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From conflue...@apache.org
Subject [CONF] Apache Camel > Simple
Date Tue, 26 Jul 2011 06:50:00 GMT
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    <h2><a href="https://cwiki.apache.org/confluence/display/CAMEL/Simple">Simple</a></h2>
    <h4>Page <b>edited</b> by             <a href="https://cwiki.apache.org/confluence/display/~davsclaus">Claus
Ibsen</a>
    </h4>
        <br/>
                         <h4>Changes (1)</h4>
                                 
    
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                    <table class="diff" cellpadding="0" cellspacing="0">
    
            <tr><td class="diff-snipped" >...<br></td></tr>
            <tr><td class="diff-unchanged" >| out.headers.foo | Object | refer
to the out header foo | <br>| headerAs(_key_,_type_) | Type | *Camel 2.5:* Converts
the header to the given type determined by its classname | <br></td></tr>
            <tr><td class="diff-added-lines" style="background-color: #dfd;">|
headers | Map | *Camel 2.9:* refer to the input headers | <br>| in.headers | Map | *Camel
2.9:* refer to the input headers | <br></td></tr>
            <tr><td class="diff-unchanged" >| property.foo | Object | refer to
the foo property on the exchange | <br>| property.foo.*OGNL* | Object | *Camel 2.8:*
refer to the foo property on the exchange and invoke its value using a Camel OGNL expression.
| <br></td></tr>
            <tr><td class="diff-snipped" >...<br></td></tr>
    
            </table>
    </div>                            <h4>Full Content</h4>
                    <div class="notificationGreySide">
        <h2><a name="Simple-SimpleExpressionLanguage"></a>Simple Expression
Language</h2>

<p>The Simple Expression Language was a really simple language you can use, but has
since grown more powerful. Its primarily intended for being a really small and simple language
for evaluating <a href="/confluence/display/CAMEL/Expression" title="Expression">Expression</a>
and <a href="/confluence/display/CAMEL/Predicate" title="Predicate">Predicate</a>
without requiring any new dependencies or knowledge of <a href="/confluence/display/CAMEL/XPath"
title="XPath">XPath</a>; so its ideal for testing in camel-core. Its ideal to cover
95% of the common use cases when you need a little bit of expression based script in your
Camel routes.</p>

<p>However for much more complex use cases you are generally recommended to choose a
more expressive and powerful language such as: </p>
<ul>
	<li><a href="/confluence/display/CAMEL/JavaScript" title="JavaScript">JavaScript</a></li>
	<li><a href="/confluence/display/CAMEL/EL" title="EL">EL</a></li>
	<li><a href="/confluence/display/CAMEL/OGNL" title="OGNL">OGNL</a></li>
	<li><a href="/confluence/display/CAMEL/Mvel" title="Mvel">Mvel</a></li>
	<li><a href="/confluence/display/CAMEL/Groovy" title="Groovy">Groovy</a></li>
	<li>one of the supported <a href="/confluence/display/CAMEL/Scripting+Languages"
title="Scripting Languages">Scripting Languages</a></li>
</ul>


<p>The simple language uses <tt>${body</tt>} placeholders for complex expressions
where the expression contains constant literals. The ${ } placeholders can be omitted if the
expression is only the token itself.</p>

<div class='panelMacro'><table class='tipMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/check.gif" width="16" height="16"
align="absmiddle" alt="" border="0"></td><td><b>Alternative syntax</b><br
/>From Camel 2.5 onwards you can also use the alternative syntax which uses $simple{ }
as placeholders.<br/>
This can be used in situations to avoid clashes when using for example Spring property placeholder
together with Camel.</td></tr></table></div>

<div class='panelMacro'><table class='tipMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/check.gif" width="16" height="16"
align="absmiddle" alt="" border="0"></td><td><b>Configuring result type</b><br
/>From Camel 2.8 onwards you can configure the result type of the <a href="/confluence/display/CAMEL/Simple"
title="Simple">Simple</a> expression. For example to set the type as a <tt>java.lang.Boolean</tt>
or a <tt>java.lang.Integer</tt> etc.</td></tr></table></div>

