Author Archives: Heidi-ann

System programming in OCaml – Part 2

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Now we are going to take a look at manipulating files in OCaml. We will be focusing on the Unix file system.

In Unix the term “file” refers to a greater range of objects that you might expect. This includes:

  • standard files like .txt, .html, .doc or .ml
  • directories (or folders if your used to windows) like /photos or /music
  • symbolic links (or shortcuts if your used to windows)
  • special files to access devices i.e. files in /dev
  • named pipe ( this is a named version of using | in the terminal )
  • sockets

All files are represented by an i-node, a data structure which holds the meta-data on the file. Directories are files that map filenames to i-nodes. The directories form a tree structure, where all files are directly or indirectly children of the root directory called ‘/’.

A absolute path name of the file is one that begins at the root. A relative path name is one that begins in the current directory. Every directory has ‘.’ and ‘..’ which are symbolic links to the current and parent directories.

OCaml makes use of the Filename module to help handle paths in a portable manner

LaTeX – The IEEE Surveys & Tutorials Way (Pt 2)

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This the second article in a series on using the IEEEtrans and LaTeX to form a survey suitable for submission to IEEE surveys & tutorials

Yesterday’s article made use of the bare bones template for journals provided by IEEEtrans, now we are going to look at the requirements of a survey in IEEE surveys & tutorials

IEEE Surveys & Tutorials

The following information is largely taken from the Information for Authors page, on the IEEE Communications Surveys & Tutorials site.
The focus of this article is a survey not a tutorial, therefore all of the points below are regarding surveys and not necessary tutorials.

IEEE Communications Survey & Tutorials is a free online journal published by the IEEE Communications Society. Article appear in both the IEEE Xplore Electronic Library and the IEEE ComSoc Digital Library

To finding existing surveys to read and use as examples, you can sign up to a guest account with IEEE ComSoc Digital Library which will give you free access, at the time of writting, the IEEE ComSoc Digital Library website was down, so I’ve not yet been able to verify this.

IEEE Communications Surveys and Tutorials is targeted for the generalist throughout the field of communications and communications networking. Intended readers include those involved in research, development, deployment, or instruction in fields related to communications.

All surveys should be tutorial in nature and should be written in a style comprehensible to readers outside the speciality of the article.

Typically, mathematical equations should be kept to a minimum, and not be used unless they are vital to the presentation. Articles intended to instruct in a mathematical area should be presented at a level comprehensible to readers with appropriate backgrounds, and the appropriate background should be carefully delineated in the introductory section of the article.

The term survey, as applied here, is defined to mean a survey of the literature. A survey article in IEEE Communications Surveys & Tutorials should provide a comprehensive review of developments in a selected area, covering its development from its inception to its current state and beyond, and illustrating its development though liberal citations from the literature. Such citations would naturally lead to an authoritative and comprehensive bibliography. The objective is to provide the reader with a sense of the history, development, and future of the topic area, including its interactions with other areas, and enough information to comprehend the development and identify the major players.

As an example, the article “A survey of markup languages” might discuss a number of markup languages, such as WML, XML, HTML, CHTML, and voiceXML. The article might define the term “markup language” and describe some general features and objectives by way of introduction. The article might then provide a time-line of events leading to the advent of markup languages, citing major milestones and breakthroughs. From there, the article might describe the markup languages in chronological order, showing how previous languages developed from previous ones through liberal citations to the literature. The article might conclude by giving the author’s well-thought-out opinions on the future.

References must be numbered sequentially, not alphabetically. The basic reference format is: [#] L. Brakmo and L. Peterson, ” TCP Vegas: End to End Congestion Avoidance on a Global Internet,” IEEE JSAC, vol. 13, no. 8, Oct. 1995, pp. 1465-80.

Authors must clearly state the category of the article in the abstract and again in the introductory section and also clearly state the scope of the article. For example, there must be a statement of the form “This article surveys the literature over the period 1990-2001 on turbo codes as they apply to wireless communications.”

Authors are encouraged to consider inclusion of multimedia materials in cases where such material would substantially improve the value of the article to the reader. HOW ???

Figures and tables should be used liberally. 

There are no limits on paper length, number of figures, references, etc.

Required formats for electronic submission is PDF.
Submit survey’s using the LaTex structure. Include the compiled pdf, figures (as eps files with fonts embedded), bios and photos in the final article, keywords, and abstract
(Note: For the best presentation of your article’s entry in IEEE Xplore, do not include equations in the abstract.)

