JP2001273177A - RDB / XML data conversion method and recording medium recording the converted data - Google Patents

Abstract

(57) [Summary] [Problem] RDB processing cannot be performed in a general browser that does not support the XML schema. First, a schema information element is created from schema information of a database (steps 51 to 5).
3) Using the template as a template for reading out and converting database items and creating data information elements (steps 54 to 57), the converted XML data is converted into an XML document instance format. By storing the schema information of the database in the XML document instance together with the data information element in the XML document instance, it is possible to refer to the schema information in a general browser.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relational database (RDB) that converts data and schema into XML (eX
The present invention relates to a technology for converting a data structure into a tensible Markup Language (Registered Markup Language) format, and more particularly to an RDB / XML data conversion method suitable for enabling RDB processing by a general Web browser and a recording medium on which the converted data is recorded. It is.

[0002]

2. Description of the Related Art XML is a markup language for describing Web documents in a computer system, and has a function of adding a new unique tag by a user.
By adding processing corresponding to the tags, HTML (HyperText Marque), a typical markup language for Web, is added.
Compared to k-up Language), more sophisticated and purposeful data exchange is possible.

For example, in XML, data in a document is
API (Applica) called OM (Document Object Model)
The program can be processed through the Option Programming Interface. Therefore, the database on the Web server side is converted into XML format and transmitted to the client,
A client-server type computer system in which processing is performed on the client side can be configured.

As software used for conversion between a relational database and XML, for example, DB2XML (copyright (c) 1999 by Volker Tur
au), XML-DBMS, ASP2XML, and the like.

However, in these conventional conversion software, the schema of the database is often treated specially. For example, XML-DBMS, ASP2XML
Now the schema is truncated. That is, the converted XM
It is not included in the L data, but includes only the converted data for the data in the database.

[0006] In DB2XML, the schema is DTD.
(Document Type Definition). In addition, other conversion software requires XML schema (XM
L Schema). However, these D
The TD and XML schema can be referenced only by a specific browser or parser.

[0007] The schema information is necessary when an application on the client side performs a date check, a length check, a consistency check, and the like, and is important data.

[0008]

The problem to be solved is that, in the prior art, in converting an RDB into a data structure of an XML format, the schema information of the RDB is truncated without being converted or converted. Even if it is done, it can only be referenced by a specific browser or parser.

An object of the present invention is to solve the problems of the prior art and to provide an RDB / XML data conversion method which enables RDB processing even in a general browser, and a recording medium on which the converted data is recorded. .

[0010]

In order to achieve the above object, according to the RDB / XML data conversion method of the present invention, first, a schema information element is created from schema information of a database, and a database item is read using the schema information element as a template. , Conversion, and creation of data information elements, the converted XML data is converted into an XML document instance format. In this way, the schema information of the database is stored as a schema information element in this XML document instance.
For example, it is stored before the data information element. That is, the converted data includes both the relational database data and the schema information, but the data structure is a format of only the instance of the XML document, and the format of the type definition of the XML document such as the DTD or the XML schema is do not use. As a result, a general browser can refer to the schema information and can be used in a client application.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a computer system that performs an RDB / XML data conversion method according to the present invention. FIG. 2 is a block diagram showing an example of the hardware configuration of a server and a client in FIG. It is.

In FIG. 2, reference numeral 1 denotes a CRT (Cathode Ray).
Tube, LCD (Liquid Crystal Display) or the like, 2 is an input device such as a keyboard or mouse, 3 is an external storage device such as a HDD (Hard Disk Drive), and 4 is a CPU (Central Processing Unit) 4a
And an information processing device that includes a main memory 4b and performs computer processing according to a storage program method.
M (Compact Disc-Read Only Memory) and DVD (Digit
al Video / Versatile Disc), etc., 6
Is a drive of the optical disk 5, and 7 is a modem or TA (Termin
al Adapter) or a communication device composed of a LAN card or the like.

A processing program and data of the RDB / XML data conversion method according to the present invention are installed in the external storage device 3 from the optical disk 5 via the drive device 6, read into the main memory 4b of the information processing device 4, and processed by the CPU 4a. Accordingly, the information processing apparatus 10 is provided with a processing function such as the conversion unit 210 as shown by the Web server 200 in FIG.

