WhiteLabel ErlangAdventures in the undocumented wilds of inet_dns

Who is this guy?Geoff Cant <nem@erlang.geek.nz>Current (xmpp|mailto):gcant@process-one.netPreviously geoff@catalyst.net.nzarchaelus on http://github, irc:freenode/#erlang

What have I been up to?ejabberd

debuggingvirtual hostingdebugging large clustersporting patchesdebugging patches

What have I been up to?Whitelabel ejabberd hosting

Web Frameworks (why Mochiweb)Other libraries (ejango, esmtp, erlydtl)DNS (OTP Undocumented)Tricks and Lessons

A rant in four parts

ErlywebYAWSinetsThe Erlang WebNitrogen

Web Frameworks

Mochiweb.(No logo, ‘cause they’re too busy coding)

Other piecesTemplatingURL RoutingForm validationEmail

TemplatingerlydtlTemplates compile to modulesWell known template syntax (Django-ish)Template

URL RoutingMust work with RESTful URLsMust be reversible - able to generate URLs tooejango.url_routes

Form ValidationGenerate forms and validate form postsCouldn’t find anything available alreadyDeclarative DSL for form specificationejango.form, ejango.form_validator

Sending Emailsmtp_fsmErlware smtpNo attachments?This should be much easier.esmtp

Mail Sending API

Mime Attachment API

DNSNeed to verify ownership of domainNeed to add XMPP SRV recordsinet:gethostbyname...To the githubs!

DNS Undocumentedinet_res:getbyname/2inet_res:nnslookup/5inet_db - cachinginet_dns - packet encoding/decoding, bugs‘dns’ -- the way forward.

Here be Dragons.Sometimes it’s undocumented for a reasonThe TXT RR is subtle.I reimplemented the same bug.

My DNS decoderTXT RRs are <<Len:8, Data:Len/binary>>* Binary pattern matching rocks

Whitelabel TricksCheck SOA to test if domain existsBypass DNS caching

YSlow OptimisationsInitially got a D on my YSlow reportDecided to gzip and minify content, move js blocks aroundejango.static:compress_docroot/1, ejango.static:serve_compressed/3

Minifying...

LessonsHierarchal modules are a world of hurt.Metaprogramming in Erlang is still too hard.Never trust ADSL routers....

Use Github.

A small plea for helpI have way too many github projectsAdopt my code?Interested in collaborating?

Fin.