PayloadFactory Mediator
The PayloadFactory Mediator transforms or replaces the contents of a message. Each argument in the mediator configuration can be a static value, or you can specify an XPath or JSON expression to get the value at runtime by evaluating the provided expression against the existing SOAP message. You can configure the format of the request or response and map it to the arguments provided.
The PayloadFactory mediator is a content aware mediator.
Syntax
<payloadFactory media-type="xml | json">
<format ../>
<args>
<arg (value="string" | expression=" {xpath} | {json} | {text} ")/>*
</args>
</payloadFactory>
You can also provide the expression inline to get the value of the Synapse message context property, instead of specifying the expression as arguments.
The media-type attribute specifies whether to format the message in XML, JSON or text. If no media type is specified, the message is formatted in XML. If you want to change the payload type of the outgoing message, such as to change it to JSON, add the messageType property after the </payloadFactory> tag. For example:
... </payloadFactory> <property name="messageType" value="application/json" scope="axis2"/>
UI Configuration
Parameters available to configure the PayloadFactory mediator are as follows:
| Parameter Name | Description |
|---|---|
| Payload Media-Type | This parameter is used to specify whether the message payload should be created in JSON, XML or text. |
| Payload Format | Define Inline: If this is selected, the payload format can be defined within the PayloadFactory mediator configuration by entering it in the text field which appears. To add content to the payload, enter variables for each value you want to add using the format $n (starting with 1 and incrementing with each additional variable, i.e., $1, $2, etc.). You will then create arguments in the same order as the variables to specify each variable's actual value. Pick from Registry: If this is selected, an existing payload format which is saved in the Registry can be selected. Click either Governance Registry or Configuration Registry as relevant to select the payload format from the resource tree. |
| Arguments | This section is used to add an argument that defines the actual value of each variable in the format definition. The arguments must be entered in the same order as the variables in the format, so that the first argument defines the value for variable $1, the second argument defines the value for variable $2, etc. An argument can specify a literal string (e.g., "John") or an XPath or JSON expression that extracts the value from the content in the incoming payload. |
Note
You can configure the mediator using XML. Click switch to source view in the Mediator window.
Examples
This section provides examples of using PayloadFactory mediator to generate XML and JSON messages.
Example 1: XML
This example is based on Sample 17: Transforming / Replacing Message Content with PayloadFactory Mediator.
<definitions xmlns="http://ws.apache.org/ns/synapse">
<sequence name="main">
<in>
<!-- using payloadFactory mediator to transform the request message -->
<payloadFactory media-type="xml">
<format>
<m:getQuote xmlns:m="http://services.samples">
<m:request>
<m:symbol>$1</m:symbol>
</m:request>
</m:getQuote>
</format>
<args>
<arg xmlns:m0="http://services.samples" expression="//m0:Code"/>
</args>
</payloadFactory>
</in>
<out>
<!-- using payloadFactory mediator to transform the response message -->
<payloadFactory media-type="xml">
<format>
<m:CheckPriceResponse xmlns:m="http://services.samples/xsd">
<m:Code>$1</m:Code>
<m:Price>$2</m:Price>
</m:CheckPriceResponse>
</format>
<args>
<arg xmlns:m0="http://services.samples/xsd" expression="//m0:symbol"/>
<arg xmlns:m0="http://services.samples/xsd" expression="//m0:last"/>
</args>
</payloadFactory>
</out>
<send/>
</sequence>
</definitions>
Example 2: JSON
This example sends a JSON message to the back end. For more information on using JSON with the ESB, see JSON Support.
<payloadFactory media-type="json">
<format>
{
"coordinates": null,
"created_at": "Fri Jun 24 17:43:26 +0000 2011",
"truncated": false,
"favorited": false,
"id_str": "$1",
"entities": {
"urls": [
],
"hashtags": [
{
"text": "$2",
"indices": [
35,
45
]
}
],
"user_mentions": [
]
},
"in_reply_to_user_id_str": null,
"contributors": null,
"text": "$3",
"retweet_count": 0,
"id": "##",
"in_reply_to_status_id_str": null,
"geo": null,
"retweeted": false,
"in_reply_to_user_id": null,
"source": "<a
href=\"http://sites.google.com/site/yorufukurou/\"
rel=\"nofollow\">YoruFukurou</a>",
"in_reply_to_screen_name": null,
"user": {
"id_str": "##",
"id": "##"
},
"place": null,
"in_reply_to_status_id": null
}
</format>
<args>
<arg expression="$.entities.hashtags[0].text" evaluator="json"/>
<arg expression="//entities/hashtags/text"/>
<arg expression="//user/id"/>
<arg expression="//user/id_str"/>
<arg expression="$.user.id" evaluator="json"/>
<arg expression="$.user.id_str" evaluator="json"/>
</args>
</payloadFactory>
<property name="messageType" value="application/json" scope="axis2"/>
Note
By default, JSON messages are converted to XML when they are received by the PayloadFactor mediator. However, if you enable the JSON stream formatter and builder, incoming JSON messages are left in JSON format, which improves performance. To enable them, uncomment the following lines in <PRODUCT_HOME>/repository/conf/axis2/axis2.xml:
<!--messageFormatter contentType="application/json"
class="org.apache.axis2.json.JSONStreamFormatter"/-->
<!--messageBuilder contentType="application/json"
class="org.apache.axis2.json.JSONStreamBuilder"/-->
When the JSON stream formatter and builder are enabled, if you specify a JSON expression in the PayloadFactory mediator, you must use the evaluator attribute to specify that it is JSON. You can also use the evaluator to specify that an XPath expression is XML, or if you omit the evaluator attribute, XML is assumed by default. For example:
| XML |
or
|
| JSON | <arg expression="$.user.id" evaluator="json" />
|
Example 3: Adding arguments
In the following configuration, the values for format parameters code and price will be assigned with values that are evaluated from arguments given in the specified order.
