Updated Jan 02, 2008 by matt.zukowski
Labels:	API

BuiltInActionTypes

Describes the various actions that Taskr can execute

Introduction

Each Taskr task executes one or more actions. An action can be anything -- a simple shell command or piece of Ruby code to execute all the way to a complex network call to an external REST service.

Each kind of action is an implementation of a Taskr Action class written in Ruby. You can think of an action as a function that takes some set of named parameters -- the particular parameters depend on the action type. Taskr comes packaged with several Action classes. This page describes each of these built-in actions and their parameters. If you are interested in implementing your own actions, please see ImplementingCustomActions.

A quick way to see all of the actions available in your Taskr server is to log in via the web-based interface (http://localhost:7007/tasks by default) and click on the Schedule New Task link. The available Action types are listed under the action_class_name pulldown. Selecting any of these actions displays the selected action's parameters.

Below is a screenshot of the "New Task" page:

Built-in Actions and their Parameters

Shell Action

The Shell action allows Taskr to execute tasks much like the Unix cron system. The Shell task simply executes some piece of shell script on the local system (i.e. the machine that the Taskr service is running on).

Parameter	Description
`command`	The shell command to execute. The command syntax depends on what shell your system is running. On a Linux system, this is probably `bash`, on Windows it's almost certainly `DOS`. For example, if you are running a `bash` shell, then the `command` parameter could be `touch /tmp/test; echo "done"`. This would update the modification timestamp of the file `/tmp/test` and print out the string "done" to `stdout`
`as_user` (optional)	Execute the `command` as the given user. If ommitted, the command will be executed as the user that the Taskr server is running as. Note that the `as_user` parameter will probably only work if Taskr is running as root.

Ruby Action

Executes the given block of Ruby code.

Parameter	Description
`code`	The Ruby code to execute. For example: `puts "Hello World!"` will print out the string "Hello World!" to `stdout`.

Rest Action

Places an HTTP REST call to the given URL. This is useful for triggering actions in other RESTful services. Since Taskr is a RESTful service, using the Rest action it is possible to talk back to the Taskr service, to for example create or delete another task.

Parameter	Description
`url`	The URL where the REST call should be sent. For example: `http://localhost:7007/tasks.xml`
`method`	The HTTP method to use when placing the call. The common methods are `GET`, `POST`, `PUT`, and `DELETE`, although other methods are possible. See http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
`params`	A hash (a.k.a. associative array) of key-value pairs to send with the request. Generally abstraction libraries like Ruby's ActiveResource and PHP's Zend_Rest_Client will automatically convert hashes/associative arrays for you, so you can specify this parameter's value in your native programming language's format.
`username` (optional)	If the REST resource requires authentication, use this to specify the username. Currently on HTTP Basic authentication is supported.
`password` (optional)	Same as above, but specifies the password credential.

Howlr Action

Send a message through a Howlr service. Howlr provides a RESTful interface for sending out emails and other kinds of messages, so the Howlr action can be used to send messages at a given time or interval. Since Howlr is a RESTful service, this is essentially just a customized version of the Rest Action described above.

Parameter	Description
`url`	The URL where the message should be posted to. For example: `http://howlr.example.foo:7008/messages.xml`
`subject`	The subject of the message.
`body`	The body of the message.
`recipients`	Comma or semi-colon separated list of recipients. For example: `joe@example.foo; <Sally Smith> ssmith@example.foo`
`from`	The message will show up as being sent from this address. For example: `Scheduler Service <taskr@example.foo>`
`username` (optional)	If your Howlr service requires authentication, use this to specify the username.
`password` (optional)	Same as above, but specifies the password credential.

Taskr4rails Action

Executes code on a remote Rails server. See Taskr4rails for more info.

Custom Actions

As mentioned above, it is fairly easy to implement and install your own actions types. Please see ImplementingCustomActions for details.