R seasonal forecasting service in Rook

rook_forecast.R

app <- function(env){
  req <- Rook::Request$new(env)
  res <- Rook::Response$new()
  
  inputData <- gsub("##","\n",req$POST()[['data']])
  write(inputData, file = "inputData.txt")
    
  
  d <- read.table( "inputData.txt", sep=",", header=TRUE, row.names=1 )
  d.startY <- as.integer( substr( row.names(d)[1], 1, 4 ) )
  d.startM <- as.integer( substr( row.names(d)[1], 6, 7 ) )
  d.ts <- ts( d, start=c(d.startY,d.startM), frequency=12 )

  library(forecast)
  
  d.hw <- HoltWinters(d.ts, beta=TRUE, gamma=TRUE, seasonal="additive")
  
  d.forecast <- forecast(d.hw)
  
  lastval = window(d.ts,start=end(d.ts),end=end(d.ts))
  combined = ts.union(lastval,d.forecast$mean)
  combined[ is.na(combined) ] <- 0
  combined <- combined[,1]+combined[,2]
  
  output <- combined
  
  names <- as.character(as.Date(time(output)),format="%Y-%m")
  write.table(output,file="outputData.txt",row.names=names,
              col.names=FALSE,eol="##",sep=",",quote=FALSE)
  
  outputData <- scan("outputData.txt",what="character")
  res$write(outputData)
  res$finish()
}