Interface layer for navigation system

A computer program product for use in a navigation system wherein the navigation system includes a navigation application program that provides navigating features to a user of the navigation system and a geographic database stored on a physical storage medium in a computer-readable physical storage format, said computer program product comprising an interface layer comprising:

• programming that accepts and processes requests for geographic data from the navigation application program;
• and
• programming that translates geographic data from said physical storage format and provides said geographic data to said navigation application program in a logical data model format, wherein said logical data model format includes uncompressed entity records of fixed lengths, and wherein said programming that translates further comprises:
• programming that unpacks said geographic data from said physical storage format into a decompressed intermediate format;
• and
• programming that transforms said geographic data from said decompressed intermediate format into data entities in said logical data format for returning to said navigation application program.

A computer program product for use in a navigation system wherein the navigation system includes a navigation application program that provides navigating features to a user of the navigation system and a geographic database stored on a physical storage medium in a computer-readable physical storage format, said computer program product comprising an interface layer comprising:

• programming that accepts and processes requests for geographic data from the navigation application program;
• programming that translates geographic data from said physical storage format and provides said geographic data to said navigation application program in a logical data model format,
• programming that allocates and frees memory of said navigation system for use as a memory pool by said interface layer;
• programming that accesses a cache memory buffer in said memory pool that stores a parcel read from said physical storage medium, wherein said parcel can be identified by means of a parcel identifier
• programming that initiates an I/O transaction from the physical storage medium to read said parcel therefrom if said cache memory buffer accessing means finds that said parcel is not stored in said cache memory buffer;
• wherein said programming that initiates an I/O transaction further comprises:
• stores parcel identifiers in a queue and
• reorders parcel identifiers while in said queue.

A method of using a computer-based navigation system wherein said navigation system includes navigation application program functions wherein said navigation application program functions are adapted to use a geographic database stored on a computer-readable medium in a physical storage format, the method comprising:

• accepting a request from one of said navigation application program functions for geographic data;
• using an index to identify the geographic data in said physical storage format for responding to said request;
• transforming geographic data stored in said physical storage format into a format usable by said navigation application program functions;
• and
• after a plurality of data entities are identified in response to said request from said one of said navigation application program functions, providing a first partial result set of said plurality of data entities in said format usable by said navigation application program functions to said one of said navigation application program functions.

A method of using a computer-based navigation system wherein said navigation system includes navigation application program functions wherein said navigation application program functions are adapted to use a geographic database stored on a computer-readable storage medium in a physical storage format, the method comprising:

• reading a metadata file from said storage medium;
• storing a portion of said metadata file in memory;
• accepting a request from one of said navigation application program functions for geographic data;
• transforming geographic data stored in said physical storage format into a format usable by said navigation application including using said metadata file to translate from a version level of said physical storage format to a version level of said navigation application program functions;
• and
• providing said transformed geographic data to said one of said navigation application program functions.

A computer program product for use in a navigation system wherein the navigation system includes a navigation application program for providing navigating features to a user of the navigation system and a geographic database stored on a physical storage medium in a computer-readable physical storage format, said computer program product comprising an interface layer comprising:

• programming that provides a C language data structure view to the navigation application program;
• programming that accepts and processes requests for geographic data from the navigation application program;
• and
• programming that translates geographic data from said physical storage format and provides said geographic data to said navigation application program as a C language data structure in a fully decompressed form.