Stephen Fry

"Education is the sum of what students teach each other in between lectures and seminars. " - Stephen Fry

Monday 16 July 2012

Running the Ocaml Server - Demo Pt 1

I've got some code here and here in OCaml & Java, that I have been tasked with running, testing and fixing. I've already taken a look at the basic syntax but now its time to get to grips with some the libraries and related packages that Signposts makes use off.


The first thing that took me by surprise was the number of files in the repo, considering that this is suppose to be a fairly straight forward project.


The repo contains a file called “_oasis”, which on closer inspection includes a collection of metadata on the project. OASIS is a tools to integrate a configure, build and install system into an OCaml project. The _oasis files tells me that the entry point for the program is “” and the build dependences are the findlib packages lwt.syntax, lwt.unix, re, re.str.

The creater of the program will have ran oasis setup”, which has generated, _tags and

According to the instructions for OASIS you can configure, build and install the Ocaml program using:

  • ocaml -configure

  • ocaml -build

  • ocaml -install


The file makes use of Re_str and two of the biuld dependences are the findlib packages re and re.str. I have found the packages here on github. Re stands for Regular expression and ocaml-re is a regular expression library doe Ocaml (that is still under development). This project has also made use of OASIS and installs without a problem

Compiling the Code

I cd into the directory and run ocaml -configure, ocaml -build and ocaml -install. This generates a new dirctory “_biuld” and a new link to an executable in _biuld

Running the Code

I run a link to the execuated in _biuld and it return the following error:
Fatal error: exception Unix.Unix_error(50, "bind", "")

This means that the socked that the code is try to bind to is already in use. I inspected the code, identified the ports that were being used and ran “sudo netstat -ap | grep ':<portnumber>' “. This identified a process already using the port, the process was in fact an earlier attempt to run the project. I identified the process ID and killed the process, re-running “sudo netstat -ap | grep ':<portnumber>' “ showed that the port was now free. I can now happily run the executable in the _build directory. As this is a client-server implementation, I now need to move my attention to the client code

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