Object validation server side is a necessity for public web services — the realisation of this necessity became Joi — the most widely adopted package for object schema descriptions.
Schema Validation Schema Validation The Enterprise Gateway can check that XML messages conform to the structure or format expected by the Web Service by validating those requests against XML Schemas. An XML Schema precisely defines the elements and attributes that constitute an instance of an XML document. It also specifies the data types of these elements to ensure that only appropriate data is allowed through to the Web Service. Contents.
Overview The Enterprise Gateway can check that XML messages conform to the structure or format expected by the Web Service by validating those requests against XML Schemas. An XML Schema precisely defines the elements and attributes that constitute an instance of an XML document. It also specifies the data types of these elements to ensure that only appropriate data is allowed through to the Web Service. For example, an XML Schema might stipulate that all requests to a particular Web Service must contain a element, which contains at most a ten character string. If the Enterprise Gateway receives a message with an improperly formed element, it rejects the message.
You can find the Schema Validation filter in the Content Filtering category of filters in the Policy Studio. Drag and drop the filter on to the policy where you want to perform schema validation. The Schema Validation dialog has three tabs, which are explained in this topic. Schema to Use Select one of the following options: Use Schema from WSDL of Web Service: Instead of selecting a specific XML schema to run in this filter, you can select this option to dynamically use the appropriate SOAP operation schema from the current Web Service Context.
When this option is selected, this filter has an additional required message attribute named webservice.context, which must be provided. This enables you to share this filter to perform validation across multiple Web Services. Select which XML Schema to validate messages with: This is the default option. The tree hierarchy contains two top-level nodes: Schema Cache and Web Services Repository. When these nodes are expanded, the contained XML Schemas are displayed in the tree.
Each schema has an associated checkbox, which you can use to select the schema to validate the incoming message. The following tutorials show how to import schemas into these global stores so that they can be selected in the Schema Validation filter:. Note: If you have a WSDL file that contains an XML Schema, and want to use this schema to validate the message, you can import the WSDL file into the Web Services Repository.
The WSDL Import Wizard automatically creates a Schema Validation filter and incorporates it into the auto-generated policy. In this case, the top-level schema in the WSDL, which is imported into the Web Services Repository, is selected by default in the filter. In this way, if the schema imports other schemas, they are available to the filter at runtime when validating the message. For more details on importing WSDL files, see the topic. Part of Message to Match A portion of the XML message can be extracted using an XPath expression. The Enterprise Gateway can then validate this portion against the specified XML Schema.
For example, administrators may only want to validate the SOAP Body part of a SOAP message. In this case, they should enter or select an XPath expression that identifies the SOAP Body of the message. This portion should then be validated against an XML Schema that defines the structure of the SOAP Body for that particular message. Click the Add or Edit buttons to add or edit an XPath expression using the Enter XPath Expression dialog. You can remove expressions by selecting the expression in the XPath Expression drop-down and clicking the Delete button. On the Enter XPath Expression dialog, there are two ways to configure XPath expressions. For more details, see the following links:.
The XPath Wizard assists administrators in creating correct and accurate XPath expressions. The wizard enables administrators to load an XML message and then run an XPath expression on it to determine what nodes are returned. Advanced The following settings are available on the Advanced tab: Allow RPC Schema Validation: When the Allow RPC Schema Validation checkbox is selected, the filter makes a best attempt to validate an RPC-encoded SOAP message.
An RPC-encoded message is defined in the WSDL as having an operation with the following characteristics:. The style attribute of the element is set to document. The use attribute of the element is set to rpc. For details on the possible values for these attributes, see of the WSDL specification. The problem with RPC-encoded SOAP messages in terms of schema validation is that the schema contained in the WSDL file does not necessarily fully define the format of the SOAP message, unlike with document-literal style messages.
With an RPC-encoded operation, the format of the message can be defined by a combination of the SOAP operation name, WSDL message parts, and schema-defined types. As a result, the schema extracted from a WSDL file may not be able to validate a message.
Another problem with RPC-encoded messages is that type information is included in each element that appears in the SOAP message. For such element definitions to be validated by a schema, the type declarations must be removed, which is precisely what the Schema Validation filter does if the checkbox is selected on this tab. It removes the type declarations and then makes a best attempt to validate the message.
However, as explained earlier, if some of the elements in the SOAP message are taken from the WSDL file instead of the schema (for example, when the SOAP operation name in the WSDL file is used as the wrapper element beneath the SOAP Body instead of a schema-defined type), the schema is not able to validate the message. Inline MTOM Attachments into Message: Message Transmission Optimization Mechanism (MTOM) provides a way to send binary data to Web Services in standard SOAP messages. MTOM leverages the include mechanism defined by XML Optimized Packaging (XOP), whereby binary data can be sent as a MIME attachment (similar to SOAP with Attachments) to a SOAP message. The binary data can then be referenced from within the SOAP message using the element. The following SOAP request contains a binary image that has been Base64-encoded so that it can be inserted as the contents of the element. /aWKKapGGyQ= When this message is converted to an MTOM message by the Enterprise Gateway (for example, using the filter) the Base64-encoded content from the element is replaced with an element.
