2003.10.09 - SLIDE 1IS 202 – FALL 2003 Prof. Ray Larson & Prof. Marc Davis UC Berkeley SIMS Tuesday and Thursday 10:30 am - 12:00 pm Fall 2003

2003.10.09 - SLIDE 1IS 202 – FALL 2003 Prof. Ray Larson & Prof. Marc Davis UC Berkeley SIMS Tuesday and Thursday 10:30 am - 12:00 pm Fall 2003 http://www.sims.berkeley.edu/academics/courses/is202/f03/ SIMS 202: Information Organization and Retrieval Lecture 14: Metadata and Markup

2003.10.09 - SLIDE 2IS 202 – FALL 2003 Lecture Overview Review –XML and Document Engineering Metadata And Markup –XML As A Metadata Lingua Franca METS –SGML vs. XML DTD Construction –XML Schemas –XML For Protocols And Metadata Languages Readings/Discussion

2003.10.09 - SLIDE 5IS 202 – FALL 2003 XML as a common syntax XML (and SGML) provide a way of expressing the structure of documents that can be verified and validated by document processing systems “Documents” can be metadata structures –Such as the description of a particular photograph in our Phone project XML thus provides a way of representing metadata descriptions as well as the content that they describe

2003.10.09 - SLIDE 6IS 202 – FALL 2003 XML as a common syntax All XML documents follow some simple rules that make them interchangeable and usable across different systems –All data and markup is in UNICODE –All elements are marked by begin and end tags –All markup is case-sensitive –XML DTD’s and/or Schemas define the valid structure (and sometimes content) of the documents

2003.10.09 - SLIDE 7IS 202 – FALL 2003 Example – METS METS – the Metadata Encoding and Transmission Standard is a new Schema intended to provide: –“a standard for encoding descriptive, administrative, and structural metadata regarding objects within a digital library, expressed using the XML schema language of the World Wide Web Consortium” METS can be used to “wrap” complex sets of data (the actual data, with rules for encoding binary forms), the metadata describing the parts of that data, and the sequence and conditions under which the data can or should be presented or displayed

2003.10.09 - SLIDE 9IS 202 – FALL 2003 SGML/XML Structure An SGML document consists of three parts: –The SGML Declaration –The Document Type Definition (DTD) –The Document Instance An XML document REQUIRES only the document instance, but for effective processing a DTD is very important XML Schema (later) provides an alternative to DTDs for XML applications

2003.10.09 - SLIDE 10IS 202 – FALL 2003 Document Type Definitions The DTD describes the structural elements and "shorthand" markup for a particular document type and defines: –Names of "legal" elements –How many times elements can appear –The order of elements in a document –Whether markup can be omitted (SGML only) –Contents of elements (i.e., nested structures) –Attributes associated with elements –Names of "entities" –Short-hand conventions for element tags (SGML only)

2003.10.09 - SLIDE 11IS 202 – FALL 2003 DTD Components The major components of a DTD are: –Entity Declarations –Element Declarations –Attribute Declarations

2003.10.09 - SLIDE 12IS 202 – FALL 2003 Document Type Definitions Entity Declarations are a "macro" definition facility for both DTD and Document instance parts –General Internal Entity Definitions referenced by &name; –General External Entity Definitions referenced by &name; –Parameter Entity Definitions (used only inside DTDs) or referenced by %name; or %name

2003.10.09 - SLIDE 13IS 202 – FALL 2003 Document Type Definitions SGML Element Declarations define the structural elements of a document and its associated markup –Omitted tag minimization indicates whether start-tags or end-tags can be omitted in the markup (o) or (-) are required in SGML but can NOT be used in XML

2003.10.09 - SLIDE 14IS 202 – FALL 2003 Document Type Definitions Content model provides a nested structural description of the elements that make up this element, e.g.:... –ANY (in SGML) may be used to indicate a content model of any elements in the DTD, in any order

2003.10.09 - SLIDE 15IS 202 – FALL 2003 Document Type Definitions Same content model in XML <!DOCTYPE memo [ … ]> –Note the XML processing instruction “Prolog” –Note that & in previous page is not legal XML

