Azure Functions to validate XML against DTD

Azure Functions to validate XML against DTD

After the release of a set of Azure Functions that will help us minimize or completely remove the need for an Integration Account:

Today, I’m going to release a new function – validate XML against DTD – that will bring additional capabilities to Logic App Consumption and Standard since this functionality is not currently supported in either of the tiers nor with the support of the Integration Account.

DTD? What is a DTD?

Yes, this is probably old school, which is not often used nowadays. But DTD, which stands for Document Type Definition, allows you to define the structure and the legal elements and attributes of an XML document.

This is a sample of a DTD file:





And this is a sample of an XML message with a reference to a DTD:




   My stock
   nine
   (099) 999-9999

The DOCTYPE declaration above contains a reference to a DTD file.

Although the use of DTDs is not very frequent to see these days, it is still very common to encounter this in RosettaNet PIPs.

Validate XML against DTD

A Document Type Definition (DTD) is a document that describes the structure of an XML document, what elements and attributes it contains, and what values it may have. DTDs form part of the W3C’s XML Standard but are typically considered to be a separate schema technology and are not typically used in conjunction with other schema formats like XSD and so on.

A DTD document can be embedded within an XML file or can exist on its own. When it is not embedded, normally, there are two ways to reference the DTD:

  • Using the PUBLIC keyword: This format is generally used to declare publicly available DTDs, standard character sets, and commonly used notations

  • Or using the SYSTEM keyword: These entities are not assumed to be known to a receiving system. Thus, such entities require a full declaration of system identification (path, etc.) when they are exchanged.
    • The SYSTEM identifier specifies the location of the DTD file. Since it does not
      start with a prefix like http:/or file:/, the path is relative to the location of
      the XML document.

This Azure Function allows you to perform XML validations against a DTD file. The function only accepts DTDs defined using the SYSTEM keyword.

To trigger this function, you need to:

  • In the Body, the XML payload that you want to be validated.
  • You should specify the following mandatory headers:
    • Content-Type as text/xml (or application/xml).
    • DTDFileName with the name of the DTD file present in the storage account.

The response will be a:

  • 200 OK – Validation successful. If it’s a valid message.
  • Or 400 Bad Request with a list of errors if there is something invalid.

Where can I download it?

You can download the complete Azure Functions source code here:

Hope you find this helpful! So, if you liked the content or found it useful and want to help me write more, you can buy (or help me buy) my son a Star Wars Lego! 

Author: Sandro Pereira

Sandro Pereira lives in Portugal and works as a consultant at DevScope. In the past years, he has been working on implementing Integration scenarios both on-premises and cloud for various clients, each with different scenarios from a technical point of view, size, and criticality, using Microsoft Azure, Microsoft BizTalk Server and different technologies like AS2, EDI, RosettaNet, SAP, TIBCO etc.

He is a regular blogger, international speaker, and technical reviewer of several BizTalk books all focused on Integration. He is also the author of the book “BizTalk Mapping Patterns & Best Practices”. He has been awarded MVP since 2011 for his contributions to the integration community.
View all posts by Sandro Pereira

Azure Function to Apply XML Validation (Advanced)

Azure Function to Apply XML Validation (Advanced)

After the release of our previous XML Validation Functions: 

It is now time to release our last Azure Function under the same context: an Azure Function to Apply XML Validation (Advanced).

As I explained in my previous posts, all the out-of-the-box Azure Integration Services capabilities to validate XMLs have a huge limitation: they don’t allow us to have a chain of XML Schemas! As I also mentioned, this is a common feature present in many Enterprise XML Schemas definitions. EDI or RosettaNet Schemas may have 2 or more schemas that define the overall structures of the messages. Blocking this way many enterprise scenarios that we need to address in our Azure integration solutions.

Our previous Azure Function allows us to solve many of those scenarios, and it can be used inside Logic Apps Consumption or Standard or even inside API Management. However, it also has a limitation: it only allows first-level chain support for XML Schemas (meaning that it will only take into consideration all the import schemas of the main XML Schema).

However, for example, in RosettaNet Schemas, it is very common that our main schema imports a “child” XML Schema and that child schema imports or includes other XML Schemas itself.

Apply XML Validation (Advanced)

What does this Azure Function do?

This Azure Function allows you to perform XML validations against an XML Schema, including support for all chains of XML Schemas. That means that it will take into consideration all depth of importation for a specific type of message. It will recursively include or import all XML Schemas, supporting this way all types of XML message validation.

To trigger this function, you need to:

  • In the Body, the XML payload that you want to be validated.
  • You should specify the following mandatory headers:
    • Content-Type as text/xml (or application/xml).
    • SchemaFileName with the name of the XML Schema (XSD) file present in the storage account.

