XQuery and send it to MQSeries. <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="activemq:MyQueue"/> <to uri="xquery:com/acme/someTransform.xquery"/> <to uri="mqseries:SomeOtherQueue"/> </route> </camelContext> Currently custom functions in XQuery might result in a NullPointerException (Camel 2.18, 2.19 and 2.20). This is expected to be fixed in Camel 2.21 377.8. Examples Here is a simple example using an XQuery expression as a predicate in a Message Filter This example uses XQuery with namespaces as a predicate in a Message Filter 377.9. Learning XQuery XQuery is a very powerful language for querying, searching, sorting and returning XML. For help learning XQuery try these tutorials Mike Kay's XQuery Primer the W3Schools XQuery Tutorial You might also find the XQuery function reference useful 377.10. Loading script from external resource Available as of Camel 2.11 You can externalize the script and have Camel load it from a resource such as "classpath:" , "file:" , or "http:" . This is done using the following syntax: "resource:scheme:location" , eg to refer to a file on the classpath you can do: .setHeader("myHeader").xquery("resource:classpath:myxquery.txt", String.class) 377.11. Dependencies To use XQuery in your camel routes you need to add the a dependency on camel-saxon which implements the XQuery language. If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions). <dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-saxon</artifactId> <version>x.x.x</version> </dependency>

Commands:
xquery:resourceUri
from("queue:foo").filter(). xquery("//foo"). to("queue:bar")
from("direct:start"). recipientList().xquery("concat('mock:foo.', /person/@city)", String.class);
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:foo="http://example.com/person" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"> <camelContext id="camel" xmlns="http://activemq.apache.org/camel/schema/spring"> <route> <from uri="activemq:MyQueue"/> <filter> <xquery>/foo:person[@name='James']</xquery> <to uri="mqseries:SomeOtherQueue"/> </filter> </route> </camelContext> </beans>
<xquery type="java.lang.String">concat('mock:foo.', /person/@city)</xquery>
from("direct:start"). transform().xquery("/people/person");
from("direct:start"). transform().xquery("/people/person/text()", String.class);
<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="activemq:MyQueue"/> <to uri="xquery:com/acme/someTransform.xquery"/> <to uri="mqseries:SomeOtherQueue"/> </route> </camelContext>
.setHeader("myHeader").xquery("resource:classpath:myxquery.txt", String.class)
<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-saxon</artifactId> <version>x.x.x</version> </dependency>