Determining the structure of relations and content of tuples from XML schema components

• US 20070067343A1
• Filed: 09/21/2005
• Published: 03/22/2007
• Est. Priority Date: 09/21/2005
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Pradhan, Mayank, Nguyen, Dung, Mihaila, George
• Application Number:
  US11/232,585
• Publication Number:
  US 20070067343A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/86 Mapping to a database

Abstract

A method for determining relationships between hierarchically structured schema components and their effects on and content of tuples, includes: analyzing the hierarchically structured schema with user-supplied mappings and finding elements or attributes mapped to a same relational table; determining relationships between the elements or attributes to be either a one-to-one relationship or a one-to-many relationship based on an information set in the hierarchically structured schema; recording the relationships; and processing a hierarchically structured document against the recorded relationships and generating tuples accordingly. The constructs of a hierarchically structured schema that may affect the cardinality between the attributes of a relation, and thus the contents of the tuples, are considered. A relationship between the hierarchically structured schema model and a relational model is established.

Claims

1. A method for determining relationships between hierarchically structured schema components and their effects on structure of relations and content of tuples, comprising:

(a) analyzing the hierarchically structured schema with user-supplied mappings and finding elements mapped to a same relational table;

(b) determining relationships between the mapped elements or attributes to be either a one-to-one relationship or a one-to-many relationship based on an information set in the hierarchically structured schema;

(c) recording the relationships; and

(d) processing a hierarchically structured document against the recorded relationships and generating tuples accordingly.

2. The method of claim 1, wherein when the hierarchically structured schema comprises a choice model group with N particles, the analyzing (a) comprises:

(a1) creating N copies of a component model;

(a2) for each copy of the component model, replacing the choice model group with a sequence model group containing a single particle, wherein the particle in each copy is different; and

(a3) repeating the creating step (a1) and the replacing step (a2) on a new set of copies of the component model, until a final set of copies is produced in which every choice model group has been replaced.

3. The method of claim 1, wherein the hierarchically structured schema comprises a choice model group and the mapped elements or attributes directly or indirectly under the choice model group are computed as part of a same effective choice model group, wherein if a lowest common ancestor model group of any element or attribute pair is a choice model group, then they belong to the same effective choice model group.

4. The method of claim 1, wherein the determining (b) comprises:

(b1) determining maxOccurs properties for particle components of the elements or attributes in a relationship;

(b2) recording a one-to-one relationship between any two elements or attributes, if each involved Particle component has a maxOccurs property equals one, wherein the involved Particle of an element comprises any particle on a path from the element or attribute to the lowest common ancestor of the two elements or attributes whose relationship is being determined; and

(b3) recording a one-to-many relationship between the elements or attributes, if one element or attribute has at least one involved Particle with maxOccurs property greater than one.

5. The method of claim 1, wherein the relationships are recorded in a data structure.

6. The method of claim 1, wherein the processing (d) comprises:

(d1) generating relations based upon the recorded relationships;

(d2) generating the tuples, wherein content of the tuples is based upon a type of a ModelGroup and maxOccurs.

7. The method of claim 6, wherein the generating (d2) comprises:

(d2i) determining if a generated relation comprises items mapped to elements or attributes belonging to a same effective choice model group in the hierarchically structured schema, wherein if the determining is true;

(d2iA) testing for an existential condition, wherein the existential condition is true if and only if at least one of the mapped elements or attributes of the effective choice model group appears in a document; and

(d2iB) generating the tuples if the existential condition is true.

8. The method of claim 6, wherein the type of the ModelGroup comprises a sequence, a choice, or all.

9. A computer readable medium with program instructions for determining relationships between hierarchically structured schema components and their effects on structure of relations and content of tuples, comprising instructions for:

(a) analyzing the hierarchically structured schema with user-supplied mappings and finding elements mapped to a same relational table;

(b) determining relationships between the mapped elements or attributes to be either a one-to-one relationship or a one-to-many relationship based on an information set in the hierarchically structured schema;

(c) recording the relationships; and

(d) processing a hierarchically structured document against the recorded relationships and generating tuples accordingly.

10. The medium of claim 9, wherein when the hierarchically structured schema comprises a choice model group with N particles, the analyzing instruction (a) comprises:

(a1) creating N copies of a component model;

(a2) for each copy of the component model, replacing the choice model group with a sequence model group containing a single particle, wherein the particle in each copy is different; and

(a3) repeating the creating instruction (a1) and the replacing instruction (a2) on a new set of copies of the component model, until a final set of copies is produced in which every choice model group has been replaced.

11. The medium of claim 9, wherein the hierarchically structured schema comprises a choice model group and the mapped elements or attributes directly or indirectly under the choice model group are computed as part of a same effective choice model group, wherein if a lowest common ancestor model group of any element or attribute pair is a choice model group, then they belong to the same effective choice model group.

12. The medium of claim 9, wherein the determining instruction (b) comprises:

(b1) determining maxOccurs properties for particle components of the elements or attributes in a relationship;

(b2) recording a one-to-one relationship between any two elements or attributes, if each involved Particle component has a maxOccurs property equals one, wherein the involved Particle of an element comprises any particle on a path from the element or attribute to the lowest common ancestor of the two elements or attributes whose relationship is being determined; and

(b3) recording a one-to-many relationship between the elements or attributes, if one element or attribute has at least one involved Particle with maxOccurs property greater than one.

13. The medium of claim 9, wherein the relationships are recorded in a data structure.

14. The medium of claim 9, wherein the processing instruction (d) comprises:

(d1) generating a structure of relations based upon the recorded relationships;

(d2) generating the tuples, wherein content of the tuples is based upon a type of a ModelGroup and maxOccurs.

16. The medium of claim 14, wherein the type of the ModelGroup comprises a sequence, a choice, or all.

15. The medium of claim 15, wherein the generating instruction (d2) comprises:

(d2i) determining if a generated relation comprises items mapped to elements or attributes belonging to a same effective choice model group in the hierarchically structured schema, wherein if the determining is true;

(d2iA) testing for an existential condition, wherein the existential condition is true if and only if at least one of the mapped elements or attributes of the effective choice model group appears in a document; and

(d2iB) generating the tuples if the existential condition is true.

17. A system, comprising:

a hierarchically structured schema comprising a plurality of elements or attributes; and

a data structure comprising relationships between the elements or attributes of the hierarchically structured schema, wherein the relationships between the elements or attributes comprises one-to-one relationships or one-to-many relationships based on an information set in the hierarchically structured schema, wherein a hierarchically structured document can be processed against the relationships and tuples are generated accordingly.

18. The system of claim 17, wherein particle components of the elements or attributes in a relationship each comprises a maxOccurs property,

wherein the involved Particle of an element comprises any particle on a path from the element or attribute to the lowest common ancestor of the two elements or attributes whose relationship is being determined,

wherein if each maxOccurs property equals one, then a one-to-one relationship between the elements or attributes is recorded in the data structure,

wherein if one element or attribute has all involved particles with maxOccurs equal to one, and other element or attribute has one or more involved particles with maxOccurs greater than one, then a one-to-many relationship between the elements or attributes is recorded in the data structure.

19. The system of claim 18, wherein if both elements or attributes comprise an involved particle with each maxOccurs property is greater than one and there is an illegal many-to-many relationship, then an error is indicated.

20. The system of claim 17, further comprising the tuples, wherein a structure of relations is based upon the recorded relationships, and content of the tuples is based upon a type of a ModelGroup and maxOccurs.

21. The system of claim 20, wherein the type of the ModelGroup comprises a sequence, a choice, or all.