Once the survey is complete it’s submitted via the ManuscriptCentral website

Ocaml 2 HTML

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As I’m often adding OCaml code to blog posts I really wanted to find an automatic way to add syntax highlighting. The first solution that I have found is caml2html but I’m still looking for something better … suggestions welcome

System programming in OCaml – Part 1

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This series of articles will follow my journey through “Unix system programming in OCaml”, available as a pdf here. After this series, I hope to move onto a series on Mirage system programming in OCaml and working with Signposts (a framework for managing end-to-end connectivity between devices using DNS infrastructure for signalling)

Introducing the Sys and Unix

The modules that give access to the system in OCaml are:

  • Sys – functions common to all OS’s that run OCaml
  • Unix – functions specific to unix

To make use of these modules in some OCaml code, we can add open Sys or/and open Unix to the top of the OCaml program.

NOTE that Unix and Sys can overwrite some of the functions in the Pervasive module, so to access a function from the Pervasive module you need to add Pervasives. in front of the function call.

When using ocamlc to compile OCaml programs that made use of  Unix, you need to pass unix.cma to the compiler e.g.

$ ocamlc unix.cma hello.ml -o hello

The same is not true of sys.cma

PASSING INFORMATION TO YOUR PROGRAM

Now we are going to consider 2 different ways of passing information from your terminal to your ocaml program

1) Passing the information as arguments to the executable. For this we are going to use Sys.argv which will return a string array of arguments passed to the program. The first index of the argument array that we use here is 1, this is because the 0th element in the array is the command used to call the program. Consider the following simple example:

open Sys;;
print_string argv.(1)
Now provided that at least one argument is passed to the program, this argument will be printed. We can now extend this program, to print the number of arguments and then exactly what the user will have just entered
open Sys;;

let args = Array.length argv;;
print_int args ;;
print_newline ();;
for i=0 to args-1 do
print_string argv.(i);
print_char ‘ ‘;
done;

2a ) Passing information using the environment variables, this can be fetched from within the OCaml programing using Sys.enviroment, this will return as array of environment variables

open Unix;;

let env = environment();;
for i=0 to (Array.length env) -1  do
print_string env.(i);
print_newline);
done;

Don’t forget then when you compile this, you need to add unix.cma to the command as we are making use of the Unix library

2b ) We can also lookup the values of environment variables using the Sys.getenv (or Unix.getenv) functions that takes a variable name and returns the value associated with it

open Sys;;

let var = argv.(1);;
print_string (getenv var)

Exceptions

Unless otherwise stated in the documentation, all function in the Unix module raise the exception Unix_error.

Exception Unix_error of error * string * string

The first argument is the error code, the second argument is the name of the system call that raised the error and third argument identifies the object on which the error was called.

If an exception reaches the top-level then the program will halt. The Unix module provides a function for clearly describing exceptions. We can make 2a use this function as follows:

open Unix;;

let prog () = 
  let env = environment();;
for i=0 to (Array.length env) -1  do
print_string env.(i);
print_newline);
done;
 done;

 handle_unix_error prog ();;

LaTeX – The IEEE Surveys & Tutorials Way (Pt 1)

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This article aims to give an overview of setting out a survey for submission to an IEEE Journal.

For this article, I will be using ubuntu 12.10, 32 Bit and Vim as my text editor.

IEEEtran is the offical LaTeX class for authors of IEEE transaction journals and coferences

My primary source of information for this article is the latest version of the IEEEtran package IEEEtrans director. Other helpful information is available here.

INSTALLATION & SETUP

The essential book on LaTeX

The IEEEtrans directory (as linked above) includes a “bare bones example of a IEEE journal, called bare_jrnl.tex. We will now use the IEEEtran LaTeX class to compile this .tex file into a pdf file.