2003.10.09 - SLIDE 16IS 202 – FALL 2003 Document Type Definitions Declared content can be: PCDATA, CDATA, RCDATA, EMPTY Inclusion and Exclusion lists can be used to indicate elements that can occur or are forbidden to occur in any sub-elements of the content model (NOT in XML), e.g.: –Says that element fn can appear anyplace in the memo

2003.10.09 - SLIDE 17IS 202 – FALL 2003 Document Type Definitions Attribute Declarations define attributes associated with (potentially) each element of a document and provide the acceptable values for those attributes

2003.10.09 - SLIDE 18IS 202 – FALL 2003 Attributes Example –In markup of a document: also, because of the default set: would be the same as There are a variety of special defaults and data types that can be given in attribute definitions

2003.10.09 - SLIDE 21IS 202 – FALL 2003 Document Using That DTD ELIB-v1.0 6 February 13 1995 March 1, 1993 Water Conditions in California Report 2 California Department of Water Resources 120-93 bulletin California Department of Water Resources 17 /elib/data/disk/disk5/documents/6/HYPEROCR/hyperocr.html /elib/data/disk/disk5/documents/6/OCR-ASCII-NOZONE

2003.10.09 - SLIDE 22IS 202 – FALL 2003 Dublin Core Review… Simple metadata for describing internet resources For “Document-Like Objects” 15 Elements

2003.10.09 - SLIDE 23IS 202 – FALL 2003 Dublin Core Elements Title Creator Subject Description Publisher Other Contributors Date Resource Type Format Resource Identifier Source Language Relation Coverage Rights Management

2003.10.09 - SLIDE 24IS 202 – FALL 2003 DC XML DTD Implementation There have been various versions This one is the one recommended (required) by the Open Archives Initiative Metadata Harvesting Protocol (OAI-MHP) Uses XML Name Spaces Available at http://dublincore.org/documents/2001/09/20/dcmes-xml/

2003.10.09 - SLIDE 25IS 202 – FALL 2003 DC Element and Attribute Definitions

2003.10.09 - SLIDE 26IS 202 – FALL 2003 DC Element Definitions (cont.)

2003.10.09 - SLIDE 27IS 202 – FALL 2003 A More Complex SGML DTD <!DOCTYPE USMARC [ <!ATTLIST USMARC Material (BK|AM|CF|MP|MU|VM|SE) "BK" id CDATA #IMPLIED>  <!ELEMENT Leader - O (LRL, RecStat, RecType, BibLevel, UCP, IndCount, SFCount, BaseAddr, EncLevel, DscCatFm, LinkRec, EntryMap)> …etc…

2003.10.09 - SLIDE 28IS 202 – FALL 2003 More Complex DTD (cont.) <!ELEMENT VarDFlds - O (NumbCode, MainEnty?, Titles, EdImprnt?, PhysDesc?, Series?, Notes?, SubjAccs?, AddEnty?, LinkEnty?, SAddEnty?, HoldAltG?, Fld9XX?)> <!ELEMENT NumbCode - O (Fld010?, Fld011?, Fld015?, Fld017*, Fld018?, Fld019*, Fld020*, Fld022*, Fld023*, Fld024*, Fld025*, Fld027*, Fld028*, Fld029*, Fld030*, Fld032*, Fld033*, Fld034*, Fld035*, Fld036?, Fld037*, Fld039*, Fld040?, Fld041?, Fld042?, Fld043?, Fld044?, Fld045?, Fld046?, Fld047?, Fld048*, Fld050*, Fld051*, Fld052*, Fld055*, Fld060*, Fld061*, Fld066?, Fld069*, Fld070*, Fld071*, Fld072*, Fld074*, Fld080?, Fld082*, Fld084*, Fld086*, Fld088*, Fld090*, Fld096*)> <!ELEMENT Titles - O (Fld210?, Fld211*, Fld212*, Fld214*, Fld222*, Fld240?, Fld242*, Fld243?, Fld245, Fld246*, Fld247*)> <!ELEMENT EdImprnt - O (Fld250?, Fld254?, Fld255*, Fld256?, Fld257?, Fld260?, Fld261?, Fld262?, Fld263?, Fld265?)> <!ELEMENT PhysDesc - O (Fld300*, Fld305*, Fld306?, Fld310?, Fld315?, Fld321*, Fld340*, Fld350?, Fld351*, Fld355*, Fld357*, Fld362*)> …etc…

