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Platform Tour

Introduction

Allura is implemented as a collection of tool applications on top of a robust and open platform. Some of the services provided by the platform include:

  • Indexing and search
  • Authentication and Authorization
  • Email integration (every tool application gets its own email address)
  • Asynchronous processing with background tasks and events
  • Markdown markup formatting
  • Simple autolinking between different artifacts in the forge
  • Attachment handling
  • Tool administration

Tools, on the other hand, provide the actual user interface and logic to manipulate forge artifacts. Some of the tools currently implemented include:

admin
This tool is installed in all projects, and allows the administration of the project's tools, authentication, and authorization
Git, Hg, SVN
These tools allow you to host a version control system in Allura. They also provides the ability to "fork" Git and Hg repos in order to provide your own extensions.
Wiki
This tool provides a basic wiki with support for comments, attachments, and notifications.
Tracker
This tool provides an extensible ticketing system for tracking feature requests, defects, or support requests.
Discussion
This tool provides a forum interface with full email integration as well. The forum also handles attachments to posts either via the web interface or via email.

The Context Object

The Pylons "context" object c has several properties which are automatically set for each request:

project
The current project
app
The current tool application object.
user
The current user

Allura platform provides the following functions to manage the context object, if you need to change the context for some situation:

Artifacts

We've mentioned artifacts a couple of times now without definition. An artifact, as used in Allura, is some object that a tool needs to store in the forge. The platform provides facilities for controlling access to individual artifacts if that's what the tool designer favors. For instance, the Discussion tool allows a user to edit or delete their own posts, but not to edit or delete others (unless the user has the 'moderate' permission on the forum itself). Some examples of artifacts in the current tools:

  • Discussion: Forum, Thread, Post, Attachment
  • Wiki: Page, Comment, Attachment
  • Tracker: Ticket, Comment, Attachment
  • SCM: Repository, Commit, Patch

In order to implement your own artifact, you should override at least a few of the methods of the allura.model.artifact.Artifact class:

from ming.orm.property import FieldProperty
from allura.model import Artifact

class NewArtifact(Artifact):
    class __mongometa__:
        name='my_new_artifact' # collection where this artifact is stored
    type_s = 'My Artifact' # 'type' of the artifact used in search results

    # Add your own properties here (beyond those provided by Artifact)
    shortname = FieldProperty(str)

    def url(self):
        'Each artifact should have its own URL '
        return self.app.url + self.shortname + '/'

    def index(self):
        'Return the fields you want indexed on this artifact'
        result = Artifact.index(self)
        result.update(type_s=self.type_s,
                      name_s=self.shortname,
                      text=self.shortname)
        return result

    def shorthand_id(self):
        'Used in the generation of short links like [my_artifact]'
        return self.shortname

Platform services provided for artifacts

Whenever you create, modify, or delete an artifact, the platform does a couple of things for you:

  • The artifact is added to the index and will appear in searches
  • A shortlink is generated for the artifact (e.g. [MyWikiPage] or [#151]). This allows you to reference the artifact from other artifacts. Whenever the commit message is displayed in the SCM tool, any references to [#151] will be automatically linked to that Ticket's page.

Shortlinks work only within a project hierarchy (in order to link to some other project's page, you'll have to use the full URL). Sometimes, a shortlink may need to be differentiated based on its location in a subproject or in one of many tools of the same type within a project. In order to do this, shortlinks may be prefixed by either the tool mount point or a project ID and tool mount point.

For instance, suppose we have an ticket tracker called 'features' and one called 'bugs'. They both have many tickets in them. To distinguish, use the tracker mount point within the reference. For example [features:#3] or [bugs:#3]

Asynchronous Processing

Much of the actual functionality of Allura comes from code that runs outside the context of a web request, in the taskd server (invoked by running paster taskd development.ini. Asynchronous processing is performed by two types of functions, tasks and events, differentiated as follows:

Task

Tasks are module-level global functions. They are annotated with the @task decorator and are invoked with the .post method. For instance, to schedule a task foobar to execute in the taskd context, you would write:

@task
def foobar(a,b,c=5): ...

foobar.post(9,1,c=15)
Event

Events are intended for "fan-out" types of events. Events have a string name, and are "listened" for by using the @event_handler decorator. The g.post_event() helper is provided to run the event handlers for a particular event in the taskd context. Multiple event handlers can be registered for each event:

@event_handler('event_name')
def handler1(topic, *args, **kwargs): ...

@event_handler('event_name')
def handler2(topic, *args, **kwargs): ...

g.post_event('event_name', 1,2,3, a=5)

Email Integration

The Allura platform provides easy-to-use email integration. Forge email addresses are of the form <topic>@<mount_point>[.<subproject>]*.<subproject>.projects.sourceforge.net. When a message is received on such an email address, the address is parsed and the sending user is identified (if possible). Based on the parsed address, the pylons context attributes c.project and c.app are set, and the application is queried to determine whether the identified user has authority to send an email to the given app/topic combination by calling c.app.has_access(user, topic). If the user has access, the message is decomposed into its component parts (if a multipart MIME-encoded message) and c.app.handle_message(topic, message) is called for each part with the following components to the msg dict:

headers
The actual headers parsed from the body of the message
message_id
The Message-ID header (which should be universally unique and is generated by the email client), used for determining which messages are replies to which other messages
in_reply_to
The In-Reply-To header, used for determining which messages are replies to which other messages
references
The References header, used for determining which messages refer to which other messages
filename
Optional, if the part is an attachment with a filename, this will be populated
content_type
The MIME content_type of the message part
payload
The actual content of the message part

The Allura platform also provides full support for sending email without worrying about the specifics of SMTP or sendmail handling. In order to send an email, simply post a task for allura.tasks.mail_tasks.sendmail with the following arguments:

fromaddr
Return address on the message (usually the topic@tool_name that generated it)
destinations
List of email addresses and/or :class:`bson.ObjectId` s for :class:`allura.model.auth.User` objects
text
Markdown-formatted body of the message (If the user has requested html or combined text+html messages in their preferences, the Markdown will be so rendered. Otherwise a plain text message will be sent.)
reply_to
Address to which replies should be sent
subject
Subject of the message
message_id
Value to put in the Message-ID header (the _id field of a :class:`allura.model.artifact.Message` is suitable for this)
in_reply_to (optional)
Value to put in the In-Reply-To header (the parent_id field of a :class:`allura.model.artifact.Message` is suitable for this)