Another Erlang XML Project, Part 2 - Converted to gen_server

A while back I wrote some code in Erlang to grab your public Amazon wishlist based off of your email address. Today I had the urge to rewrite it using OTP, specifically gen_server. The code is up on github. Switching it over to use gen_server is fairly trivial since the sequential code is already written. Basically all that needs to be done is to setup the handle_call method to send any email addresses over to the get_wishlist method for retrieval. Here’s what the handle_call looks like:

handle_call(Email_addr, _From, State) ->
%Reply back with the result from get_wishlist
Reply = get_wishlist(Email_addr),
{reply, Reply, State}.

The rest of the functions look pretty much as they did before so I won’t put them here. One other change I made was to start_link to have it also run inets:start() so we can make the http requests in the other functions.

Here’s how the thing works:

[zeusfaber@der-dieb ebin]$ erl
Erlang (BEAM) emulator version 5.6.5 [source] [64-bit] [smp:2] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.6.5 (abort with ^G)
1> c(’../src/amazon_wishlist_otp.erl’).
{ok,amazon_wishlist_otp}
2> amazon_wishlist_otp:start_link().
ok
3> gen_server:call(amazon_wishlist_otp, “SOMEADDR@SOMEPLACE.com”).
[[“Algorithms on Strings, Trees and Sequences: Computer Science and Computational Biology”,
“Algorithms: Sequential, Parallel, and Distributed”,
“Starting Forth: An Introduction to the Forth Language and Operating System for Beginners and Professionals (Prentice-Hall Software Series)”,
“Biobazaar: The Open Source Revolution and Biotechnology”,
“Nmap Network Scanning: The Official Nmap Project Guide to Network Discovery and Security Scanning”,
“American Nerd: The Story of My People”,
“FreeDarko presents The Macrophenomenal Pro Basketball Almanac: Styles, Stats, and Stars in Today’s Game”,
“CP Technologie USB TO SERIAL ADAPTER ( CP-US-03 )”,
“Made to Stick: Why Some Ideas Survive and Others Die”]]

Comments

Nice job Joe. I just tested this and it works as expected. I’m emailing it to a co-worker now as an example of how to use xmerl in the real world.

-Andrew

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