2003.10.09 - SLIDE 29IS 202 – FALL 2003 Complex DTD (cont.) <!ATTLIST Fld245 AddEnty (No|Yes|Blank) #IMPLIED NFChars (0|1|2|3|4|5|6|7|8|9|Blnk) #IMPLIED> …etc…

2003.10.09 - SLIDE 30IS 202 – FALL 2003 Document Markup All document markup is derived from the DTD for the particular document type In SGML the DTD should be referenced in the document using the DOCTYPE declaration: or or The doctype_declaration_subset can be any combination of elements, entity, and attribute declarations

2003.10.09 - SLIDE 31IS 202 – FALL 2003 HTML HTML was not originally "real" SGML, the DTD was invented after the language It is often more concerned with the form of the output on the screen than with the structural contents of the HTML docs Relies on the application (such as Netscape) to implement interesting actions like hypertext linking XHTML is now a W3C “recommendation” that applies XML conventions to HTML, and provides a growing set of capabilities within an XML framework (our phones use XHTML)

2003.10.09 - SLIDE 33IS 202 – FALL 2003 What are XML Schemas? An XML vocabulary for expressing your data's structure AND content types, and even the business rules involved in processing the data Written in XML themselves Support namespaces for combining multiple schemas in the same documents –The slides in this section are based on an XML tutorial by Roger L. Costello

2003.10.09 - SLIDE 34IS 202 – FALL 2003 Example 32.904237 73.620290 2 Is this data valid? To be valid, it must meet these constraints (data business rules): 1. The location must be comprised of a latitude, followed by a longitude, followed by an indication of the uncertainty of the lat/lon measurements. 2. The latitude must be a decimal with a value between -90 to +90 3. The longitude must be a decimal with a value between -180 to +180 4. For both latitude and longitude the number of digits to the right of the decimal point must be exactly six digits. 5. The value of uncertainty must be a non-negative integer 6. The uncertainty units must be either meters or feet. We can express all these data constraints using XML Schemas

2003.10.09 - SLIDE 35IS 202 – FALL 2003 Validating your data 32.904237 73.620290 2 -check that the latitude is between -90 and +90 -check that the longitude is between -180 and +180 - check that the fraction digits is 6 for lat and lon... XML Schema validator Data is ok!

2003.10.09 - SLIDE 36IS 202 – FALL 2003 Purpose of XML Schemas Specify: –the structure of instance documents "this element contains these elements, which contains these other elements, etc" –the datatype of each element/attribute "this element shall hold an integer with the range 0 to 12,000" (DTDs don't do too well with specifying datatypes like this)

2003.10.09 - SLIDE 37IS 202 – FALL 2003 Motivation for XML Schemas Why Schemas? People are dissatisfied with DTDs –It's a different syntax You write your XML (instance) document using one syntax and the DTD using another syntax --> bad, inconsistent –Limited datatype capability DTDs support a very limited capability for specifying datatypes. You can't, for example, express "I want the element to hold an integer with a range of 0 to 12,000" –Desire a set of datatypes compatible with those found in databases DTD supports 10 datatypes; XML Schemas supports 44+ datatypes

2003.10.09 - SLIDE 38IS 202 – FALL 2003 Highlights of XML Schemas XML Schemas are a tremendous advancement over DTDs: –Enhanced datatypes 44+ versus 10 Can create your own datatypes –Example: "This is a new type based on the string type and elements of this type must follow this pattern: ddd-dddd, where 'd' represents a digit". –Written in the same syntax as instance documents less syntax to remember –Object-oriented'ish Can extend or restrict a type (derive new type definitions on the basis of old ones) –Can express sets, i.e., can define the child elements to occur in any order

2003.10.09 - SLIDE 39IS 202 – FALL 2003 Highlights of XML Schemas Can specify element content as being unique (keys on content) and uniqueness within a region Can define multiple elements with the same name but different content Can define elements with nil content Can define substitutable elements - e.g., the "Book" element is substitutable for the "Publication" element.