In FIG. 1, reference numeral 100 denotes a client, 2
00 and 200a are Web servers, and 300 is an RDB (relational database). In FIG. 1, FIG. 1A shows an example of the configuration of a computer system for performing the RDB / XML data conversion processing according to the present invention, and FIG. 1B shows the conventional RDB / XML data conversion processing. 2 shows an example of the configuration of a computer system for performing the processing.

In the conventional computer system shown in FIG. 1 (b), a schema-incompatible Web
In response to a request from the browser 110 via the Internet or an intranet, the Web server 200a
Is the DB of the requested database from the RDB 300
The conversion unit 21 reads the schema 310 and the data 320
0a is converted to an XML file 120a including an XML schema and data, and the converted XML file 12
0a is returned to the client 100.

However, the XML schema in the XML file 120a converted by the conversion unit 210a cannot be referred to by the schema non-compliant Web browser 110 on the client 100 side.
It cannot be used on the 00 side.

On the other hand, in the computer system of the present embodiment shown in FIG. 1A, in response to a request from the non-schema-compliant Web browser 110 of the client 100 via the Internet or an intranet, the W
The eb server 200 sends the requested D
The B schema 310 and the data 320 are read, and the conversion unit 2
At 10, RDB / XML data conversion processing according to the present invention is performed.

That is, in the conversion unit 210, first, RD
By creating a schema information element from the DB schema 310 of B300 and using it as a template for reading and converting database items and creating a data information element corresponding to the data 320, XML data in XML document instance format is used. Convert to

An XML file 120 in which the DB schema 310 is stored as a schema information element together with a data information element in an XML document instance,
Return to client 100. In the client 100,
The XML file 120 is stored in the external storage device 3 shown in FIG.
Or on the optical disk 5 or the like.

As described above, X converted by conversion section 210
In the ML file 120, the XML schema is X
The data is stored together with the data in the ML document instance, and can be used by the schema non-compliant Web browser 110 on the client 100 side.

Hereinafter, a specific example of the RDB / XML data conversion operation according to the present invention by the conversion unit 210 will be described with reference to FIGS. 3 and 4.

FIG. 3 is an explanatory view showing a specific example of the table configuration of the RDB in FIG. 1, and FIG. 4 is an explanatory view showing a specific example of the configuration of the XML file in FIG.

FIG. 3 shows a specific example of a table to be converted. Here, a table having "table 1" as a table name is shown. This "Table 1"
Is divided into two tables, a system table 10 for storing schema information and a data table 20 for storing data information.

The system table 10 is "table 1".
Indicates what items are included, and indicates what the type information of those items is.
In item 3, "item 1", "item 2", "item 3"
The type information (type, length, identity) is stored in correspondence with the item named. Therefore, it can be seen that “Table 1” includes three items, “item 1”, “item 2”, and “item 3”.

The data table 20 stores the actual data records of “Table 1”. In this example, there are three data records 21, 22, and 23, each of which holds a value for "item 1", "item 2", and "item 3".

FIG. 4 shows “Table 1” shown in FIG.
FIG. 2 illustrates an example of XML data after conversion by a conversion unit 210 in FIG. 1. Such XML data is sent to the client 100 in FIG.
It is recorded on the external storage device 3 or the optical disk 5 shown in FIG.

In this example, the converted XML data is roughly composed of two parts. That is, it includes a schema information element 30 and a data information element 40.

The schema information element 30 expresses schema information and is created based on the system table 10 in FIG. At this time, each row 11, 12, 13 in the system table 10 of FIG.
33 corresponds. In particular, item type information, length information, identity information, and the like are represented by attributes 311, 312, 313, and the like.

Similarly, the data information element 40 expresses data information and is created based on the data table 20 in FIG. At this time, the data records 21, 22, and 23 in the data table 20 in FIG.
2, 43.

Next, an operation example of the RDB / XML data conversion processing according to the present invention based on such a specific example will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 5 is a flowchart showing an example of a processing procedure according to the RDB / XML data conversion method according to the present invention. FIG. 6 is a flowchart showing a detailed example of the processing in step 53 in FIG. 5, and FIG. 6 is a flowchart showing a detailed example of the processing in step 56 in FIG.

FIG. 5 shows an outline of a process for converting “Table 1” shown in FIG. 3 into XML data shown in FIG. 4. First, a database (RDB3 in FIG. 1)
00) to make it accessible (step 5)
1).

