ISO/IEC TR 24716:2007
(Main)Information technology — Programming languages, their environment and system software interfaces — Native COBOL Syntax for XML Support
Information technology — Programming languages, their environment and system software interfaces — Native COBOL Syntax for XML Support
ISO/IEC TR 24716:2007 specifies the syntax and semantics for XML support in COBOL. The purpose of ISO/IEC TR 24716:2007 is to promote a high degree of portability in implementations, even though some elements are subject to trial before completion of a final design suitable for standardization. This specification builds on the syntax and semantics defined in ISO/IEC 1989:2002.
Technologies de l'information — Langages de programmation, leur environnement et interfaces du logiciel système — Syntaxe COBOL native pour support XML
General Information
Standards Content (Sample)
TECHNICAL ISO/IEC
REPORT TR
24716
First edition
2007-12-15
Information technology — Programming
languages, their environment and system
software interfaces — Native COBOL
Syntax for XML Support
Technologies de l'information — Langages de programmation, leur
environnement et interfaces du logiciel système — Syntaxe COBOL
native pour support XML
Reference number
ISO/IEC TR 24716:2007(E)
©
ISO/IEC 2007
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ISO/IEC TR 24716:2007(E)
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ISO/IEC TR 24716:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope.1
2 Normative references.1
3 Conformance to this Technical Report .1
4 Terms and definitions .1
5 Description techniques.2
6 Changes to ISO/IEC 1989:2002.2
6.1 Changes to 8, Language fundamentals .2
6.2 Changes to 9, I-O, objects, and user-defined functions.3
6.3 Changes to 12, Environment division .6
6.4 Changes to 13, Data division.8
6.5 Changes to 14, Procedure division.14
6.6 Changes to Annex F (informative) Substantive changes list .31
Annex A (normative) Language element lists .32
Annex B (informative) Unresolved technical issues.34
Annex C (informative) XML processing concepts .35
Bibliography .45
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ISO/IEC TR 24716:2007(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
In exceptional circumstances, the joint technical committee may propose the publication of a Technical Report
of one of the following types:
— type 1, when the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts;
— type 2, when the subject is still under technical development or where for any other reason there is the
future but not immediate possibility of an agreement on an International Standard;
— type 3, when the joint technical committee has collected data of a different kind from that which is
normally published as an International Standard (“state of the art”, for example).
Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether
they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to
be reviewed until the data they provide are considered to be no longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC TR 24716, which is a Technical Report of type 2, was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 22, Programming languages, their environments
and system software interfaces, in collaboration with INCITS Techmical Committee J4, Programming
language COBOL.
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ISO/IEC TR 24716:2007(E)
Introduction
This Technical Report provides extensions so that COBOL can process XML documents as easily as it can
read files. The new syntax to process XML documents,
⎯ is based on the familiar approach used with COBOL I/O support,
⎯ provides Document Object Model (DOM) style parsing,
⎯ handles multiple input sources to handle XML in an extremely flexible manner,
⎯ reads, updates, and writes XML documents,
⎯ checks that XML documents are well-formed, and
⎯ provides an optional validity check of an XML document against a schema or Document Type Definition
(DTD).
Technical Report ISO/IEC 24716 extends the COBOL specification defined in ISO/IEC 1989:2002, Information
technology — Programming languages — COBOL. It provides new syntax to read, write, and update XML
documents in COBOL.
Annex A forms a normative part of this Technical Report. Annex B and Annex C and the Bibliography are for
information only.
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TECHNICAL REPORT ISO/IEC TR 24716:2007(E)
Information technology — Programming languages, their
environment and system software interfaces — Native COBOL
Syntax for XML Support
1 Scope
This Technical Report specifies the syntax and semantics for XML support in COBOL. The purpose of this
Technical Report is to promote a high degree of portability in implementations, even though some elements
are subject to trial before completion of a final design suitable for standardization.
This specification builds on the syntax and semantics defined in ISO/IEC 1989:2002.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 1989:2002, Information technology — Programming languages — COBOL
Extensible Markup Language (XML) 1.0 (Fourth Edition), W3C Recommendation, 16 August 2006
Extensible Markup Language (XML) 1.1 (Second Edition), W3C Recommendation, 16 August 2006
Namespaces in XML 1.1, W3C Recommendation, 4 February 2004
XML Schema Part 1: Structures, W3C Recommendation, 28 October 2004
XML Schema Part 2: Datatypes, W3C Recommendation, 28 October 2004
3 Conformance to this Technical Report
This Technical Report is based on ISO/IEC 1989:2002. Conformance to this Technical Report does not
require a full implementation of ISO/IEC 1989:2002. The interaction of the features of this technical report with
features that are not provided by an implementation of ISO/IEC 1989:2002 is processor dependent.