<p>To get the body of the in message: <tt>"body"</tt>, or <tt>"in.body"</tt>
or <tt>"${body}"</tt>.</p>

<p>A complex expression must use ${ } placeholders, such as: <tt>"Hello ${in.header.name}
how are you?"</tt>.</p>

<p>You can have multiple tokens in the same expression: <tt>"Hello ${in.header.name}
this is ${in.header.me} speaking"</tt>.<br/>
However you can <b>not</b> nest tokens (i.e. having another ${ } placeholder in
an existing, is not allowed).</p>

<div class='panelMacro'><table class='infoMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/information.gif" width="16"
height="16" align="absmiddle" alt="" border="0"></td><td><b>File language
is now merged with Simple language</b><br />From Camel 2.2 onwards, the <a
href="/confluence/display/CAMEL/File+Language" title="File Language">File Language</a>
is now merged with <a href="/confluence/display/CAMEL/Simple" title="Simple">Simple</a>
language which means you can use all the file syntax directly within the simple language.</td></tr></table></div>

<h3><a name="Simple-Variables"></a>Variables</h3>

<div class='table-wrap'>
<table class='confluenceTable'><tbody>
<tr>
<th class='confluenceTh'> Variable </th>
<th class='confluenceTh'> Type </th>
<th class='confluenceTh'>  Description </th>
</tr>
<tr>
<td class='confluenceTd'> exchangeId </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> the exchange id </td>
</tr>
<tr>
<td class='confluenceTd'> id </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> the input message id </td>
</tr>
<tr>
<td class='confluenceTd'> body </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> the input body </td>
</tr>
<tr>
<td class='confluenceTd'> in.body </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> the input body </td>
</tr>
<tr>
<td class='confluenceTd'> body.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> the input body invoked using
a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> in.body.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> the input body invoked using
a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> bodyAs(<em>type</em>) </td>
<td class='confluenceTd'> Type </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> Converts the body to the given
type determined by its classname. The converted body can be null. </td>
</tr>
<tr>
<td class='confluenceTd'> mandatoryBodyAs(<em>type</em>) </td>
<td class='confluenceTd'> Type </td>
<td class='confluenceTd'> <b>Camel 2.5:</b> Converts the body to the given
type determined by its classname, and expects the body to be not null. </td>
</tr>
<tr>
<td class='confluenceTd'> out.body </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> the output body </td>
</tr>
<tr>
<td class='confluenceTd'> header.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the input foo header </td>
</tr>
<tr>
<td class='confluenceTd'> headers.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the input foo header </td>
</tr>
<tr>
<td class='confluenceTd'> in.header.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the input foo header </td>
</tr>
<tr>
<td class='confluenceTd'> in.headers.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the input foo header </td>
</tr>
<tr>
<td class='confluenceTd'> header.foo[bar] </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> regard input foo header as a
map and perform lookup on the map with bar as key </td>
</tr>
<tr>
<td class='confluenceTd'> in.header.foo[bar] </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> regard input foo header as a
map and perform lookup on the map with bar as key </td>
</tr>
<tr>
<td class='confluenceTd'> in.headers.foo[bar] </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> regard input foo header as a
map and perform lookup on the map with bar as key </td>
</tr>
<tr>
<td class='confluenceTd'> header.foo.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> refer to the input foo header
and invoke its value using a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> in.header.foo.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> refer to the input foo header
and invoke its value using a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> in.headers.foo.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> refer to the input foo header
