在 Ubuntu 18.04 VM (VirtualBox) 上运行的 Shiny Server 应用程序存在 OpenStreetMaps 问题（Java 错误）

Question

I am new to Shiny Server and not well versed in Linux so bear with me.

I'm running Shiny Server on Ubuntu 18.04, which is a virtual machine (VirtualBox). I am employing the OpenStreetMaps package in my app, which uses the rJava package. I had some trouble getting the rJava and OpenStreetMaps packages installed but finally managed after manually installing Java Runtime Environment and Java Development Kit with the terminal commands below:

* sudo apt update
* sudo apt install default-jre
* sudo apt install default-jdk
* sudo R CMD javareconf
* sudo su - -c "R -e \"install.packages('rJava', repos='https://cran.rstudio.com/')\""
* sudo su - -c "R -e \"install.packages('OpenStreetMap', repos='https://cran.rstudio.com/')\""

All packages are in a global library /usr/local/lib/R/site-library.

When running the app through Shiny Server the error I get is:

ERROR: An error has occurred. Check your logs or contact the app author for clarification.

When running the app through RStudio server I get the following error:

Error in .jcall("java/lang/Class", "Ljava/lang/Class;", "forName", cl, : RcallMethod: cannot determine object class

Error in .jfindClass(as.character(class)) : Java Exception .jfindClass(as.character(class))new("jobjRef", jobj = , jclass = "java/lang/Throwable")

Warning: Error in .tryJava: Java classes could not be loaded. Most likely because Java is not set up with your R installation.

Here are some trouble shooting tips:

1. Install Java (for mac consider installing java 1.6 from https://support.apple.com/kb/DL1572?locale=en_US )

2. Run R CMD javareconf in the terminal. If you are using Mac OS X >= 10.7 you may want to try R CMD javareconf JAVA_CPPFLAGS=-I/System/Library/Frameworks/JavaVM.framework/Headers instead.

   188: stop

   187: .tryJava

   186: openmap

   185: [/home/amsp/Documents/MobileLab/app.R#326]

   183: .func

   180: contextFunc

   179: env$runWith

   172: ctx$run

   171: self$.updateValue

   169: map.latlon

   167: renderPlot [/home/amsp/Documents/MobileLab/app.R#347]

   165: func

   125: drawPlot

   111: reactive:plotObj

   95: drawReactive

   82: origRenderFunc

   81: output$plot_map1

   1: runApp

I've tried to run Run R CMD javareconf and it doesn't solve this issue.

Checking Java yields:

java -version

openjdk version "11.0.6" 2020-01-14

OpenJDK Runtime Environment (build 11.0.6+10-post-Ubuntu-1ubuntu118.04.1)

OpenJDK 64-Bit Server VM (build 11.0.6+10-post-Ubuntu-1ubuntu118.04.1, mixed mode, sharing)

javac -version

javac 11.0.6

I'm wondering if maybe it is a permissions problem? Any help would be greatly appreciated! Thank you!

Answer 1

Turns out the whole thing seems like a versioning issue. OpenStreetMap doesn't seem to like Java 11, but most things are generally compatible with 8.

Reboot the VM to get a clean start and don't try to access either shiny or Rstudio before executing. Remove Java 11 and install java 8

sudo apt-get remove openjdk-11*

sudo apt-get install openjdk-8*

sudo R CMD javareconf

sudo service rstudio-server restart

sudo service shiny-server restart

Then accessed Shiny and it worked.