Erlang Tutorial
Erlang Useful Resources
Selected Reading
- Erlang - Web Programming
- Erlang - Drivers
- Erlang - Performance
- Erlang - Concurrency
- Erlang - OTP
- Erlang - Distributed Programming
- Erlang - Ports
- Erlang - Databases
- Erlang - Emails
- Erlang - Processes
- Erlang - Funs
- Erlang - Binaries
- Erlang - BIFS
- Erlang - Guards
- Erlang - Pattern Matching
- Erlang - Preprocessors
- Erlang - Header Files
- Erlang - Macros
- Erlang - Exceptions
- Erlang - Records
- Erlang - Tuples
- Erlang - Maps
- Erlang - Atoms
- Erlang - File I/O
- Erlang - Lists
- Erlang - Strings
- Erlang - Numbers
- Erlang - Recursion
- Erlang - Modules
- Erlang - Functions
- Erlang - Decision Making
- Erlang - Loops
- Erlang - Operators
- Erlang - Variables
- Erlang - Data Types
- Erlang - Shell
- Erlang - Basic Syntax
- Erlang - Environment
- Erlang - Overview
- Erlang - Home
Erlang Useful Resources
Selected Reading
- Who is Who
- Computer Glossary
- HR Interview Questions
- Effective Resume Writing
- Questions and Answers
- UPSC IAS Exams Notes
Erlang - Web Programming
Erlang - Web Programming
In Erlang, the inets pbrary is available to build web servers in Erlang. Let’s look at some of the functions available in Erlang for web programming. One can implement the HTTP server, also referred to as httpd to handle HTTP requests.
The server implements numerous features, such as −
Secure Sockets Layer (SSL)
Erlang Scripting Interface (ESI)
Common Gateway Interface (CGI)
User Authentication (using Mnesia, Dets or plain text database)
Common Logfile Format (with or without disk_log(3) support)
URL Apasing
Action Mappings
Directory Listings
The first job is to start the web pbrary via the command.
inets:start()
The next step is to implement the start function of the inets pbrary so that the web server can be implemented.
Following is an example of creating a web server process in Erlang.
For example
-module(helloworld).
-export([start/0]).
start() ->
inets:start(),
Pid = inets:start(httpd, [{port, 8081}, {server_name,"httpd_test"},
{server_root,"D://tmp"},{document_root,"D://tmp/htdocs"},
{bind_address, "localhost"}]), io:fwrite("~p",[Pid]).
The following points need to be noted about the above program.
The port number needs to be unique and not used by any other program. The httpd service would be started on this port no.
The server_root and document_root are mandatory parameters.
Output
Following is the output of the above program.
{ok,<0.42.0>}
To implement a Hello world web server in Erlang, perform the following steps −
Step 1 − Implement the following code −
-module(helloworld).
-export([start/0,service/3]).
start() ->
inets:start(httpd, [
{modules, [
mod_apas,
mod_auth,
mod_esi,
mod_actions,
mod_cgi,
mod_dir,
mod_get,
mod_head,
mod_log,
mod_disk_log
]},
{port,8081},
{server_name,"helloworld"},
{server_root,"D://tmp"},
{document_root,"D://tmp/htdocs"},
{erl_script_apas, {"/erl", [helloworld]}},
{error_log, "error.log"},
{security_log, "security.log"},
{transfer_log, "transfer.log"},
{mime_types,[
{"html","text/html"}, {"css","text/css"}, {"js","apppcation/x-javascript"} ]}
]).
service(SessionID, _Env, _Input) -> mod_esi:depver(SessionID, [
"Content-Type: text/html
", "<html><body>Hello, World!</body></html>" ]).
Step 2 − Run the code as follows. Compile the above file and then run the following commands in erl.
c(helloworld).
You will get the following output.
{ok,helloworld}
The next command is −
inets:start().
You will get the following output.
ok
The next command is −
helloworld:start().
You will get the following output.
{ok,<0.50.0>}
Step 3 − You can now access the url - http://localhost:8081/erl/hello_world:service.
Advertisements