and invoke its value using a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> out.header.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the out header foo </td>
</tr>
<tr>
<td class='confluenceTd'> out.headers.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the out header foo </td>
</tr>
<tr>
<td class='confluenceTd'> headerAs(<em>key</em>,<em>type</em>)
</td>
<td class='confluenceTd'> Type </td>
<td class='confluenceTd'> <b>Camel 2.5:</b> Converts the header to the given
type determined by its classname </td>
</tr>
<tr>
<td class='confluenceTd'> headers </td>
<td class='confluenceTd'> Map </td>
<td class='confluenceTd'> <b>Camel 2.9:</b> refer to the input headers </td>
</tr>
<tr>
<td class='confluenceTd'> in.headers </td>
<td class='confluenceTd'> Map </td>
<td class='confluenceTd'> <b>Camel 2.9:</b> refer to the input headers </td>
</tr>
<tr>
<td class='confluenceTd'> property.foo </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> refer to the foo property on the exchange </td>
</tr>
<tr>
<td class='confluenceTd'> property.foo.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.8:</b> refer to the foo property on
the exchange and invoke its value using a Camel OGNL expression. </td>
</tr>
<tr>
<td class='confluenceTd'> sys.foo </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> refer to the system property </td>
</tr>
<tr>
<td class='confluenceTd'> sysenv.foo </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> refer to the system environment
</td>
</tr>
<tr>
<td class='confluenceTd'> exception </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.4:</b> Refer to the exception object
on the exchange, is <b>null</b> if no exception set on exchange. Will fallback
and grab caught exceptions (<tt>Exchange.EXCEPTION_CAUGHT</tt>) if the Exchange
has any. </td>
</tr>
<tr>
<td class='confluenceTd'> exception.<b>OGNL</b> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.4:</b> Refer to the exchange exception
invoked using a Camel OGNL expression object </td>
</tr>
<tr>
<td class='confluenceTd'> exception.message </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.0.</b> Refer to the exception.message
on the exchange, is <b>null</b> if no exception set on exchange. Will fallback
and grab caught exceptions (<tt>Exchange.EXCEPTION_CAUGHT</tt>) if the Exchange
has any. </td>
</tr>
<tr>
<td class='confluenceTd'> exception.stacktrace </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.6.</b> Refer to the exception.stracktrace
on the exchange, is <b>null</b> if no exception set on exchange. Will fallback
and grab caught exceptions (<tt>Exchange.EXCEPTION_CAUGHT</tt>) if the Exchange
has any. </td>
</tr>
<tr>
<td class='confluenceTd'> date:<em>command:pattern</em> </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 1.5.</b> Date formatting using the <tt>java.text.SimpleDataFormat</tt>
patterns. Supported commands are: <b>now</b> for current timestamp, <b>in.header.xxx</b>
or <b>header.xxx</b> to use the Date object in the IN header with the key xxx.
<b>out.header.xxx</b> to use the Date object in the OUT header with the key xxx.</td>
</tr>
<tr>
<td class='confluenceTd'> bean:<em>bean expression</em> </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 1.5.</b> Invoking a bean expression using
the <a href="/confluence/display/CAMEL/Bean" title="Bean">Bean</a> language. Specifying
a method name you must use dot as separator. In Camel 2.0 we also support the ?method=methodname
syntax that is used by the <a href="/confluence/display/CAMEL/Bean" title="Bean">Bean</a>
component. </td>
</tr>
<tr>
<td class='confluenceTd'> properties:<em>locations:key</em> </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> Lookup a property with the given
key. The <tt>locations</tt> option is optional. See more at <a href="/confluence/display/CAMEL/Using+PropertyPlaceholder"
title="Using PropertyPlaceholder">Using PropertyPlaceholder</a>. </td>
</tr>
<tr>
<td class='confluenceTd'> threadName </td>
<td class='confluenceTd'> String </td>
<td class='confluenceTd'> <b>Camel 2.3:</b> Returns the name of the current
thread. Can be used for logging purpose. </td>
</tr>
<tr>
<td class='confluenceTd'> ref:xxx </td>
<td class='confluenceTd'> Object </td>
<td class='confluenceTd'> <b>Camel 2.6:</b> To lookup a bean from the <a
href="/confluence/display/CAMEL/Registry" title="Registry">Registry</a> with the
given id. </td>
</tr>
</tbody></table>
</div>


