KR20030054605A - Apparatus and method XML document retrieval supporting XML query language tightly-coupled with database query language - Google Patents

Abstract

PURPOSE: An XML document search system and a method for the same are provided to enable a user to search for an XML document in a database, storing plural XML documents, by using an integrated query which tightly couples an XML query with a database query. CONSTITUTION: The system comprises a search management module(110), a syntax analysis module(120), a query process module(130), a result process module(140) and a database engine(200). The search management module(110) performs a function of an interface with the database engine(200), and controls the syntax analysis module(120), the query process module(130), and the result process module(140). The syntax analysis module(120) analyzes the syntax on the XML query input via the search management module(110), checks whether the input XML query follows a preset query context rule, and generates a syntax tree for the input XML query in a case that the input XML query does not follow the preset query context rule. At this time the syntax analysis module(120) receives the integrated query which tightly couples the XML query with a database query, and checks an effectiveness of the input XML query. The query process module(130) processes the XML query by using the generated syntax tree. The result process module(140) converts the query process result of the query process module(130) into the type appropriate for the database engine(200), and transmits the converted result to the search management module(110).

Description

Apparatus and method XML document retrieval supporting XML query language tightly-coupled with database query language}

The present invention relates to an XML document retrieval apparatus and a method thereof, and more particularly, to search for an XML (eXtensible Markup Language) document stored in a database by using an integrated query in which a database query and an XML query are tightly coupled. A document retrieval apparatus and a method thereof are provided.

XML is a next-generation Internet electronic document standard that improves on the shortcomings of Hyper Text Markup Language (HTML) and Standard Generalized Markup Language (SGML). XML is platform-independent, easy to transmit and exchange document information, and has the advantage of expressing the rich meaning of a document. In addition, XML was adopted as a recommendation by the W3C in February 1998, and the use of XML has become more active since then.

As a result of this trend, the generation and distribution of XML documents is rapidly increasing, and as a result, interest in an XML document management system for managing XML documents is increasing.

The XML document management system is evolving from a file system based system to a database system based system. This is because as the amount of documents managed increases, existing database management functions such as quick search of documents, sharing among multiple users, backup and recovery in case of failure are required.

On the other hand, since the XML document model is a hierarchical structure with an ordered sequence between elements, it is different from a model for dealing with structured data such as an existing relational data model or an object-oriented data model. When constructing a new database management system that supports or managing using an existing database system, it is necessary to make up for the differences between the two models. In other words, when storing an XML document in a database, a function of converting and storing a difference between two models and a query function reflecting XML model characteristics when searching an XML document are required.

There are two types of XML queries: content-based queries, attribute-based queries, and structure-based queries.

A content-based query is a query on the content itself that an XML document wants to represent. Therefore, in content-based query, pure text data excluding element tag information is performed in XML document, and accurate comparison of the entire text content within the selected category is performed. Functional considerations are needed.

Attribute-based queries allow comparison based on the definition of attribute values and comparison search by attribute values. Basically, an attribute will have a lot of data, so an accurate comparison is sufficient.

Structure-based queries should consider the existence of elements that make up a document, relationships between element hierarchies, relationships within the same hierarchy, and relationships across hierarchies. In the relationship between the hierarchies, there is a ancestor / child relationship and parent-child relationship. In the same hierarchy, there is a sibling ordering (Sibling Following Sibling). And when you look at the entire element hierarchy that composes the document, there is a line / post relationship according to this order because the order is defined between each element in a depth-first manner. Therefore, you should be able to specify the element you want by this structural relationship.

XML documents are highly biased depending on the application, and sometimes one book can be a single document. In addition to searching through the entire document with the corresponding Document Type Definition (DTD) type, the information desired from the specified XML document It is also necessary to be able to find. It is also possible to search from documents of various DTD types, and consider whether to target the complete XML document or the partial documents that make up the document within a single document.

The search result is linked to the search object, and the extraction object may be an element or an attrit or content constituting the element, or may obtain only one of the sub-element hierarchies constituting the element to be searched. You can also get

In consideration of the above characteristics, the W3C is currently trying to establish a query language standard for XML documents, and XML query languages such as XPath, XQL, and XML-QL have been proposed.

