Simple

Since Camel 1.1

The Simple Expression Language was a really simple language when it was created, but has since grown more powerful. It is primarily intended for being a very small and Camel specific scripting language used anywhere in Camel such as with EIPs and Route.

The simple language is designed with intent to cover almost all the common use cases when little need for scripting in your Camel routes.

However, for much more complex use cases, then a more powerful language is recommended such as: Groovy.

The simple language uses ${body} placeholders for dynamic expressions and functions.

Alternative syntax

You can also use the alternative syntax which uses $simple{ } as placeholders. This can be used in situations to avoid clashes when using, for example, Spring property placeholder together with Camel.

See also the CSimple language which is pre compiled.

A quick Simple Language example

You often use Simple together with EIPs such as Content-Based Router EIP.

In the example below we want to route the message depending on whether a message header with key foo is equal to different values:

  • Java

  • XML

  • YAML

from("direct:a")
    .choice()
        .when(simple("${header.foo} == 'bar'"))
            .to("direct:b")
        .when(simple("${header.foo} == 'cheese'"))
            .to("direct:c")
        .otherwise()
            .to("direct:d");
<route>
    <from uri="direct:a"/>
    <choice>
        <when>
            <simple>${header.foo} == 'bar'</simple>
            <to uri="direct:b"/>
        </when>
        <when>
            <simple>${header.foo} == 'cheese'</simple>
            <to uri="direct:c"/>
        </when>
        <otherwise>
            <to uri="direct:d"/>
        </otherwise>
    </choice>
</route>
- from:
    uri: direct:a
    steps:
      - choice:
          when:
            - simple: "${header.foo} == 'bar'"
              steps:
                - to:
                    uri: direct:b
            - simple: "${header.foo} == 'cheese'"
              steps:
                - to:
                    uri: direct:c
          otherwise:
            steps:
              - to:
                  uri: direct:d

Simple Language options

The Simple Language can be configured globally. However, its seldom needed.

The Simple language supports 3 options, which are listed below.

Name Default Java Type Description

pretty (common)

false

Boolean

To pretty format the output (only JSon or XML supported).

resultType (common)

String

Sets the class of the result type (type from output).

trim (advanced)

true

Boolean

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

Built-in Simple Functions

The Simple language has many built-in functions which allows access to various part of Camel and the current Exchange, the message payload such as body and headers, and much more.

Function Response Type Description

bean(name.method)

Object

Invoking a bean expression using the Bean language. Specifying a method name, you must use dot as the separator. We also support the ?method=methodname syntax that is used by the Bean component. Camel will by default lookup a bean by the given name. However, if you need to refer to a bean class (such as calling a static method), then you can prefix with the type, such as bean:type:fqnClassName.

body.OGNL

Object

The body invoked using a Camel OGNL syntax. For example to invoke the getCountryCode on the message body, you can use ${body.getCountryCode()}. In the message body is a POJO then you can use a short-hand syntax ${body.countryCode}.

bodyAs(type).OGNL

Object

Converts the body to the given type determined by its classname and then invoke methods using a Camel OGNL syntax.

bodyAs(type)

<T>

Converts the body to the given type determined by its classname.

bodyOneLine

String

Converts the body to a String and removes all line-breaks, so the string is in one line.

bodyType

Class

The message body class.

body

Object

The message body

camelContext.OGNL

Object

The CamelContext invoked using Camel OGNL syntax.

camelId

String

The name of the Camel application (ie CamelContext).

capitalize()

String

Capitalizes the message body as a String value (upper case every words)

capitalize(exp)

String

Capitalizes the expression as a String value (upper case every words)

collate(size)

List

The collate function iterates the message body and groups the data into sub lists of specified size. This can be used with the Splitter EIP to split a message body and group/batch the split sub message into a group of N sub lists. This method works similar to the collate method in Groovy.

concat(exp,exp,separator

String

Performs a string concat using two expressions (message body as default) with optional separator (uses comma by default).

convertTo(exp,type).OGNL

Object

Converts the expression to the specified type and then invoke methods using a Camel OGNL syntax.

convertTo(exp,type)

<T>

Converts the expression to the specified type.

convertTo(type)

<T>

Converts the message body to the specified type.

date-with-timezone:command:timezone:pattern

String

Date formatting using java.text.SimpleDateFormat timezones and patterns. See data:command function for additional documentation on the commands.

date:command:pattern

String

Date formatting using java.text.SimpleDateFormat patterns. See data:command function for additional documentation on the commands.

date:command

Date

Evaluates to a java.util.Date object. Supported commands are: now for current timestamp, exchangeCreated for the timestamp when the current exchange was created, header.xxx to use the Long/Date object in the header with the key xxx. variable.xxx to use the Long/Date in the variable with the key xxx. exchangeProperty.xxx to use the Long/Date object in the exchange property with the key xxx. file for the last modified timestamp of the file (only available with a File consumer). Command accepts offsets such as: now-24h or header.xxx+1h or now+1h30m-100.

empty(kind)

<T>

Creates a new empty object of the given kind. The string kind creates an empty String object. The list creates an empty ArrayList, and map creates an empty LinkedHashMap object.

env.key

String

Refers to the OS system environment variable with the given key. For example env.HOME to refer to the home directory.

exception.OGNL

Object

Same as exception and then invoke Camel OGNL syntax.

exception.message

String

The message from the Exchange object. See exception for more details.

exception.stacktrace

String

The stacktrace from the Exchange object. See exception for more details.

exception

Throwable

The Exception object on the exchange, is null if no exception is set on the Exchange. Will fallback and grab any caught exceptions stored as exchange property (Exchange.EXCEPTION_CAUGHT)

exchange.OGNL

Object

The current Exchange invoked using Camel OGNL syntax.

exchangeId

String

The id of the current Exchange.

exchangeProperty.key.OGNL

Object

Same as exchangeProperty.key and then invoke Camel OGNL syntax.

exchangeProperty.key

Object

Returns the value of the exchange property with the given key. Returns null if the property does not exists.

exchange

Exchange

The current Exchange object.

fromRouteId

String

Returns the original route id where this Exchange was created.

hash(exp,algorithm)

String

Returns a hashed value (string in hex decimal) of the given expression. The algorithm can be SHA-256 (default) or SHA3-256.

header.key.OGNL

Object

Same as header.key and then invoke Camel OGNL syntax.

header.key

Object

The message header with the given key.

headerAs(key,type)

<T>

The message header with the given key, converted to the given type.

header[key].OGNL

Object

Deprecated Same as header[key] and then invoke Camel OGNL syntax.