<h3><a name="Simple-OGNLexpressionsupport"></a>OGNL expression support</h3>
<p><b>Available as of Camel 2.3</b></p>

<p>The <a href="/confluence/display/CAMEL/Simple" title="Simple">Simple</a>
and <a href="/confluence/display/CAMEL/Bean" title="Bean">Bean</a> language now
supports a Camel OGNL notation for invoking beans in a chain like fashion.<br/>
Suppose the Message IN body contains a POJO which has a <tt>getAddress()</tt>
method.</p>

<p>Then you can use Camel OGNL notation to access the address object:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address}"</span>)
simple(<span class="code-quote">"${body.address.street}"</span>)
simple(<span class="code-quote">"${body.address.zip}"</span>)
</pre>
</div></div>

<p>Camel understands the shorthand names for getters, but you can invoke any method
or use the real name such as:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address}"</span>)
simple(<span class="code-quote">"${body.getAddress.getStreet}"</span>)
simple(<span class="code-quote">"${body.address.getZip}"</span>)
simple(<span class="code-quote">"${body.doSomething}"</span>)
</pre>
</div></div>

<p>You can also use the null safe operator (<tt>?.</tt>) to avoid NPE if
for example the body does NOT have an address</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body?.address?.street}"</span>)
</pre>
</div></div>

<p>Its also possible to index in <tt>Map</tt> or <tt>List</tt>
types, so you can do:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body[foo].name}"</span>)
</pre>
</div></div>
<p>To assume the body is <tt>Map</tt> based and lookup the value with <tt>foo</tt>
as key, and invoke the <tt>getName</tt> method on that value.</p>

<p>You can access the <tt>Map</tt> or <tt>List</tt> objects
directly using their key name (with or without dots) :</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body[foo]}"</span>)
simple(<span class="code-quote">"${body[<span class="code-keyword">this</span>.is.foo]}"</span>)
</pre>
</div></div>

<p>Suppose there was no value with the key <tt>foo</tt> then you can use
the null safe operator to avoid the NPE as shown:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body[foo]?.name}"</span>)
</pre>
</div></div>

<p>You can also access <tt>List</tt> types, for example to get lines from
the address you can do:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address.lines[0]}"</span>)
simple(<span class="code-quote">"${body.address.lines[1]}"</span>)
simple(<span class="code-quote">"${body.address.lines[2]}"</span>)
</pre>
</div></div>

<p>There is a special <tt>last</tt> keyword which can be used to get the
last value from a list.</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address.lines[last]}"</span>)
</pre>
</div></div>

<p>And to get the 2nd last you can subtract a number, so we can use <tt>last-1</tt>
to indicate this:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address.lines[last-1]}"</span>)
</pre>
</div></div>

<p>And the 3rd last is of course:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address.lines[last-2]}"</span>)
</pre>
</div></div>

<p>And yes you can combine this with the operator support as shown below:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${body.address.zip} &gt; 1000"</span>)
</pre>
</div></div>

<h3><a name="Simple-Operatorsupport"></a>Operator support</h3>
<p><b>Available as of Camel 2.0</b><br/>
We added a basic set of operators supported in the simple language in Camel 2.0. The parser
is limited to only support a single operator. </p>

<p>To enable it the left value must be enclosed in ${ }. The syntax is:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
${leftValue} OP rightValue
</pre>
</div></div>
<p>Where the <tt>rightValue</tt> can be a String literal enclosed in <tt>'
'</tt>, <tt>null</tt>, a constant value or another expression enclosed in
${ }.<br/>
Camel will automatically type convert the rightValue type to the leftValue type, so its able
to eg. convert a string into a numeric so you can use &gt; comparison for numeric values.</p>

