[ANN] RailsCron 0.2 plugin

Rails
1

I received feedback from some of you, saying that it would be cool if
RailsCron was even easier to manage. So I implemented a graceful
start/restart inside of the plugin’s init.rb. If you don’t like it,
comment it out and send me the feedback.

Also, I finished an update to RailsCron that allows you to attach
asynchronous processing methods to your ActiveRecord models. i.e.:

class EmailQueue < ActiveRecord::Base
background :deliver, :every => 10 #seconds, or 1.minute, etc

def self.deliver
	#process the queue
end

end

If your deliver method takes a minute to process (like some of my
async methods do), then RailsCron will NOT load up multiple threads of
the same command every 10 seconds. Rather RailsCron checks to see if
the command is currently running, and doesn’t start a new one. You
can overrride this with:

RailsCron.options[:overlap] = true

Is there a better name to use than overlap? Anyhow, have fun, and
feedback is always welcome and encouraged!

Repository:
http://svn.kylemaxwell.com/rails_cron/

Bug Tracker:
http://dev.kylemaxwell.com

–
Kyle M.
Chief Technologist
E Factor Media // FN Interactive
removed_email_address@domain.invalid
1-866-263-3261

2

Kyle-

This is totally sweet. I am using it to implement some new features

on http://yakimaherald.com. i will give you feedback and maybe a
patch or two once I get it worked out.

Thanks
-Ezra

On Jan 25, 2006, at 12:26 PM, Kyle M. wrote:

–
Kyle M.
Chief Technologist
E Factor Media // FN Interactive
removed_email_address@domain.invalid
1-866-263-3261

Rails mailing list
removed_email_address@domain.invalid
http://lists.rubyonrails.org/mailman/listinfo/rails

-Ezra Z.
Yakima Herald-Republic
WebMaster

509-577-7732
removed_email_address@domain.invalid

3

Hi Kyle ~

This looks like it might solve several items that I need to automate. I
will be sure to check it out and send you some feedback. I usually
would
set up a cron job on a linux box to execute the action I needed.

Thx!

~ Ben

4

Hello Kyle,
I know this is the plugin I need. Can you maybe give me a simple
example of what I might need in the model and controller? What I’m
trying to do is process then purge emails recorded in a table.
Thank You,
jeff

5

Awesome awesome work Kyle!

On 26/01/2006, at 7:26 AM, Kyle M. wrote:

RailsCron.options[:overlap] = true

Is there a better name to use than overlap? Anyhow, have fun, and
feedback is always welcome and encouraged!

maybe it would make more sense to have this as an option to the
“background” method. i.e.

class EmailQueue < ActiveRecord::Base
background :deliver, :every => 10, :concurrent => true
end

(would be good if we had a ‘seconds’ method for fixnum which just
returned itself, so you would write 10.seconds)

– tim

6

One useful addition worth considering is adding this RegEX as a define
or even as a helper to AR in the format of “validates_format_of_url
:url” to be a shorthand for the REGEX.

Source: http://www.nshb.net/node/252

class Company < ActiveRecord::Base
validates_format_of :url, :with =>
/^(http|https)://[a-z0-9]+([-.]{1}[a-z0-9]+).[a-z]{2,5}(([0-9]{1,5})?/.)?$/ix
end

-Nb

 Nathaniel S. H. Brown                           http://nshb.net
7

HTTP URL Validation is a Rails plugin that allows you
to validate a URL
entered in a form. It validates if the URL exists by
hitting it with a HEAD
request. There’s the option to also check that the URL
returns content of
a specified type. Hereâ??s how you can use it your
model:

Class Article < ActiveRecord::Base
validates_http_url :url, :content_type =>
“text/html”
validates_http_utl :photo, :content_type => “image”
end

This example will make sure the value entered for the
URL field points to a
publicly accessible HTML page, and the photo field
points to an image.

You can get the plugin at
http://www.ccjr.name/blog/2006/01/25/http-url-validator/

Cheers,

Cloves Carneiro Jr
http://www.ccjr.name/blog

Find your next car at http://autos.yahoo.ca

8

It only allows for URL’s without the HTTP AUTH syntax you mentioned.

/^(http|https|ftp|smb)://(a-z0-9]+:[a-z0-9]+@)?[a-z0-9]+([-.]{1}[a-z0-9]
+).[a-z]{2,5}(([0-9]{1,5})?/.)?$/ix

Without testing, the above should work in such a case.

-Nb

 Nathaniel S. H. Brown                           http://nshb.net
9

Nathaniel S. H. Brown wrote:

One useful addition worth considering is adding this RegEX as a define or even as a helper to AR in the format of “validates_format_of_url :url” to be a shorthand for the REGEX.