header[key]

Object

Deprecated The message header with the given key.

headers.key

Object

Deprecated The message header with the given key.

headers.size

int

The number of headers

headers:_key_

Object

Deprecated The message header with the given key.

headers[key]

Object

Deprecated The message header with the given key.

headers

Map

All the message headers as a java.util.Map.

hostname

String

Returns the local hostname (may be null if not possible to resolve).

id

String

The message id

iif(predicate,trueExp,falseExp)

Object

Evaluates the predicate expression and returns the value of trueExp if the predicate is true, otherwise the value of falseExp is returned. This function is similar to the ternary operator in Java.

isEmpty(exp)

boolean

Whether the expression is null or empty (list/map types are tested if they have 0 elements).

isEmpty

boolean

Whether the message body is null or empty (list/map types are tested if they have 0 elements).

join(separator,prefix,exp

String

The join function iterates the message body (by default) and joins the data into a String. The separator is by default a comma. The prefix is optional. The join uses the message body as source by default. It is possible to refer to another source (simple language) such as a header via the exp parameter. For example join('&','id=','$\{header.ids}')

jq(exp)

Object

When working with JSon data, then this allows using the JQ language, for example, to extract data from the message body (in JSon format). This requires having camel-jq JAR on the classpath.

jq(input,exp)

Object

Same as jp(exp) but to use the input expression as the source of the JSon document.

jsonpath(exp)

Object

"When working with JSon data, then this allows using the JsonPath language, for example, to extract data from the message body (in JSon format). This requires having camel-jsonpath JAR on the classpath.

jsonpath(input,exp)

Object

Same as jsonpath(exp) but to use the input expression as the source of the JSon document.

length()

int

The payload length (number of bytes) of the message body

length(exp)

int

The payload length (number of bytes) of the expression.

list(val1,val2,…​)

List

The list function creates an java.util.ArrayList with the given set of values.

logExchange

String

Dumps the exchange for logging purpose (uses ExchangeFormatter to format the output).

lowercase()

String

Lowercases the message body

lowercase(exp)

String

Lowercases the expression

mandatoryBodyAs(type).OGNL

Object

Same as mandatoryBodyAs(type) and then invoke Camel OGNL syntax.

mandatoryBodyAs(type)

<T>

Converts the message body to the given type determined by its classname. If the body is null then an exception is thrown.

map(key1,value1,…​)

Map

The map function creates a java.util.LinkedHashMap with the given set of pairs.

messageAs(type).OGNL

Object

Same as messageAs(type) and then invoke Camel OGNL syntax.

messageAs(type)

<T>

Converts the message to the given type determined by its classname.

messageHistory(false)

String

Same as messageHistory but without the exchange details (only includes the route stack-trace). This can be used if you do not want to log sensitive data from the message itself.

messageHistory

String

The message history of the current exchange (how it has been routed). This is similar to the route stack-trace message history the error handler logs in case of an unhandled exception.

messageTimestamp

long

The message timestamp (millis since epoc) that this message originates from. Some systems like JMS, Kafka, AWS have a timestamp on the event/message that Camel received. This method returns the timestamp if a timestamp exists. The message timestamp and exchange created are different. An exchange always has a created timestamp which is the local timestamp when Camel created the exchange. The message timestamp is only available in some Camel components when the consumer is able to extract the timestamp from the source event. If the message has no timestamp, then 0 is returned.

normalizeWhitespace()

String

Normalizes the whitespace in the message body by cleaning up excess whitespaces.

normalizeWhitespace(exp)

String

Normalizes the whitespace in the expression by cleaning up excess whitespaces.

null

null

Returns a null value.

originalBody

Object

The original incoming message body (only available if Camel has been configured with allowUseOriginalMessage=true).

pretty(exp)

String

Converts the expression to a String, and attempts to pretty print (if JSon or XML) otherwise return the value as-is.

prettyBody

String

Converts the message body to a String, and attempts to pretty print (if JSon or XML) otherwise return the value as-is.

properties:key:default

String

Lookup a property placeholder with the given key. If the key does not exist nor has a value, then an optional default value can be specified.

propertiesExist:key

boolean

Checks whether a property placeholder with the given key exists or not. The result can be negated by prefixing the key with !.

random(max)

int

Returns a random Integer between 0 (included) and max (excluded).

random(min,max)

int

Returns a random Integer between min (included) and max (excluded),

ref:_key_

Object

To look up a bean from the Camel Registry with the given key.

replace(from,to)

String

Replace all the string values in the message body. To make it easier to replace single and double quotes, then you can use XML escaped values &quot; as double quote, &apos; as single quote, and &empty; as empty value.

replace(from,to,ex[])

String

Replace all the string values in the given expression. To make it easier to replace single and double quotes, then you can use XML escaped values &quot; as double quote, &apos; as single quote, and &empty; as empty value.

routeGroup

String

Returns the route group of the current route the Exchange is being routed. Not all routes have a group assigned, so this may be null.

routeId

String

Returns the route id of the current route the Exchange is being routed.

size()

int

The size of the message body. If the payload is java.util.Collection or java.util.Map based then the size is the number of elements; otherwise the payload size in bytes.

size(exp)

int

The size of the expression. If the payload is java.util.Collection or java.util.Map based then the size is the number of elements; otherwise the payload size in bytes.

skip(number)

Iterator

The skip function iterates the message body and skips the first number of items. This can be used with the Splitter EIP to split a message body and skip the first N number of items.

split(exp,separator)

String[]

Splits the expression as a String value using the separator into a String array. The separator is comma by default.

split(separator)

String[]

Splits the message body as a String value using the separator into a String array. The separator is comma by default.

stepId

String

Returns the id of the current step the Exchange is being routed. Returns null if there are no steps.

substring(num1)

String

Returns a substring of the message body. If the number is positive, then the returned string is clipped from the beginning. If the number is negative, then the returned string is clipped from the ending.

substring(num1,num2)

String

Returns a substring of the message body. If the number is positive, then the returned string is clipped from the beginning. If the number is negative, then the returned string is clipped from the ending.

substring(num1,num2,exp)

String

Returns a substring of the given expression. If the number is positive, then the returned string is clipped from the beginning. If the number is negative, then the returned string is clipped from the ending.

substringAfter(after)

String

Returns a substring of the message body that comes after. Returns null if nothing comes after.

substringAfter(exp,after)

String

Returns a substring of the expression that comes after. Returns null if nothing comes after.

substringBefore(before)

String

Returns a substring of the message body that comes before. Returns null if nothing comes before.

