Shiny App that establish connection between R and Aspen Plus

[pboliveira]

I'm trying to create a shiny app that will explore the connection between R and Aspen Plus (a chemical process simulator).

I was able to establish this connection successfully using the RDCOMClient package.

Below is an example of this connection:

# Package
library(RDCOMClient)

# COM Object
Aspen <- RDCOMClient::COMCreate("Apwn.Document")

# Path to .bkp simulation file
Path <- "C:/Users/Pedro/Desktop/RAspen/pump.bkp"

# Invoke COM Object
RDCOMClient::.COM(obj = Aspen, name = "InitFromFile2", Path)

Aspen[["Visible"]] <- TRUE
Aspen$visible()
Aspen[["SuppressDialogs"]] <- 1
Aspen$SuppressDialogs()

# Reinitialize Simulation
Aspen$Reinit()

# Run Simulation
Aspen$Run2()

# Calling variable result from simulation 
Aspen$Application()$Tree()$FindNode('/Data/Blocks/P1/Input/PRES')$Value()

# Close Aspen Plus
Aspen$Close()

The problem I'm having occurs when trying to create a shiny app with a numeric input that represents a input variable from the simulation. The Aspen$Application()Tree() FindNode("/Data/Blocks/P1/Input/PRES")$Value() code represents the output pressure of a pump and has an initial value of 15 bar.

When I put this expression as the value of a numeric input I get the following error: Error in force (default): attempt to apply non-function. I don't understand why the code works in a regular R script but not in a shiny app

Any idea?

Here is my shiny app:

{# Pacotes -----
  library(shiny)
  library(RDCOMClient)
}

{# Aspen Plus Connection -----
  # COM Object
  Aspen <- RDCOMClient::COMCreate("Apwn.Document")
  
  # Path to .bkp simulation file
  Path <- "pump.bkp"
  
  # Invoke COM Object
  RDCOMClient::.COM(obj = Aspen, name = "InitFromFile2", Path)
  
}

{# UI -----
  ui <- fluidPage(
    
    titlePanel("Aspen Plus Simple Pump Simulation"),
    
    sidebarLayout(
      sidebarPanel(
        fluidRow(
          actionButton(
            inputId = "runAspen",
            label = "Run",
            icon = icon("arrow-alt-circle-right"),
            width = "100%"
          )
        ),
        br(),
        fluidRow(
          actionButton(
            inputId = "closeAspen",
            label = "Fechar Simulação",
            icon = icon("times"),
            width = "100%"
          )
        ),
        br(),
        fluidRow(
          numericInput(
            inputId = "dischargePressureP1",
            label = "P1 Discharge Pressure",
            # value = 5,
            value = (Aspen$Application()$Tree()$FindNode("/Data/Blocks/P1/Input/PRES")$Value()),
            min = 1,
            max = 100,
            step = 1
          )
        )
      ),
      
      mainPanel(
        
      )
    )
    
  )
}

{# SERVER -----
  server <- function(input, output, session) {
    
    observeEvent(input$closeAspen, {
      # Close Aspen Plus
      Aspen$Close()
    })
    
    observeEvent(input$runAspen, {
      # Reinitialize Simulation
      Aspen$Reinit()
      # Run Simulation
      Aspen$Run2()
    })
    
    
    
  }
}

shinyApp(ui = ui, server = server)