<p>The following operators are supported:</p>
<div class='table-wrap'>
<table class='confluenceTable'><tbody>
<tr>
<th class='confluenceTh'> Operator </th>
<th class='confluenceTh'> Description </th>
</tr>
<tr>
<td class='confluenceTd'> == </td>
<td class='confluenceTd'> equals </td>
</tr>
<tr>
<td class='confluenceTd'> &gt; </td>
<td class='confluenceTd'> greater than </td>
</tr>
<tr>
<td class='confluenceTd'> &gt;= </td>
<td class='confluenceTd'> greater than or equals </td>
</tr>
<tr>
<td class='confluenceTd'> &lt; </td>
<td class='confluenceTd'> less than </td>
</tr>
<tr>
<td class='confluenceTd'> &lt;= </td>
<td class='confluenceTd'> less than or equals </td>
</tr>
<tr>
<td class='confluenceTd'> != </td>
<td class='confluenceTd'> not equals </td>
</tr>
<tr>
<td class='confluenceTd'> contains </td>
<td class='confluenceTd'> For testing if contains in a string based value </td>
</tr>
<tr>
<td class='confluenceTd'> not contains </td>
<td class='confluenceTd'> For testing if not contains in a string based value </td>
</tr>
<tr>
<td class='confluenceTd'> regex </td>
<td class='confluenceTd'> For matching against a given regular expression pattern defined
as a String value </td>
</tr>
<tr>
<td class='confluenceTd'> not regex </td>
<td class='confluenceTd'> For not matching against a given regular expression pattern
defined as a String value </td>
</tr>
<tr>
<td class='confluenceTd'> in </td>
<td class='confluenceTd'> For matching if in a set of values, each element must be separated
by comma. </td>
</tr>
<tr>
<td class='confluenceTd'> not in </td>
<td class='confluenceTd'> For matching if not in a set of values, each element must
be separated by comma. </td>
</tr>
<tr>
<td class='confluenceTd'> is </td>
<td class='confluenceTd'> For matching if the left hand side type is an instanceof the
value. </td>
</tr>
<tr>
<td class='confluenceTd'> not is </td>
<td class='confluenceTd'> For matching if the left hand side type is not an instanceof
the value. </td>
</tr>
<tr>
<td class='confluenceTd'> range </td>
<td class='confluenceTd'> For matching if the left hand side is within a range of values
defined as numbers: <tt>from..to</tt> </td>
</tr>
<tr>
<td class='confluenceTd'> not range </td>
<td class='confluenceTd'> For matching if the left hand side is not within a range of
values defined as numbers: <tt>from..to</tt> </td>
</tr>
</tbody></table>
</div>


<p>And the following operators can be used to group expressions:</p>
<div class='table-wrap'>
<table class='confluenceTable'><tbody>
<tr>
<th class='confluenceTh'> Operator </th>
<th class='confluenceTh'> Description </th>
</tr>
<tr>
<td class='confluenceTd'> and </td>
<td class='confluenceTd'> and is used to group two expressions </td>
</tr>
<tr>
<td class='confluenceTd'> or </td>
<td class='confluenceTd'> or is used to group two expressions </td>
</tr>
</tbody></table>
</div>


<div class='panelMacro'><table class='infoMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/information.gif" width="16"
height="16" align="absmiddle" alt="" border="0"></td><td><b>Using and,or
operators</b><br />In <b>Camel 2.4 or older</b> the <tt>and</tt>
or <tt>or</tt> can only be used <b>once</b> in a simple language expression.
From <b>Camel 2.5</b> onwards you can use these operators multiple times.</td></tr></table></div>

<p>The syntax for AND is:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
${leftValue} OP rightValue and ${leftValue} OP rightValue 
</pre>
</div></div>

<p>And the syntax for OR is:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
${leftValue} OP rightValue or ${leftValue} OP rightValue 
</pre>
</div></div>

<p>Some examples:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.foo} == 'foo'"</span>)

<span class="code-comment">// ' ' can be omitted
</span>simple(<span class="code-quote">"${in.header.foo} == foo"</span>)

