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Troubleshooting Web Service Consumer Connector - Mule 4

To troubleshoot Anypoint Connector for Web Service Consumer (Web Service Consumer Connector), become familiar with the information about enabling wire logging, troubleshooting access attachments, troubleshooting design-time WSDL issues, and interpreting commonly thrown messages.

Enable Wire Logging

To begin troubleshooting Web Service Consumer Connector, look at the transport request and response on the Web Service Consumer. If you are using the underlying HTTP transport, you can enable wire logging to see the exact HTTP message, the transmission headers, and the response status.

To enable wire logging:

  1. Access Anypoint Studio and navigate to the Package Explorer view.

  2. Open your application’s project name.

  3. Open the src/main/resources path folder.

  4. Open the log4j2.xml file inside the folder.

  5. If the following line is already in the log4j2.xml file, uncomment it to enable it; otherwise, add it:

    <AsyncLogger name="org.mule.service.http.impl.service.HttpMessageLogger" level="DEBUG" />

  6. Save your changes.

  7. Click the project name in Package Explorer and then click Run > Run As > Mule Application.

  8. Navigate to the Console view to read the HTTP messages in the logger:

    POST /essentials/delta HTTP/1.1
soapaction:
Host: ilt.mulesoft-training.com
User-Agent: AHC/1.0
Connection: keep-alive
Accept: */*
Content-Type: text/xml; charset=UTF-8
Transfer-Encoding: chunked

b1
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns0:listAllFlights xmlns:ns0="http://soap.training.mulesoft.com/"/></soap:Body></soap:Envelope>

DEBUG 2021-04-06 15:04:23,058 [[wsc-base].wsc-dispatcher.11 SelectorRunner] [processor: ; event: ] org.mule.service.http.impl.service.HttpMessageLogger.wsc-dispatcher: REQUESTER
0


DEBUG 2021-04-06 15:04:23,319 [[wsc-base].wsc-dispatcher.11 SelectorRunner] [processor: ; event: ] org.mule.service.http.impl.service.HttpMessageLogger.wsc-dispatcher: REQUESTER
HTTP/1.1 200
Date: Tue, 06 Apr 2021 18:04:23 GMT
Content-Type: text/xml; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
MULE_ENCODING: UTF-8
Strict-Transport-Security: max-age=31536000; includeSubdomains;
X-Content-Type-Options: 1
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block

bfe
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns2:listAllFlightsResponse xmlns:ns2="http://soap.training.mulesoft.com/">...

Troubleshoot Access Attachments

Some servers respond to requests by sending MTOM (Message Transmission Optimization Mechanism) messages. These messages separate their data into parts, which enables different types of content data to coexist in the same HTTP message.

MTOM is in charge of sending binary data in a separate part and referencing that part from the corresponding field within the SOAP envelope. Web Service Consumer users interact with these messages (multipart) only with the MTOM configuration.

Refer to the following documentation for further information about MTOM:

Beginning with version 1.6.4, Web Service Consumer Connector enables you to configure MTOM for request messages that also automatically manage MTOM responses, regardless of the MTOM setting in the Web Service Consumer global configuration. Incoming messages with MTOM are treated as MTOM-enabled, regardless of whether MTOM is configured in the Web Service Consumer global configuration.

The following example shows the Web Service Consumer Connector global configuration with MTOM enabled:

Web Service Consumer global element configuration with MTOM field set to TRUE
Figure 1. Web Service Consumer Connector Global Element

In the XML editor, the <wsc:config> and mtomEnabled configurations look like this:

<wsc:config name="Web_Service_Consumer_Config" doc:name="Web Service Consumer Config">
    <wsc:connection wsdlLocation="http://ilt.mulesoft-training.com/essentials/delta?wsdl" service="TicketServiceService" port="TicketServicePort" address="http://ilt.mulesoft-training.com/essentials/delta" mtomEnabled="true">
        <wsc:web-service-security actor="http://schemas.xmlsoap.org/soap/actor/next" />
    </wsc:connection>
</wsc:config>

Depending on the server side multipart setting, the server might send some binary data as a Base64-encoded text field or as a referenced binary part in the MIME message.

To troubleshoot how to access the binary data:

  • If the server sends the binary data as Base64-encoded text field, you must access this field as part of the message.
    Base64 decoding is automatically performed by Web Service Consumer.

  • If the server sends the binary data as a referenced binary part, you must access this field as an attachment.

    The following example shows an image sent as an attachment with MTOM by a web service server. You use DataWeave to access and transform the image into JSON. In this case, Base64 encoding is required:

    import * from dw::core::Strings
import dw::core::Binaries
output application/json
ns nam http://mynamespace.com
---
{
...
"image": Binaries::toBase64(payload.attachments[0]),
...
}

Troubleshoot Design Time WSDL Issues

Errors related to incorrect WSDL recognition, acquisition, or parsing sometimes lead to the following issues:

  • DataSense does not correctly expose the message metadata defined in the WSDL.

  • In the Web Service Consumer Connector configuration screen, the Operations field does not show any web service operation names for the connector to invoke:

    Web Service Consumer Connector Operations field shows empty
    Figure 2. Web Service Consumer Connector Operations field

  • In the Web Service Consumer Connector global element configuration, the Port and Address fields are not automatically filled when a WSDL location is provided.

    In the Web Service Consumer Connector global element window
    Figure 3. Web Service Consumer Connector Global Element

To resolve these issues:

  • Check the integrity of your WSDL by using your preferred online or desktop viewer applications.
    Because every parsing error during the configuration is not shown during design-time, implementing an external application helps detect them.

  • If you do not add the WSDL as a resource in the application’s src/main/resources folder in Studio, check for a correct connection to the server hosting the WSDL.
    Sometimes you need to add custom HTTP settings, such as OAuth settings or user/password settings, to access an HTTP server in an HTTP security layer. See Setting a Custom HTTP Transport Configuration.