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
document type definition
DTD
specification of the markup language that defines the elements, attributes, comments, and entities that a
document may contain and specifies the relationships among them within the document
4.2
external document type definition
external DTD
DTD that is outside the file containing the XML document
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ISO/IEC TR 24716:2007(E)
4.3
internal document type definition
internal DTD
DTD that is in the same file as the XML document
4.4
XML document
unit of data that is well-formed as defined either in XML 1.0 or XML 1.1
4.5
XML element
portion of an XML document, the boundaries of which are either delimited by start-tags and end-tags, or, for
empty elements, by an empty-element tag
NOTE Each element has a type, identified by name, and may have a set of attribute specifications.
4.6
XML file
file with XML organization
4.7
XML Schema
XML language for constructing schemas that describe the syntax of XML documents. Each schema defines a
class of XML documents by constraining the structures and data types of instance documents that conform to
the schema
5 Description techniques
Description techniques and language fundamentals are the same as those described in ISO/IEC 1989:2002.
6 Changes to ISO/IEC 1989:2002
These changes refer to clause and rule numbers in ISO/IEC 1989:2002.
6.1 Changes to 8, Language fundamentals
[a] Add the following reserved words to the list in 8.9, Reserved Words
DOCUMENT
END-OPEN
IDENTIFIED
VERSION-XML
[b] In 8.10, Context-sensitive words, change the context for ATTRIBUTE to read:
"IDENTIFIED clause, DELETE statement, READ statement, REWRITE statement, SET statement,
START statement, and WRITE statement"
[c] In 8.10, Context-sensitive words, change the context for ONLY to read:
"Object-view, SHARING clause of the file control entry, SHARING phrase of the OPEN statement,
USAGE clause, READ statement, REWRITE statement, and WRITE statement"
[d] Add the following context-sensitive words to the list in 8.10, Context-sensitive words
CHECK TYPE clause of the file control entry
DISCARD CLOSE statement
DTD TYPE clause of the file control entry
ELEMENT DELETE statement, READ statement, REWRITE statement, START
statement, and WRITE statement
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ISO/IEC TR 24716:2007(E)
NAMESPACE IDENTIFIED clause
RAW IDENTIFIED clause
SCHEMA TYPE clause of the file control entry
STACK OPEN statement
VALIDITY TYPE clause of the file control entry
XML ACCESS clause and ORGANIZATION clause
6.2 Changes to 9, I-O, objects, and user-defined functions
[a] 9.1.3, File connector, second paragraph, second sentence, add "XML" to the end of the list of types of file
organization in the parenthetical and to the end of the list of access modes in the parenthetical.
[b] 9.1.6, Fixed file attributes, change the third sentence to read:
"The file organizations are sequential, relative, indexed, and XML."
[c] 9.1.7, Organization,
[1] Change the first sentence to read:
"The file organizations are sequential, relative, indexed, and XML."
[2] add 9.1.7.4, XML, as follows:
"9.1.7.4 XML
XML is a file organization used for data that is in the format of an XML document or a sequence of XML
documents. An XML document can be on a traditional file medium or it can be in memory. An XML document
is a string of text that is given a structure by the presence of tags, which separate the document into elements.
XML documents are organized in a hierarchical manner, similar to a COBOL record structure, where an
element may contain other elements. Within the context of its superordinate elements, each subordinate
element may be stored, retrieved, or deleted based on its tag name. The element position vector for an XML
file associates an element position or an attribute position with each data item for which an IDENTIFIED
clause is specified.
COBOL allows multiple documents in a file that is open in the input, output, or extend mode. COBOL allows
only one document in a file that is open in the i-o mode. The XML 1.0 and 1.1 recommendations do not
consider the processing of anything beyond a single document. Therefore, many XML processors might not
consider multiple-document files to be well-formed.
