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Java in Adaptive Server Enterprise

Glossary

Glossary

This glossary describes Java and Java-SQL terms used in this book. For a description of Adaptive Server and SQL terms, refer to the Adaptive Server Glossary.

A generic term for the data transfers specified by select, fetch, insert, and update T-SQL commands. An assignment sets a source value into a target data item.

If a class/jar is installed with installjava and the -jar option, then the JAR is retained in the database and the class is linked in the database with the associated jar. See retained JAR .

The compiled form of Java source code that is run by the Java VM.

A class is the basic element of Java programs, containing a set of variable declarations and methods. A class is the master copy that determines the behavior and attributes of each instance of that class. See class instance .

A file of type "class" (for example, myclass.class) that contains the compiled bytecode for a Java class. See Java file and Java archive (JAR) .

An single copy of each of the fields of the class. Class instances are strongly typed by the class name.

Conversions between Java and SQL datatypes.

The declared datatype of a Java-SQL data item. It is either the datatype of the runtime value or a supertype of it.

In XML, every valid document has a DTD that describes the elements available in that document type. A DTD can be embedded in the XML document or referenced by it.

A metalanguage designed for Web applications that lets you define your own markup tags and attributes for different kinds of documents. XML is a subset of SGML.

A markup language designed to format XML documents into HTML or other XML documents with different attributes and tags.

An externalization of a Java instance is a byte stream that contains sufficient information for the class to reconstruct the instance. Externalization is defined by the externalizable interface. All Java-SQL classes must be either externalizable or serializable. See serialization .

A friendly method can be called only by methods of other classes in the same package.

A subset of SGML designed for the Web.

Installed Java classes and methods have been placed in the Adaptive Server system by the installjava utility.

A particular copy of a class. An object that is contained in the Java VM. See class instance .

A unique type of class that lets a class inherit particular methods.

A platform-independent format for collecting classes in a single file.

A Java-SQL API that is a standard part of the Java Class Libraries that control Java application development. JDBC provides capabilities similar to those of ODBC.

A toolset from Sun Microsystems that allows you to write and test Java programs from the operating system.

A file of type "java" (for example, myfile.java) that contains Java source code. See class file and Java archive (JAR) .

An instance of a Java class that is contained in the storage of the Java VM. Java instances that are referenced in SQL are either values of Java columns or Java objects.

A SQL column whose datatype is a Java-SQL class.

A public Java class that has been installed in the Adaptive Server system. It consists of a set of variable definitions and methods.A class instance consists of an instance of each of the fields of the class. Class instances are strongly typed by the class name.A subclass is a class that is declared to extend (at most) to one other class. That other class is called the direct superclass of the subclass. A subclass has all of the variables and methods of its direct and indirect superclasses, and may be used interchangeably with them.

Conversions between Java and SQL datatypes. See "Datatype Mapping Between Java and SQL" .

A SQL variable whose datatype is a Java-SQL class.

The Java interpreter that processes Java in the server. It is invoked by the SQL implementation.

A Java datatype is mappable if it is either:

• Listed in the first column of Table 7-3 , or

• A public Java-SQL class that is installed in the Adaptive Server system.

A SQL datatype is mappable if it is either:

• Listed in the first column of Table 7-4 , or

• A public Java-SQL class that is built-in or installed in the Adaptive Server system.

A Java method is mappable if all of its parameter and result datatypes are mappable.

A set of instructions, contained in a Java class, for performing a task. A method can be declared static, in which case it is called a class method. Otherwise, it is an instance method. Class methods can be referenced by qualifying the method name with either the class name or the name of an instance of the class. Instance methods are referenced by qualifying the method name with the name of an instance of the class. The method body of an instance method can reference the variables local to that instance

A Java operation for converting a reference to a class instance to a reference to an instance of a subclass of that class. This operation is written in SQL with the convert function. See also widening conversion .

A package is a set of related classes. A class either specifies a package or is part of an anonymous default package. A class can use Java import statements to specify other packages whose classes can then be referenced.

An SQL stored procedure, or a Java method with a void result type.

Public fields and methods, as defined in Java.

A JAR that is installed by the installjava utility with the -jar option. A retained JAR is associated in the database with the classes it contains.

A serialization of a Java instance is a byte stream containing sufficient information to identify its class and reconstruct the instance. All Java-SQL classes must be either externalizable or serializable. See externalization .

The current SQL standard.

The working draft for the next revision of the SQL standard.

See datatype mapping .

A class below another class in a hierarchy. It inherits attributes and behavior from classes above it. A subclass may be used interchangeably with its superclasses. The class above the subclass is its direct superclass. See superclass , narrowing conversion , and widening conversion .

A class above one or more classes in a hierarchy. It passes attributes and behavior to the classes below it. It may not be used interchangeably with its subclasses. See subclass , narrowing conversion , and widening conversion .

Java-SQL classes that have the same fully qualified name but are installed in different databases.

A 16-bit character set defined by ISO 10646 that supports many languages.

In XML, a valid document has a DTD and adheres to it. It is also a well-formed document .

In Java, a variable is local to a class, to instances of the class, or to a method. A variable that is declared static is local to the class. Other variables declared in the class are local to instances of the class. Those variables are called fields of the class. A variable declared in a method is local to the method.

A Java class that has been installed in a SQL system is visible in SQL if it is declared public; a field or method of a Java instance is visible in SQL if it is both public and mappable. Visible classes, fields, and methods can be referenced in SQL. Other classes, fields, and methods cannot, including classes that are private, protected, or friendly, and fields and methods that are either private, protected, or friendly, or are not mappable.

In XML, the necessary characteristics of a well-formed document include: all elements with both start and end tags, attribute values in quotes, all elements properly nested.

A Java operation for converting a reference to a class instance to a reference to an instance of a superclass of that class. This operation is written in SQL with the convert function. See also narrowing conversion .