CN103064876A - Method for obtaining spatial data servitization facing geographic information application - Google Patents

Abstract

The invention discloses a spatial data service acquisition method oriented to geographic information applications, comprising: a spatial data service query step; a step of obtaining a query execution plan; and a spatial processing object query language nested in the object query conforming to the structure The spatial query function specified by the query language multimedia extension framework (SQL/MM). After the query statement is parsed by the distributed query execution engine, the spatial query function is passed to the back-end relational database with spatial expansion for execution. The query statement is submitted to the database through the data service Query retrieval, and aggregate the distributed query results and return them to the data service requester. By applying the present invention, it is possible to smoothly cope with continuously updated heterogeneous large-scale data resource access query, query statements encapsulated in the form of object query, and enhance query and retrieval efficiency of geographic information data.

Description

Service-oriented acquisition method of spatial data for geographic information applications

technical field

The present invention relates to geographic information technology in the field of information, in particular to a method for spatial data service query and acquisition oriented to geographic information applications.

Background technique

The acquisition of geographic information data in the network service environment, technical innovation is carried out in the mode of direct connection between the traditional client and the geospatial database for data query, and the spatial data resource is accessed by the middleware specially responsible for query processing in the way of data service With query retrieval, the sharing and interoperability of geospatial data resources is realized through data service integration. The spatial data service acquisition method for geographic information applications provides an interface for spatial data access and query through the service release of data resources. While shielding the back-end complex heterogeneous data source interface, the improved object query statement Handle users' data access and processing requests, and realize the sharing and interoperability of various geographic information vector raster data resources in the back-end database.

In the traditional geographic information spatial data access and query methods, there is no effective support for the storage and query of heterogeneous data sources. The spatial data resources published in the form of network services have brought many conveniences to the acquisition of geographic information data, data processing, and the release and use of information retrieval services.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a spatial data service-based acquisition method for geographic information applications. By improving the existing technology and adapting to the traditional way of processing single data storage, it can be successfully handled. Continuously update heterogeneous large-scale data resource access queries, query statements encapsulated in the form of object queries, and enhance the query and retrieval efficiency of geographic information data. It mainly realizes the query operation of the spatial database with the help of network services, and embeds the spatial analysis operation function in the query process, and the network service returns the results of the spatial data query and analysis, and obtains the operation results after the query analysis.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A method for acquiring spatial data as a service for geographic information applications, the method comprising:

A. The query steps of spatial data service;

B. After defining the analytical rules of the query language for spatial processing objects, use the ANTLR compiler to construct the program to realize the recognizer, compiler and converter for the specific grammar; the query statement is checked for the correctness of the identifier and query keywords through the lexical analysis process Check and get the output Token character stream, the character stream is used as the input element of the grammatical analysis process, analyze the content of the context-free grammatical content according to the custom rules, and check the logical compliance of the semantics; the spatial object query statement uses the compiler to construct the program to realize the grammar The parser, using the recursive descent syntax analysis method, has a wider expression range of syntax analysis rules; generates an abstract syntax tree AST during the query syntax analysis process, and obtains the query execution plan after query inspection and optimization;

C. Spatial processing object query language nests spatial query functions conforming to the SQL/MM specification of the structured query language multimedia extension framework in the object query. After the query statement is parsed by the distributed query execution engine, the spatial query function is passed to the backend to have the space The extended relational database is executed, and the query statement is submitted to the database through the data service for query retrieval, and the distributed query results are aggregated and returned to the data service requester.

Wherein, the step A specifically includes lexical analysis, abstract syntax tree generation, grammar type checking, query logic optimization and physical optimization, and query plan generation.

The spatial data service acquisition method oriented to geographic information applications provided by the present invention has the following advantages:

The access and acquisition method of spatial data service provides access to distributed storage spatial data in the form of data service, and provides access methods for spatial data service release and spatial data service integration. The access and acquisition methods of spatial data services are expanded on the basis of spatial data services, and spatial analysis and query operations in the process of spatial service data acquisition are supported by adding spatial functions and operators. The access and acquisition method of spatial data service is conducive to the integration of distributed spatial data resources, and on the basis of data resource integration, the analysis process of further spatial data processing operations can be customized for use by upper-level spatial analysis and processing services .

