Difference Between DTD and XSD (With Table)

DTD (Document Type Definition) and XSD (XML Schema Definition) are both related to a markup language, known as XML (Extensible Markup Language). XML is mainly used for storing and transferring data.   

Since most of the client machines require getting data from the server, XML is an effective method of fetching it. Although, both DTD and XSD are related to the same markup language, XML, they differ from each other in a lot of aspects. 

DTD vs XSD 

The difference between DTD and XSD is that DTD (Document Type Definition) has less control over XML, whereas XSD (XML Schema Definition) provides better control over XML. DTD is a type of document which is used to define the structure of XML, and XSD is a way used to describe the structure and content of XML.   

DTD stands for Document Type Definition. It is a type of document which is used to define the structure of an XML (Extensible Markup Language) document. The attributes of the XML language are precisely defined by DTD. DTD can further be classified into two parts, namely, internal DTD and external DTD. The grammar and validity of the structure of the XML document are checked by DTD.  

XSD stands for XML Schema Definition. It is a way that is being used to describe the structure and content of an XML document. XSD was first published in 2001 and was again brought back in 2004. The rules for all the attributes and elements of an XML document are precisely defined by the XSD. Also, the vocabulary and the correctness in the structure of the XML file are mainly checked by XSD.   

Comparison Table Between DTD and XSD  

Parameters of Comparison             DTD             XSD 
Full-form  DTD stands for Document Type Definition XSD stands for XML Schema Definition. 
Written in DTD is derived from SGML (Standard Generalized Markup Language) syntax. XSD is written in XML  
Features DTD can be used to define the structure of an XML document. XSD can be used to describe the structure and contents of an XML document. 
Control  DTD has less control over XML. XSD provides better control over XML. 
Capability  DTD does not support Namespace and datatypes. XSD supports Namespace and datatypes.  
Learning   DTD is not easy to learn. XSD is easy to learn because here we do not need to learn a new language. 
Extensible  DTD is not extensible.  XSD is extensible. 

What is DTD? 

DTD stands for Document Type Definition and is a type of document which is used to define the structure of an XML (Extensible Markup Language) file. The attributes of the XML language are precisely defined by DTD. It is mainly used to check the grammar and validity of the structure of the XML file.   

DTD can further be divided into two parts, namely, external DTD and internal DTD. The DTD elements declared within the XML file, are known as internal DTD, whereas the DTD elements declared in some other files, are known as external DTD.   

DTD is derived from SGML (Standard Generalized Markup Language) syntax. It does not support Namespace and Datatypes and has less control over XML. DTD is also not extensible.  

A person using DTD cannot strongly type in it. However, it does, at times, act as the extended version of the XML. DTD is not simple to learn. DTD is precisely declarations that define a document type for SGML. 

What is XSD? 

XSD stands for XML Schema Definition and is a way which is used to describe and content of an XML (Extensible Markup Language) document. The rules for all the attributes and elements of an XML document are precisely defined by the XSD. It is mainly used to check the vocabulary and correctness of the structure of an XML file.   

XSD files are of two types, namely, simple Type and complex Type. The Type which, allows having text-based elements and contains fewer attributes, child elements, and cannot be left empty, is known as the simple Type XSD. The Type which, allows the holding of multiple attributes and elements, contains sub-elements, and cannot be left empty, is known as complex Type XSD.  

XML is used for writing XSD. It supports Namespace and Datatypes for elements and attributes. XSD is extensible and gives us more control over the XML document.  

XSD is precisely used to describe the elements in an XML document. Learning XSD is comparatively easier than that of DTD because here, we do not need to learn a new language.  

Main Differences Between DTD and XSD. 

  1. DTD stands for Document Type Definition, whereas XSD stands for XML Schema Definition.  
  2. DTD is mainly used to define the structure of an XML file, whereas XSD is mainly used to describe the structure and contents of an XML file.  
  3. DTD is not extensible, whereas XSD is extensible.  
  4. DTD is derived from SGML (Standard Generalized Markup Language) syntax, whereas XSD is written in XML.  
  5. DTD is not aware of Namespace, whereas XSD supports Namespace.  
  6. DTD does not support Datatypes, whereas XSD supports Datatypes for elements and attributes.  
  7. DTD has less control over XML, whereas XSD provides more control over XML.  
  8. DTD is comparatively harder to learn than XSD, whereas XSD is simple to learn as here we do not need to learn a new language.  

Conclusion  

DTD (Document Type Definition) and XSD (XML Schema Definition) might both be related to the same markup language, XML (Extensible Markup Language), yet they differ from each other in a lot of attributes.  

DTD is a type o Document that is mainly used to define the structure of the XML file. It checks the grammar and validity of the structure of the XML file. DTD is derived from the SGML (Standard Generalized Markup Language) syntax and is the declarations that define a document type of SGML. DTD is also harder to learn and is not extensible. It does not support Namespace and Datatypes.  

XSD, on the other hand, is a way that is used to define the structure and contents of the XML file. It also checks the vocabulary and correctness of the structure of the XML file. XSD is written in XML and describes the elements in an XML document. XSD is comparatively easier to learn than that of DTD, as here, the user is not required to learn a new language. Unlike DTD, XSD supports Namespace and Datatypes for elements and attributes. It is extensible.  

The main point of difference between DTD and XSD is that DTD has less power over XML, whereas XSD provides more control over XML. 

References 

  1. https://dl.acm.org/doi/abs/10.1145/1017074.1017095 
  2. https://www.sciencedirect.com/science/article/abs/pii/S095070510600150X 
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