The file format OPEN statement for an XML file establishes a connection to the physical file. The file position
indicator maintains the document number of the current document in the XML file. An XML-document format
OPEN statement creates an internal representation of the current document. The READ statement transfers
data into associated data items described in the file section. The START statement positions the element
position vector to attributes or elements within the internal representation. The DELETE statement, REWRITE
statement, and WRITE statement change the internal representation, but do not change the physical file. The
XML-document format CLOSE statement optionally writes an XML document based on the internal
representation and then deletes the internal representation; the file remains in the open state. A file format
CLOSE statement closes the physical file.
COBOL processes documents that conform to XML 1.0 or XML 1.1.
On input, COBOL resolves character references, predefined entity references, general entity references, and
parameter entity references consistent with the TYPE clause of the file control entry, and makes the content of
CDATA sections available to the program. COBOL does end-of-line normalization and attribute-value
normalization as specified in the applicable XML recommendation. All required parts of the XML document are
made available to the COBOL program with the exception of Processing Instructions.
COBOL, by default writes XML documents that are well-formed with respect to XML 1.0 or optionally to
XML 1.1.
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ISO/IEC TR 24716:2007(E)
All XML documents written by COBOL start with an XML declaration that includes the version information and
an encoding declaration. If a DTD is included, the XML declaration also includes a standalone document
declaration with a value of “yes.”
XML documents written by COBOL contain predefined references and character references as required by the
appropriate XML Recommendation.
XML documents written by COBOL do not contain general entity references, parameter entity references,
CDATA sections, processing instructions, or white space. The implementor may include comments.
NOTE The term 'white space' is defined in XML 1.1."
[d] 9.1.8, Access modes,
[1] In the first paragraph, last sentence, add "XML" to the list of access modes.
[2] In the second paragraph, add the following as a new last sentence:
"A file with organization XML may be accessed only in XML access mode."
[3] Add the following:
"9.1.8.4 XML access mode
When a file is accessed in XML access mode, the order of access of the documents in that file is the
sequential order of the documents in that file.
Within each document, START statements may be used to set the element position vector to a specific
occurrence of an attribute or element."
[e] 9.1.11, File position indicator, second paragraph, insert the following text after "for a relative file,":
"the document number of the current document for an XML file,"
[f] Add the following after 9.1.11, File position indicator:
"9.1.11a Element position vector
The element position vector is a conceptual entity that exists for each XML file to maintain the positions of
attributes and elements within each level in the hierarchy of an XML document. Position is maintained for
each attribute or element in the COBOL record description that is described with an IDENTIFIED clause.
Attributes and elements may be accessed by their attribute names or element names, respectively, as long as
all containing elements are indicated by the element position vector.
The element position vector is set only by CLOSE, OPEN, READ, and START statements. The XML-
document format OPEN statement for a file open in input mode or i-o mode sets the element position vector to
the first XML element associated with each COBOL data item that has an IDENTIFIED clause and to the first
attribute, if any, of each of those elements. The XML-document format OPEN statement for a file open in
extend mode or output mode sets the element position vector at the start of a new document. The START
statement positions the element position vector to a specific occurrence of an attribute or element. The READ
statement accesses occurrences of elements sequentially and repositions the element position vector. The
READ statement accesses occurrences of attributes sequentially when the associated IDENTIFIED clause
contains the USING phrase and repositions the element position vector. The READ statement accesses the
specified occurrence of an attribute when the associated IDENTIFIED clause contains the BY phrase, but
does not reposition the element position vector. The CLOSE statement causes the element position vector to
indicate that no valid position has been established."
[g] 9.1.12.1, Successful completion, add the following new entries:
“6) I-O status = 08. The input-output statement is successfully executed but a READ statement ignored
one or more XML attributes or elements, or both, because there is no COBOL data item with which
one or more attributes or elements can be associated.
7) I-O status = 09. The input-output statement is successfully executed but the referenced DTD or
schema is not available; the requested validity check of the XML document was not done."
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ISO/IEC TR 24716:2007(E)
[h] 9.1.12.4, Invalid key condition with unsuccessful completion, I-O status 23, rule 3, change the period to ";
or" at the end of 3d and insert the following text:
“e) an attempt is made to access a document that does not exist at the current file position in an XML
file; or
f) an attempt is made to access an attribute or element that does not exist at the current position in
the internal representation of an XML file."