The response will be a:

  • 200 OK – Validation successful. If it’s a valid message.
  • Or 400 Bad Request with a list of errors if there is something invalid.

Notice that by default, if you send a message to be validated against a schema that doesn’t have the same target namespace and root node, the response will be an OK. This function also validates that type of message, so if you send a message that doesn’t correspond to that schema, you will get a 400 Bad Request.

Where can I download it?

You can download the complete Azure Functions source code here:

Hope you find this helpful! So, if you liked the content or found it useful and want to help me write more, you can buy (or help me buy) my son a Star Wars Lego! 

Thanks to my team member Luís Rigueira for helping me realize and implement this idea.

Author: Sandro Pereira

Sandro Pereira lives in Portugal and works as a consultant at DevScope. In the past years, he has been working on implementing Integration scenarios both on-premises and cloud for various clients, each with different scenarios from a technical point of view, size, and criticality, using Microsoft Azure, Microsoft BizTalk Server and different technologies like AS2, EDI, RosettaNet, SAP, TIBCO etc.

He is a regular blogger, international speaker, and technical reviewer of several BizTalk books all focused on Integration. He is also the author of the book “BizTalk Mapping Patterns & Best Practices”. He has been awarded MVP since 2011 for his contributions to the integration community.
View all posts by Sandro Pereira

Azure Function to Apply XML Validation (Intermedium)

Azure Function to Apply XML Validation (Intermedium)

After the release of our Azure Function to Apply XML Validation (Basic), it is now time for another Azure Function under the same context: an Azure Function to Apply XML Validation (Intermedium).

You may be wondering why a new Azure Function is required to archive the same? And why not only one with all capabilities?

Both are good questions that I will be happy to respond to. First of all, in my last blog post, I mentioned that, in the next few days, we will be releasing two additional versions of this function with more functionalities/capabilities. And to answer the second question, the main reason why I decided to do 3 different versions is performance. The basic function has fewer capabilities, but it will have better performance. Of course, the advanced function will have all the capabilities, but it will have a small overhead in the overall performance.

The previous Azure Function is great for basic validations, similar to what we can archive using the default out-of-the-box capabilities inside:

  • Logic Apps Standard;
  • Logic Apps Consumption using the Integration Account;
  • Or in API Management

Of course, the basic XML Validation Function it is a good approach to replace the dependency of the Integration Account in Logic App Consumption.

But all of them have a huge limitation! None of those services allow a chain of XML Schemas!

What do you mean by a chain of XML Schemas?

XML Schema provides mechanisms to include or import other XML Schema documents, enabling the reuse and extension of schema definitions across multiple files. This capability is essential for managing complex schemas in a modular and maintainable manner.

  1. Include: The include element is used when you want to incorporate definitions from another schema that is in the same target namespace. By using include, you can split your schema definitions into separate, smaller files for better manageability and readability while treating them as part of a single schema during validation. The included schema essentially becomes a subset of the including schema, allowing for the extension or redefinition of elements and types within the same namespace.
  2. Import: The import element is used to incorporate definitions from another schema that is in a different target namespace or from no namespace into the current schema. This allows you to reference and use types and elements defined in an external schema within your current schema document. Importing is crucial when you need to integrate or reference types defined in a completely separate schema, possibly managed by a different organization or standard body.

Both include and import mechanisms facilitate the construction of complex XML schemas from modular components, promoting reuse and simplifying the management of schema definitions. They enable schema designers to build upon existing standards and to organize their schema definitions logically and efficiently.

This a common feature present in many Enterprise XML Schemas definitions. EDI or RosettaNet Schemas may have 2 or more schemas that define the overall structures of the messages.

Apply XML Validation (Intermedium)

What does this Azure Function do?

This Azure Function allows you to perform XML validations against an XML Schema, including first-level chain support for XML Schemas. That means that it will take into consideration all the import schemas of the main XML Schema

To trigger this function, you need to:

  • In the Body, the XML payload that you want to be validated.
  • You should specify the following mandatory headers:
    • Content-Type as text/xml (or application/xml).
    • SchemaFileName with the name of the XML Schema (XSD) file present in the storage account.

The response will be a:

  • 200 OK – Validation successful. If it’s a valid message.
  • Or 400 Bad Request with a list of errors if there is something invalid.

Notice that by default, if you send a message to be validated against a schema that doesn’t have the same target namespace and root node, the response will be an OK. This function also validates that type of message, so if you send a message that doesn’t correspond to that schema, you will get a 400 Bad Request.

Where can I download it?

You can download the complete Azure Functions source code here:

Hope you find this helpful! So, if you liked the content or found it useful and want to help me write more, you can buy (or help me buy) my son a Star Wars Lego! 

