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 Event mediator is a content aware mediator.
Syntax
<payloadFactory media-type="xml | json">
<format ../>
<args>
<arg (value="string" | expression=" {xpath} | {json} ")/>*
</args>
</payloadFactory>
The media-type attribute specifies whether to format the message in XML or JSON. 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 or XML. |
| 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
For example, 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 expression="//m0:symbol" xmlns:m0="http://services.samples/xsd">
<arg expression="//m0:last" xmlns:m0="http://services.samples/xsd">
</arg></arg></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>
Samples
The following samples demonstrate the use of the PayloadFactory mediator.