This contains a reference to a newly created MIME part that contains the binary content. The following request shows the resulting MTOM message. POST /services/uploadImages HTTP/1.1 Host: SOAPbox Content-Type: Multipart/Related;boundary=MIMEboundary; type='application/xop+xml'; start='; start-info='text/xml' -MIMEboundary Content-Type: application/xop+xml; charset=UTF-8; type='text/xml' Content-Transfer-Encoding: 8bit Content-ID: -MIMEboundary Content-Type: image/gif Content-Transfer-Encoding: binary Content-ID: // binary octets for image -MIMEboundary When attempting to validate the MTOM message with an XML Schema, it is crucial that you are aware of the format of the element. Will it contain the Base64-encoded binary data, or will it contain the element with a reference to a MIME part?
For example, the XML Schema definition for element might look as follows. Env:Receiver fault:MessageBlocked XSD Error: Unknown element 'id' (line: 2, column: 8) The following screenshot shows how to use the Set Message filter to return a customized SOAP Fault in a policy. If the Schema Validation filter succeeds, the message is routed on to the target Web Service. However, if the schema validation fails, the Set Message filter (named Set Custom Fault Message) is invoked.
The filter sets the contents of the xsd.errors message attribute (the schema validation errors) to the custom SOAP Fault message as shown in the example error. The Reflect filter (named Return SOAP Fault) then writes the message back to the client.
![Schema Validation Error Schema Validation Error](http://www.stylusstudio.com/images/screenshots/multiple_error_reporting.gif)
Handling Validation Errors When an invalid instance is encountered, a will be raised or returned, depending on which method or function is used. Exception jsonschema.exceptions. ValidationError ( message, validator=, path=, cause=None, context=, validatorvalue=, instance=, schema=, schemapath=, parent=None ) The instance didn’t properly validate under the provided schema. The information carried by an error roughly breaks down into: What Happened Why Did It Happen What Was Being Validated. Message A human readable message explaining the error.
Validator The name of the failed. Validatorvalue The value for the failed validator in the schema. Schema The full schema that this error came from. This is potentially a subschema from within the schema that was passed in originally, or even an entirely different schema if a was followed. Relativeschemapath A containing the path to the failed validator within the schema. Absoluteschemapath A containing the path to the failed validator within the schema, but always relative to the original schema as opposed to any subschema (i.e. The one originally passed into a validator class, not ).
Schemapath Same as. Relativepath A containing the path to the offending element within the instance. The deque can be empty if the error happened at the root of the instance. Absolutepath A containing the path to the offending element within the instance. The absolute path is always relative to the original instance that was validated (i.e.
The one passed into a validation method, not ). The deque can be empty if the error happened at the root of the instance. Path Same as. Instance The instance that was being validated. This will differ from the instance originally passed into validate if the validator object was in the process of validating a (possibly nested) element within the top-level instance. The path within the top-level instance (i.e.
) could be used to find this object, but it is provided for convenience. Context If the error was caused by errors in subschemas, the list of errors from the subschemas will be available on this property.
The and of these errors will be relative to the parent error. Cause If the error was caused by a non-validation error, the exception object will be here. Currently this is only used for the exception raised by a failed format checker in. Parent A validation error which this error is the of. None if there wasn’t one. In case an invalid schema itself is encountered, a is raised.
Exception jsonschema.exceptions. SchemaError ( message, validator=, path=, cause=None, context=, validatorvalue=, instance=, schema=, schemapath=, parent=None ) The provided schema is malformed. The same attributes are present as for s.
These attributes can be clarified with a short example. 0 1 2 Since our schema contained nested subschemas, it can be helpful to look at the specific part of the instance and subschema that caused each of the errors. This can be seen with the and attributes. With validators like, the attribute can be used to see the sub-errors which caused the failure. Since these errors actually came from two separate subschemas, it can be helpful to look at the attribute as well to see where exactly in the schema each of these errors come from. In the case of sub-errors from the attribute, this path will be relative to the of the parent error. ErrorTrees If you want to programmatically be able to query which properties or validators failed when validating a given instance, you probably will want to do so using objects.
Class jsonschema.exceptions. ErrorTree ( errors= ) ErrorTrees make it easier to check which validations failed. Errors The mapping of validator names to the error objects (usually s) at this level of the tree.
contains ( index ) Check whether instanceindex has any errors. getitem ( index ) Retrieve the child tree one level down at the given index.
If the index is not in the instance that this tree corresponds to and is not known by this tree, whatever error would be raised by instance.getitem will be propagated (usually this is some subclass of. iter ( ) Iterate (non-recursively) over the indices in the instance with errors. len ( ) Same as. Totalerrors The total number of errors in the entire tree, including children. Consider the following example. Note This function is a heuristic.
Its return value may change for a given set of inputs from version to version if better heuristics are added. Relevance ( validationerror ) A key function that sorts errors based on heuristic relevance. If you want to sort a bunch of errors entirely, you can use this function to do so. Using this function as a key to e.g. Or will cause more relevant errors to be considered greater than less relevant ones. Within the different validators that can fail, this function considers and to be weak validation errors, and will sort them lower than other validators at the same level in the instance.
If you want to change the set of weak or strong validators you can create a custom version of this function with and provide a different set of each.