Thanks to my team member Luís Rigueira for helping me realize and implement this idea.

Author: Sandro Pereira

Sandro Pereira lives in Portugal and works as a consultant at DevScope. In the past years, he has been working on implementing Integration scenarios both on-premises and cloud for various clients, each with different scenarios from a technical point of view, size, and criticality, using Microsoft Azure, Microsoft BizTalk Server and different technologies like AS2, EDI, RosettaNet, SAP, TIBCO etc.

He is a regular blogger, international speaker, and technical reviewer of several BizTalk books all focused on Integration. He is also the author of the book “BizTalk Mapping Patterns & Best Practices”. He has been awarded MVP since 2011 for his contributions to the integration community.
View all posts by Sandro Pereira

Azure Function to Apply XML Validation (Basic)

Azure Function to Apply XML Validation (Basic)

After the release of our two previous Azure Functions that will help us minimize or completely remove the need for an Integration Account:

Today is the correct time to release another Azure Function that will replace another Integration Account functionality: an Azure Function to Apply XML Validation.

Of course, you can apply out-of-the-box this functionality in:

  • Logic App Standard (without the need for an Integration Account)

    
        
    
    

However, Logic App Consumption requires an Integration Account to provide those same capabilities out of the box.

Once again, our main objective in creating this specific version of this function was to use it inside Logic Apps Consumption to avoid needing an Integration Account. But that we will address later on in another blog post.

If you are wondering what I mean by this specific version of this function, well, in the next few days, we will be releasing two additional versions of this function with more functionalities. But, once again, that we will address later on in another blog post.

Apply XML Validation (Basic)

XML (Extensible Markup Language) validation is the process of checking an XML document against a set of rules to ensure its structure and content adhere to a specific format or standard. This process is crucial for ensuring that the XML document is both well-formed and valid.

  1. Well-formed XML: This means that the XML document follows the basic syntax rules laid out by the XML specification. These rules include proper nesting of elements, correct use of opening and closing tags, attribute value quoting, and more. A well-formed XML document is one that can be correctly parsed and understood by an XML parser.
  2. Valid XML: Beyond being well-formed, a valid XML document also adheres to a specific schema or Document Type Definition (DTD) that defines the structure, content, and relationships within the document. Validation against a schema or DTD ensures that the XML document contains the expected elements, attributes, and data types, and that these components are organized in a defined way.

There are several schema languages used for XML validation, with the most common being:

  • DTD (Document Type Definition): An older schema language that defines the structure and allowed content within an XML document. – Not supported in the Azure Function.
  • XML Schema (also known as XSD): A more powerful and expressive schema language that allows for more detailed specifications of the content and structure, including data types and namespace support.

XML validation is performed using XML parsers or validation tools, which can programmatically check a document against its DTD or XSD to ensure compliance. This is a critical step in many data exchange, configuration management, and content authoring workflows, ensuring that the data is correctly structured and interpretable by receiving systems or applications.

What does this Azure Function do?

This Azure Function allows you to perform basic XML validations against an XML Schema.

To trigger this function, you need to:

  • In the Body, the XML payload that you want to be validated.
  • You should specify the following mandatory headers:
    • Content-Type as text/xml (or application/xml).
    • SchemaFileName with the name of the XML Schema (XSD) file present in the storage account.

The response will be a:

  • 200 OK – Validation successful. If it’s a valid message.
  • Or 400 Bad Request with a list of errors if there is something invalid.

Notice that by default, if you send a message to be validated against a schema that doesn’t have the same target namespace and root node, the response will be an OK. This function also validates that type of message, so if you send a message that doesn’t correspond to that schema, you will get a 400 Bad Request.

Where can I download it?

You can download the complete Azure Functions source code here:

Hope you find this helpful! So, if you liked the content or found it useful and want to help me write more, you can buy (or help me buy) my son a Star Wars Lego! 

Thanks to my team member Luís Rigueira for helping me realize and implement this idea.

Author: Sandro Pereira

Sandro Pereira lives in Portugal and works as a consultant at DevScope. In the past years, he has been working on implementing Integration scenarios both on-premises and cloud for various clients, each with different scenarios from a technical point of view, size, and criticality, using Microsoft Azure, Microsoft BizTalk Server and different technologies like AS2, EDI, RosettaNet, SAP, TIBCO etc.

He is a regular blogger, international speaker, and technical reviewer of several BizTalk books all focused on Integration. He is also the author of the book “BizTalk Mapping Patterns & Best Practices”. He has been awarded MVP since 2011 for his contributions to the integration community.
View all posts by Sandro Pereira