Shiny - Updating global variable and seeing the result in current session - shiny

Question

I am working with global variables that update after time X. This issue I am coming across is it updates the global variable but the current session doesn't update accordingly, however, any new session open uses the updated global variable.
Question: how do I get the current session to use the updated global variable? I thought wrapping it in a reactive would work but it doesn't.
Code:
library(shiny)
library(shinydashboard)
####/GLOBAL/####
num <- 4
####/UI/####
header <- dashboardHeader()
sidebar <- dashboardSidebar()
body <- dashboardBody(
verbatimTextOutput("test")
)
ui <- dashboardPage(header, sidebar, body)
####/SERVER/####
server <- function(input, output, session) {
data <- reactive({num})
output$test <- renderText({ data() })
observe({
invalidateLater(0.5*60*1000,session)
num <<- sample(1:1000,1,replace=T)
})
}
shinyApp(ui, server)
If you wait 30+ seconds and then open up a new session you will see that the number has changed from 4 but the original session still shows 4. They should be showing the same number.

Answer 1

Solved! Realized I needed to wrap it in a reactiveValues versus reactive. I also made the updating a value a dataframe versus a single number because that fits my real dashboard's problem.
library(shiny)
library(shinydashboard)
####/GLOBAL/####
dataset <- data.frame(ColA = c("dogs", "cats", "birds"), ColB = c(10, 2, 2), stringsAsFactors = FALSE)
####/UI/####
header <- dashboardHeader()
sidebar <- dashboardSidebar()
body <- dashboardBody(
box(width = 3, tableOutput("test"))
)
ui <- dashboardPage(header, sidebar, body)
####/SERVER/####
server <- function(input, output, session) {
values <- reactiveValues(n = dataset)
data <- reactive({values$n})
output$test <- renderTable({ data() })
observe({
invalidateLater(0.5*60*1000,session)
new1 <- sample(1:10,1,replace=T)
new2 <- sample(1:10,1,replace=T)
new3 <- sample(1:10,1,replace=T)
print(new1)
print(new2)
print(new3)
dat <- data.frame(ColA = c("dogs", "cats", "birds"), ColB = c(new1, new2, new3), stringsAsFactors = FALSE)
values$n <- dat
dataset <<- dat
})
}
shinyApp(ui, server)