Description of drawings

Figure 1 is a schematic diagram of a hierarchical model of spatial data access and acquisition;

Fig. 2 is a schematic diagram of spatial data access and integration model based on SQL/MM query in the present invention;

Fig. 3 is a schematic flowchart of a method for acquiring spatial data as a service according to the present invention.

Detailed ways

The method of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments of the present invention.

Figure 1 is a schematic diagram of the hierarchical model of spatial data access and acquisition; as shown in Figure 1, a customized service-centric model architecture is built for the grid computing environment, and services such as multi-protocol binding and local and remote versatility are used. Features, virtualize computing and storage resources at different levels to integrate and collaborate across multiple distributed nodes.

Spatial data access and acquisition middleware integrates distributed heterogeneous data file resources and relational databases into the grid environment, follows the standard message format of network services, and establishes an interactive channel for data requests and responses between the server and the client. In addition to the data access and update functions, the middleware supports expansion through custom execution activity documents, so as to add more custom activities to the data service to expand service-oriented data query and update operations. The hierarchical model of underlying data source, access and integration middleware and upper layer data service is shown in the figure.

The underlying data resources support general data storage media, including relational databases, XML databases and general data files. Data services based on data access and integration middleware provide data resource acquisition interfaces to the upper layer, interact with clients through data service descriptions in the form of WSRF or WSI, and respond to client data queries and access requests.

Data access and integration middleware provides an extensible programming framework for structured data resources such as relational databases and files, and implements external service access interfaces for structured resources in a data grid environment, and provides data processing-oriented workflows through service models The engine implements service-oriented data access, update, and conversion operations.

Fig. 2 is a schematic diagram of the spatial data access and integration model based on SQL/MM query in the present invention; the key components in the execution process of the spatial data access and acquisition middleware include a data service register for registering data request services, and a grid responsible for data service generation The data service factory and the data service instance of the corresponding data resource. In the process of data service generation, registration and consumption, the grid data service factory (GDSF) is a persistent service running in the service container, creates a grid data service instance (GDS) according to the received request, and source link. The Data Access and Integration Service Registrar (GDSR) is used to register and find the grid data service required by the user, and can also find the GDSF that creates the grid data service. The data processing execution document defines the query result return format obtained by the user. The response document executes operations through the GDS document and returns data resource query processing results for the client. The grid data service GDS establishes links with data resource entities such as back-end relational databases, XML databases, and data files, and performs query interactions.

In the process of spatial data service access, the back-end data source is regarded as a single logical resource, and the data access and integration middleware shields the details of the database driver, data format, and transmission mechanism for the interaction between distributed spatial data resources and services. The data access and integration middleware performs query operations on common data sources, and realizes the service release of distributed heterogeneous geospatial data in the grid environment.

For spatial data service-oriented access queries, it is necessary to configure spatial data source links and corresponding spatial data access behavior rules in the data access and integration middleware to support spatial data object query operations that conform to the SQL/MM specification and the spatial data during the query process Analyze processing function calls.

In the process of spatial data access and integration processing, Activity (behavior) is the basic working module of service middleware, and each type of behavior is responsible for completing a specific data query, conversion, transmission or related processing tasks. Among them, the spatial data interface behavior is used to obtain the access interface of the back-end spatial data source; the spatial data access and organization behavior is used to access the spatial data object in the registered resource; the spatial data write behavior is responsible for writing data to the integrated data source; the spatial The data conversion behavior is responsible for the conversion between data transmission formats; the output data transmission behavior is responsible for sending the data to the remote data receiving device; in addition, the access and integration middleware also has the management control behavior. In the spatial data access and integration middleware, the data service interacts with the back-end database through the spatial query conforming to the SQL/MM specification.

