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/* $Id$ */ Leto DB Server is a multiplatform database server or a database management system, chiefly intended for client programs, written on Harbour, be able to work with dbf/cdx files, located on a remote server. Contents -------- 1. Directory structure 2. Building binaries 2.1 Borland Win32 C compiler 2.2 Linux GNU C compiler 2.3 xHarbour Builder 2.4 Mingw C compiler 2.5 Building letodb with hbmk 2.6 Addition functions support 3. Running and stopping server 4. Server configuration 4.1 letodb.ini 4.2 Authentication 5. Features of work with the letodb server 5.1 Connecting to the server from client programs 5.2 Filters 6. Variables management 7. Functions list 7.1 Connection management functions 7.2 Transaction functions 7.3 Additional functions for current workarea 7.4 Additional rdd functions 7.5 Setting client paramenter 7.6 File functions 7.7 Management functions 7.8 User account management functions 7.9 Server variable management functions 7.10 Calling udf-functions on the server 7.11 Functions for bitmap filters 8. Management utility 9. Server-side functions 1. Directory structure bin/ - server executable file doc/ - documentation include/ - source header files lib/ - rdd library source/ client/ - rdd sources common/ - some common source files client/ - server sources tests/ - test programs, samples utils/ manage/ - server management utilities 2. Building binaries The letodb server can be compiled only by the Harbour compiler, and client library - both Harbour, and xHarbour. For OS Windows the letodb server can be compiled as Windows service (the macro by __WIN_SERVICE__ should be initialized), or as the daemon (process) for what it's necessary to set a macro __WIN_DAEMON__. For Linux it is necessary to set a macro __LINUX_DAEMON__. The server and the client library can be built with the support of the driver BMDBFCDX/BMDBFNTX. In this case, the basic rdd letodb server will be used instead DBFCDX/DBFNTX driver BMDBFCDX/BMDBFNTX, and supported the same functionality that BMDBF*. To build on this mode, in build scripts (letodb.hbp, rddleto.hbp for hbmk2 and makefile.* for other compilers) it's need to set a macro __BM. You can pass option -env for hbmk2 utility: hbmk2 -env:__BM=yes letodb.hbp hbmk2 -env:__BM=yes rddleto.hbp The server can be built with the support of functions leto_Zip and leto_UnZip. To build on this mode, in build script (letodb.hbp) it's need to set a macro __ZIP: hbmk2 -env:__ZIP=yes letodb.hbp 2.1 Borland Win32 C compiler An environment variable HB_PATH, which defines a path to the Harbour directory, must be set before compiling. This can be done, for example, by adding a line in a make_b32.bat: SET HB_PATH=c:\harbour If you use xHarbour, uncomment a line 'XHARBOUR = yes' in makefile.bc. Then run the make_b32.bat and you will get server executable file letodb.exe in a bin/ directory and rdd library rddleto.lib in a lib/ directory. 2.2 Linux GNU C compiler An environment variable HB_ROOT, which defines a path to the Harbour directory, must be set before compiling. Or just change the value of HRB_DIR in the Makefile.linux. Then run the make_linux.sh and you will get server executable file letodb in a bin/ directory and rdd library librddleto.a in a lib/ directory. 2.3 xHarbour Builder Run the make_xhb.bat to build binaries with this compiler. Probably, you will need to change the path to your xHarbour Builder copy in the make_xhb.bat. Default value is: set XHB_PATH=c:\xhb 2.4 Mingw C compiler An environment variable HB_PATH, which defines a path to the Harbour directory, must be set before compiling. This can be done, for example, by adding a line in a make_mingw.bat: SET HB_PATH=c:\harbour If you use xHarbour, uncomment a line 'XHARBOUR = yes' in makefile.gcc. Then run the make_mingw.bat and you will get server executable file letodb.exe in a bin/ directory and rdd library librddleto.a in a lib/ directory. 