<span class="code-comment">// here Camel will type convert '100' into the type of in.header.bar
and <span class="code-keyword">if</span> its an <span class="code-object">Integer</span>
'100' will also be converter to an <span class="code-object">Integer</span>
</span>simple(<span class="code-quote">"${in.header.bar} == '100'"</span>)

simple(<span class="code-quote">"${in.header.bar} == 100"</span>)

<span class="code-comment">// 100 will be converter to the type of in.header.bar so
we can <span class="code-keyword">do</span> &gt; comparison
</span>simple(<span class="code-quote">"${in.header.bar} &gt; 100"</span>)
</pre>
</div></div>

<div class='panelMacro'><table class='infoMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/information.gif" width="16"
height="16" align="absmiddle" alt="" border="0"></td><td><b>Comparing
with different types</b><br />When you compare with different types such as String
and int, then you have to take a bit care. Camel will use the type from the left hand side
as 1st priority. And fallback to the right hand side type if both values couldn't be compared
based on that type.<br/>
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:
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"100 &lt; ${in.header.bar}"</span>)
</pre>
</div></div>
<p>which then ensures the int type is used as 1st priority.</p>

<p>This may change in the future if the Camel team improves the binary comparison operations
to prefer numeric types over String based. It's most often the String type which causes problem
when comparing with numbers.</p></td></tr></table></div>

<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
<span class="code-comment">// testing <span class="code-keyword">for</span>
<span class="code-keyword">null</span>
</span>simple(<span class="code-quote">"${in.header.baz} == <span class="code-keyword">null</span>"</span>)

<span class="code-comment">// testing <span class="code-keyword">for</span>
not <span class="code-keyword">null</span>
</span>simple(<span class="code-quote">"${in.header.baz} != <span class="code-keyword">null</span>"</span>)
</pre>
</div></div>

<p>And a bit more advanced example where the right value is another expression</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.date} == ${date:now:yyyyMMdd}"</span>)

simple(<span class="code-quote">"${in.header.type} == ${bean:orderService?method=getOrderType}"</span>)
</pre>
</div></div>

<p>And an example with contains, testing if the title contains the word Camel</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.title} contains 'Camel'"</span>)
</pre>
</div></div>

<p>And an example with regex, testing if the number header is a 4 digit value:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.number} regex '\d{4}'"</span>)
</pre>
</div></div>

<p>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.<br/>
This also works for numbers etc, as Camel will convert each element into the type of the left
hand side.</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.type} in 'gold,silver'"</span>)
</pre>
</div></div>

<p>And for all the last 3 we also support the negate test using not:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.type} not in 'gold,silver'"</span>)
</pre>
</div></div>

<p>And you can test if the type is a certain instance, eg for instance a String</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.type} is 'java.lang.<span class="code-object">String</span>'"</span>)
</pre>
</div></div>
<p>We have added a shorthand for all <tt>java.lang</tt> types so you can
write it as:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.type} is <span class="code-object">String</span>"</span>)
</pre>
</div></div>

<p>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:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.number} range 100..199"</span>)
</pre>
</div></div>
<p>Notice we use <tt>..</tt> in the range without spaces. Its based on the
same syntax as Groovy.</p>

<div class='panelMacro'><table class='tipMacro'><colgroup><col width='24'><col></colgroup><tr><td
valign='top'><img src="/confluence/images/icons/emoticons/check.gif" width="16" height="16"
align="absmiddle" alt="" border="0"></td><td><b>Can be used in Spring
XML</b><br />As the Spring XML does not have all the power as the Java DSL with
all its various builder methods, you have to resort to use some other languages<br/>
for testing with simple operators. Now you can do this with the simple language. In the sample
below we want to test if the header is a widget order: 
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-xml">
    <span class="code-tag">&lt;from uri=<span class="code-quote">"seda:orders"</span>&gt;</span>
       <span class="code-tag">&lt;filter&gt;</span>
           <span class="code-tag">&lt;simple&gt;</span>${in.header.type}
== 'widget'<span class="code-tag">&lt;/simple&gt;</span>
           <span class="code-tag">&lt;to uri=<span class="code-quote">"bean:orderService?method=handleWidget"</span>/&gt;</span>
       <span class="code-tag">&lt;/filter&gt;</span>
    <span class="code-tag">&lt;/from&gt;</span>
</pre>
</div></div></td></tr></table></div> 