The data access and integration middleware deployed under the service container publishes the access behaviors corresponding to heterogeneous spatial data sources in the data grid service container in the form of data services. After receiving the spatial data service query request from the client, register the data request service in the data service register, and call the grid data service factory GDSF to create a new data service GDS instance. After the SQL/MM spatial query is parsed by the data service , forward it to the backend database with spatial expansion to execute the query operation, and return the spatial data retrieval result to the query request client through the data service interface.

With the assistance of the access and integration middleware, the data organization form and query behavior execution process of the back-end spatial data source are transparent to the service calling client, and the data source index information is stored in the access and integration middleware hash mapping table, and the middleware passes Retrieve the data resource registry to obtain resource usage information, and return specific corresponding data services according to client call requests.

Fig. 3 is a schematic flow chart of the spatial data service acquisition method of the present invention, as shown in Fig. 3, the method includes the following steps:

Step 1: The query process of spatial data services includes lexical analysis, abstract syntax tree generation, syntax type checking, query logic optimization and physical optimization, and query plan generation. In the analysis of spatial data service query statements, according to the design of the query statement syntax, the analysis rules and query processing scripts are defined for the syntax analysis, and the parser records the tags contained in the split query statement according to the defined syntax analysis rules , operators, and query keywords. In the description of query syntax parsing rules, refer to the metagrammatical symbol representation method of the context-free grammar of Extended Backus-Naur Form (EBNF). , operator precedence and other constraints to describe the sequence of symbol sets.

Step 2: After the parsing rules of the spatial processing object query language are defined, the Recognizers, Compilers and Translators for specific grammars are implemented with the aid of the ANTLR compiler construction program. The query statement checks the correctness of the identifier and query keywords through the lexical analysis process and obtains the output Token character stream. The character stream is used as the input element of the syntax analysis process, and the context-free grammar content is analyzed according to the custom rules to check the semantics. Logical specification compliance. The query statement of spatial object implements the syntax parser with the help of the compiler construction program, uses the recursive descent syntax analysis method, and has a wider expression range of syntax analysis rules. An Abstract Syntax Tree (AST) is generated during query syntax parsing, and the query execution plan is obtained through query inspection and optimization.

Step 3: Spatial processing object query language nests spatial query functions conforming to the Structured Query Language Multimedia Extension Framework (SQL/MM) specification in the object query. After the query statement is parsed by the distributed query execution engine, the spatial query function is passed to the The terminal is executed by a relational database with space expansion. The query statement is submitted to the database through the data service for query retrieval, and the distributed query results are aggregated and returned to the data service requester.

The access and acquisition method of spatial data service provides an access path for distributed query of spatial data in the form of data service, and this method is convenient for providing a path for multi-database integrated access of legacy systems containing spatial data.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (2)

1. A spatial data service acquisition method for geographic information applications, characterized in that the method comprises: A. The query steps of spatial data service; B. After defining the analytical rules of the query language for spatial processing objects, use the ANTLR compiler to construct the program to realize the recognizer, compiler and converter for the specific grammar; the query statement is checked for the correctness of the identifier and query keywords through the lexical analysis process Check and get the output Token character stream, the character stream is used as the input element of the grammatical analysis process, analyze the content of the context-free grammatical content according to the custom rules, and check the logical compliance of the semantics; the spatial object query statement uses the compiler to construct the program to realize the grammar The parser, using the recursive descent syntax analysis method, has a wider expression range of syntax analysis rules; generates an abstract syntax tree AST during the query syntax analysis process, and obtains the query execution plan after query inspection and optimization; C. Spatial processing object query language nests spatial query functions conforming to the SQL/MM specification of the structured query language multimedia extension framework in the object query. After the query statement is parsed by the distributed query execution engine, the spatial query function is passed to the backend to have the space The extended relational database is executed, and the query statement is submitted to the database through the data service for query retrieval, and the distributed query results are aggregated and returned to the data service requester. 2. The spatial data service-oriented acquisition method for geographic information applications according to claim 1, wherein said step A specifically includes lexical analysis, abstract syntax tree generation, grammar type checking, query logic optimization and physical optimization, The phase of query plan generation.

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