2.5 Building letodb with hbmk Now there is a possibility to build letodb with a Harbour make utility, provided by Viktor Szakats. The command line syntax is: hbmk2 [-hb10|-xhb] rddleto.hbp letodb.hbp [-target=tests/test_ta.prg] Optional parameters: -hb10 - Harbour version is 1.0 or 1.0.1, -xhb - xHarbour, -target="blank"\test_ta.prg - build the test, too. 2.6 Addition functions support LetoDB use Harbour expression engine for evaluating index expressions and filters, and allows a call of the following functions: ABS, ALLTRIM, AT, CHR, CTOD, DATE, DAY, DELETED, DESCEND, DTOC, DTOS, EMPTY, I2BIN, L2BIN, LEFT, LEN, LOWER, LTRIM, MAX, MIN, MONTH, PAD, PADC, PADL, PADR, RAT, RECNO, RIGHT, ROUND, RTRIM, SPACE, STOD, STR, STRZERO, SUBSTR, REPLICATE, TIME, TRANSFORM, TRIM, UPPER, VAL, YEAR, hb_ATokens, hb_WildMatch If it's necessary to add this set of functions, in the source/server.prg module it's necessary to add a line: REQUEST <cFName1>[, ...] And then rebuild server. 3. Running and stopping server Just run it: letodb.exe ( under Windows ) ./letodb ( under Linux ) To shutdown the server, run the same executable with a 'stop' parameter: letodb.exe stop ( under Windows ) ./letodb stop ( under Linux ) To reload letoudf.hrb module, run the same executable with a 'reload' parameter: letodb.exe reload ( under Windows ) ./letodb reload ( under Linux ) For windows service (server should be compiled with __WIN_SERVICE__ flag): To install and uninstall service, you must have administrative privileges. To install service, run letodb with 'install' parameter: letodb.exe install To uninstall service, run letodb with 'uninstall' parameter: letodb.exe uninstall To start and stop server, run service manager. 4. Server configuration 4.1 letodb.ini You may provide configuration file letodb.ini if you isn't satisfied with default parameters values. Currently following parameters exists ( default values are designated ), they should be written in section [MAIN]: [MAIN] Port = 2812 - server port number; Ip = - ip address, where Letodb listens for connections; If it doesn't set, all net interfaces ( all ip addresses ), available on the computer, are used. TimeOut = -1 - connection timeout; DataPath = - path to a data directory on a server; LogPath = letodb.log - path and name of a log file; Default_Driver = CDX - default RDD to open files on server ( CDX/NTX ); Memo_Type = - memo type ( FPT/DBT ). Default: FPT for DBFCDX, DBT for DBFNTX; Lower_Path = 0 - if 1, convert all paths to lower case; EnableFileFunc = 0 - if 1, using of file functions ( leto_file(), leto_ferase(), leto_frename() is enabled; EnableAnyExt = 0 - if 1, creating of data tables and indexes with any extention, other than standard ( dbf,cdx,ntx ) is enabled; EnableUDF = 1 - if 1 (by default), using of udf functions with prefix "UDF_*" is enabled, if 2, using of udf functions with any names is enabled, if 0, udf calls is disabled; Pass_for_Login = 0 - if 1, user authentication is necessary to login to the server; Pass_for_Manage = 0 - if 1, user authentication is necessary to use management functions ( Leto_mggetinfo(), etc. ); Pass_for_Data = 0 - if 1, user authentication is necessary to have write access to the data; Pass_File = "leto_users" - the path and name of users info file; Crypt_Traffic = 0 - if 1, the data passes to the network encrypted; Share_Tables = 0 - if 0 (default, this mode server was the only from the start of a letodb project), the letodb opens all tables in an exclusive mode, what allows to increase the speed. If 1 (new mode, added since June 11, 2009), tables are opened in the same mode as client applications opens them, exclusive or shared, what allows the letodb to work in coexistence with other types of applications. No_Save_WA = 0 - When this mode is set, each dbUseArea() will cause a real file open operation and creating a new workarea on the server ( in default mode each file is opened only one time and have only one real workarea for all users ). Theoretically this new mode may increase the speed in case of a big number of active users. It isn't properly tested yet, so for production use default mode is recommended. Cache_Records - The number of records to read into the cache Max_Vars_Number = 10000 - Maximum number of shared variables Max_Var_Size = 10000 - Maximim size of a text variable Trigger = <cFuncName> - Global function letodb RDDI_TRIGGER PendingTrigger = <cFuncName>- Global function letodb RDDI_PENDINGTRIGGER EnableSetTrigger = 0 - if 1, allows to change trigger settings, using dbInfo( DBI_TRIGGER, ... ) Tables_Max = 5000 - Number of tables Users_Max = 500 - Number of users Debug = 0 - Debug level Optimize = 0 - if 1, SET HARDCOMMIT OFF AutOrder = 0 - SET AUTORDER setting ForceOpt = 0 - _SET_FORCEOPT setting It is possible to define [DATABASE] structure if you need to have a directory, where files are opened via other RDD: [DATABASE] DataPath = - (mandatory option) Driver = CDX - ( CDX/NTX ) You can define as many [DATABASE] sections, as needed. In Windows environment the letodb.ini must be placed in a directory, from where server is started. In Linux the program looks for it in the directory from where the server is started and, if unsuccessfully, in the /etc directory. 4.2 Authentication To turn authentication subsystem on you need to set one of the following letodb.ini parameters to 1: Pass_for_Login, Pass_for_Manage, Pass_for_Data. But before you need to create, at least, one user with admin rights, because when authentication subsystem works, only authenticated users with admin rights are able to add/change users and passwords. To add a user, you need to include a call of LETO_USERADD() in your client side program, for example: LETO_USERADD( "admin", "secret:)", "YYY" ) where "YYY" is a string, which gives rights to admin, manage and write access. You may also use the utils/manager/console.prg program to set or change authentication data. To connect to a server with an authentication data ( username and password ) you need to use LETO_CONNECT() function. 5. Features of work with the letodb server 5.1 Connecting to the server from client programs To be able to connect to the server you need to link the rddleto library to your aplication and add at start of a main source file two lines: REQUEST LETO RDDSETDEFAULT( "LETO" ) To open a dbf file on a server, you need to write in a SET PATH TO statement or in the USE command directly a path to the server in a standard form //ip_address:port/data_path/file_name. If a 'DataPath' parameter of a server configuration file is set to a non empty value, you need to designate not the full path to a file on the server, but only a relative ( relatively the 'DataPath' ). For example, if the you need to open a file test.dbf, which is located on a server 192.168.5.22 in a directory /data/mydir and the 'DataPath' parameter value ( of a letodb.ini server configuration file ) is '/data', the syntax will be the following: USE "//192.168.5.22:2812/mydir/test" If the server doesn't run or you write a wrong path, you'll get open error. It is possible to check accessibility of a server before opening files by using the leto_Connect( cAddress ) function, which returns -1 in case of unsuccessful attempt: IF leto_Connect( "//192.168.5.22:2812/mydir/" ) == -1 Alert( "Can't connect to server ..." ) ENDIF At connection with the server the client send to it information about codepage, which the server then uses for operations of indexation, a filtration and for some other operations. The client codepage should be established before connection with the letodb server. 5.2 Filters The filter is established usually: by the SET FILTER TO command or by a call dbSetFilter() function. The filter which can be executed on the server, is called optimized. If the filter can't be executed on the server, it is not optimized. Such filter is slow as from the server all records, which are all the same requested then are filtered on the client. To set the optimized filter, it is necessary, that in logical expression for the filter there were no variables or the functions defined on the client. To check, whether the filter is optimized, it is necessary to caall the LETO_ISFLTOPTIM() function. 