substringBefore(exp,before)

String

Returns a substring of the expression that comes before. Returns null if nothing comes before.

substringBetween(after,before

String

Returns a substring of the message body that are between before and after. Returns null if nothing comes between.

substringBetween(exp,after,before

String

Returns a substring of the expression that are between before and after. Returns null if nothing comes between.

sys.key

String

Deprecated To lookup the JVM system property with the given key.

sysenv.key

String

To lookup the JVM system property with the given key.

threadId

String

Returns the id of the current thread.

threadName

String

Returns the name of the current thread.

trim()

String

The trim function trims the message body by removing all leading and trailing white spaces.

trim(exp)

String

The trim function trims the expression by removing all leading and trailing white spaces.

type:name.field

Object

To refer to a type or field by its fully qualified classname. For example: type:org.apache.camel.Exchange.FILE_NAME.

uppercase()

String

Uppercases the message body

uppercase(exp)

String

Uppercases the expression

uuid(kind)

String

Returns a UUID using the Camel UuidGenerator. You can choose kind between default, classic, short, simple and random as the kind. If no kind is given, then default is used. It is also possible to use a custom UuidGenerator and bind the bean to the Registry with an id. For example ${uuid(myGenerator)} where the id is myGenerator.

variable.key.OGNL

Object

To look up the variable with the given key and then invoke Camel OGNL syntax.

variable.key

Object

To look up the variable with the given key.

variableAs(key,type)

<T>

To look up the variable with the given key, and convert the value to the given type determined by its classname

variable[key]

Object

Deprecated To look up the variable with the given key.

variables.size

int

The number of Exchange variables

variables

Map

All the variables from the current Exchange as a java.util.Map.

xpath(exp)

Object

When working with XML data, then this allows using the XPath language, for example, to extract data from the message body (in XML format). This requires having camel-xpath JAR on the classpath.

xpath(input,exp)

Object

When working with XML data, then this allows using the XPath language, for example, to extract data from the message body (in XML format). This requires having camel-xpath JAR on the classpath. For input you can choose header:key, exchangeProperty:key or variable:key to use as input for the JSon payload instead of the message body.

Attachment Functions

From Camel 4.10 onwards then Camel has built-in attachment functions making it easy to obtain details from attachments stored on the Camel Message such as from HTTP file uploads, email with file attachments etc.

This requires having camel-attachments JAR on the classpath.

Function Response Type Description

attachment.key.OGNL

Object

Refer to the attachment with the given key on the Exchange and invoke its value using a Camel OGNL syntax.

attachmentContent(key)

Object

The content of the attachment.

attachmentContentAs(key,type)

Object

The content of the attachment, converted to the given type.

attachmentContentAsText(key)

String

The content of the attachment as text (ie String).

attachmentHeader(key,name)

Object

The attachment header with the given name.

attachmentHeaderAs(key,name,type)

<T>

The attachment header with the given name, converted to the given type.

attachment[key]

DataHandler

The jakarta.activation.DataHandler for the given attachment.

attachments.size

int

The number of attachments. Is 0 if there are no attachments.

attachments

Map

All the attachments as a Map<String,jakarta.activation.DataHandler>.

Base64 Functions

From Camel 4.18 onwards then Camel has built-in base64 functions to make it easy to encode/decode.

This requires having camel-base64 JAR on the classpath.

Function Response Type Description

base64Decode()

byte[]

Base64 decodes the message body

base64Decode(exp)

byte[]

Base64 decodes the expression

base64Encode()

String

Base64 encodes the message body

base64Encode(exp)

String

Base64 encodes the expression

Built-in Operators

The simple language has limited support for operators that are used in predicates to evaluate whether a condition is either true or false.

Camel operators require the left value must be enclosed in ${ }. The syntax is:

${leftValue} OP rightValue

Where the rightValue can be a string literal enclosed in ' ', null, a constant value or another expression enclosed in ${ }.

There must be spaces around the operator.

Camel will automatically type convert the rightValue type to the leftValue type, so it is able to e.g., convert a string into a numeric, so you can use > comparison for numeric values.

The following operators are supported:

Operator Description

==

equals

=~

equals ignore case (will ignore case when comparing String values)

>

greater than

>=

greater than or equals

<

less than

<=

less than or equals

!=

not equals

!=~

not equals ignore case (will ignore case when comparing String values)

~~

For testing if contains by ignoring case sensitivity in a string-based value

!~~

For testing if it does not contain by ignoring case sensitivity in a string-based value

contains

For testing if contains in a string-based value

!contains

For testing if it does not contain in a string-based value

endsWith

For testing if the left-hand side string ends with the right-hand string.

!endsWith

For testing if the left-hand side string does not end with the right-hand string.

in

For matching if in a set of values, each element must be separated by comma. If you want to include an empty value, then it must be defined using double comma, e.g. ',, bronze,silver,gold', which is a set of four values with an empty value and then the three medals.

!in

For matching if not in a set of values, each element must be separated by comma. If you want to include an empty value, then it must be defined using double comma, e.g. ',,bronze,silver,gold', which is a set of four values with an empty value and then the three medals.

is

For matching if the left-hand side type is an instance of the value.

!is

For matching if the left-hand side type is not an instance of the value.

range

For matching if the left-hand side is within a range of values defined as numbers: from..to.

!range

For matching if the left-hand side is not within a range of values defined as numbers: from..to.

regex

For matching against a given regular expression pattern defined as a String value

!regex

For not matching against a given regular expression pattern defined as a String value

startsWith

For testing if the left-hand side string starts with the right-hand string.

!startsWith

For testing if the left-hand side string does not start with the right-hand string.

And the following unary operators can be used:

Operator Description

++

To increment a number by one. The left-hand side must be a function, otherwise parsed as literal.

--

To decrement a number by one. The left-hand side must be a function, otherwise parsed as literal.

And the following special symbols:

Symbol Description

\n

To use newline character.

\t

To use tab character.

\r

To use carriage return character.

\}

To use the } character as text. This may be needed when building a JSon structure with the simple language.

And the following logical operators can be used to group expressions:

Operator Description

&&

The logical and operator is used to group two expressions.

||

The logical or operator is used to group two expressions.