To find out the location that we need to place IEEEtran.cls in, use:

$ locate article.cls

For me, the first location returned is /usr/share/texlive/texmf-dist/tex/latex/base/article.cls

I now need to move the IEEEtran.cls that I download into the same directory as article.cls. So move the the IEEEtrans directory and execute:

$ sudo cp  IEEEtran.cls

You can now tell Tex about this new LaTeX class using:

$ sudo texthash

Latex is already installed on my system but to allow us of the IEEEtran class, you may also need:

$ sudo apt-get install texlive-fonts-recommended

If you get an error of the form:

Font OT1/ptm/m/n/9=ptmr7t at 9.0pt not loadable: Metric (TFM) file not found
Then it is likely that you need to install the texlive-fonts-recommended package.
Now we are going to compile the bare_jrnl.tex, by moving to its directory and excauting:
$ latex bare_jrnl.tex
You can now view the outputted document using:
$ xdvi bare_jrnl
NEXT STEPS
Now you have a bare bones copy of your paper, you can customize it to meet your specific requirements and add the content of your paper. I will look at this in more detail tomorrow. is the Information for Authors

Signposts – The installation

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This is a guide to the installation of Signpost on a 64 bit edition of ubuntu 12.04.

The steps of the installation process are:

1    install OCaml
2    install and set up OPAM
3    use OPAM to install the latest OCaml compiler and switch to this new compiler version
4    Add the remote repositories required for signposts to OPAM
5    Install the libraries required using OPAM
6    Download the code for signpost
7    Set up vswitch
8    Generate and place keys
9    Install iodine and set up password
10    Run Signposts

1 INSTALLING OCAML
OCaml 3.12.1 is available from the ubuntu repositories, this is not a up to date version of the compiler but it will do to bootstrap the process.

$ sudo apt-get install ocaml

2 INSTALLING & SET UP OPAM

OPAM is a useful package manager for OCaml code such as signposts. To download the initialize:

$ git clone git://github.com/OCamlPro/opam.git
$ cd opam && ./configure && make
$ sudo make install
$ opam init
$ eval ‘opam config -env’
$ echo “$ which opam && eval ‘opam config -env'” >> ~/.profile


3 SWITCH TO LATEST OCAML COMPILER
To see the compiler versions avaliable on OPAM use:

$ opam switch -list

To see the version of the OCaml compiler that is currently in use, use

$ ocaml -version

Then switch the OCaml 4.00.1 using

$ opam switch 4.00.1
$ eval ‘opam config -env’

This process may take quite a while. You can now check the version of OCaml again, it it should show that the PATH is now pointing towards a new OCaml compiler version

4 REMOTE REPOSITORIES

To view the current remote respositories that OPAM is using, enter:

$ opam remote -list

This should give you the following output:

[curl]     default     http://opam.ocamlpro.com

To add the remote respositories required for signposts enter the following:

$ opam remote -kind git -add dev https://github.com/mirage/opam-repo-dev.git
$ opam remote -kind git -add mirage git://github.com/mirage/opam-repo.git

Checking the current remote repositories as before, now returns

[git]       mirage     git://github.com/mirage/opam-repo.git
[git]   mirage-dev     git://github.com/mirage/opam-repo-dev.git
[curl]     default     http://opam.ocamlpro.com


5 INSTALL LIBRARIES

To install the required packages from OPAM and the package manager use:

$ opam install lwt cstruct mirage mirage-net ocamlgraph uri rpc oasis ssl
$ sudo apt-get install libnfnetlink-dev libnl-3-dev libnl-cli-3-dev libnl-genl-3-dev libnl-nf-3-dev libnl-route-3-dev

Some the packages here are not the most upto date, to get the updates

$ git clone https://github.com/crotsos/mirage-platform.git
$ cd mirage-platform/
$ make all install
$ git clone https://github.com/crotsos/mirage-net.git
$ cd mirage-net/
$ make all install
$ git clone https://github.com/crotsos/ocaml-openflow.git
$ cd ocaml-openflow/
$ make all install
$ git clone https://github.com/crotsos/ocaml-dns.git
$ cd ocaml-dns/
$ make all install
$ git clone https://github.com/crotsos/ocaml-crypto-keys.git
$ cd ocaml-crypto-keys/
$ make all install

In the future, you update your packages using:

$ opam update
$ opam upgrade

6 GET SIGNPOST CODE

To download a copy of the Signpost Code using:

$ git clone https://github.com/crotos/signpostd
$ cd signpostd
$ make

7 VSWITCH

$ sudo wget https://www.dropbox.com/s/4n0hwgoycm3838g/openvswitch_mod.ko?dl=1 -O /lib/modules/`uname -r`/extra/openvswitch_mod.ko
$ sudo wget https://www.dropbox.com/s/f7ivv8upe0bfurf/brcompat_mod.ko?dl=1 -O /lib/modules/`uname -r`/extra/brcompat_mod.ko
$ sudo depmod -a
$ modprobe openvswitch_mod
$ sudo modprobe brocompat_mod
$ sudo ovs-vsctl add-br br0
$ sudo ovs-vsctl add-port br0 eth0
$ sudo ifconfig eth0 up
$ sudo ifconfig br0 up
$ sudo ovs-vsctl set-fail-mode br0 standalone
$ sudo ovs-vsctl set-controller br0 tcp:localhost
$ sudo ln -s /etc/init.d/openvswitch-switch /etc/rcS.d/S10openvswitch-switch
$ sudo chmod 777 /etc/network/interfaces
$ echo “pre-up ifconfig eth0 up” >> /etc/network/interfaces

8 KEY GENERATION

For the each client we wish to add to the signposts personal cloud we need to generate a private and associated key. To generate these key we will be using onpenssl. On each client we need to generate the private key and place it into the signposd/conf directory when we need to generate the public key from this and place on the server un signpostd/conf/authorized_keys

on the client

$ openssl genrsa -out conf/signpost.pem 2046

and on the server

$ openssl rsa -in conf/signpost.pem -pubout -out conf/authorized_keys/clientname.pub

9 IODINE

To install iodine from the ubuntu package manager
sudo apt-get install iodine

OpenWrt & Linksys WRT54GL Router – Meet & Greet

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OpenWrt is a firmware for embedded devices used to router traffic. In this case we will be considering the use of OpenWRT in domestic routers such as the test hardware Linksys Wireless-G Broadband Router WRT54GL v1.1.

OpenWrt is Linux based so it included the Linux kernel as well as BusyBox. It has a package manager called opkg (similar to apt in ubuntu).

Before installing OpenWrt on a router, you must enable that the device is OpenWrt compatible, you can do this my ensuring the device is listed here 

HARDWARE SPECIFICATIONS

Before exploring OpenWrt, We are going to take a closer look at the hardware available:

CPU: Broadcom BCM5352 @ 200 MHz
RAM: 16 MB
Flash Memory:  4 MB

QUICK CHECK – to ensure the hardware is what we believe it to be, we can check the prefix of the serial number using the information here 

This hardware is fully supported by OpenWrt, but there have been issues with the limited amount of flash memory:
http://wiki.openwrt.org/toh/linksys/wrt54g#hardware
https://forum.openwrt.org/viewtopic.php?id=28223

The solution to this issues, has also been documented. This is to use OpenWrt 8.09 r14511 (code name “kamikaze”) instead of the most up-to date version OpenWrt 10.03.1-rc6 (code name “backfire”)

PICKING A VERSION

To start with we are going to install OpenWrt in Linksys Web GUI. There are many versions of OpenWrt available, so we need to identify to first version we will try:

  • The OpenWrt version is Kamilaze, due to a bug in backfire and instability of attitude adjustment
  • The recommended version is 8.09 within Kamilaze
  • The CPU is broadcom so the prefix is bcrm
  • For here, i can see the hardware supports both brcm-2.4 and brcm47xx
  • The difference between brcm-2.4 and brcm47xx is explained here 
  • For ease, we will download a image file, this will end with .bin
  • If both JFFS2 and SquashFS is available, use SpuashFS images
  • Look into the version history to determine with version of 8.09 is best and what is different between kamikaze, backfire and attitude adjustment

The image I am going to test is  http://downloads.openwrt.org/kamikaze/8.09/brcm-2.4/openwrt-wrt54g-squashfs.bin

INSTALLATION

Step 1: Download http://downloads.openwrt.org/kamikaze/8.09/brcm-2.4/openwrt-wrt54g-squashfs.bin to my Downloads directory
Step 2: Plug in router to mains and to computer via ethernet (use port 1 not internet port)
Step 3: Direct the browser to http://192.168.1.1 and log in
Step 4: Navigate to Administation > Firmware update, select openwrt-wrt54g-squashfs.bin and update

ALL IS LOOKING WELL 🙂

COMMUNICATION VIA WEB GUI 
Direct the browser to http://192.168.1.1, log in and your presented with the web interface luci

COMMUNICATION VIA TELNET
The router should now be telnet(able) to 192.168.1.1. To test this:
$ telnet 192.168.1.1
This returns the recipe for KAMIKAZE 🙂

Now to ensure that tftp is available to prevent bricking, enter:

  $ nvram set boot_wait=on
  $ nvram set boot_time=10
  $ nvram commit && reboot




 COMMUNICATION VIA SSH



CONFIGURING 



The network configuration is stored in /etc/config/network. The initial contents of this file for our set up is:


The content of the initial configuration file is


 #### VLAN configuration

config switch eth0

option vlan0    “0 1 2 3 5*”

option vlan1    “4 5”


#### Loopback configuration

config interface loopback

option ifname   “lo”

option proto    static

option ipaddr   127.0.0.1

option netmask  255.0.0.0


#### LAN configuration

config interface lan

option type     bridge

option ifname   “eth0.0”

option proto    static

option ipaddr   192.168.1.1

option netmask  255.255.255.0


#### WAN configuration

config interface        wan

option ifname   “eth0.1”

option proto    dhcp


Once we have edited this file, to make the new configuration take after we need to :

$ /etc/init.d/network restart


SWITCH

The switch section of the above configuration file is responsible for making one peoice of hardware, appear as several independent interfaces. The part of the configuration file which specifies the switch characteristics is:


 #### VLAN configuration

config switch eth0

option vlan0    “0 1 2 3 5*”

option vlan1    “4 5”


In the above configuration: The numbers 0-5 represent the port numbers, so VLAN0 includes ports 0 to 5* and VLAN1 includes ports 4 and 5. The * in 5*

indicates the PVID.




As shown in the above diagram, this switch separates the LAN ports and thWAN ports .


INTERFACES

The other statements in the configuration file describe the interfaces. The interfaces are logical networks, for the setting of IP address, routes and other magic.


The 3 interfaces that we have here are named loopback, lan and wan. The physical interfaces associated with these logical interfaces are lo, eth0.0 and eth0.1.


 

					

		
		
	

							
	

				

			
						

				Lots of things to be getting on with …
			

										

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Friends often wonder what I’m working (and so do I sometimes) so here’s my to-do list for the rest of this week:


DOCUMENTING OCAML 




    

  • Review some examples of ocaml code and hows its documented
    • 

  • Investigate if ocamldoc is worth implementing
    • 

  • using ocaml-dns as an example of documentation
    • 

  • put together a blog post of methods of documenting OCaml code and decide a style of documentation that you be useful in Signposts
    • 

  • Next week, work through the core signposts core, adding documentation
    • 



SIGNPOSTS INSTALLATION



    

  • working through the process of installing signposts from a scratch, currently do as far as key generation
    • 

  • Generate the keys required for signpost and potential write a script to help automate the process
    • 

  • Run Signposts on my main machine, test client and server implementation
    • 

  • Next week, follow documentation to set up signposts on an Eee PC  
    • 

  • Produce a clear set on instruction on how to install, set up and run signposts
    • 



UPnP TACTIC FOR SIGNPOSTS


    

  • Research the UPnP interface provided by routers
    • 

  • Review the other signposts tactics to generate an outline of the API for implementing tactics
    • 

  • Next week, Write a tactic in OCaml for signposts that makes use of UPnP, use the method of documenting OCaml highlights earlier
    • 



FRAMEWORK FOR ANALYSIS OF URBAN WI-FI 


    

  • finish reading and taking notes on “Usage Patterns in an Urban Wi-Fi network”
    • 

  • Produce a draft outline of the framework for analyzing urban Wi-Fi
    • 

  • Next week, reading though some other papers in the area and add detail to framework
    • 



PAWS ROUTER TRIAL SETUP


    

  • once permission for the network is granted, set up the router using the provided interface
    • 

  • install and set-up OpenWRT on the router
    • 

  • Investigate best firmware for ftp, ssh and vpn on the router
    • 

  • produce results and share, before 15th Nov
    • 



INTERLEAVING OF SIGNPOSTS & PAWS


    

  • consider the overlap of signposts & paws
    • 

  • find use cases that highlight the potential for inter connection
    • 

  • produce some slides/blog post on findings and ideas, before 15th Nov
    • 


					

		
		
	

							
	

				

			
						

				Public Access WiFi Service
			

										

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Whilst at the All Hands Digital Economy Conference, I met Arjuna Sathiaseelan who told me about a new project called “PAWS: Public Access WiFi Service“. It sounds quite interesting and I might be joining the team in the next few months. The project poster is here : de2012