2003.10.09 - SLIDE 40IS 202 – FALL 2003 BookStore.dtd

2003.10.09 - SLIDE 41IS 202 – FALL 2003 ATTLIST ELEMENT ID #PCDATA NMTOKEN ENTITY CDATA BookStore Book Title Author Date ISBN Publisher This is the vocabulary that DTDs provide to define your new vocabulary

2003.10.09 - SLIDE 42IS 202 – FALL 2003 element complexType schema sequence http://www.w3.org/2001/XMLSchema string integer boolean BookStore Book Title Author Date ISBN Publisher http://www.books.org (targetNamespace) This is the vocabulary that XML Schemas provide to define your new vocabulary One difference between XML Schemas and DTDs is that the XML Schema vocabulary is associated with a name (namespace). Likewise, the new vocabulary that you define must be associated with a name (namespace). With DTDs neither set of vocabulary is associated with a name (namespace) [DTDs pre-dated namespaces].

2003.10.09 - SLIDE 43IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> BookStore.xsd xsd = Xml-Schema Definition

2003.10.09 - SLIDE 44IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> <!ELEMENT Book (Title, Author, Date, ISBN, Publisher)>

2003.10.09 - SLIDE 45IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> All XML Schemas have "schema" as the root element.

2003.10.09 - SLIDE 46IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> The elements and datatypes that are used to construct schemas - schema - element - complexType - sequence - string come from the http://…/XMLSchema namespace

2003.10.09 - SLIDE 47IS 202 – FALL 2003 element complexType schema sequence http://www.w3.org/2001/XMLSchema string integer boolean XMLSchema Namespace

2003.10.09 - SLIDE 48IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> Says that the elements defined by this schema - BookStore - Book - Title - Author - Date - ISBN - Publisher are to go in this namespace

2003.10.09 - SLIDE 49IS 202 – FALL 2003 BookStore Book Title Author Date ISBN Publisher http://www.books.org (targetNamespace) Book Namespace (targetNamespace)

2003.10.09 - SLIDE 50IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> This is referencing a Book element declaration. The Book in what namespace? Since there is no namespace qualifier it is referencing the Book element in the default namespace, which is the targetNamespace! Thus, this is a reference to the Book element declaration in this schema. The default namespace Is http://www.books.org which is the targetNamespace!

2003.10.09 - SLIDE 51IS 202 – FALL 2003 <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.books.org" xmlns="http://www.books.org" elementFormDefault="qualified"> This is a directive to any instance documents which conform to this schema: Any elements used by the instance document which were declared in this schema must be namespace qualified.

2003.10.09 - SLIDE 52IS 202 – FALL 2003 Referencing a schema in an XML instance document <BookStore xmlns ="http://www.books.org" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.books.org BookStore.xsd"> My Life and Times Paul McCartney July, 1998 94303-12021-43892 McMillin Publishing... 1. First, using a default namespace declaration, tell the schema-validator that all of the elements used in this instance document come from the http://www.books.org namespace. 2. Second, with schemaLocation tell the schema-validator that the http://www.books.org namespace is defined by BookStore.xsd (i.e., schemaLocation contains a pair of values). 3. Third, tell the schema-validator that the schemaLocation attribute we are using is the one in the XMLSchema-instance namespace. 1 2 3

2003.10.09 - SLIDE 53IS 202 – FALL 2003 schemaLocation type noNamespaceSchemaLocation http://www.w3.org/2001/XMLSchema-instance nil XMLSchema-instance Namespace

2003.10.09 - SLIDE 54IS 202 – FALL 2003 Referencing a schema in an XML instance document BookStore.xml BookStore.xsd targetNamespace="http://www.books.org" schemaLocation="http://www.books.org BookStore.xsd" - defines elements in namespace http://www.books.org - uses elements from namespace http://www.books.org A schema defines a new vocabulary. Instance documents use that new vocabulary.