6. Variables management Letodb allows to manage variables, which are shared between applications, connected to the server. Variables are separated into groups and may be of logical, integer or character type. You can set a variable, get it, delete or increment/decrement ( numerical, of course ). All operations on variables are performed consecutively by one thread, so the variables may work as semaphores. See the functions list for a syntax of appropriate functions and tests/test_var.prg for a sample. Letodb.ini may contain lines to determine the maximum number of variables and a maximum size of a text variable. 7. Functions list 7.1 Connection management functions Below is a full ( at least, for the moment I write it ) list of functions, available for using in client applications with RDD LETO linked. LETO_CONNECT( cAddress, [ cUserName ], [ cPassword ], [ nTimeOut ], [ nBufRefreshTime ] ) --> nConnection, -1 if failed nBufRefreshTime defines the time interval in 0.01 sec. After this time is up, the records buffer must be refreshed, 100 by default (1 sec) LETO_CONNECT_ERR() --> nError LETO_DISCONNECT( [ cConnString | nConnection ] ) --> nil LETO_SETCURRENTCONNECTION( [ cConnString | nConnection ] ) --> nConnection LETO_GETCURRENTCONNECTION() --> nConnection LETO_GETSERVERVERSION() --> cVersion LETO_GETLOCALIP() --> IP address of client station LETO_ADDCDPTRANSLATE(cClientCdp, cServerCdp ) --> nil LETO_PATH( [<cPath>], [cConnString | nConnection] ) --> cOldPath LETO_PING( [ cConnString | nConnection ] ) --> lResult 7.2 Transaction functions LETO_BEGINTRANSACTION( [ nBlockLen ], [ lParseTrans ] ) Parameter <nBlockLen> can be used for set memory allocation block size. For big transaction it can improve transaction speed at the client side. if parameter <lParseTransRec> is .F., transaction buffer isn't processing during record parsing from server. LETO_ROLLBACK() LETO_COMMITTRANSACTION( [ lUnlockAll ] ) --> lSuccess LETO_INTRANSACTION() --> lTransactionActive 7.3 Additional functions for current workarea LETO_COMMIT() This function can be used for current workarea instead of calls: dbCommit() dbUnlock() The client sends to the server 3 packages: for record updating on the server, for commit record and area unlock. Leto_Commit sends only one package for all these operations LETO_SUM( <cFieldNames>|<cExpr>, [ cFilter ], [xScope], [xScopeBottom] ) --> nSumma if one field or expression passed, or {nSumma1, nSumma2, ...} for several fields The first parameter of leto_sum if comma separated fields or expressions: leto_sum("Sum1,Sum2", cFilter, cScopeTop, cScopeBottom) return an array with values of sum fields Sum1 and Sum2. If "#" symbol passed as field name, leto_sum returns a count of evaluated records, f.e: leto_sum("Sum1,Sum2,Sum1+Sum2,#", cFilter, cScopeTop, cScopeBottom) --> {nSum1, nSum2, nSum3, nCount} If only one field name or expression is passed, leto_sum() returns a numeric value LETO_GROUPBY(cGroup, <cFields>|<cExpr>, [cFilter], [xScopeTop], [xScopeBottom]) --> aValues {{xGroup1, nSumma1, nSumma2, ...}, ...} This function return two-dimensional array. The first element of each row is a value of <cGroup> field, elements from 2 - sum of comma separated fields or expressions, represented in <cFields>. If "#" symbol passed as field name in cFields, leto_groupby return a count of evaluated records in each group LETO_ISFLTOPTIM() --> lFilterOptimized dbInfo( DBI_BUFREFRESHTIME[, nNewVal]) --> nOldVal Setting new value for area skip and seek buffers refresh time in 0.01 sec. If -1: using connection setting. If 0 - buffers are used anyway. dbInfo( DBI_CLEARBUFFER ) This command cleared skip buffer. 7.4 Additional rdd functions leto_CloseAll( [ cConnString | nConnection ] ) --> nil Close all workareas for specified or default connection 7.5 Setting client paramenter LETO_SETSKIPBUFFER( nSkip ) --> nCount (buffer statistic using) This buffer is intended for optimization of multiple calls of skip. This function set size in records of skip buffer for current workarea. By default, the size of skip buffer is 10 records. Skip buffer is bidirectional. Skip buffer is refreshed after BUFF_REFRESH_TIME (1 sec) If parameter <nSkip> is absent, function returns bufferr statictic (number of buffer shooting) LETO_SETSEEKBUFFER( nRecsInBuf ) --> nCount (buffer statistic using) This buffer is intended for optimization of multiple calls of seek. This function set size in records of seek buffer for current index order. If record is found in seek buffer on dbSeek(), it's not loaded from server. Like skip buffer, seek buffer is refreshed after BUFF_REFRESH_TIME (1 sec) If parameter <nRecsInBuf> is absent, function returns bufferr statictic (number of buffer shooting) By default, seek buffer is turned off. LETO_SETFASTAPPEND( lFastAppend ) --> lFastAppend (previous value) If the fast append mode isn't set, record is added on the server at once after a dbAppend() function call. If this mode is set, record is added by dbCommit() call, or after a call of functions of navigation. By default a mode fast append isn't set. The switch working on all workareas. RddInfo( RDDI_REFRESHCOUNT, <lSet>,, [nConnection] ) By default, the RDDI_REFRESHCOUNT flag is set to true. If this flag is set, RecCount() function retrieve records count from server, if doesn't set - use last value from server. If other applications are appending records to the table, new value of records count won't be immediately received. If RDDI_REFRESHCOUNT flag is cleared, dbGoto(0) cleared record buffer and set eof and other flags instead of server request. RddInfo( RDDI_BUFKEYCOUNT, <lSet>,, [nConnection] ) By default, the RDDI_BUFKEYCOUNT flag is set to false. If this flag isn't set, ordKeyCount() function retrieve key count from server, if set - use last value from server. RddInfo( RDDI_BUFKEYNO, <lSet>,, [nConnection] ) By default, the RDDI_BUFKEYNO flag is set to false. If this flag isn't set, ordKeyNo() function retrieve value from server, if set - use last value from server. RddInfo( RDDI_CLIENTID,,, [nConnection] ) Returns self client ID (nUserStru) number. 7.6 File functions The <cFileName> parameter of all file functions can contain a connection string to the letodb server in a format: //ip_address:port/data_path/file_name. If the connection string is omitted, the current active connection is used: /data_path/file_name. All files is searching at the DataPath catalog on the server. The ".." symbols are disabled. LETO_FILE( cFileName ) --> lFileExists Determine if file exist at the server, analog of File() function LETO_FERASE( cFileName ) --> -1 if failed Delete a file at the server. LETO_FRENAME( cFileName, cFileNewName ) --> -1 if failed Rename a file: <cFileName> --> <cFileNewName>. <cFileNewName> should be without connection string. LETO_MEMOREAD( cFileName ) --> cStr Returns the contents of file at the server as character string, analog of MemoRead() function. Leto_MemoWrite( cFileName, cBuf ) --> lSuccess Writes a character string into a file at the server, analog of MemoWrit() function. LETO_MAKEDIR( cDirName ) --> -1 if failed Creates a directory at the server LETO_DIREXIST( cDirName ) --> lDirExists Determine if directory exist at the server LETO_DIRREMOVE( cDirName ) --> -1 if failed Delete a directory at the server. LETO_FERROR() --> nError Returns an error code of last file function. Leto_FileRead( cFileName, nStart, nLen, @cBuf ) --> -1 if failed Read a content of file at the server from <nStart> offset and <nLen> length Leto_FileWrite( cFileName, nStart, cBuf ) --> lSuccess Write <cBuf> character string to a file at the server from <nStart> offset Leto_FileSize( cFileName ) --> -1 if failed Returns a length of a file at the server Leto_FileAttr( cFileName [, cNewAttr] ) --> cAttr Get or set file attributes Leto_Directory( cDir[, cAttr] ) --> aDirectory Returns a content of directory at the server in the same format as Directory() function 7.7 Management functions LETO_MGGETINFO() --> aInfo This function returns parameters of current connection as 17-element array of char type values: 1 - count of active users 2 - max count of users 3 - opened tables 4 - max opened tables 5 - time elapsed 6 - count of operations 7 - bytes sent 8 - bytes read 9 - opened indexes 10 - max opened indexes 11 - data path 12 - max day wait 13 - ulWait 14 - count of transactions 15 - count successfully of transactions 16 - current memory used 17 - max