On Fri, 2010-08-20 at 12:58 -0400, Sharpie wrote: > > Donald Paul Winston wrote: > > > > Aren't you the guy who created Rserve? > > > > I'd like to develop a web app so clients can perform exploratory data > > analysis with their browser with no installed software, not even java (I > > don't like applets). I thought R would be excellent for this but I need > > some issues cleared up before I invest a lot of time working with it. > > > > Well, Simon is the one who create Rserve. However, if you have questions > about Rserve it may be best to start a new thread or at least change the > subject header of your message. This discussion was about creating > stand-alone executables that use R code for deployment on a desktop. > > > Donald Paul Winston wrote: > > > > It appears R insists on directing plot output to a file. Is their a > > graphics device that keeps the output in memory so it can be returned to > > my java app as a stream of bytes? If I have to wait for it to write to a > > "unique file" and then read it back again then I don't think that's going > > to work. My web app needs to support hundreds of concurrent clients. > > > > As far as I know all R graphics output that does not go to a screen device, > such as an X window, must be directed to some sort of file. I am not aware > of a graphics device that provides output to something other than a screen > or a file, but there very well may be such a device in existence.
This was essentially the conclusion of Donald's earlier thread... > The functionality you could describe could be implemented by writing a R > graphics device that forwards the R plotting commands to... well anywhere > you want, really. As the author of an R graphics device, I can say the > trickiest part of such an undertaking will be calculating font metrics so > that R can properly position text in the graphics. Everything else is very > straight-forward. I believe Donald wants the _rendered_ output. That is, a stream of bytes that represent a png, jpeg, etc. Toward this end, we have already discussed using an OS-level fifo to avoid disk I/O, and I think this is the easiest route for Donald. Alternatively, Donald might look into the X11 graphics driver, where Cairo is used to write pngs. In particular, the in_do_saveplot function (src/main/modules/X11/devX11.c) calls cairo_surface_write_to_png, in order to save a png to file. Cairo also provides the cairo_surface_write_to_png_stream function, which might be used to send png data to a memory buffer (i.e. a raw vector). I don't think it would be too difficult to modify in_do_saveplot to accommodate this. > I have plans to write a device that forwards the plotting commands to a > socket connection that allows another program to execute them. In my case, > an Erlang backbone is used to route the results back to web clients using > websockets. The idea is to have the plot rendered directly in the client's > browser using a JavaScript library like RaphealJS. However, the school year > is upon me and the project will probably remain on the drawing board until > next summer. > > > Donald Paul Winston wrote: > > > > Is REngine.jar and REngineRserve.jar all I need in my web app? > > > > I can't comment on REngine as I have not used it. > > > Donald Paul Winston wrote: > > > > Also, how come their is no shutdown command from the command line for > > Rserve. I see one in the java client api. Do I have to write my own? > > > > I find that on UNIX a SIGTERM, SIGSTOP or SIGKILL signal broadcast using a > command line utility such as kill does the job. > > -Charlie > > ----- > Charlie Sharpsteen > Undergraduate-- Environmental Resources Engineering > Humboldt State University -- Matthew S. Shotwell Graduate Student Division of Biostatistics and Epidemiology Medical University of South Carolina ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
