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XML Extender Administration and Programming


Glossary

absolute location path
The full path name of an object. The absolute path name begins at the highest level, or "root" element, which is identified by the forward slash (/) or back slash (\) character.

access and storage method
Associates XML documents to a DB2 database through two major access and storage methods: XML columns and XML collections. See also XML column and XML collection.

administrative support tables
A tables used by a DB2 extender to process user requests on XML objects. Some administrative support tables identify user tables and columns that are enabled for an extender. Other administrative support tables contain attribute information about objects in enabled columns. Synonymous with metadata table.

API
See application programming interface.

application programming interface (API)

(1) A functional interface supplied by the operating system or by a separately orderable licensed program. An API allows an application program that is written in a high-level language to use specific data or functions of the operating system or the licensed programs.

(2) In DB2, a function within the interface, for example, the get error message API.

(3) In DB2, a function within the interface. For example, the get error message API.

attribute
See XML attribute.

attribute_node
A representation of an attribute of an element.

browser
See Web browser.

B-tree indexing
The native index scheme provided by the DB2 engine. It builds index entries in the B-tree structure. Supports DB2 base data types.

cast function
A function that is used to convert instances of a (source) data type into instances of a different (target) data type. In general, a cast function has the name of the target data type. It has one single argument whose type is the source data type; its return type is the target data type.

character large object (CLOB)
A character string of single-byte characters, where the string can be up to 2 GB. CLOBs have an associated code page. Text objects that contain single-byte characters are stored in a DB2 database as CLOBs.

CLOB
Character large object.

column data
The data stored inside of a DB2 column. The type of data can be any data type supported by DB2.

compose
To generate XML documents from relational data in an XML collection.

condition
A specification of either the criteria for selecting XML data or the way to join the XML collection tables.

DAD
See Document access definition.

data interchange
The sharing of data between applications. XML supports data interchange without needing to go through the process of first transforming data from a proprietary format.

data source
A local or remote relational or nonrelational data manager that is capable of supporting data access via an ODBC driver that supports the ODBC APIs.

data type
An attribute of columns and literals.

datalink
A DB2 data type that enables logical references from the database to a file that is stored outside the database.

DBCLOB
Double-byte character large object.

decompose
Separates XML documents into a collection of relational tables in an XML collection.

default casting function
Casts the SQL base type to a UDT.

default view
A representation of data in which an XML table and all of its related side tables are joined.

distinct type
See user-defined type.

Document Access Definition (DAD)
Used to define the indexing scheme for an XML column or mapping scheme of an XML collection. It can be used to enable an XML Extender column of an XML collection, which is XML formatted.

Document type definition (DTD)
A set of declarations for XML elements and attributes. The DTD defines what elements are used in the XML document, in what order they can be used, and which elements can contain other elements. You can associate a DTD with a document access definition (DAD) file to validate XML documents.

double-byte character large object (DBCLOB)
A character string of double-byte characters, or a combination of single-byte and double-byte characters, where the string can be up to 2 GB. DBCLOBs have an associated code page. Text objects that include double-byte characters are stored in a DB2 database as DBCLOBs.

DTD
(1) .
(2) See Document type definition.

DTD reference table (DTD_REF table)
A table that contains DTDs, which are used to validate XML documents and to help applications to define a DAD. Users can insert their own DTDs into the DTD_REF table. This table is created when a database is enabled for XML.

DTD_REF table
DTD reference table.

DTD repository
A DB2 table, called DTD_REF, where each row of the table represents a DTD with additional metadata information.

EDI
Electronic Data Interchange.

Electronic Data Interchange (EDI)
A standard for electronic data interchange for business-to-business (B2B) applications.

element
See XML element.

element_node
A representation of an element. An element_node can be the root element or a child element.

embedded SQL
SQL statements coded within an application program. See static SQL.

Extensible Stylesheet language (XSL)
A language used to express stylesheets. XSL consists of two parts: a language for transforming XML documents, and an XML vocabulary for specifying formatting semantics.