<h4><a name="Simple-Usingand%2For"></a>Using and / or</h4>
<p>If you have two expressions you can combine them with the <tt>and</tt>
or <tt>or</tt> operator.<br/>
For instance:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.title} contains 'Camel' and ${in.header.type'}
== 'gold'"</span>)
</pre>
</div></div>

<p>And of course the <tt>or</tt> is also supported. The sample would be:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.title} contains 'Camel' or ${in.header.type'}
== 'gold'"</span>)
</pre>
</div></div>

<p><b>Notice:</b> Currently <tt>and</tt> or <tt>or</tt>
can only be used <b>once</b> in a simple language expression. This might change
in the future.<br/>
So you <b>cannot</b> do:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
simple(<span class="code-quote">"${in.header.title} contains 'Camel' and ${in.header.type'}
== 'gold' and ${in.header.number} range 100..200"</span>)
</pre>
</div></div>

<h3><a name="Simple-Samples"></a>Samples</h3>
<p>In the Spring XML sample below we filter based on a header value:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-xml">
    <span class="code-tag">&lt;from uri=<span class="code-quote">"seda:orders"</span>&gt;</span>
       <span class="code-tag">&lt;filter&gt;</span>
           <span class="code-tag">&lt;simple&gt;</span>in.header.foo<span
class="code-tag">&lt;/simple&gt;</span>
           <span class="code-tag">&lt;to uri=<span class="code-quote">"mock:fooOrders"</span>/&gt;</span>
       <span class="code-tag">&lt;/filter&gt;</span>
    <span class="code-tag">&lt;/from&gt;</span>
</pre>
</div></div>

<p>The Simple language can be used for the predicate test above in the <a href="/confluence/display/CAMEL/Message+Filter"
title="Message Filter">Message Filter</a> pattern, where we test if the in message
has a <tt>foo</tt> header (a header with the key <tt>foo</tt> exists).
If the expression evaluates to <b>true</b> then the message is routed to the <tt>mock:foo</tt>
endpoint, otherwise its lost in the deep blue sea <img class="emoticon" src="/confluence/images/icons/emoticons/wink.gif"
height="20" width="20" align="absmiddle" alt="" border="0"/>.</p>

<p>The same example in Java DSL:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
    from(<span class="code-quote">"seda:orders"</span>)
        .filter().simple(<span class="code-quote">"in.header.foo"</span>).to(<span
class="code-quote">"seda:fooOrders"</span>);
</pre>
</div></div>

<p>You can also use the simple language for simple text concatenations such as:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
   from(<span class="code-quote">"direct:hello"</span>).transform().simple(<span
class="code-quote">"Hello ${in.header.user} how are you?"</span>).to(<span class="code-quote">"mock:reply"</span>);
</pre>
</div></div>
<p>Notice that we must use ${ } placeholders in the expression now to allow Camel to
parse it correctly. </p>

<p>And this sample uses the date command to output current date.</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
   from(<span class="code-quote">"direct:hello"</span>).transform().simple(<span
class="code-quote">"The today is ${date:now:yyyyMMdd} and its a great day."</span>).to(<span
class="code-quote">"mock:reply"</span>);
</pre>
</div></div>

