• A5_defineAliases Function
• a5_force_close_all Function
• a5wcb_createDialogUsingXbasic Function
• compile_module Function
• evaluate_for_object Function
• evaluate_for_output Function
• evaluate_with Function
• hasChildRecords Function
• node_request Function
• node_request_result Function
• showvarscript Function
• Xbasic Functions and Methods
• xbasic_caller_execution_level Function
• xbasic_engine_logging_end Function
• xbasic_engine_logging_enum Function
• xbasic_engine_logging_get Function
• xbasic_engine_logging_set Function
• xbasic_engine_logging_start Function
• xbasic_eval_context_add Function
• xbasic_eval_context_drop Function
• xbasic_eval_context_eval Function
• xbasic_eval_context_listener Function
• xbasic_eval_context_send Function
• xbasic_eval_context_send_object Function
• xbasic_execution_level Function
• xbasic_extract_functions Function
• xbasic_remove_duplicate_dims Function
• xbasic_remove_functions Function
• xbasic_script_cleanup Function
• xbasic_script_compile Function
• xbasic_script_tokenize Function
• xbasic_search_replace Function
• xbasic_stack_function Function
• xbasic_stack_variable_get Function
• xbasic_stack_variables_dump Function
• xbasic_system_of_eq Function
• xbasic_trace_pause Function
• xbasic_trace_resume Function
• xbasic_variable_scope Function
• xbasic_variables_aggregate Function

node_request Function

Syntax

Arguments

nodeService

Name of the node service to run.

pData

Pointer to parameters to pass to the node service.

flagRestartNode

.t. or .f. value. Default .f.

Flag indicating whether or not the node server should be restarted when node_request is called. .t. restarts the node server. Restarting the node server can be useful for debugging purposes. flagRestartNode should be set to .f. in a production environment.

flagShowCommandWindow

.t. or .f. value. Default .f.

Show the command window for the node service handler (allows developer to see feedback using console.log() in the handler).

flagAllowDebug

.t. or .f. value. Default .f.

Enable node debugger (requires that the node debugger be launched).

Description

Calls a node service from Xbasic. Returns a JSON string.

The node_request function calls a node service for a web project. The web project must include a 'node_services' folder with the named node service. If the service is not present in the project, you will receive an error from node.

Below is an example call - it assumes a node service called 'eval' that reads javascript to execute from a 'content' property, then returns the result.

dim req as p
dim req.content as c = "1+1"
? node_request("eval",req)
= {"_id":"d18fa451-5c15-4cbf-8085-92fe24890e4d","error":"command eval was not recognized for command d18fa451-5c15-4cbf-8085-92fe24890e4d","result":null}

Add a node_services to the projects 'node' subfolder - save a file called 'eval.js' that has the following contents:

exports.handler = function(packet,response,sendResponse) {
	var e;
	var attachments = null;
	try {
	    response.result = eval(packet.content);
	    if( Buffer.isBuffer(response.result) ) {
	    	attachments = [{ name : 'data' , type : 'binary' , data : response.result }];
	    	response.result = 'binary data in attachment';	    	
	    }
	} catch( e ) {
	    response.error = e.message;
	}
	sendResponse(response,attachments);
};

The node service handler consumes a 'packet' that contains the parameters for the command. In this case, the parameter required is called "content", and gets evaluated, data is returned in a result parameter.

With 'node_services/eval.js' defined, now our example should work, notice that the result of evaluation is in a field called 'result', notice also that 'error' is blank.

dim req as p
dim req.content as c = "1+1"
? node_request("eval",req)
= {"_id":"d21a4938-d8bd-455f-9e82-e70bcc675316","error":"","result":2}

An example of a valid request with a handled error would be to pass a javascript expression that is invalid.

dim req as p
dim req.content as c = "1+"
? node_request("eval",req)
= {"_id":"4bee3d41-7816-4f0c-8b3f-ca853fa2ef0c","error":"Unexpected end of input","result":null}

Automatic Node Restart

If you edit a Node Service, Alpha Anywhere will automatically set flagRestartNode to .T. in Live and Working Preview. If Node is not restart, any changes made to a Node Service will not be detected.