memory used LETO_MGGETUSERS( [<cTableId>|<nTable>] ) --> aInfo Function returns two-dimensional array, each row is info about user: aInfo[i,1] - user number aInfo[i,2] - ip address aInfo[i,3] - net name of client aInfo[i,4] - program name aInfo[i,5] - timeout LETO_MGGETTABLES( [<cUserId>|<nUser>] ) --> aInfo Function returns two-dimensional array, each row is info about opened tables: aInfo[i,1] - table number aInfo[i,2] - table name LETO_MGGETLOCKS( [<cUserId>|<nUser>] ) --> aInfo Function returns two-dimensional array, each row is info about locks: aInfo[i,1] - table name aInfo[i,2] - character string with list of locked records LETO_MGGETTIME() --> aDateTime Function returns array {<dDate>, <nSeconds>}: dDate - server date; nSeconds - seconds after midnight. Convert this values to datetime variable (Harbour): hb_DTOT( aDateTime[1], aDateTime[2] ) LETO_MGKILL( <nUser>|<cUserId> ) Kill user number <nUser> LETO_LOCKCONN( lOnOff ) --> lSuccess After leto_lockconn( .t. ) request new connections are blocked by server, until leto_lockconn( .f. ) called LETO_LOCKLOCK( lOnOff, nSecs ) --> lSuccess This function wait until any updates are closed, commit all changes and trying to lock server from any updates from clients. It returns True, if lock is succesfull. 7.8 User account management functions LETO_USERADD( cUserName, cPass [, cRights ] ) --> lSuccess LETO_USERPASSWD( cUserName, cPass ) --> lSuccess LETO_USERRIGHTS( cUserName, cRights ) --> lSuccess LETO_USERFLUSH() --> lSuccess LETO_USERGETRIGHTS() --> cRights 7.9 Server variable management functions LETO_VARSET( cGroupName, cVarName, xValue[, nFlags[, @xRetValue]] ) --> lSuccess This function assign value <xValue> to variable <cVarName> from group <cGroupName> Optional parameter <nFlags> defines function mode: LETO_VCREAT - if variable doesn't exist, it's created; LETO_VOWN - own user variable (free after user disconnect); LETO_VDENYWR - write deny for other users; LETO_VDENYRD - read deny for other users; LETO_VPREVIOUS - retusn previos value to <xRetValue> parameter. LETO_VARGET( cGroupName, cVarName ) --> xValue Function return value of variable <cVarName> from group <cGroupName> LETO_VARINCR( cGroupName, cVarName ) --> nValue Function increment value of variable <cVarName> from group <cGroupName> LETO_VARDECR( cGroupName, cVarName ) --> nValue Function decrement value of variable <cVarName> from group <cGroupName> LETO_VARDEL( cGroupName, cVarName ) --> lSuccess Function delete variable <cVarName> from group <cGroupName> LETO_VARGETLIST( [cGroupName [, nMaxLen]] ) --> aList Function return two-dimensional array with variables: { {<cVarName>, <value>}, ...} 7.10 Calling udf-functions on the server LETO_UDF( cSeverFunc, xParam1, ... ) --> xResult This function is called from client application. A string <cServerFunc> contains a server connection string and name of udf function: //ip_address:port/funcname A <funcname> function should be defined on the letodb server. The first parameter of udf function is nUserStru. Udf function can return result (any type) to client. Examples of udf-functions are in the tests/letoudf.prg LETO_UDFEXIST( cSeverFunc ) --> lExist leto_udfExist check the existance of udf-function at the letodb server. <cSeverFunc> parameter is the same as for leto_udf(). LETO_PARSEREC( cRecBuf ) --> nil This function is necessary for calling, if udf-function returns as result the buffer of record which should be current after of it works. LETO_PARSERECODRS( cRecBuf ) --> nil This function is necessary for calling to fill the skip-buffer as a result of udf-function UDF_dbEval. After calling this function, the data from the skip-buffer can be received by dbSkip() calls. See sample in comments for UDF_dbEval() in tests/letoudf.prg 7.11 Functions for bitmap filters If letodb compiled with rdd BMDBFCDX/BMDBFNTX, then there is support the following functions: LBM_DbGetFilterArray() --> aFilterRec LBM_DbSetFilterArray( aFilterRec ) --> nil LBM_DbSetFilterArrayAdd( aFilterRec ) --> nil LBM_DbSetFilterArrayDel( aFilterRec ) --> nil Purpose and the parameters of these functions is the same as for the corresponding functions BM_*. LBM_DbSetFilter( [<xScope>], [<xScopeBottom>], [<cFilter>] ) -> nil This function set bitmap filter by current index order and for condition, defined in <xScope>, <xScopeBottom>, <cFilter> parameters. The current record after LBM_DbSetFilter() is the first record satisfying filter condition. 