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Version: 5.x

EXTERNAL operator

The EXTERNAL operator creates an action that implements accessing to an external system.

Syntax​

EXTERNAL externalCall [PARAMS paramExpr1, ..., paramExprN] [TO propertyId1. ..., propertyIdM]

externalCall - an external call defined by one of the following syntaxes:

HTTP [requestType] connectionStrExpr [BODYURL bodyStrExpr] [HEADERS headersPropertyId] [COOKIES cookiesPropertyId] [HEADERSTO headersToPropertyId] [COOKIESTO cookiesToPropertyId]
TCP [CLIENT] connectionStrExpr
UDP [CLIENT] connectionStrExpr
SQL connectionStrExpr EXEC execStrExpr
LSF connectionStrExpr lsfExecType execStrExpr

Description​

The EXTERNAL operator creates an action that makes a request to an external system.

Parameters​

  • HTTP

    Keyword. Specifies that the operator is executing a web server HTTP request.

  • requestType

    Keyword. Defines the method of the HTTP request:

    • POST
    • GET
    • PUT
    • DELETE

    The default value is POST.

  • TCP

    Keyword. Specifies that the operator is executing a TCP request.

  • UDP

    Keyword. Specifies that the operator is executing a UDP request.

  • CLIENT

    Keyword. Specifies that the request is executing on the client. By default, the request is executed on the server.

  • SQL

    Keyword. Specifies that the operator executes an SQL server command or commands.

  • LSF

    Keyword. Specifies that the operator executes an action of another lsFusion server.

  • connectionStrExpr

    Expression. HTTP: http request string. SQL: DBMS connection string. LSF: URL of an lsFusion server (application).

  • bodyStrExpr

    Expression. Continuation of http request string in BODY. Relevant when BODY has > 1 parameter. If not specified, the parameters are passed in multipart format.

  • headersPropertyId

  • headersToPropertyId

    Property ID containing request headers. The property must have exactly one parameter: the name of the request's header. This parameter must belong to a string class. If the property is not specified, headers are ignored/not set.

  • cookiesPropertyId

  • cookiesToPropertyId

    Property ID containing request cookies. The property must have exactly one parameter: the name of the cookie. This parameter must belong to a string class. If the property is not specified, cookies are ignored/not set.

  • lsfExecType

    Keyword. Specifies the way of defining the action:

    • EXEC – the name of the action is specified.
    • EVAL – the code of the action is specified in the lsFusion language. It is assumed that this code contains a declaration of an action named run. This is the action that will be called.
    • EVAL ACTION – the action code in the lsFusion language is specified. To access a parameter, the special character $ and the parameter number (starting from 1) are used.

  • execStrExpr

    Expression. SQL: SQL query command(s). LSF: The name of an action or code, depending on how the action is defined.

  • paramExpr1, ..., paramExprN

    List of expressions whose values will be used as the call parameters.

  • propertyId1, ..., propertyIdM

    List of property IDs (without parameters) to which the results will be written.

Examples​

testExportFile = DATA FILE ();

externalHTTP()  {
    EXTERNAL HTTP GET 'https://www.cs.cmu.edu/~chuck/lennapg/len_std.jpg' TO exportFile;
    open(exportFile());
    // braces are escaped as they are used in internationalization
    EXTERNAL HTTP 'http://tryonline.lsfusion.org/exec?action=getExamples' 
             PARAMS JSONFILE('\{"mode"=1,"locale"="en"\}') TO exportFile; 
    IMPORT FROM exportFile() FIELDS () TEXT caption, TEXT code DO
        MESSAGE 'Example : ' + caption + ', code : ' + code;

    // passes the second and third parameters to BODY url-encoded
    EXTERNAL HTTP 'http://tryonline.lsfusion.org/exec?action=doSomething&someprm=$1' 
             BODYURL 'otherprm=$2&andonemore=$3' PARAMS 1,2,'3'; 
}
externalSQL ()  {
    // getting all barcodes of products with the name meat
    EXPORT TABLE FROM bc=barcode(Article a) WHERE name(a) LIKE '%Meat%';
    // reading prices for read barcodes 
    EXTERNAL SQL 'jdbc:mysql://$1/test?user=root&password=' 
             EXEC 'select price AS pc, articles.barcode AS brc from $2 x JOIN articles ON x.bc=articles.barcode' 
             PARAMS 'localhost', exportFile() 
             TO exportFile; 

    // writing prices for all products with received barcodes
    LOCAL price = INTEGER (INTEGER);
    LOCAL barcode = STRING[30] (INTEGER);
    IMPORT FROM exportFile() TO price=pc,barcode=brc;
    FOR barcode(Article a) = barcode(INTEGER i) DO
        price(a) <- price(i);
}
externalLSF()  {
    EXTERNAL LSF 'http://localhost:7651' EXEC 'System.testAction[]';
};