<payloadFactory media-type="xml">
<format>
<m:checkpriceresponse xmlns:m="http://services.samples/xsd">
<m:code>$1</m:code>
<m:price>$2</m:price>
</m:checkpriceresponse>
</format>
<args>
<arg xmlns:m0="http://services.samples/xsd" expression="//m0:symbol"/>
<arg xmlns:m0="http://services.samples/xsd" expression="//m0:last"/>
</args>
</payloadFactory>
Example 4: Suppressing the namespace
To prevent the ESB from adding the default Synapse namespace in an element in the payload format, use xmlns="" as shown in the following example.
<ser:getPersonByUmid xmlns:ser="http://service.directory.com>
<umid xmlns="">sagara</umid>
</ser:getPersonByUmid>
Example 5: Including a complete SOAP envelope as the format
In the following configuration, an entire SOAP envelope is added as the format defined inline. This is useful when you want to generate the result of the PayloadFactory mediator as a complete SOAP message with SOAP headers.
<payloadFactory media-type="xml"> <format> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"> <soapenv:Body> <error> <mes>$1</mes> </error> </soapenv:Body> </soapenv:Envelope> </format> <args> <arg value=" Your request did not return any results. Please enter a valid EIN and try again"/> </args> </payloadFactory>
Example 6: Adding expression inline xml
In the following configuration, the values for format parameters code and price will be assigned with values from Synapse message context properties symbol and last.
<payloadFactory media-type="xml">
<format>
<m:checkpriceresponse xmlns:m="http://services.samples/xsd">
<m:code>$ctx:symbol</m:code>
<m:price>$ctx:last</m:price>
</m:checkpriceresponse>
</format>
</payloadFactory>
Example 6: Adding expression inline json
In the following configuration, the values for format parameters code and price will be assigned with values from Synapse message context properties symbol and last.
<payloadFactory media-type="json">
<format>
"tags":{
"name":"$ctx:symbol",
"value":"$ctx:last"
}
</format>
</payloadFactory>
Example 7: Uploading a file to an HTTP endpoint via a multipart request
This is introduced in the WSO2 Carbon 4.4.X Update 1612, which was released on 14th September 2017. For more information on applying the update, go to Getting Started with WUM.
The below example configuration uses VFS to upload the file in the specified location to the given HTTP endpoint via a HTTP multipart request.
<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
name="smooksample"
startOnLoad="true"
statistics="disable"
trace="disable"
transports="vfs">
<target>
<inSequence>
<enrich>
<source clone="true" type="body"/>
<target property="originalBody" type="property"/>
</enrich>
<property name="messageType"
scope="axis2"
type="STRING"
value="multipart/form-data"/>
<payloadFactory media-type="xml">
<format>
<root xmlns="">
<customFieldOne>$1</customFieldOne>
<customFieldTwo>$2</customFieldTwo>
<file xmlns="http://org.apache.axis2/xsd/form-data"
charset="US-ASCII"
content-type="text/plain"
filename="$3"
name="file1">$4</file>
</root>
</format>
<args>
<arg value="Some value 1"/>
<arg value="Some value 2"/>
<arg evaluator="xml" expression="$trp:FILE_NAME"/>
<arg evaluator="xml" expression="$ctx:originalBody"/>
</args>
</payloadFactory>
<header name="Content-Type" scope="transport" value="multipart/form-data"/>
<property name="messageType"
scope="axis2"
type="STRING"
value="multipart/form-data"/>
<property name="OUT_ONLY" scope="default" type="STRING" value="true"/>
<send>
<endpoint>
<address format="rest" uri="http://localhost:3000/upload/"/>
</endpoint>
</send>
</inSequence>
</target>
<parameter name="transport.PollInterval">5</parameter>
<parameter name="transport.vfs.FileURI">file:///<YOUR_FILE_LOCATION></parameter>
<parameter name="transport.vfs.ContentType">application/octet-stream</parameter>
<parameter name="transport.vfs.ActionAfterProcess">DELETE</parameter>
<parameter name="transport.vfs.FileNamePattern">.*\..*</parameter>
<description/>
</proxy>
In the above example, the following property mediator configuration sets the message type as multipart/form-data.
<property name="messageType"
scope="axis2"
type="STRING"
value="multipart/form-data"/>
The below file parameter of the payload factory mediator defines the HTTP multipart request.
Do not change the http://org.apache.axis2/xsd/form-data namesapce.
<file xmlns="http://org.apache.axis2/xsd/form-data" charset="US-ASCII" content-type="text/plain" filename="$3" name="file1">$4</file>
Also, the below property mediator configuration sets the content of the uploaded file.
<header name="Content-Type" scope="transport" value="multipart/form-data"/>
<property name="messageType"
scope="axis2"
type="STRING"
value="multipart/form-data"/>
Samples
The following samples demonstrate the use of the PayloadFactory mediator.