Further, an empty XML document is created (step 5).
2). That is, “<? Xm” in the XML document shown in FIG.
l Create tags of "version =" 1.0 "encoding =" shift_jis "?>" and "<table 1>" and "</ table 1>". This is the initial processing.

Next, a schema information element is created in the empty XML document (step 53). That is, tags from “<schema>” to “</ schema>” in the XML document shown in FIG. 4 are created. The details of this process will be described later with reference to FIG.

Thereafter, all records are selected from "Table 1" (Step 54), and are made fetchable. Then, while each record is fetched (Step 55), a data information element is created for each of them (Step 54). 56). That is, “<data>” 41 to 43 in the XML document illustrated in FIG. 4 and corresponding tags of “</ data>” are created. The details of this process will be described later with reference to FIG.

The processing in steps 55 and 56 is repeated until all the records selected in the processing in step 54 are exhausted (step 57), and then the database (RDB 300 in FIG. 1) is closed (step 5).
8).

As described above, FIG. 4 including the XML data obtained by converting the database (“Table 1”) shown in FIG.
Is generated.

Next, the details of the schema information element creation processing in step 53 in FIG. 5 will be described with reference to FIG.

First, "<Table 1"
An element having an element name of "schema" is created as a child (lower-level element) of an element composed of ">" and "</ table 1>" (step 61). That is, “<
Schema> ”and“ </ schema> ”). This element will be the parent of all elements created below.

Next, from the system table 10 shown in FIG. 3, the condition of “table name =“ table 1 ”” (“FROM
In the table 1), each record is selected (step 62). Then, the processing of the following steps 63 to 66 is repeated until all the selected records disappear (step 67).

That is, the values of the item name, type, length, and identity of the record are extracted (step 6).
3) Using the value of the retrieved item name as an element name, a child having the values of the type, length, and identity retrieved from the record in the values of the attributes “type”, “length”, and “identity” (lower) Element (Step 6
4). Thereby, the elements 31 to 33 in the XML document shown in FIG. 4 are created.

Further, it is determined whether or not the value of the type is "date" (step 65). Only in the case of "date", the elements of the element names "year", "month" and "day" are further child (lower) elements. Is made (step 66). Thereby, the XM shown in FIG.
Each element in the L document (<year type = "year" length = "2" /
>, <Month type = "month" Length = "2"/>,<day type = "
Day length = “2” /> is created, and the schema information element 40 shown in FIG.

Next, the details of the data information element creation processing in step 56 in FIG. 5 will be described with reference to FIG.

First, "<Table 1"
An element having an element name of “data” is created as a child (lower element) of an element composed of “>” and “</ table 1>” (step 71). That is, an element composed of tags “<data>” and “</ data>” in FIG. 4 is created. This element will be the parent of all elements created below.

Next, a set of child (lower) elements of the schema element created in the schema information element creation processing in step 53 in FIG. 5 described in detail with reference to FIG. 6 is extracted (step 72). Then, the following steps 73 to 7 are performed until the set of the elements disappears (step 76).
Each processing at 5,751 to 753 is repeated.

That is, the child (lower) element is extracted (step 73), and an item having the same item name as the element value extracted in step 73 is extracted from the record extracted in the processing in step 55 of FIG. 5 (step 73). 74). Then, it is determined whether the value of the attribute “type” of the element extracted in step 73 is “date” (step 75).

If the result of this determination is "date", the following two processes (steps 752 and 753) are performed. First,
A child (lower) element having the same element name as the element extracted in step 73 is created (step 752). Further, as the child (lower) element, each element having the element name “year”, “month”, and “day” is created. As the data, values obtained by decomposing the value of the item extracted in step 74 into year-month-day are set (step 753).

If the result of the determination in step 75 is not "date", a child (lower) element having the same element name as the element extracted in step 73 and having the value of the item extracted in step 74 as data is created. (Step 75
1).

As described above with reference to FIGS. 1 to 7, in the RDB / XML data conversion method of this embodiment, first,
By creating a schema information element from the schema information of the database and using it as a template for reading, converting, and creating data information elements of database items, the converted XML data is converted into an XML document instance format. .