The syntax for AND is:

${leftValue} OP rightValue && ${leftValue} OP rightValue

And the syntax for OR is:

${leftValue} OP rightValue || ${leftValue} OP rightValue

Some examples:

// exact equals match
simple("${header.foo} == 'foo'")

// ignore case when comparing, so if the header has value FOO, this will match
simple("${header.foo} =~ 'foo'")

// here Camel will type convert '100' into the type of header.bar and if it is an Integer '100' will also be converter to an Integer
simple("${header.bar} == '100'")

simple("${header.bar} == 100")

// 100 will be converter to the type of header.bar, so we can do > comparison
simple("${header.bar} > 100")

// if the value of header.bar was 100, value returned will be 101. header.bar itself will not be changed.
simple("${header.bar}++")

Using Operators with different Java Object types

When you compare with different types such as String and int, then you have to take a bit of care. Camel will use the type from the left-hand side as first priority. And fallback to the right-hand side type if both values couldn’t be compared based on that type. This means you can flip the values to enforce a specific type. Suppose the bar value above is a String.

Then you can flip the equation:

simple("100 < ${header.bar}")

which then ensures the int type is used as first priority.

This may change in the future if the Camel team improves the binary comparison operations to prefer numeric types to String-based. It’s most often the String type which causes problems when comparing with numbers.

// testing for null
simple("${header.baz} == null")

// testing for not null
simple("${header.baz} != null")

And a bit more advanced example where the right value is another expression

simple("${header.date} == ${date:now:yyyyMMdd}")

simple("${header.type} == ${bean:orderService?method=getOrderType}")

And an example with contains, testing if the title contains the word Camel

simple("${header.title} contains 'Camel'")

And an example with regex, testing if the number header is a 4-digit value:

simple("${header.number} regex '\\d{4}'")

And finally an example if the header equals any of the values in the list. Each element must be separated by comma, and no space around. This also works for numbers etc., as Camel will convert each element into the type of the left-hand side.

simple("${header.type} in 'gold,silver'")

And for all the last 3, we also support the negate test using not:

simple("${header.type} !in 'gold,silver'")

And you can test if the type is a certain instance, e.g., for instance a String

simple("${header.type} is 'java.lang.String'")

We have added a shorthand for all java.lang types, so you can write it as:

simple("${header.type} is 'String'")

Ranges are also supported. The range interval requires numbers and both from and end are inclusive. For instance, to test whether a value is between 100 and 199:

simple("${header.number} range 100..199")

Notice we use .. in the range without spaces. It is based on the same syntax as Groovy.

simple("${header.number} range '100..199'")

As the XML DSL does not have all the power as the Java DSL with all its various builder methods, you have to resort to using some other languages for testing with simple operators. Now you can do this with the simple language. In the sample below, we want to test it if the header is a widget order:

<from uri="seda:orders">
   <filter>
       <simple>${header.type} == 'widget'</simple>
       <to uri="bean:orderService?method=handleWidget"/>
   </filter>
</from>

Combining multiple expression using AND / OR

If you have two expressions you can combine them with the && (and) or || (or) operator.

For instance:

simple("${header.title} contains 'Camel' && ${header.type'} == 'gold'")

And of course the || is also supported. The sample would be:

simple("${header.title} contains 'Camel' || ${header.type'} == 'gold'")

OGNL Expression Support

The Simple and Bean languages support a OGNL like notation for invoking methods (using reflection) in a fluent builder like style.

OGNL (Object-Graph Navigation Language) is a powerful expression language used in Java. In Camel you can use OGNL dot notation to invoke methods. If you for instance have a body that contains a POJO that has a getFamilyName method then you can construct the Simple syntax as follows:

simple("${body.familyName}")

Or use similar syntax as in Java:

simple("${body.getFamilyName()}")

Camel’s OGNL support is for invoking methods only. You cannot access fields. Camel support accessing the length field of Java arrays.

When using OGNL then camel-bean JAR is required to be on the classpath.

Built-in Functions supporting OGNL

The following functions support OGNL syntax:

Variable Response Type Description

attachment.key.OGNL

Object

Refer to the attachment with the given key on the Exchange. This requires having camel-attachments JAR on classpath.

bodyAs(type)

<T>

The message body converted to the given type

body

Object

The message body

camelContext

CamelContext

The CamelContext

convertTo(exp,type)

<T>

Converts the expression to the specified type

exception

Throwable

If the exchange failed due to an exception

exchangeProperty.key

Object

The value from the exchange property with the given key

exchange

Exchange

The current Exchange

header.key

Object

The value from the message header with the given key

mandatoryBodyAs(type)

<T>

The message body converted to the given type

messageAs(type)

<T>

The org.apache.camel.Message as a specialized instance

variable.key

Object

The value from the variable with the given key

Basic OGNL examples

Suppose the Message body contains a POJO which has a getAddress() method. Then you can use Camel OGNL notation to access the address object:

simple("${body.address}")
simple("${body.address.street}")
simple("${body.address.zip}")

Camel understands the shorthand names for getters, but you can invoke any method or use the real name such as:

simple("${body.address}")
simple("${body.getAddress.getStreet}")
simple("${body.getAddress().getStreet()}")
simple("${body.address.getZip}")
simple("${body.doSomething}")

You can also use the null safe operator (?.) to avoid NullPointerException if, for example, the body does NOT have an address:

simple("${body?.address?.street}")

Advanced OGNL examples

It is also possible to index in Map or List types, so you can do:

simple("${body[foo].name}")

To assume the body is Map based and look up the value with foo as key, and invoke the getName method on that value.

If the key has space, then you must enclose the key with quotes, for example, 'foo bar':

simple("${body['foo bar'].name}")

You can access the Map or List objects directly using their key name (with or without dots) :

simple("${body[foo]}")
simple("${body[this.is.foo]}")

Suppose there was no value with the key foo then you can use the null safe operator to avoid the NPE as shown:

simple("${body[foo]?.name}")

You can also access List types, for example, to get lines from the address you can do:

simple("${body.address.lines[0]}")
simple("${body.address.lines[1]}")
simple("${body.address.lines[2]}")

There is a special last keyword which can be used to get the last value from a list.

simple("${body.address.lines[last]}")

And to get the 2nd last you can subtract a number, so we can use last-1 to indicate this:

simple("${body.address.lines[last-1]}")

And the third last is, of course:

simple("${body.address.lines[last-2]}")

And you can call the size method on the list with

simple("${body.address.lines.size}")

Camel supports the length field for Java arrays as well, e.g.:

String[] lines = new String[]{"foo", "bar", "cat"};
exchange.getMessage().setBody(lines);

simple("There are ${body.length} lines")

You can also use the length function from Camel 4.18: simple("There are ${length()} lines")

And yes, you can combine this with the Simple operators such as checking if a zip code is larger than 1000:

simple("${body.address.zip} > 1000")

EIP Examples

In the XML DSL sample below, we filter based on a header value:

<from uri="seda:orders">
   <filter>
       <simple>${header.foo}</simple>
       <to uri="mock:fooOrders"/>
   </filter>
</from>

The Simple language can be used for the predicate test above in the Message Filter pattern, where we test if the in message has a foo header (a header with the key foo exists). If the expression evaluates to true, then the message is routed to the mock:fooOrders endpoint, otherwise the message is dropped.