Source: http://www.nshb.net/node/252

class Company < ActiveRecord::Base
validates_format_of :url, :with => /^(http|https)://[a-z0-9]+([-.]{1}[a-z0-9]+).[a-z]{2,5}(([0-9]{1,5})?/.)?$/ix
end

Technically a URL can also start with ftp:// smb:// etc

Does this also allow stuff like:
http://username:removed_email_address@domain.invalid/?q=r&me=you#some_id

Sorry, my REGEX skills are quite poor…

Jeroen

10

Nathaniel S. H. Brown wrote:

It only allows for URL’s without the HTTP AUTH syntax you mentioned.

/^(http|https|ftp|smb)://(a-z0-9]+:[a-z0-9]+@)?[a-z0-9]+([-.]{1}[a-z0-9]
+).[a-z]{2,5}(([0-9]{1,5})?/.)?$/ix

Depending on how complete you want it to be, you might want to get rid
of explicit scheme matching completely. RFC 1738 indicates that
[A-Za-z.±]+ should work instead of (http|https|ftp|smb).

11

Alex Y. wrote:

Nathaniel S. H. Brown wrote:

It only allows for URL’s without the HTTP AUTH syntax you mentioned.

/^(http|https|ftp|smb)://(a-z0-9]+:[a-z0-9]+@)?[a-z0-9]+([-.]{1}[a-z0-9]

+).[a-z]{2,5}(([0-9]{1,5})?/.)?$/ix

Depending on how complete you want it to be, you might want to get rid
of explicit scheme matching completely. RFC 1738 indicates that
[A-Za-z.±]+ should work instead of (http|https|ftp|smb).

I agree. It should be up to the user though if they want to allow more
exotic protocols. I personally would never include this in a plugin, I
would just copy and paste the regex from Nathan’s homepage and modify it
to fit my needs.

Jeroen

12

El 26/01/2006, a las 06:04 AM, Jeroen H.
escribió:

Technically a URL can also start with ftp:// smb:// etc

Most of the time you require a user to enter an URL only HTTP (and
sometimes FTP and mailto) is allowed. At least in my applications.

Patrice_______________________________________________
Rails mailing list
removed_email_address@domain.invalid
http://lists.rubyonrails.org/mailman/listinfo/rails

13

At 1/26/2006 06:38 AM, you wrote:

Alex
Or go all the way with the regexp from RFC 2396
http://www.ietf.org/rfc/rfc2396.txtUniform Resource Identifiers
(URI): Generic Syntax on page 29. (the remainder is best viewed in a
monospaced font or just visit the RFC on the web.
-Rob

RFC 2396 URI Generic Syntax August 1998

B. Parsing a URI Reference with a Regular Expression

As described in Section 4.3, the generic URI syntax is not

sufficient
to disambiguate the components of some forms of URI. Since the
“greedy algorithm” described in that section is identical to the
disambiguation method used by POSIX regular expressions, it is
natural and commonplace to use a regular expression for parsing the
potential four components and fragment identifier of a URI
reference.

The following line is the regular expression for breaking-down a URI
reference into its components.

   ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
    12            3  4          5       6  7        8 9

The numbers in the second line above are only to assist readability;
they indicate the reference points for each subexpression (i.e.,

each
paired parenthesis). We refer to the value matched for
subexpression
as $. For example, matching the above expression to

   http://www.ics.uci.edu/pub/ietf/uri/#Related

results in the following subexpression matches:

   $1 = http:
   $2 = http
   $3 = //www.ics.uci.edu
   $4 = www.ics.uci.edu
   $5 = /pub/ietf/uri/
   $6 = <undefined>
   $7 = <undefined>
   $8 = #Related
   $9 = Related

where <undefined> indicates that the component is not present, as is
the case for the query component in the above example.  Therefore,

we
can determine the value of the four components and fragment as

   scheme    = $2
   authority = $4
   path      = $5
   query     = $7
   fragment  = $9

and, going in the opposite direction, we can recreate a URI

reference
from its components using the algorithm in step 7 of Section 5.2.

Berners-Lee, et. al. Standards Track [Page 29]

14

Jeroen H. wrote:

[A-Za-z.±]+ should work instead of (http|https|ftp|smb).

I agree. It should be up to the user though if they want to allow more
exotic protocols. I personally would never include this in a plugin, I
would just copy and paste the regex from Nathan’s homepage and modify it
to fit my needs.
You could use a scheme whitelist that the first bracket group gets
compared against, couldn’t you? Something like:

class UriMatcher < Regexp
def initialize(whitelist)
super(###uri_regex_here###)
@whitelist = Set.new(whitelist)
end
def =~(str)
return @whitelist.include? self.match(str)[1]
end
end

class Company < ActiveRecord::Base
schemes = [‘http’, ‘https’, ‘ftp’]
validates_format_of :url, :with => UriMatcher.new(schemes)
end

I guess the overriding principle here is to Do The Simplest Thing That
Can Possibly Work :slight_smile:

15

On 1/25/06, Jeff B. removed_email_address@domain.invalid wrote:

RailsCron was even easier to manage. So I implemented a graceful
#process the queue

Kyle M.

