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| − | 'C' functions defined in shared libraries can be used on Linux.
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| − | ==Defining the C functions==
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| − | The shared library must include the following four elements:
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| − | ====The include file "lianja_api.h"====
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| − | <code lang="c">
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| − | #include "lianja_api.h"
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| − | </code>
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| − | ====The API_SHARED_FUNCTION_TABLE structure====
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| − | Used to define the 'C' functions and objects included in the library:
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| − | <code lang="c">
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| − | // API function address table
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| − | static struct API_FUNCTION_ADDRESS_TABLE *api_function_address_table = NULL;
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| − | // Add all functions and objects to this structure as follows:
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| − | // Name, C Function Name Type
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| − | //
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| − | // Make sure the last entry is NULL.
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| − | //
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| − | static struct API_SHARED_FUNCTION_TABLE api_function_table[7] = {
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| − | {"schar", "fnSamplesCharacter", API_FUNCTION},
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| − | {"stype", "fnSamplesType", API_FUNCTION},
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| − | {"slog", "fnSamplesLogical", API_FUNCTION},
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| − | {"snum", "fnSamplesNumeric", API_FUNCTION},
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| − | {"sopen", "fnSamplesOpen", API_FUNCTION},
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| − | {"myclass", "clsMyClass", API_CLASS},
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| − | {NULL, NULL, -1}
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| − | } ;
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| − | </code>
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| − | ====The initAPI() function====
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| − | <code lang="c">
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| − | // This function is used to define function addresses for API calls.
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| − | int initAPI(struct API_FUNCTION_ADDRESS_TABLE *function_address_table)
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| − | {
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| − | api_function_address_table = function_address_table;
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| − | return 0;
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| − | }
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| − | </code>
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| − | ====The getFunctions() function====
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| − | <code lang="c">
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| − | // This function is used to return the function names of the API.
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| − | struct API_SHARED_FUNCTION_TABLE *getFunctions(void)
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| − | {
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| − | return api_function_table;
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| − | }
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| − | </code>
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| − | ==Using the 'C' functions and classes:==
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| − | Shared libraries are loaded using the SET LIBRARY TO <library> [ADDITIVE] command or the [[REQUIRE()]], [[REQUIRE_ONCE()]], [[INCLUDE()]] or [[INCLUDE_ONCE()]] functions. By default library files are accessed from the directory defined by the DB_LIBDIR environment variable.
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| − | If full path information is specified, the shared library files can be loaded from other directories, e.g.
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| − | <code lang="recital">
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| − | // pdf.so is in the DB_LIBDIR directory
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| − | set library to pdf
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| − | //mylib.so is in /opt/lianja/myapplibs
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| − | set library to /opt/lianja/myapplibs/mylib
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| − | </code>
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| − | The function [[LOADLIBRARY()|LOADLIBRARY(<library>)]] can also be used to load additional shared libraries. The name of the shared library file including the full path and file extension must be specified.
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| − | The [[SET LIBRARY|SET LIBRARY TO]] or [[RELEASE LIBRARY|RELEASE LIBRARY <library>]] commands are used to close all or specified shared libraries.
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| − | The [[LIST PROCEDURE]] and [[DISPLAY PROCEDURE]] commands include loaded shared library function names in their listings and the [[LIST CLASSES]] and [[DISPLAY CLASSES]] commands include loaded shared library class names in their listings.
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| − | Loaded shared library functions can be used in the same way as an internal function. Loaded shared library classes can be used in the same way as system classes.
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| − | [[Category:Documentation]]
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| − | [[Category:SDK]]
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