The same example in Java DSL:

from("seda:orders")
    .filter().simple("${header.foo}")
        .to("seda:fooOrders");

You can also use the simple language for simple text concatenations such as:

from("direct:hello")
    .transform().simple("Hello ${header.user} how are you?")
    .to("mock:reply");

Notice that we must use ${ } placeholders in the expression now to allow Camel to parse it correctly.

And this sample uses the date command to output current date.

from("direct:hello")
    .transform().simple("The today is ${date:now:yyyyMMdd} and it is a great day.")
    .to("mock:reply");

And in the sample below, we invoke the bean language to invoke a method on a bean to be included in the returned string:

from("direct:order")
    .transform().simple("OrderId: ${bean:orderIdGenerator}")
    .to("mock:reply");

Where orderIdGenerator is the id of the bean registered in the Registry. If using Spring, then it is the Spring bean id.

If we want to declare which method to invoke on the order id generator bean we must prepend .method name such as below where we invoke the generateId method.

from("direct:order")
    .transform().simple("OrderId: ${bean:orderIdGenerator.generateId}")
    .to("mock:reply");

We can use the ?method=methodname option that we are familiar with the Bean component itself:

from("direct:order")
    .transform().simple("OrderId: ${bean:orderIdGenerator?method=generateId}")
    .to("mock:reply");

You can also convert the body to a given type, for example, to ensure that it is a String you can do:

<transform>
  <simple>Hello ${bodyAs(String)} how are you?</simple>
</transform>

There are a few types which have a shorthand notation, so we can use String instead of java.lang.String. These are: byte[], String, Integer, Long. All other types must use their FQN name, e.g. org.w3c.dom.Document.

It is also possible to look up a value from a header Map:

<transform>
  <simple>The gold value is ${header.type[gold]}</simple>
</transform>

In the code above we look up the header with name type and regard it as a java.util.Map and we then look up with the key gold and return the value. If the header is not convertible to Map, an exception is thrown. If the header with name type does not exist null is returned.

You can nest functions, such as shown below:

<setHeader name="myHeader">
  <simple>${properties:${header.someKey}}</simple>
</setHeader>

Using Substring Function

You can use the substring function to more easily clip the message body. For example if the message body contains the following 10 letters ABCDEFGHIJ then:

<setBody>
  <simple>${substring(3)}</simple>
</setBody>

Then the message body after the substring will be DEFGHIJ. If you want to clip from the end instead, then use negative values such as substring(-3).

You can also clip from both ends at the same time such as substring(1,-1) that will clip the first and last character in the String.

If the number is higher than the length of the message body, then an empty string is returned, for example substring(99).

Instead of the message body then a simple expression can be nested as input, for example, using a variable, as shown below:

<setBody>
  <simple>${substring(1,-1,${variable.foo})}</simple>
</setBody>

Substring Before, After, or Between

In Camel 4.18 there are additional substring methods to make it easier to select a part of a string.

For example suppose the message body contains 'Hello great big World how are you', then you select different parts:

// select text before `World` -> `Hello great big `
.setHeader("foo", simple("${substringBefore('World'}"))

// select text after `World` -> ` how are you`
.setHeader("foo2", simple("${substringAfter('World'}"))

// select text between `great` ... `how` -> ` big World `
.setHeader("foo2", simple("${substringBetween('great', 'how'}"))

// NOTE: and you can wrap this with trim to remove spaces:

// select text before `World` -> `Hello great big`
.setHeader("foo", simple("$trim{${substringBefore('World'}}")})

// select text after `World` -> `how are you`
.setHeader("foo2", simple("$trim{${substringAfter('World'}}"))

// select text between `great` ... `how` -> `big World`
.setHeader("foo2", simple("$trim{${substringBetween('great', 'how'}}"))

Replacing double and single quotes

You can use the replace function to more easily replace all single or double quotes in the message body, using the XML escape syntax. This avoids to fiddle with enclosing a double quote or single quotes with outer quotes, that can get confusing to be correct as you may need to escape the quotes as well. So instead you can use the XML escape syntax where double quote is &quot; and single quote is &apos; (yeah that is the name).

For example, to replace all double quotes with single quotes:

from("direct:order")
  .transform().simple("${replace(&quot; , &apos;)}")
  .to("mock:reply");

And to replace all single quotes with double quotes:

<setBody>
  <simple>${replace(&apos; , &quot;)}</simple>
</setBody>

Or to remove all double quotes:

<setBody>
  <simple>${replace(&quot; , &empty;)}</simple>
</setBody>

Setting the result type

You can now provide a result type to the Simple expression, which means the result of the evaluation will be converted to the desired type. This is most usable to define types such as booleans, integers, etc.

For example, to set a header as a boolean type, you can do:

.setHeader("cool", simple("true", Boolean.class))

And in XML DSL

<setHeader name="cool">
  <!-- use resultType to indicate that the type should be a java.lang.Boolean -->
  <simple resultType="java.lang.Boolean">true</simple>
</setHeader>

Using new lines or tabs in XML DSLs

It is easier to specify new lines or tabs in XML DSLs as you can escape the value now

<transform>
  <simple>The following text\nis on a new line</simple>
</transform>

Leading and trailing whitespace handling

The trim attribute of the expression can be used to control whether the leading and trailing whitespace characters are removed or preserved. The default value is true, which removes the whitespace characters.

<setBody>
  <simple trim="false">You get some trailing whitespace characters.     </simple>
</setBody>

Loading script from external resource

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", e.g., to refer to a file on the classpath you can do:

.setHeader("myHeader").simple("resource:classpath:mysimple.txt")

Pretty XML or JSon

From Camel 4.18 onwards then the Simple language can pretty format the output.