In this way, the schema information of the database is stored in the XML document instance as a schema information element, for example, before the data information element by a compact and efficient conversion algorithm. In other words, the converted data includes both the relational database data and schema information, but has a data structure in the form of only an instance of the XML document, and defines the type of the XML document such as the DTD and the XML schema. Do not use the form by this,
General browsers can also refer to the schema information and can be used in client applications.

Conventionally, in conversion from an RDB to a data structure in the XML format, problems such as truncation of schema information and referencing only by a specific browser or parser are solved. Data can be used, and, for example, a client-side application can perform a date check, a length check, a consistency check, and the like based on the schema information.

The present invention is not limited to the examples described with reference to FIGS. 1 to 7, and can be variously modified without departing from the gist thereof. For example, in this example,
Although the schema information of the database is stored as a schema information element in the XML document instance before the data information element, the schema information of the database may be stored after the data information element.

In this example, the case where a specific table having the name "table 1" is converted to the XML format has been described. However, the table to be converted may be any relational table having schema information. Absent.

In this embodiment, an optical disk such as a CD-ROM or a DVD is used as a recording medium for recording a program or converted XML data.
isk) may be used as a recording medium. Regarding the installation of the program, the program may be downloaded online via a communication device and installed in an external storage device instead of from these recording media.

[0056]

According to the present invention, data and schema of RDB (relational database) can be efficiently converted to XML.
After conversion to the format, the converted data can be widely used in general browsers. If this mechanism is incorporated into, for example, a Web-compatible application that cooperates with a database, it is possible to improve functionality without being bound by various Web restrictions.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a computer system that performs an RDB / XML data conversion method according to the present invention.

FIG. 2 is a block diagram illustrating an example of a hardware configuration of a server and a client in FIG.

FIG. 3 is an explanatory diagram showing a specific example of a table configuration of an RDB in FIG. 1;

FIG. 4 is an explanatory diagram showing a specific configuration example of an XML file in FIG. 1;

FIG. 5 is a flowchart illustrating an example of a processing procedure according to the RDB / XML data conversion method according to the present invention.

FIG. 6 is a flowchart showing a detailed example of a process in step 53 in FIG. 5;

FIG. 7 is a flowchart showing a detailed example of a process in step 56 in FIG. 5;

[Explanation of symbols]

1: display device, 2: input device, 3: external storage device, 4:
Information processing device, 4a: CPU, 4b: main memory, 5: optical disk, 6: drive device, 7: communication device, 10: system table, 11 to 13: row, 20: data table,
21 to 23: data record, 30: schema information element, 31: element (item 1), 32: element (item 2), 33: element (item 3), 311: attribute (type), 3
12: attribute (length), 313: attribute (identity), 40: data information element, 41 to 53: data element, 100: client, 110: schema-incompatible web browser, 120, 120a: XML file, 200, 200a : Web server, 210, 210
a: conversion unit, 300: RDB, 310: DB schema,
320: data.

Claims (3)

[Claims] 1. A relational database (RDB)
XM data and schema information by computer processing
An L document is converted into an L document by reading schema information of a conversion target database from the relational database, creating a schema information element serving as a template of the XML document, and storing the XML document including the schema information element in a storage device. Storing; reading the XML document from the storage device;
Obtaining data from the relational database based on the schema information element of the ML document, creating a data information element, and adding the data information element to the XML document, wherein the schema information of the RDB is converted to the XML as the schema information element. An RDB / XML data conversion method characterized by being stored in a document instance. 2. A relational database (RDB)
XM data and schema information by computer processing
A method of converting an XML document including only the top-level tag into a work area of a storage device, reading schema information of a database to be converted from the relational database, and including the XML information in the schema information. Creating an element for each item to be added, and adding a schema information element composed of each element as a lower element to the XML document; and, in a unit of the schema information element, from the relational database to the schema information element. The data corresponding to each element is obtained, and a data information element is created using the schema information element as a template.
And adding the schema information of the RDB to the XML document instance as the schema information element.
ML data conversion method. 3. A relational database (RDB)
3. A computer-readable recording medium for recording XML document data created by converting data and schema information by computer processing, and the RDB / XML data according to claim 1 or 2. A recording medium characterized by recording XML document data converted by a conversion method and having a structure in which the schema information of the RDB is stored in the XML document instance as the schema information element.