<p>And in the sample below we invoke the bean language to invoke a method on a bean
to be included in the returned string:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
   from(<span class="code-quote">"direct:order"</span>).transform().simple(<span
class="code-quote">"OrderId: ${bean:orderIdGenerator}"</span>).to(<span class="code-quote">"mock:reply"</span>);
</pre>
</div></div>
<p>Where <tt>orderIdGenerator</tt> is the id of the bean registered in the
<a href="/confluence/display/CAMEL/Registry" title="Registry">Registry</a>. If
using Spring then its the Spring bean id.</p>

<p>If we want to declare which method to invoke on the order id generator bean we must
prepend <tt>.method name</tt> such as below where we invoke the <tt>generateId</tt>
method.</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
   from(<span class="code-quote">"direct:order"</span>).transform().simple(<span
class="code-quote">"OrderId: ${bean:orderIdGenerator.generateId}"</span>).to(<span
class="code-quote">"mock:reply"</span>);
</pre>
</div></div>

<p>And in Camel 2.0 we can use the <tt>?method=methodname</tt> option that
we are familiar with the <a href="/confluence/display/CAMEL/Bean" title="Bean">Bean</a>
component itself:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
   from(<span class="code-quote">"direct:order"</span>).transform().simple(<span
class="code-quote">"OrderId: ${bean:orderIdGenerator?method=generateId}"</span>).to(<span
class="code-quote">"mock:reply"</span>);
</pre>
</div></div>

<p>And from Camel 2.3 onwards you can also convert the body to a given type, for example
to ensure its a String you can do:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-xml">
  <span class="code-tag">&lt;transform&gt;</span>
    <span class="code-tag">&lt;simple&gt;</span>Hello ${bodyAs(String)}
how are you?<span class="code-tag">&lt;/simple&gt;</span>
  <span class="code-tag">&lt;/transform&gt;</span>
</pre>
</div></div>

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

<p>Its also possible to lookup a value from a header <tt>Map</tt> in <b>Camel
2.3</b> onwards:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-xml">
  <span class="code-tag">&lt;transform&gt;</span>
    <span class="code-tag">&lt;simple&gt;</span>The gold value is ${header.type[gold]}<span
class="code-tag">&lt;/simple&gt;</span>
  <span class="code-tag">&lt;/transform&gt;</span>
</pre>
</div></div>

<p>In the code above we lookup the header with name <tt>type</tt> and regard
it as a <tt>java.util.Map</tt> and we then lookup with the key <tt>gold</tt>
and return the value.<br/>
If the header is not convertible to Map an exception is thrown. If the header with name <tt>type</tt>
does not exist <tt>null</tt> is returned.</p>

<h3><a name="Simple-Settingresulttype"></a>Setting result type</h3>
<p><b>Available as of Camel 2.8</b></p>

<p>You can now provide a result type to the <a href="/confluence/display/CAMEL/Simple"
title="Simple">Simple</a> expression, which means the result of the evaluation will
be converted to the desired type. This is most useable to define types such as booleans, integers,
etc.</p>

<p>For example to set a header as a boolean type you can do:</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-java">
.setHeader(<span class="code-quote">"cool"</span>, simple(<span class="code-quote">"<span
class="code-keyword">true</span>"</span>, <span class="code-object">Boolean</span>.class))
</pre>
</div></div>

<p>And in XML DSL</p>
<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
<pre class="code-xml">
      <span class="code-tag">&lt;setHeader headerName=<span class="code-quote">"cool"</span>&gt;</span>
        <span class="code-tag"><span class="code-comment">&lt;!-- use resultType
to indicate that the type should be a java.lang.Boolean --&gt;</span></span>
        <span class="code-tag">&lt;simple resultType=<span class="code-quote">"java.lang.Boolean"</span>&gt;</span>true<span
class="code-tag">&lt;/simple&gt;</span>
      <span class="code-tag">&lt;/setHeader&gt;</span>
</pre>
</div></div>


<h3><a name="Simple-Dependencies"></a>Dependencies</h3>
<p>The <a href="/confluence/display/CAMEL/Simple" title="Simple">Simple</a>
language is part of <b>camel-core</b>.</p>
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