2003.10.09 - SLIDE 55IS 202 – FALL 2003 Note multiple levels of checking BookStore.xmlBookStore.xsd XMLSchema.xsd (schema-for-schemas) Validate that the xml document conforms to the rules described in BookStore.xsd Validate that BookStore.xsd is a valid schema document, i.e., it conforms to the rules described in the schema-for-schemas

2003.10.09 - SLIDE 56IS 202 – FALL 2003 Default Value for minOccurs and maxOccurs The default value for minOccurs is "1" The default value for maxOccurs is "1" Equivalent!

2003.10.09 - SLIDE 57IS 202 – FALL 2003 Much More to XMLSchema! This was an overview of some basics There are many other features, such as: –The ability to import other schemas or parts of schemas –Ability to specify many data types –Etc. XMLSchema definitions are at W3C –http://www.w3.org/TR/xmlschema-0/ is a good place to start

2003.10.09 - SLIDE 59IS 202 – FALL 2003 Other Protocols and Metadata Systems Using XML SOAP (Simple Object Access Protocol) DAV/DASL (Distributed Authoring and Versioning) SDLIP (Simple Digital Library Interoperability Protocol) RDF (Resource Description Framework) ADL Gazetteer Protocol OAI-MHP (already discussed) MPEG-7 (more next time) METS Also versions of MARC and other formats in XML

2003.10.09 - SLIDE 60IS 202 – FALL 2003 SGML and XML Sources and Resources Books: –van Herwijnen, Eric. Practical SGML. (2nd Ed.) Boston: Kluwer Academic Publishers, 1994. –Goldfarb, Charles F. The SGML Handbook. Oxford: Clarenden Press, 1990. (and MANY XML books) Web Sites: –The W3C web site (all XML standards documents) http://www.w3.org –Robin Cover’s SGML/XML Site http://www.oasis-open.org/cover/sgml-xml.html

2003.10.09 - SLIDE 62IS 202 – FALL 2003 Discussion – Vam Makam Kirk covers examples of DTDs for books and newspapers. Many individuals and corporations have been creating numerous DTDs for themselves and general purposes. What are some innovative and useful ideas for areas where designing DTDs might be useful? For ideas that may have already been thought of, how could they be improved or extended?

2003.10.09 - SLIDE 63IS 202 – FALL 2003 Discussion – Vam Makam However, recent XML DTDs have emerged, newer ideas such as XML schemas have presented themselves as a better option. Given the thought process and work gone into designing existing DTDs, at what point is it worth modifying an existing DTD to an XML schema? Now that you have learned how to design a dtd and have basic knowledge about XML, what are some existing technologies that combined with XML become more useful?

2003.10.09 - SLIDE 64IS 202 – FALL 2003 Discussion – Annie Yeh Kirk addresses the advantages of using external DTDs, the reusability of public DTDs, the ability to focus on content rather than structure, easier management or multiple documents, and easier data error checking. What are some of the existing repositories in which we can store these DTDs? What are some of the ways with which we can facilitate this process? What are their pros and cons? What are some of the more ideal interfaces with which to facilitate this?

2003.10.09 - SLIDE 65IS 202 – FALL 2003 Discussion – Annie Yeh What are the differences between DTDs and Schemas, and what are the pros and cons of each?

2003.10.09 - SLIDE 66IS 202 – FALL 2003 Next Time Metadata for Motion Pictures: MPEG-7 Readings/Discussion –MPEG-7 (Part 1) (J. M. Martinez, R. Koenen, F. Pereira) –MPEG-7 (Part 2) (J. Martinez)

2003.10.09 - SLIDE 67IS 202 – FALL 2003

2003.10.09 - SLIDE 1IS 202 – FALL 2003 Prof. Ray Larson & Prof. Marc Davis UC Berkeley SIMS Tuesday and Thursday 10:30 am - 12:00 pm Fall 2003

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2003.10.09 - SLIDE 1IS 202 – FALL 2003 Prof. Ray Larson & Prof. Marc Davis UC Berkeley SIMS Tuesday and Thursday 10:30 am - 12:00 pm Fall 2003

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