Extensive Stylesheet Language Transformation (XSLT)
A language used to transform XML documents into other XML documents. XSLT is designed for use as part of XSL, which is a stylesheet language for XML.

external file
A file that exists in a file system external to DB2.

foreign key
A key that is part of the definition of a referential constraint and that consists of one or more columns of a dependent table.

full text search
Using the DB2 Text Extender, a search of text strings anywhere without regard to the document structure.

index
A set of pointers that are logically ordered by the values of a key. Indexes provide quick access to data and can enforce uniqueness on the rows in the table.

Java Database Connectivity (JDBC)
An application programming interface (API) that has the same characteristics as Open Database Connectivity (ODBC) but is specifically designed for use by Java database applications. Also, for databases that do not have a JDBC driver, JDBC includes a JDBC to ODBC bridge, which is a mechanism for converting JDBC to ODBC; JDBC presents the JDBC API to Java database applications and converts this to ODBC. JDBC was developed by Sun Microsystems, Inc. and various partners and vendors.

JDBC
Java Database Connectivity.

join
A relational operation that allows for retrieval of data from two or more tables based on matching column values.

joined view
A DB2 view created by the "CREATE VIEW" statement which join one more tables together.

large object (LOB)
A sequence of bytes, where the length can be up to 2 GB. A LOB can be of three types: binary large object (BLOB), character large object (CLOB), or double-byte character large object (DBCLOB).

LOB
Large object.

local file system
A file system that exists in DB2

location path
Location path is a sequence of XML tags that identify an XML element or attribute. The location path identifies the structure of the XML document, indicating the context for the element or attribute. A single slash (/) path indicates that the context is the whole document. The location path is used in the extracting UDFs to identify the elements and attributes to be extracted. The location path is also used in the DAD file to specify the mapping between an XML element, or attribute, and a DB2 column when defining the indexing scheme for XML column. Additionally, the location path is used by the Text Extender for structural-text search.

locator
A pointer which can be used to locate an object. In DB2, the large object block (LOB) locator is the data type which locates LOBs.

mapping scheme
A definition of how XML data is represented in a relational database. The mapping scheme is specified in the DAD. The XML Extender provides two types of mapping schemes: SQL mapping and relational database node (RDB_node) mapping.

metadata table
See administrative support table.

multiple occurrence
An indication of whether a column element or attribute can be used more than once in a document. Multiple occurrence is specified in the DAD.

node
In database partitioning, synonymous with database partition.

object
In object-oriented programming, an abstraction consisting of data and the operations associated with that data.

ODBC
Open Database Connectivity.

Open Database Connectivity
A standard application programming interface (API) for accessing data in both relational and nonrelational database management systems. Using this API, database applications can access data stored in database management systems on a variety of computers even if each database management system uses a different data storage format and programming interface. ODBC is based on the call level interface (CLI) specification of the X/Open SQL Access Group and was developed by Digital Equipment Corporation (DEC), Lotus, Microsoft, and Sybase. Contrast with Java Database Connectivity.

overloaded function
A function name for which multiple function instances exist.

partition
A fixed-size division of storage.

path expression
See location path.

predicate
An element of a search condition that expresses or implies a comparison operation.

primary key
A unique key that is part of the definition of a table. A primary key is the default parent key of a referential constraint definition.

procedure
See stored procedure.

query
A request for information from the database based on specific conditions; for example, a query might be a request for a list of all customers in a customer table whose balance is greater than 1000.

RDB_node
Relational database node.