[i] 9.1.12.4, Invalid key condition with unsuccessful completion, I-O status 24, rule 4, change to read:
“4) I-O status = 24. This condition exists because:
“a) an attempt is made to write beyond the externally-defined boundaries of a physical relative or
indexed file; the implementor specifies the manner in which these boundaries are defined; or
b) a sequential WRITE statement is attempted for a relative file and the number of significant digits in
the relative record number is larger than the size of the relative key data item described for the
file; or
c) an attempt is made to close an XML document in an in-memory XML file and the XML document to
be created is larger than the associated length of that memory."
[j] 9.1.12.4, Invalid key condition with unsuccessful completion, add the following text:
“5) I-O status = 25. An attempt is made to delete an XML attribute or element at an invalid position."
[k] 9.1.12.5, Permanent error condition with unsuccessful completion, rule 3, I-O status = 34, first sentence,
insert the following text after "externally-defined boundaries of":
"an XML file or"
[l] 9.1.12.5, Permanent error condition with unsuccessful completion, add the following text:
"8) I-O status = 3A. An OPEN statement is attempted on an XML document that is not well-formed.
9) I-O status = 3B. A CLOSE statement is attempted on an XML document that is not valid.
10) I-O status = 3C. An OPEN statement with the I-O phrase is attempted on a multiple document file.
11) I-O status = 3D. An OPEN statement is attempted on a document in a file that is open in the input or
i-o mode and the coded character set used for encoding the document could not be determined."
[m] 9.1.12.6, Logic error condition with unsuccessful completion, add the following text:
"10) I-O status = 4A. An attempt is made to write XML that is not well-formed by a document-format
CLOSE statement, a REWRITE statement, or a WRITE statement.
11) I-O status = 4B. An attempt is made to reference a file connector that is not open by an
XML-document format CLOSE statement or an XML-document format OPEN statement.
12) I-O status = 4C. The execution of a READ statement is unsuccessful because duplicate names are
specified in IDENTIFIED clauses at the same level in the hierarchy of the associated record
description entry.
13) I-O status = 4D. An attempt is made by an XML-document format CLOSE statement to reference a file
connector that does not have an open document.
14) I-O status = 4E. An attempt is made by a WRITE or REWRITE statement to create XML text with an
attribute name or element name that cannot be represented in the coded character set used for the
encoding of the XML document."
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ISO/IEC TR 24716:2007(E)
6.3 Changes to 12, Environment division
[a] Add a new file control entry format to 12.3.4.1, General format:
"Format 5 (XML):
SELECT [ OPTIONAL ] file-name-1
device-name-1
⎧ ⎫
⎨ ⎬
… [ USING data-name-1 ]
⎧ ⎧ ⎫⎫
⎩ literal-1 ⎭
⎪ ⎪
TO
⎨ ⎬
DATA data-name-9
ASSIGN
⎨ ⎬
⎩ ⎭
data-name-10 LENGTH IS data-name-11
⎪ ⎪
⎩ ⎭
USING data-name-1
[ ACCESS MODE IS XML ]
[ FILE STATUS IS data-name-4 ]
ORGANIZATION IS XML
DTD
⎡ ⎧ ⎫ ⎤
| INPUT |
⎧ ⎫
⎡ ⎤
DTD literal-3
TYPE IS CHECK VALIDITY ON ⎨ ⎬
⎢ ⎨ ⎧ ⎫ ⎧ ⎫⎬ ⎥
⎣ ⎦
⎨ ⎬ ⎨ ⎬ ⎩| OUTPUT |⎭
EXTERNAL
⎣ ⎩ ⎩ SCHEMA ⎭ ⎩ data-name-12 ⎭⎭ ⎦
[ VERSION-XML IS literal-4 ].
NOTE ORGANIZATION is a required word in the XML format, rather than optional, so that XML can
be a context-sensitive word. "
[b] Add the following new file control entry syntax rules to 12.3.4.2:
"FORMAT 5
“14) The physical file associated with file-name-1 shall have organization XML. The associated file
description entry shall not be a sort-merge file description entry.
15) Data-name-9 shall reference a data item of category alphanumeric or national and shall not be
subordinate to the file description entry for file-name-1.
16) Data-name-10 shall reference a data item of category data-pointer and shall not be subordinate to the
file description entry for file-name-1.
17) Data-name-11 shall reference an unsigned integer data item described without the picture symbol 'P'
and shall not be subordinate to the file description entry for file-name-1.
18) Data-name-12 shall reference a data item of category alphanumeric or national and shall not be
subordinate to the file description entry for file-name-1.