Currently, many XML document management systems utilize existing database systems to provide XML query capabilities that reflect the characteristics of XML models. That is, the XML document management system is configured by adding a separate module for managing the XML document on the database system. For example, an XML store that converts an XML document into a data model provided by the database system when storing the XML document, and converts a query word for the XML document into a database query word (that is, SQL) to be delivered to the database system for processing. Configure XML Document Finder on top of the database system.

By the way, this method treats all the data stored in the database as XML, and can freely construct the XML query language utilizing the characteristics of the XML document, while in order to link the XML document with the data managed in the existing database, Has to be converted to XML model, so it is inconvenient to integrate existing database data with new XML data.

Therefore, in order to solve the problem, the present invention uses an integrated query combined with a database query and an XML query so that a large amount of XML data and existing data can be linked to each other, and a search can be performed using an API inside the database engine. An object of the present invention is to provide an XML document retrieval apparatus and a method for performing an XML query optimized processing.

In order to achieve the above object, the XML document retrieval apparatus provided by the present invention receives an integrated query in which a database query word and an XML query word are tightly coupled through an external device, analyzes the integrated query, and analyzes the syntax for the integrated query. A query processing module for generating a tree, a query processing module for executing a query required by an integrated XML query using the syntax tree generated by the parse module, and processing a query execution result of the query processing module in a database engine And a search management module that controls the syntax analysis module, the query processing module, and the result processing module, and performs an interface with a database engine.

In addition, in order to achieve the above object, the XML document retrieval method provided by the present invention is a first process of generating an integrated query in a form in which a database query and an XML query is tightly coupled, and analyzing the integrated query to the integrated query A second process of generating a syntax tree for the query, a third process of traversing the syntax tree using a database engine API and performing a search for the query, and a form suitable for processing the search result in a database engine And a fourth process of converting the fourth process and a fifth process of transmitting a result of performing the fourth process to a database engine.

1 is a syntax rule of an integrated query language combined with a DB query language and an XML query language;

1A and 1B illustrate an example of a query for searching an XML document according to an embodiment of the present invention;

2 is a functional block diagram of an XML document retrieval apparatus according to an embodiment of the present invention;

2A is a flowchart illustrating a method of searching an XML document according to an embodiment of the present invention;

3 is a diagram showing an example of an XML document management system including the XML document retrieval apparatus of the present invention;

3A is a process flow diagram illustrating a process of retrieving a document from the XML document management system shown in FIG.

♣ Explanation of symbols for the main parts of the drawing ♣

100: XML document search device 110: search management module

120: parse module 130: query processing module

140: result processing module 200: database engine

300: database

Hereinafter, a method of generating a disposable key according to an embodiment of the present invention with reference to the accompanying drawings in more detail.

1 is a syntax rule of an integrated query language combined with a DB query language and an XML query language, and FIGS. 1A and 1B illustrate examples of a query word for searching an XML document according to an embodiment of the present invention. In the present invention, in order to be able to use a large amount of XML data and the existing data, using a combined query combined with a database query and XML query, Figure 1 is an illustration of such a combined query. Referring to FIG. 1, in order to generate the integrated query, a new predicate 20 for supporting the characteristics of the XML query is added to the search condition 10 constituting the WHERE clause of SQL, which is a database query language. Do it.

That is, in general, predicates supporting SQL include <comparison preicate>, <in predicate>, <like predicate>, and <related predicate>. However, in addition to these conventional predicates, < add contains predicate> (20) At this time, 'xml_query (25)', one of the arguments of <contains predicate> (20), is an attribute conforming to XML query language notation.

Therefore, when constructing a query as illustrated in FIG. 1, since an attribute of an XML query language is combined with a syntax supporting SQL, a large amount of XML data and existing data can be used in conjunction with such a query. To do that.

In the example of FIG. 1A, the Title element is searched among all the elements of the Paper DTD since the class name of the FROM clause is Paper_Element. In the example of FIG. 1B, the Title element is searched among all the elements of the Book DTD because the class name of the FROM clause is Book_Element. In the case of the XML query language such as the examples 1 and 2 (210 to 220) that the query query itself cannot be specified, the query query target can be specified using the FROM clause provided by the database query language. .