The main motivation behind the Public Access WiFi Service (PAWS) is to enable digital inclusion, which is important in the interest of social equality to ensure access to everyday services and benefits that are enjoyed by the majority, and ensure that all members of society are able to participate fully in the Digital Economy. Not only do the digitally excluded in societies currently not have access to these benefits, alternative provision of public services is a costly endeavour. While amongst the elderly the primary factor in digital exclusion is cultural (commonly that they do not perceive value in it), amongst younger demographics who want to be online, affordability is cited as the primary barrier, named by over 40% of digitally excluded 16-44 year olds. Most digital inclusion initiatives assume affordable broadband access, indeed the commercial imperative at the moment is to convert existing users to higher speeds, rather than deploy more widely; however we believe the notion of connectivity for all being governed by the simple market economics is a major impediment to achieving the benefits of a Digital Economy, and that basic Internet should be made available to all for societal benefit; a sentiment recently expressed by Berners-Lee. Although there is no single ‘magic bullet’ to remove socio-economic barriers, there are infrastructural solutions that could drastically reduce them. Our proposal is a first step in this direction: a feasibility study to establish technical requirements and identify the current practices and needs of the digitally excluded. Following successful demonstration, we hope that government policy can be nudged to support industry uptake leading to national deployment.


Our proposed programme of research seeks to inform and develop technology enabling free Internet connectivity for all, paving the way to new access models. We propose PAWS (Public Access WiFi Service), a new Internet access paradigm based on Lowest Cost Denominator Networking (LCD-Net) – a set of techniques making use of the available unused capacity in home broadband networks and allowing Less-than-Best-Effort access to these resources (lower quality service compared to the standard Internet service offered to paid users). Case study deployment of this technology will be underpinned by a programme of social research which will establish a socio-economic profile of the area, recruit potential participants and, most importantly, conduct a longitudinal multi-method assessment of participants’ current practices and subsequent experiences of this technology.


PAWS takes the approach of community-wide participation, where broadband customers can volunteer to share their high-speed broadband Internet connection for free with fellow citizens. Initiatives in the past have looked at sharing a user’s broadband Internet connection via their wireless connection (for e.g. BT FON). Although these methods are gaining worldwide acceptance, they are usually viewed as an extension of a user’s paid service – PAWS will extend this to support free access by users. As it is essential to ensure that the free user traffic does not impact perceived performance of the bandwidth donor, we will explore the impact of free services available through LBE access (also known as the Scavenger Class) to the network. These methods allow a person to use a shared link without competing for the resources of those who have shared their Internet connection. We will also explore the benefits offered by our proposed method to users and network operators. It is necessary for this work to be conducted ‘in the wild’ as it requires the deployment of technology to end-users, and subsequent assessment of its impact. The project will increase access opportunities, enabling digital inclusion and in turn supporting the UK Government’s ‘digital by default’ programme with its associated cost savings and service improvements”


Source: http://gow.epsrc.ac.uk/NGBOViewGrant.aspx?GrantRef=EP/K012703/1

					

		
		
	

							
	

				

			
						

				Getting to grips with OPAM
			

										

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What is OPAM ?


OPAM is a OCaml Package Manager. Its basic use is similar to apt-get on linux, both package managers help to automate the process of installing, removing and updating software by tracking the complex web of dependencies that exist between bodies of code.

Why use OPAM ?


OPAM gives the user more control of the choice of specific libraries and compiler versions used to run OCaml code. 


How to do I run OPAM ?


I am only going to run OPAM and not install it (long story). To do this, I executed the following from my root directory 


wget http://opam.ocamlpro.com/build/opam64 


chmod +x opam64 


./opam64 init 


How can install a package using OPAM ? What is the advantage over using OPAM intend of using the traditional methods ?


You can view the list of available packages using ./opam64 list and you can search using ./opam64 search .


On of the libraries used by Signposts is lwt. Lwt is a very useful library for anyone who want to do multi-threading in Ocaml. So I try the following query:


opam64 search lwt


Available packages for system:


cohttp   --  HTTP library for Lwt, Async and Mirage


lwt   --  A cooperative threads library for OCaml


lwt-zmq   --  Lwt-friendly wrapping around ZeroMQ sockets


release   --  Release is a multi-process Lwt-enabled daemon framework for OCaml.


The second of these results is the package that I want to install so


How do I install a package from a Ocaml project on Git ?


Firstly find the package that you want to install, for me this is git://github.com/mirage/opam-repo-dev


opam remote -add dev git://github.com/mirage/opam-repo-dev

Now in future, when I issue opam upgrade, the latest version of the git repo will be downloaded and any depandencies recompiled