8. Management utility There are two management utilities, GUI and console, the sources are in utils/manage directory. GUI utility, manage.prg, is made with the HwGUI library. If you have HwGUI, just write in the line 'set HWGUI_INSTALL=' in utils/manage/bld.bat a path to your HwGUI directory and run the bld.bat, it will build manage.exe for you. For those, who doesn't use HwGUI, there is a console mode utility, console.prg. Build a console.exe with a make/bat files, which you use to build Harbour single-file programs, you just need to add rddleto.lib to the libraries list. Run the console.exe with a server name or ip and port as a parameter: console.exe server_name:nPort console.exe ip_address:nPort The server_name and ip_address in a command line must be without leading slashes ( '//' ), because Clipper/Harbour interprets them in a special way. 9. Server-side functions These functions can be run from the client by function leto_udf, and also from the functions defined in a file letoudf.hrb. The first parameter such function always nUserStru leto_Alias( nUserStru, cClientAlias ) --> cRealAlias This function return server alias for client alias <cClientAlias>. The server alias then can be user in usial rdd-operations leto_RecLock( nUserStru [, nRecord] ) --> lSuccess leto_Reclock function locked record with <nRecord> number, or a current record. leto_RecUnLock( nUserStru [, nRecord] ) --> Nil leto_RecUnlock function unlocked record with <nRecord> number, or a current record. leto_RecLockList( nUserStru, aRecNo ) --> lSuccess leto_ReclockList function locked records with number in the <aRecNo> array. If any record isn't locked, all records are unlocked, and function returns .F. result. This function can be used at the server from letoodf.prg module, or from client by a call leto_UDF( "leto_RecLockList", aRecNo ). leto_TableLock( <nUserStru>, [<nFlag>], [<Secs>]) --> lSuccess leto_TableUnLock( <nUserStru>, [<nFlag>]) nFlag - parameter from 1 to 32, nSecs - seconds for wait locking (1 by default) These functions are intended for concurrent access to the table for actions except updating of the data. leto_SelectArea( nUserStru, nAreaId ) --> lSuccess leto_areaID( nUserStru ) --> nAreaId Function return internal id of current workarea leto_ClientID() --> nUserStru Function return client ID (nUserStru), -1 if failed letoUseArea( nUserStru, cFileName, cAlias, lShared, lReadOnly, cdp ) --> nAreaId letoOrdListAdd( nUserStru, cBagName ) --> Nil letoOrdCreate( nUserStru, cBagName, cKey, cTagName, lUnique, cFor, cWhile, lAll, nRecNo, nNext, lRest, lDesc, lCustom, lAdditive ) --> Nil letoCloseArea( nUserStru ) --> Nil The functions letoUseArea, letoOrdListAdd, letoOrdCreate, letoCloseArea, leto_RecLock, leto_RecLock is intended for using in udf-functions instead of rdd functions: dbUseArea, OrdListAdd, OrdCreate, dbCloseArea, RLock, dbUnlock Server variable management functions: LETO_VARSET( nUserStru, cGroupName, cVarName, xValue[, nFlags ) --> lSuccess LETO_VARGET( nUserStru, cGroupName, cVarName ) --> xValue LETO_VARINCR( nUserStru, cGroupName, cVarName ) --> nValue LETO_VARDECR( nUserStru, cGroupName, cVarName ) --> nValue LETO_VARDEL( nUserStru, cGroupName, cVarName ) --> lSuccess LETO_VARGETLIST( nUserStru, [cGroupName, [lValue]] ) --> aList Zip/Unzip functions: leto_Zip( nUserStru, [cDirName], [acFiles], [nLevel], [lOverwrite], [cPassword], [acExclude], [lWithPath] ) --> cZip leto_UnZip( nUserStru, [cDirName], cZip, [cPassword], [lWithPath] ) --> lSuccess parameters: cDirName - directory relatively DataPath; cZip - archive body to unzip; other parameters is the same as parameters of hb_ZipFile/hb_UnZipFile functions. Calling functions from a client: leto_UDF("leto_Zip", [cDirName], ...) leto_UDF("leto_UnZip", [cDirName], cZip, ...) 