Troubleshooting Must Understand Error

If your Mule Web Service Consumer app throws the error WSC:CANNOT_DISPATCH, and the third-party server returns in the HTTP response the <faultcode>soap:MustUnderstand</faultcode> as the exception for the connector caused error, this indicates that the Web Service Consumer connector configuration has the Security setting Must Understand field set to the default value of true.

To avoid this issue, set the Must understand field to false. The default value of this attribute to true is on the connector side, but on the SOAP protocol side the implicit value for the Must Understand attribute is false when is not present. If you do not explicitly need to use the Must Understand attribute for SOAP request, set the value to false.

Web Service Consumer configuration setting Must Understand value to false

The returned HTTP response might come with a compressed or uncompressed payload body for you to check the <faultcode>soap:MustUnderstand</faultcode> exception. If the HTTP response header Content-Encoding is gzip, it indicates that the payload body is compressed, for example, review the following HTTP response where you can see compressed characters such as �RMo�0 �W���:

HTTP/1.1 500 Internal Server Error
X-OPNET-Transaction-Trace: a2_ba571488-537c-4839-94a9-48f3f08fadf3
Content-Encoding: gzip
Content-Type: multipart/related; type="application/xop+xml"; boundary="uuid:83b066a2-fb96-4abf-a687-dd178a5b3e29"; start="<root.message@cxf.apache.org>"; start-info="text/xml"
Content-Length: 363
X-Cnection: close
Date: Wed, 23 Nov 2022 13:41:25 GMT
Connection: close
Set-Cookie: dc=dcs; Path=/; Version=1; Secure; Httponly; Max-Age=900
Strict-Transport-Security: max-age=31536000

�???????�RMo�0�W���N!�c-�M�:i��֞�1�&(h�_h���v���l?[�iJ��4X,`��t��sHs�pɥ�,C�Og8]�GOZYT��#u]��R+����=Vk�`�f�{��Y��x[+�]�0�(G÷*ӲT�����]$������?"�!ksj�
��9$��x��:ڪ/�t��5Q���+��#!�ɏ@��z��} pH^r��e7�/�T6���r�09�o
ٽ�hȂ����g%Y�&Ine�@��}������@%q�_�,}�i�E0g���`֘�v�n�|�~K��}�?dJ[֜;k-���`+ף������^�����Y9E??

To decompress the payload body of the response, your Mule app must catch the thrown error using an Error Handler component, and then use the Compression Module Decompress operation to decompress the response.

In Studio, navigate to the Decompress operation configuration screen, and set the Compressed field to the following expression to read compressed payload and catch the exception: error.exception.errorMessage.typedAttributes.value.headers.

Compressed field set with expression value

Subsequently, you can use a Logger component in your Mule app to log the entire payload body with the exception, for example, the following logs show the decompressed payload SOAP body with <faultcode>soap:MustUnderstand</faultcode>:

INFO  2022-11-23 14:57:05,247 [[MuleRuntime].uber.05: [ri-uhip-integration-esb-1095brequesttransmitterservice2_11-02-20221].BulkRequestTransmitter:\soapkit-config.BLOCKING @3f46eb07] [processor: BulkRequestTransmitter:\soapkit-config/processors/4/errorHandler/0/processors/2; event: 58ed0ad0-6b57-11ed-b9ce-147ddaa4cf6c] org.mule.runtime.core.internal.processor.LoggerMessageProcessor: --uuid:223e386d-3093-4df4-b5f9-9cb3b9a493a2
Content-Type: application/xop+xml; charset=UTF-8; type="text/xml"
Content-Transfer-Encoding: binary
Content-ID: <root.message@cxf.apache.org>

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><soap:Fault><faultcode>soap:MustUnderstand</faultcode><faultstring>MustUnderstand headers: [{http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd}Security] are not understood.</faultstring></soap:Fault></soap:Body></soap:Envelope>
--uuid:223e386d-3093-4df4-b5f9-9cb3b9a493a2--

Troubleshooting Systems Properties

  • mule.soap.maxAttributeSize (default value = 524288)

The XML parser library has a value limit for the mule.soap.maxAttributeSize system property that specifies maximum allowed length of attribute values, in characters. The limit protects against possible Denial-of-Service (DoS) attacks, wherein XML-based web services may be attacked by specifically crafted documents that could cause processing problems by excessive memory or computing power usage.

The default value is 524288 characters and it is a reasonable default value for normal usage. You can change it to a higher value if input documents can legitimately exceed the default limit, or to a lower value if specific attacks are observed or the system has a lower resource allocation.

One signal to change the value limit is when the exception javax.xml.stream.XMLStreamException: Maximum attribute size limit (524288) exceeded occurs when processing legitimate documents.

To change this value, you have to set the mule.soap.maxAttributeSize system property with the accurate number according to your needs. Refer to the Knowledge article How can I set Mule and Java system properties at startup?). The maximum value allowed is 2147483647 (Integer.MAX_VALUE in Java). If you set 0 or if you don’t set the property, the connector takes the default value.

Understand Common Throws

Here is a list of common throw messages and how to interpret them.

  • WSC:SOAP_FAULT

    Error matching the SOAP response with the format provided by the WSDL.
    Every CXF SOAP fault error is wrapped in a `WSC:SOAP_FAULT`.

  • WSC:BAD_REQUST

    The Web Service Consumer Connector operation does not exist in the WSDL.
    The request body is not a valid XML.

  • WSC:INVALID_WSDL

    The WSDL is poorly formatted.

  • WSC:EMPTY_RESPONSE

    Occurs when mandatory fields are missing from the response (Illegal Empty Response).

See Also

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