19) The OPTIONAL phrase shall not be specified when the DATA or LENGTH phrase is specified."
[c] Change 12.3.4.3 file control entry general rule 1:
[1] subrule 1b, add data-name-9, data-name-10, and data-name-11 to both lists.
[2] add the following additional subrules:
"n) The same specification of the TYPE clause, when data-name-12, if specified, references an
external data item.
o) The same specification of the VERSION-XML clause."
[d] Change 12.3.4.3 file control entry general rule 3:
[1] add the following text at the end of the first sentence:
"; or to a memory location referenced by either data-name-9 or the content of data-name-10"
[2] subrule 3a, change in part to read:
"When device-name-1 or literal-1 is specified and the USING phrase is omitted …"
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ISO/IEC TR 24716:2007(E)
[3] add the following new subrules:
"c) If data-name-9 is specified, one or more XML documents are contained in the data item referenced
by data-name-9. The XML document is said to be in-memory.
d) If data-name-10 is specified, one or more XML documents begin at the address specified by the
content of the data item referenced by data-name-10 and continue for the number of bytes
specified by the content of the data item referenced by data-name-11. The XML document is said
to be in-memory."
[e] Add the following new file control entry general rule to 12.3.4.3:
"FORMAT 5
“10) The XML format defines a file connector for an XML file. "
[f] In 12.3.4.4.1, general format of the ACCESS MODE clause, add "XML" to the stack in the curly braces.
[g] In 12.3.4.4.2, syntax rules of the ACCESS MODE clause, add the following new syntax rules:
"3) The DYNAMIC, RANDOM, and SEQUENTIAL phrases shall not be specified for an XML file.
4) The XML phrase may be specified only for an XML file."
[h] In 12.3.4.4.3, general rules of the ACCESS MODE clause,
[1] Change general rule 1 to read:
"1) If the ACCESS MODE clause is not specified,
a) if the organization is XML, XML access is assumed,
b) for other organizations, sequential access is assumed."
[2] add the following new general rule:
"5) If the access mode is XML, documents within the file are accessed in sequential order. Elements in
the current document can be accessed via their element names only when all containing elements are
indicated by the element position vector."
[i] In 12.3.4.9.1, General format [ORGANIZATION clause],
[1] Add the heading "FORMAT 1 (sequential-relative-indexed)" before the existing format.
[2] Add the following after the existing format:
"Format 2 (XML):
ORGANIZATION IS XML"
[j] In 12.3.4.9.2, General rules [ORGANIZATION clause], add the following:
“4a) The XML phrase specifies that the file organization is XML. XML organization is a permanent logical
file structure in which each constituent record is an XML document."
[k] Make the following changes to 12.3.6, SAME clause
[1] Syntax rule 7, insert the following text after "a report file":
", an XML file,"
[2] Add the following new syntax rule:
"6a) A given file-name that represents an XML file may be specified in one file-area format SAME clause,
and shall not be specified in a record-area format or sort-merge-area format SAME clause."
[l] Add the following after 12.3.4.15, SHARING clause:
"12.3.4.16 TYPE clause
The TYPE clause specifies the SCHEMA or DTD that describes the XML document.
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ISO/IEC TR 24716:2007(E)
12.3.4.16.1 General format
DTD
⎧ ⎫
| INPUT |
⎧ ⎫
⎡ ⎤
DTD literal-1 CHECK VALIDITY ON ⎨ ⎬
TYPE IS ⎨ ⎧ ⎫ ⎧ ⎫⎬
⎣ ⎦
⎩| OUTPUT |⎭
EXTERNAL ⎨ ⎬ ⎨ ⎬
⎩ ⎭
⎩ SCHEMA ⎭ ⎩ data-name-1 ⎭
12.3.4.16.2 Syntax rules
1) Literal-1 shall be an alphanumeric or national literal and shall not be a figurative constant.
2) Data-name-1 may be qualified.
12.3.4.16.3 General rules
1) If the TYPE clause is specified without the EXTERNAL phrase, then the document is described by an
internal DTD.
2) If the EXTERNAL phrase and the DTD phrase are specified, the document is described by the
external DTD specified by literal-1 or data-name-1.
3) If the SCHEMA phrase is specified, the document is described by the schema specified by literal-1 or
data-name-1. Schemas are defined in XML Schema Part 1: Structures and XML Schema Part 2:
Datatypes.
4) If the INPUT phrase is specified, when an XML-document
...
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