2 is a functional block diagram of an XML document retrieval apparatus according to an embodiment of the present invention. 2, the XML document search apparatus 100 according to an embodiment of the present invention includes a search management module 110, a parser module 120, a query processing module 130, and a result processing module 140. It is configured to, and retrieves the database 300 through the database engine 200.

The search management module 110 performs an interface with the database engine 200 and controls the syntax analysis module 120, the query processing module 130, and the result processing module 140. That is, the search management module 110 receives the XML query word and the query processing object from the database engine 200 and delivers it to the parsing module 120, and receives the processing result for the corresponding query word from the result processing module 140. Transfer to the engine 200.

The parsing module 120 analyzes the syntax of the XML query input through the search management module 110 to check whether the XML query violates the preset XML query syntax, and if not, the XML query Create a syntax tree for. At this time, the parser module 120 receives an integrated query in which the database query and the XML query are tightly coupled and checks the validity of the XML query. An example of an integrated XML query is the same as the example shown in FIGS. 1A and 1B.

The query processing module 130 performs a query required by the XML query using the syntax tree generated by the parse module 120. At this time, the query processing module 130 traverses the syntax tree using the API of the database engine 200 and searches for the corresponding query. The API of the database engine 200 depends on the complexity of the syntax tree. Repeat the query several times.

The result processing module 140 converts the query performance result of the query processing module 130 into a form suitable for processing by the database engine 200 and transmits the result to the search management module 110.

Fig. 2A is a process flowchart of the XML document retrieval method by the XML document retrieval apparatus. Referring to FIG. 2A, when the XML query word and the query processing object are transmitted from the database engine 200, the XML document search method of the present invention is disclosed.

That is, when the XML query word and the query processing object transmitted from the database engine 200 are transferred to the search management module 110 (s101), the search management module 110 transmits the XML query word to the parsing module 120 ( s102). In this case, the XML query transmitted from the database engine 200 is an integrated query in which the database query and the existing XML query are tightly coupled.

Then, the syntax analysis module 120 analyzes the syntax for the integrated query (s103), generates a syntax tree for it, and transfers the syntax tree to the search management module 110 (s104).

Then, the search management module 110 transmits the syntax tree transmitted from the syntax analysis module 120 and the query processing object transmitted from the database engine 200 to the query processing module 130 in step S101. s105).

Meanwhile, the query processing module 130 that has received the syntax tree and the query processing object traverses the syntax tree using an API of the database engine and searches for the corresponding query (s106). That is, the query processing module 130 uses the query processing plan for the syntax tree received from the search management module 110, or traverses the syntax tree, and is provided by the database engine 200 such as basic predicate processing and information search. Perform the following functions in turn. At this time, depending on the complexity of the syntax tree delivered to the query processing module 130, the process (s106) may be repeated several times. The database engine 200 directly accesses the database, obtains an XML search result, and delivers the result to the query processing module 130.

When the query processing module 130 transmits the XML search result to the search management module 110 (s107), the search management module 110 transmits the XML search result to the result processing module 140 (s108). The result processing module 140 converts the XML search result into a form suitable for processing by the database engine (S109). In addition, the result processing module 140 delivers the final result generated in this way to the search management module 110 (s110), the search management module 110 transmits the processing result to the database engine 200 ( s111).

In this case, the processing result of the query processing module 130 may be a single type or a complex type including a weight value resulting from the information retrieval, and may be an object or a set of objects. Therefore, the result processing module 140 processes the results so that the database engine 200 can further process these various intermediate result types (s109), and the result processing module 140 processes the results of the search management module 110. Transfer to the database engine 200 via.

Then, the database engine 200 integrates the result of the database query word processed by the database engine 200 and the result processed by the XML document retrieval device and delivers the result to the XML application program.

3 is a diagram showing an example of an XML document management system including the XML document search apparatus 100 of the present invention. Referring to FIG. 3, the XML document management system includes an XML document store 340 and a DB search unit 360. In this case, the XML document store 340 may include a database application program interface 350. It is developed using, and is used when storing the XML document 310 and DTD document 320 in the application 330.

In addition, the application 330 may access information stored in the database 370 using a database query API provided by the database application program interface 350.