In Java DSL you turn this on via the boolean parameter that is set as true below:

from("direct:xml")
    .setBody().simple("<person><name>Jack</name></person>", true)
    .to("mock:result");

from("direct:json")
    .setBody().simple("{ \"name\": \"Jack\", \"age\": 44 }", true)
    .to("mock:result");

from("direct:text")
    .setBody().simple("Hello ${body}", true)
    .to("mock:result");

In YAML DSL you specific pretty: true as follows:

route:
  from:
    uri: direct:xml
    steps:
      - setBody:
          simple:
            expression: "<person><name>Jack</name></person>"
            pretty: true
      - to:
          uri: mock:result

And in XML DSL you use the pretty attribute to true as show below:

<route>
  <from uri="direct:json"/>
  <setBody>
    <simple pretty="true">{ "name": "Jack", "age": 44 }</simple>
  </setBody>
  <to uri="mock:result"/>
</route>

Spring Boot Auto-Configuration

When using simple 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-core-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 118 options, which are listed below.

Name Description Default Type

camel.cloud.consul.service-discovery.acl-token

Sets the ACL token to be used with Consul.

String

camel.cloud.consul.service-discovery.block-seconds

The seconds to wait for a watch event, default 10 seconds.

10

Integer

camel.cloud.consul.service-discovery.configurations

Define additional configuration definitions.

Map

camel.cloud.consul.service-discovery.connect-timeout-millis

Connect timeout for OkHttpClient.

Long

camel.cloud.consul.service-discovery.datacenter

The data center.

String

camel.cloud.consul.service-discovery.enabled

Enable the component.

true

Boolean

camel.cloud.consul.service-discovery.password

Sets the password to be used for basic authentication.

String

camel.cloud.consul.service-discovery.properties

Set client properties to use. These properties are specific to what service call implementation are in use. For example if using a different one, then the client properties are defined according to the specific service in use.

Map

camel.cloud.consul.service-discovery.read-timeout-millis

Read timeout for OkHttpClient.

Long

camel.cloud.consul.service-discovery.url

The Consul agent URL.

String

camel.cloud.consul.service-discovery.user-name

Sets the username to be used for basic authentication.

String

camel.cloud.consul.service-discovery.write-timeout-millis

Write timeout for OkHttpClient.

Long

camel.cloud.dns.service-discovery.configurations

Define additional configuration definitions.

Map

camel.cloud.dns.service-discovery.domain

The domain name;.

String

camel.cloud.dns.service-discovery.enabled

Enable the component.

true

Boolean

camel.cloud.dns.service-discovery.properties

Set client properties to use. These properties are specific to what service call implementation are in use. For example if using a different one, then the client properties are defined according to the specific service in use.

Map

camel.cloud.dns.service-discovery.proto

The transport protocol of the desired service.

_tcp

String

camel.cloud.kubernetes.service-discovery.api-version

Sets the API version when using client lookup.

String

camel.cloud.kubernetes.service-discovery.ca-cert-data

Sets the Certificate Authority data when using client lookup.

String

camel.cloud.kubernetes.service-discovery.ca-cert-file

Sets the Certificate Authority data that are loaded from the file when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-cert-data

Sets the Client Certificate data when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-cert-file

Sets the Client Certificate data that are loaded from the file when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-key-algo

Sets the Client Keystore algorithm, such as RSA when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-key-data

Sets the Client Keystore data when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-key-file

Sets the Client Keystore data that are loaded from the file when using client lookup.

String

camel.cloud.kubernetes.service-discovery.client-key-passphrase

Sets the Client Keystore passphrase when using client lookup.

String

camel.cloud.kubernetes.service-discovery.configurations

Define additional configuration definitions.

Map

camel.cloud.kubernetes.service-discovery.dns-domain

Sets the DNS domain to use for DNS lookup.

String

camel.cloud.kubernetes.service-discovery.enabled

Enable the component.

true

Boolean

camel.cloud.kubernetes.service-discovery.lookup

How to perform service lookup. Possible values: client, dns, environment. When using client, then the client queries the kubernetes master to obtain a list of active pods that provides the service, and then random (or round robin) select a pod. When using dns the service name is resolved as name.namespace.svc.dnsDomain. When using dnssrv the service name is resolved with SRV query for .…​svc…​ When using environment then environment variables are used to lookup the service. By default environment is used.

environment

String

camel.cloud.kubernetes.service-discovery.master-url

Sets the URL to the master when using client lookup.

String

camel.cloud.kubernetes.service-discovery.namespace

Sets the namespace to use. Will by default use namespace from the ENV variable KUBERNETES_MASTER.

String

camel.cloud.kubernetes.service-discovery.oauth-token

Sets the OAUTH token for authentication (instead of username/password) when using client lookup.

String

camel.cloud.kubernetes.service-discovery.password

Sets the password for authentication when using client lookup.

String

camel.cloud.kubernetes.service-discovery.port-name

Sets the Port Name to use for DNS/DNSSRV lookup.

String

camel.cloud.kubernetes.service-discovery.port-protocol

Sets the Port Protocol to use for DNS/DNSSRV lookup.

String

camel.cloud.kubernetes.service-discovery.properties

Set client properties to use. These properties are specific to what service call implementation are in use. For example if using a different one, then the client properties are defined according to the specific service in use.

Map

camel.cloud.kubernetes.service-discovery.trust-certs

Sets whether to turn on trust certificate check when using client lookup.

false

Boolean

camel.cloud.kubernetes.service-discovery.username

Sets the username for authentication when using client lookup.

String

camel.language.constant.enabled

Whether to enable auto configuration of the constant language. This is enabled by default.

Boolean

camel.language.constant.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.csimple.enabled

Whether to enable auto configuration of the csimple language. This is enabled by default.

Boolean

camel.language.csimple.pretty

To pretty format the output (only JSon or XML supported).

false

Boolean

camel.language.csimple.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.exchange-property.enabled

Whether to enable auto configuration of the exchangeProperty language. This is enabled by default.

Boolean

camel.language.exchange-property.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.file.enabled

Whether to enable auto configuration of the file language. This is enabled by default.

Boolean

camel.language.file.pretty

To pretty format the output (only JSon or XML supported).

false

Boolean

camel.language.file.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.header.enabled

Whether to enable auto configuration of the header language. This is enabled by default.

Boolean

camel.language.header.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.ref.enabled

Whether to enable auto configuration of the ref language. This is enabled by default.

Boolean

camel.language.ref.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.simple.enabled

Whether to enable auto configuration of the simple language. This is enabled by default.

Boolean

camel.language.simple.pretty

To pretty format the output (only JSon or XML supported).

false

Boolean

camel.language.simple.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.tokenize.enabled

Whether to enable auto configuration of the tokenize language. This is enabled by default.

Boolean

camel.language.tokenize.group-delimiter

Sets the delimiter to use when grouping. If this has not been set then token will be used as the delimiter.

String

camel.language.tokenize.source

Source to use, instead of message body. You can prefix with variable:, header:, or property: to specify kind of source. Otherwise, the source is assumed to be a variable. Use empty or null to use default source, which is the message body.