RDB_node mapping
The location of the content of an XML element, or the value of an XML attribute, which are defined by the RDB_node. The XML Extender uses this mapping to determine where to store or retrieve the XML data.

relational database node (RDB_node)
A node that contains one or more element definitions for tables, optional columns, and optional conditions. The tables and columns are used to define how the XML data is stored in the database. The condition specifies either the criteria for selecting XML data or the way to join the XML collection tables.

result set
A set of rows returned by a stored procedure.

result table
A table which contains rows as the result of an SQL query or an execution of a stored procedure.

root element
The top element of an XML document.

root ID
A unique identifier that associates all side tables with the application table.

scalar function
An SQL operation that produces a single value from another value and is expressed as a function name, followed by a list of arguments enclosed in parentheses.

schema
A collection of database objects such as tables, views, indexes, or triggers. It provides a logical classification of database objects.

section search
Provides the text search within a section which can be defined by the application. To support the structural text search, a section can be defined by the Xpath's abbreviated location path.

side table
Additional tables created by the XML Extender to improve performance when searching elements or attributes in an XML column.

simple location path
A sequence of element type names connected by a single slash (/).

SQL mapping
A definition of the relationship of the content of an XML element or value of an XML attribute with relational data, using one or more SQL statements and the XSLT data model. The XML Extender uses the definition to determine where to store or retrieve the XML data. SQL mapping is defined with the SQL_stmt element in the DAD.

static SQL
SQL statements that are embedded within a program, and are prepared during the program preparation process before the program is executed. After being prepared, a static SQL statement does not change, although values of host variables specified by the statement may change.

stored procedure
A block of procedural constructs and embedded SQL statements that is stored in a database and can be called by name. Stored procedures allow an application program to be run in two parts. One part runs on the client and the other part runs on the server. This allows one call to produce several accesses to the database.

structural text index
To index text strings based on the tree structure of the XML document, using the DB2 Text Extender.

subquery
A full SELECT statement that is used within a search condition of an SQL statement.

table space
An abstraction of a collection of containers into which database objects are stored. A table space provides a level of indirection between a database and the tables stored within the database. A table space:

text_node
A representation of the CDATA text of an element.

top element_node
A representation of the root element of the XML document in the DAD.

UDF
See user-defined function.

UDT
See user-defined type.

uniform resource locator (URL)
An address that names an HTTP server and optionally a directory and file name, for example: http://www.ibm.com/data/db2/extenders.

UNION
An SQL operation that combines the results of two select statements. UNION is often used to merge lists of values that are obtained from several tables.

URL
Uniform resource locator.

user-defined function (UDF)
A function that is defined to the database management system and can be referenced thereafter in SQL queries. It can be one of the following functions:

user-defined type (UDT)
A data type that is not native to the database manager and was created by a user. See distinct type.

user table
A table that is created for and used by an application.

validation
The process of using a DTD to ensure that the XML document is valid and to allow structured searches on XML data. The DTD is stored in the DTD repository.

valid document
An XML document that has an associated DTD. To be valid, the XML document cannot violate the syntactic rules specified in its DTD.

Web browser
A client program that initiates requests to a Web server and displays the information that the server returns.

well-formed document
An XML document that does not contain a DTD. Although in the XML specification, a document with a valid DTD must also be well-formed.

XML
eXtensible Markup Language.

XML attribute
Any attribute specified by the ATTLIST under the XML element in the DTD. The XML Extender uses the location path to identify an attribute.

XML collection
A collection of relation tables which presents the data to compose XML documents, or to be decomposed from XML documents.

XML column
A column in the application table that has been enabled for the XML Extender UDTs.

XML element
Any XML tag or ELEMENT as specified in the XML DTD. The XML Extender uses the location path to identify an element.

XML object
Equivalent to an XML document.

XML Path Language
A language for addressing parts of an XML document. XML Path Language is designed to be used by XSLT. Every location path can be expressed using the syntax defined for XPath.

XML table
An application table which includes one or more XML Extender columns.

XML tag
Any valid XML markup language tag, mainly the XML element. The terms tag and element are used interchangeably.

XML UDF
A DB2 user-defined function provided by the XML Extender.

XML UDT
A DB2 user-defined type provided by the XML Extender.

XPath
A language for addressing parts of an XML document.

XPath data model
The tree structure used to model and navigate an XML document using nodes.

XSL
XML Stylesheet Language.

XSLT
XML Stylesheet Language Transformation.


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