LOGO Đặc tả hình thức Đặc tả hình thức GVHD:Thầy Nguyễn Trần Thi Văn Vũ Minh Hải 07110037 Lâm Chí Hiền 07110041 Nguyễn Công Hiếu 07110045 Chiếng Mành Sâm 07110100 Thành Viên: LOGO Entities and External DTD Subsets Entities and External DTD Subsets What is an entity? 1 Internal general entities 2 External general entities 3 Internal parameter entities 4 External parameter entities 5 LOGO How to build a document from pieces 6 Entities and DTDs in well-formed documents 7 LOGO  Document pieces, or “storage units” • This is often a file (an external entity) or a character string delimited by quotes and included as part of the entity’s declaration (an internal entity).  Simplify writing of documents and DTD grammars  Modularize documents and DTD grammars  Most entities have names by which you can refer to them What is an entity? 1 LOGO  Type of Entities Entities General Entities Parameter Entities Internal General Entities External General Entities Internal Parameter Entities External Parameter Entities What is an entity? (cont) 1 LOGO  Type of Entities  Parsed and Unparsed Entities? Entities Entities Parsed Entities Parsed Entities Unparsed Entities Unparsed Entities Internal Entities Internal Entities External Entities External Entities Internal Entities Internal Entities What is an entity? (cont) 1 LOGO  Parsed Entities: A parsed entity's contain well-formed XML text  Unparsed entities: Binary data, non-XML text (Aren’t well supported) What is an entity? (cont) 1 LOGO a. Defining an Internal General Entity Reference  Internal general entity references are defined in the DTD with the <!ENTITY> tag, which has the following format:  <!ENTITY name “replacement text”> Internal general entities (cont) 2 LOGO Commonly used text or text that’s hard to type? Commonly used text or text that’s hard to type? Need replacement text Need replacement text Solution: An <!ENTITY> tag in the DTD Solution: An <!ENTITY> tag in the DTD In C we have: #define PI 3,14159 Reference Internal general entities 2 LOGO  General entity references begin with an ampersand (&) and end with a semicolon (;)  For instance, &lt; is a general entity reference for the less than sign (<)  Entity names consist of any set of alphanumeric characters and the underscore. Whitespace and other punctuation characters are prohibited. Internal general entities (cont) 2 [...]... embed just any XML document as an external parsed entity 5/6/15 Đặc tả hình thức Nhóm 7 28 LOGO For example For example Chris Hoiles Catcher 5/6/15 Đặc tả hình thức Nhóm 7 29 LOGO Text declarations  must have an encoding . LOGO Đặc tả hình thức Đặc tả hình thức GVHD:Thầy Nguyễn Trần Thi Văn Vũ Minh Hải 07110037 Lâm Chí Hiền 07110041 Nguyễn