String

camel.language.tokenize.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.language.variable.enabled

Whether to enable auto configuration of the variable language. This is enabled by default.

Boolean

camel.language.variable.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks.

true

Boolean

camel.resilience4j.automatic-transition-from-open-to-half-open-enabled

Enables automatic transition from OPEN to HALF_OPEN state once the waitDurationInOpenState has passed.

false

Boolean

camel.resilience4j.bulkhead-enabled

Whether bulkhead is enabled or not on the circuit breaker. Default is false.

false

Boolean

camel.resilience4j.bulkhead-max-concurrent-calls

Configures the max amount of concurrent calls the bulkhead will support.

25

Integer

camel.resilience4j.bulkhead-max-wait-duration

Configures a maximum amount of time which the calling thread will wait to enter the bulkhead. If bulkhead has space available, entry is guaranteed and immediate. If bulkhead is full, calling threads will contest for space, if it becomes available. maxWaitDuration can be set to 0. Note: for threads running on an event-loop or equivalent (rx computation pool, etc), setting maxWaitDuration to 0 is highly recommended. Blocking an event-loop thread will most likely have a negative effect on application throughput.

0

Integer

camel.resilience4j.circuit-breaker

Refers to an existing io.github.resilience4j.circuitbreaker.CircuitBreaker instance to lookup and use from the registry. When using this, then any other circuit breaker options are not in use.

String

camel.resilience4j.config

Refers to an existing io.github.resilience4j.circuitbreaker.CircuitBreakerConfig instance to lookup and use from the registry.

String

camel.resilience4j.configurations

Define additional configuration definitions.

Map

camel.resilience4j.enabled

Enable the component.

true

Boolean

camel.resilience4j.failure-rate-threshold

Configures the failure rate threshold in percentage. If the failure rate is equal or greater than the threshold the CircuitBreaker transitions to open and starts short-circuiting calls. The threshold must be greater than 0 and not greater than 100. Default value is 50 percentage.

Float

camel.resilience4j.ignore-exception

Configure a list of exceptions that are ignored and neither count as a failure nor success. Any exception matching or inheriting from one of the list will not count as a failure nor success, even if the exceptions is part of recordExceptions.

List

camel.resilience4j.micrometer-enabled

Whether to enable collecting statistics using Micrometer. This requires adding camel-resilience4j-micrometer JAR to the classpath.

false

Boolean

camel.resilience4j.minimum-number-of-calls

Configures the minimum number of calls which are required (per sliding window period) before the CircuitBreaker can calculate the error rate. For example, if minimumNumberOfCalls is 10, then at least 10 calls must be recorded, before the failure rate can be calculated. If only 9 calls have been recorded the CircuitBreaker will not transition to open even if all 9 calls have failed. Default minimumNumberOfCalls is 100.

100

Integer

camel.resilience4j.permitted-number-of-calls-in-half-open-state

Configures the number of permitted calls when the CircuitBreaker is half open. The size must be greater than 0. Default size is 10.

10

Integer

camel.resilience4j.record-exception

Configure a list of exceptions that are recorded as a failure and thus increase the failure rate. Any exception matching or inheriting from one of the list counts as a failure, unless explicitly ignored via ignoreExceptions.

List

camel.resilience4j.sliding-window-size

Configures the size of the sliding window which is used to record the outcome of calls when the CircuitBreaker is closed. slidingWindowSize configures the size of the sliding window. Sliding window can either be count-based or time-based. If slidingWindowType is COUNT_BASED, the last slidingWindowSize calls are recorded and aggregated. If slidingWindowType is TIME_BASED, the calls of the last slidingWindowSize seconds are recorded and aggregated. The slidingWindowSize must be greater than 0. The minimumNumberOfCalls must be greater than 0. If the slidingWindowType is COUNT_BASED, the minimumNumberOfCalls cannot be greater than slidingWindowSize . If the slidingWindowType is TIME_BASED, you can pick whatever you want. Default slidingWindowSize is 100.

100

Integer

camel.resilience4j.sliding-window-type

Configures the type of the sliding window which is used to record the outcome of calls when the CircuitBreaker is closed. Sliding window can either be count-based or time-based. If slidingWindowType is COUNT_BASED, the last slidingWindowSize calls are recorded and aggregated. If slidingWindowType is TIME_BASED, the calls of the last slidingWindowSize seconds are recorded and aggregated. Default slidingWindowType is COUNT_BASED.

COUNT_BASED

String

camel.resilience4j.slow-call-duration-threshold

Configures the duration threshold (seconds) above which calls are considered as slow and increase the slow calls percentage. Default value is 60 seconds.

60

Integer

camel.resilience4j.slow-call-rate-threshold

Configures a threshold in percentage. The CircuitBreaker considers a call as slow when the call duration is greater than slowCallDurationThreshold Duration. When the percentage of slow calls is equal or greater the threshold, the CircuitBreaker transitions to open and starts short-circuiting calls. The threshold must be greater than 0 and not greater than 100. Default value is 100 percentage which means that all recorded calls must be slower than slowCallDurationThreshold.

Float

camel.resilience4j.throw-exception-when-half-open-or-open-state

Whether to throw io.github.resilience4j.circuitbreaker.CallNotPermittedException when the call is rejected due circuit breaker is half open (and was not attempted but rejected immediately) or open (always rejected). This option is only in use when there is NOT a fallback configured on the circuit breaker. When there is a fallback then the fallback is always executed and CallNotPermittedException is not thrown.

false

Boolean

camel.resilience4j.timeout-cancel-running-future

Configures whether cancel is called on the running future. Defaults to true.

true

Boolean

camel.resilience4j.timeout-duration

Configures the thread execution timeout. Default value is 1 second.

1000

Integer

camel.resilience4j.timeout-enabled

Whether timeout is enabled or not on the circuit breaker. Default is false.

false

Boolean

camel.resilience4j.timeout-executor-service

References to a custom thread pool to use when timeout is enabled (uses ForkJoinPool#commonPool() by default).

ExecutorService

camel.resilience4j.wait-duration-in-open-state

Configures the wait duration (in seconds) which specifies how long the CircuitBreaker should stay open, before it switches to half open. Default value is 60 seconds.

