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52 lines
2.8 KiB
HTML
52 lines
2.8 KiB
HTML
<!--
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Copyright JS Foundation and other contributors, http://js.foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<script type="text/html" data-help-name="switch">
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<p>Route messages based on their property values or sequence position.</p>
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<h3>Details</h3>
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<p>When a message arrives, the node will evaluate each of the defined rules
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and forward the message to the corresponding outputs of any matching rules.</p>
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<p>Optionally, the node can be set to stop evaluating rules once it finds one
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that matches.</p>
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<p>The rules can be evaluated against an individual message property, a flow or global
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context property, environment variable or the result of a JSONata expression.</p>
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<h4>Rules</h4>
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<p>There are four types of rule:</p>
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<ol>
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<li><b>Value</b> rules are evaluated against the configured property</li>
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<li><b>Sequence</b> rules can be used on message sequences, such as those
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generated by the Split node</li>
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<li>A JSONata <b>Expression</b> can be provided that will be evaluated
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against the whole message and will match if the expression returns
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a true value.</li>
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<li>An <b>Otherwise</b> rule can be used to match if none of the preceeding
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rules have matched.</li>
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</ol>
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<h4>Notes</h4>
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<p>The <code>is true/false</code> and <code>is null</code> rules perform strict
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comparisons against those types. They do not convert between types.</p>
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<p>The <code>is empty</code> and <code>is not empty</code> rules passes for Strings, Arrays and Buffers that have
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a length of 0, or Objects that have no properties. It does not pass for <code>boolean</code>, <code>null</code>
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or <code>undefined</code> values.</p>
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<h4>Handling message sequences</h4>
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<p>By default, the node does not modify the <code>msg.parts</code> property of messages
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that are part of a sequence.</p>
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<p>The <b>recreate message sequences</b> option can be enabled to generate new message sequences
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for each rule that matches. In this mode, the node will buffer the entire incoming
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sequence before sending the new sequences on. The runtime setting <code>nodeMessageBufferMaxLength</code>
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can be used to limit how many messages nodes will buffer.</p>
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</script>
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