[WebServices two-step forward] Top _ DTD parameter entity and schema Data Type

Data Type of the top _ DTD parameter entity and schema -- zhanglong, Shengsi yuan, edited by Xuan Yu

DTD parameter entity	Data Type
Entity reference	Basic Data Type
Why schema?	Extended Data Type
Document Structure	Features of Data Types

DTD parameter entity
This entity is not used in a specific instantiation document, but is used inside the DTD document.
For example, we define an object like this:<! Entity % address "Street, city, zip code, Country">
Then, you can use"% Address ;"To reference it:<! Element Contact (person name, phone number, % address;)>
This is the concept of a parameter object.

Type		Normal entity	Parameter entity
Usage		Used in XML documents	It is only used in the declaration of elements and attributes in the DTD.
Statement Method	Internal	<! Entity entity name "text content">	<! Entity % entity name "text content">
	External	<! Entity entity name system "external File URL">	<! Entity % entity name system "external File URL">
Reference Method		& Entity name;	% Entity name;

 

 

Entity reference
In fact, XML already has five built-in entities, that is, the entity reference we often call.
This is to avoid confusion between character data and some special symbols used in tags. Therefore, XML provides entity references.

Character	Entity reference
&	& Amp;
>	& Gt;
<	& Lt;
"	& Quot;
'	& Apos;

 

 

Why schema?
Limitations of DTD
1) DTD does not comply with the XML syntax (one syntax is used when writing an XML document instance, and the other syntax is used when writing a DTD)
2) The DTD data type is limited (inconsistent with the database data type)
3) The DTD cannot be expanded.
New Schema Features
1) Schema is based on XML syntax
2) The schema can be processed using a tool that can process the XML smell.
3) The schema greatly expands the data type and can customize the data type.
4) Schema supports element inheritance-object-oriented
5) Schema supports attribute groups.

 

 

Schema document structure

<? XML version = "1.0"?> <Xs: schema xmlns: xs = "http://www.w3.org/2001/XMLSchema" targetnamespace = "http: // mynamespace/mychema"> <! -- Put the actual content --> </Xs: schema>

1) <Xs: Schema: indicates that all schema documents use schema as their root element.
2) xmlns: Xs: indicates that the elements and data types used to construct the schema come from http://www.w3.org/2001/xmlschemanamespace
3) targetnamespace: indicates that the elements and data types defined in this schema belong to the http: // mynamespace/mychema namespace

 

 

Schema Data Type
Simple Type
1. built-in data types (built-in data types)
1) Basic Data Types
2) Extended Data Types
2. User-defined data types (defined by simpletype)
Complex type (defined by complextype, which is often used in WebServices and is required)

 

 

Basic Data Type

Basic Data Type	Description
String	String
Boolean	Boolean
Decimal	Number representing a specific precision
Float	32-bit floating point number with single precision
Double	Double-precision 64-bit floating point number
Duration	Duration
Datetime	Represents a specific time
Time	It indicates a specific time, but it is repeated every day.
Date	Represents a date
Hexbinary	Hexadecimal number
Anyuri	Indicates a URI used to locate a file.
Notation	Notation type

 

 

Extended Data Type

Extended Data Type	Description
ID	Used to uniquely identify an element
Idref	Refer to the element or attribute of ID type
Entity	Entity type
Nmtoken	Nmtoken type
Nmtokens	Nmtoken type set
Long	Integer value. The value range is-9223372036854775808 and 9223372036854775807.
Int	Integer value. The value range is-2147483648 and 2147483647.
Short	Integer value. The value range is-32768 and 32767.
Byte	Integer value. The value range is-128 and 127.

 

 

Features of Data Types

Features of Data Types	Description
Enumeration	Select from the specified dataset to specify the user's selection value.
Totaldigits	Precisely specify the number of digits
Fractiondigits	Limit the maximum decimal point, used to control the precision (must be greater than or equal to zero)
Length	Specify the length of data, that is, precisely specify the maximum allowed characters
Maxlength	Maximum allowed characters
Minlength	Minimum Allowed characters
Maxexclusive	Maximum value (less than) of the specified data)
Maxcompute sive	Maximum Value of the specified data (less than or equal)
Minexclusive	Specify the minimum value (greater)
Mininclusive	Specify the minimum value (greater than or equal)
Pattern	Specify the data display specification, that is, specify the allowed value mode, similar to a regular expression
Whitespace	Blank processing (retain: preserve, replace: replace, merge: Collapse)