60

Integer

camel.resilience4j.writable-stack-trace-enabled

Enables writable stack traces. When set to false, Exception.getStackTrace returns a zero length array. This may be used to reduce log spam when the circuit breaker is open as the cause of the exceptions is already known (the circuit breaker is short-circuiting calls).

true

Boolean

camel.rest.api-component

The name of the Camel component to use as the REST API. If no API Component has been explicit configured, then Camel will lookup if there is a Camel component responsible for servicing and generating the REST API documentation, or if a org.apache.camel.spi.RestApiProcessorFactory is registered in the registry. If either one is found, then that is being used.

String

camel.rest.api-context-path

Sets a leading context-path the REST API will be using. This can be used when using components such as camel-servlet where the deployed web application is deployed using a context-path.

String

camel.rest.api-context-route-id

Sets the route id to use for the route that services the REST API. The route will by default use an auto assigned route id.

String

camel.rest.api-host

To use a specific hostname for the API documentation (such as swagger or openapi) This can be used to override the generated host with this configured hostname.

String

camel.rest.api-property

Allows to configure as many additional properties for the api documentation. For example set property api.title to my cool stuff.

Map

camel.rest.api-vendor-extension

Whether vendor extension is enabled in the Rest APIs. If enabled then Camel will include additional information as vendor extension (eg keys starting with x-) such as route ids, class names etc. Not all 3rd party API gateways and tools supports vendor-extensions when importing your API docs.

false

Boolean

camel.rest.binding-mode

Sets the binding mode to use. The default value is off.

off

RestBindingMode

camel.rest.binding-package-scan

Package name to use as base (offset) for classpath scanning of POJO classes are located when using binding mode is enabled for JSon or XML. Multiple package names can be separated by comma.

String

camel.rest.client-request-validation

Whether to enable validation of the client request to check: 1) Content-Type header matches what the Rest DSL consumes; returns HTTP Status 415 if validation error. 2) Accept header matches what the Rest DSL produces; returns HTTP Status 406 if validation error. 3) Missing required data (query parameters, HTTP headers, body); returns HTTP Status 400 if validation error. 4) Parsing error of the message body (JSon, XML or Auto binding mode must be enabled); returns HTTP Status 400 if validation error.

false

Boolean

camel.rest.client-response-validation

Whether to check what Camel is returning as response to the client: 1) Status-code and Content-Type matches Rest DSL response messages. 2) Check whether expected headers is included according to the Rest DSL repose message headers. 3) If the response body is JSon then check whether its valid JSon. Returns 500 if validation error detected.

false

Boolean

camel.rest.component

The Camel Rest component to use for the REST transport (consumer), such as netty-http, jetty, servlet, undertow. If no component has been explicit configured, then Camel will lookup if there is a Camel component that integrates with the Rest DSL, or if a org.apache.camel.spi.RestConsumerFactory is registered in the registry. If either one is found, then that is being used.

String

camel.rest.component-property

Allows to configure as many additional properties for the rest component in use.

Map

camel.rest.consumer-property

Allows to configure as many additional properties for the rest consumer in use.

Map

camel.rest.context-path

Sets a leading context-path the REST services will be using. This can be used when using components such as camel-servlet where the deployed web application is deployed using a context-path. Or for components such as camel-jetty or camel-netty-http that includes a HTTP server.

String

camel.rest.cors-headers

Allows to configure custom CORS headers.

Map

camel.rest.data-format-property

Allows to configure as many additional properties for the data formats in use. For example set property prettyPrint to true to have json outputted in pretty mode. The properties can be prefixed to denote the option is only for either JSON or XML and for either the IN or the OUT. The prefixes are: json.in. json.out. xml.in. xml.out. For example a key with value xml.out.mustBeJAXBElement is only for the XML data format for the outgoing. A key without a prefix is a common key for all situations.

Map

camel.rest.enable-cors

Whether to enable CORS headers in the HTTP response. The default value is false.

false

Boolean

camel.rest.enable-no-content-response

Whether to return HTTP 204 with an empty body when a response contains an empty JSON object or XML root object. The default value is false.

false

Boolean

camel.rest.endpoint-property

Allows to configure as many additional properties for the rest endpoint in use.

Map

camel.rest.host

The hostname to use for exposing the REST service.

String

camel.rest.host-name-resolver

If no hostname has been explicit configured, then this resolver is used to compute the hostname the REST service will be using.

alllocalip

RestHostNameResolver

camel.rest.inline-routes

Inline routes in rest-dsl which are linked using direct endpoints. Each service in Rest DSL is an individual route, meaning that you would have at least two routes per service (rest-dsl, and the route linked from rest-dsl). By inlining (default) allows Camel to optimize and inline this as a single route, however this requires to use direct endpoints, which must be unique per service. If a route is not using direct endpoint then the rest-dsl is not inlined, and will become an individual route. This option is default true.

true

Boolean

camel.rest.json-data-format

Name of specific json data format to use. By default, jackson will be used. Important: This option is only for setting a custom name of the data format, not to refer to an existing data format instance.

jackson

String

camel.rest.port

The port number to use for exposing the REST service. Notice if you use servlet component then the port number configured here does not apply, as the port number in use is the actual port number the servlet component is using. eg if using Apache Tomcat its the tomcat http port, if using Apache Karaf its the HTTP service in Karaf that uses port 8181 by default etc. Though in those situations setting the port number here, allows tooling and JMX to know the port number, so its recommended to set the port number to the number that the servlet engine uses.

String

camel.rest.producer-api-doc

Sets the location of the api document the REST producer will use to validate the REST uri and query parameters are valid accordingly to the api document. The location of the api document is loaded from classpath by default, but you can use file: or http: to refer to resources to load from file or http url.

String

camel.rest.producer-component

Sets the name of the Camel component to use as the REST producer.

String

camel.rest.scheme

The scheme to use for exposing the REST service. Usually http or https is supported. The default value is http.

String

camel.rest.skip-binding-on-error-code

Whether to skip binding on output if there is a custom HTTP error code header. This allows to build custom error messages that do not bind to json / xml etc, as success messages otherwise will do.

false

Boolean

camel.rest.use-x-forward-headers

Whether to use X-Forward headers to set host etc. for OpenApi. This may be needed in special cases involving reverse-proxy and networking going from HTTP to HTTPS etc. Then the proxy can send X-Forward headers (X-Forwarded-Proto) that influences the host names in the OpenAPI schema that camel-openapi-java generates from Rest DSL routes.

false

Boolean

camel.rest.validation-levels

Allows to configure custom validation levels when using camel-openapi-validator with client request/response validator.

Map

camel.rest.xml-data-format

Name of specific XML data format to use. By default jaxb will be used, but jacksonXml is also supported. Important: This option is only for setting a custom name of the data format, not to refer to an existing data format instance.

jaxb

String
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