Meanwhile, XML data (eg, DTD document 310 and XML document 320) stored using the XML document store 340 may be stored according to a storage schema and a storage model that are promised to the XML document search apparatus 100. This makes it possible to search through the XML document search apparatus 100. At this time, the XML document retrieval apparatus 100 is developed using a function provided by the database engine 200, and interoperates with the database engine 200. That is, a query process is performed on a large amount of XML documents stored in a database using an API (eg, a data access API) provided by the database engine 200.

3A is a process flowchart illustrating a process of searching for a document in the XML document management system shown in FIG. 3. Referring to FIG. 3A, first, the XML application 330 generates a user integration query and transmits it to the database application program interface 350 (s301), and the database application program interface 350 integrates the engine based on the information. A query is generated and transmitted to the database engine 200 (S302).

In this case, the integrated query refers to a form in which an existing database query word and an XML query word are integrated, and examples thereof are shown in FIGS. 1A and 1B. In other words, the query interface structure of the general database is used as it is, and the XML query is entered using the CONTAINS predicate in the WHERE clause of the SQL statement that is added to the database query.

Therefore, the user integration query configured by the XML application 330 is transmitted to the database engine 200 through the query API of the database application program interface 350 (S301 and S302). Then, the database engine 200 extracts the XML query from the engine integrated query (s303), and transmits the XML query to the XML document search apparatus 100 together with the query processing target (s305). In addition, the database engine 200 extracts the XML query and performs a database search based on the remaining database query (S304).

On the other hand, the XML document search apparatus 100 performs a search for the XML document by the XML query word transmitted from the database engine 200 (s306), and transmits the processing result to the database engine 200 (s307). Then, the database engine 200 integrates the XML query result transmitted from the XML document search apparatus 100 and the SQL query result by the self search (s308), generates an engine final result, and then applies the engine final result to the database application. Transfer to the program interface 350 (s309). The database application program interface 350 receiving the engine final result generates and transmits the user final result to the XML application program (s310).

The above description is merely an example of an embodiment, and the present invention is not limited to the above-described embodiment and can be variously changed within the scope of the appended claims. For example, the shape and structure of each component specifically shown in the embodiment of the present invention can be modified.

The XML document search apparatus and method thereof of the present invention as described above have an advantage that a large amount of XML data and existing data can be easily used by using an integrated query in which a database query word and an XML query word are tightly coupled. In addition, by using the integrated query, there is an effect that can be reinforced through the query of the database query disadvantage.

On the other hand, instead of using the query language, which is a database application program API, directly using the API provided by the database engine inside the database, it is possible to process XML query processing considering the characteristics of XML data and XML query words. The advantage is that it can be optimized.

Claims (4)

In the XML document retrieval apparatus, A syntax analysis module that receives an integrated query in which a database query word and an XML query word are tightly coupled through an external device, analyzes the integrated query, and generates a syntax tree for the integrated query word; A query processing module that performs a query required by an integrated XML query using a syntax tree generated by the parse module; A result processing module for converting the query execution result of the query processing module into a form suitable for processing by a database engine; And a search management module which controls the syntax analysis module, the query processing module, and the result processing module and interfaces with a database engine. The method of claim 1, wherein the query processing module An XML document retrieval apparatus for retrieving a query while traversing the syntax tree using an API of a database engine. In the XML document search method, A first process of generating an integrated query in which a database query and an XML query are tightly coupled; A second process of analyzing the unified query and generating a syntax tree for the unified query; A third step of traversing the syntax tree using a database engine API to perform a search for the query; A fourth process of converting the search result into a form suitable for processing by a database engine; And a fifth process of transmitting the result of performing the fourth process to a database engine. In order to perform the XML document retrieval method, a program of instructions that can be executed by a digital processing apparatus is tangibly embodied, and in a recording medium that can be read by a digital processing apparatus, A first process of generating an integrated query in which a database query and an XML query are tightly coupled; A second process of analyzing the unified query and generating a syntax tree for the unified query; A third step of traversing the syntax tree using a database engine API to perform a search for the query; A fourth process of converting the search result into a form suitable for processing by a database engine; And a fifth process of transmitting a result of performing the fourth process to a database engine.