Rails mailing list
removed_email_address@domain.invalid
http://lists.rubyonrails.org/mailman/listinfo/rails

I just posted an example on my blog:
http://www.kylemaxwell.com/articles/2006/01/26/simple-emailqueue-for-rails

–
Kyle M.
Chief Technologist
E Factor Media // FN Interactive
removed_email_address@domain.invalid
1-866-263-3261

16

On 1/26/06, Timo H. removed_email_address@domain.invalid wrote:

          @@last_db_update = Time.now.to_i
          @@task_list = find(:all)

solves it.

Yeah, I feel a little sheepish… It’s fixed in the trunk, and I’ll
probably tag up 0.2.1 with this, and the :concurrent option sometime
today or tomorrow.

–
Kyle M.
Chief Technologist
E Factor Media // FN Interactive
removed_email_address@domain.invalid
1-866-263-3261

17

Hi Kyle,

looks great.

There’s a small bug in RailsCron#task_list: @@last_db_update is not
updated, so the DB is always queried. Changing

      @@task_list = find(:all)

to

      @@last_db_update = Time.now.to_i
      @@task_list = find(:all)

solves it.

I agree to Tim, that :overlap should be settable on a per-task basis
(and that :concurrent would make a nice option-name for it).

Thanks for the nice plugin.

Timo

Am 25.01.2006 um 21:26 schrieb Kyle M.:

18

I’m a newbie, and having trouble installing the plugin.

I did “ruby script/plugin source
http://svn.kylemaxwell.com/rails_cron/tags/0.2/”, and it is added ok.
When I do “ruby script/plugin list”, I see the following for the new
source:

lib
http://svn.kylemaxwell.com/rails_cron/tags/0.2/lib/
tasks
http://svn.kylemaxwell.com/rails_cron/tags/0.2/tasks/

This doesn’t seem correct. There are other plugins listed (i.e.
account_location, acts_as_taggable, etc), so I was thinking there would
be something like “rails_cron” instead of “lib” and “tasks”. What am I
doing wrong?

Thanks in advance!

Nate

19

That regex seems broken.

It says that a URI can start with everything other than any of the
following
items “:/?#”. Meaning that a URI can start with a “@” or a “%” or any of
the
other million keys that aren’t those four?

Alex Y.'s mention of RFC 1738 looks much closer to what a URI should
start with [a-z.±]+

/^([a-z.±]+)://(a-z0-9]+:[a-z0-9]+@)?[a-z0-9]+([-.]{1}[a-z0-9]+).[a-z
]{2,5}(([0-9]{1,5})?/.)?$/ix

The “I” flag negates the second case of A-Z.

I really like the concept of the URI Matcher, but it would be far
simpler to
have a helper method for AR with usage like so:

validates_format_of_uri :link, :schemes => [ ‘mailto’, ‘http’, ‘https’ ]

That is what I was suggesting go into the Plugin. Or even simply mapping
the
above Regex into a define like so:

REGEX_URI =
/^([a-z.±]+)://(a-z0-9]+:[a-z0-9]+@)?[a-z0-9]+([-.]{1}[a-z0-9]+).[a-z
]{2,5}(([0-9]{1,5})?/.)?$/ix

So you can use it within the original code:

validates_format_of :uri, :with => REGEX_URI

This would be a simple method of implementation, and would stick to the
DRY
principle as I am sure if you have one URI column in your database, you
are
likely to have another.

-Nb

 Nathaniel S. H. Brown                           http://nshb.net
20

Nathaniel S. H. Brown wrote:

That regex seems broken.

It says that a URI can start with everything other than any of the following
items “:/?#”. Meaning that a URI can start with a “@” or a “%” or any of the
other million keys that aren’t those four?

Yup. It’s a superset. The regex from the RFC only serves to separate
the constituent parts of a URI, not to validate them. From page 12,
though:

Scheme names consist of a sequence of characters beginning with a
lower case letter and followed by any combination of lower case
letters, digits, plus ("+"), period ("."), or hyphen ("-").  For
resiliency, programs interpreting URI should treat upper case

letters
as equivalent to lower case in scheme names (e.g., allow “HTTP” as
well as “http”).

   scheme        = alpha *( alpha | digit | "+" | "-" | "." )