# Design¶

The design of Stalker is mentioned in the following sections.

## Introduction¶

Stalker is an Open Source Production Asset Management Library. Although it is designed VFX and Animation studios in mind, its flexible Project Management muscles will allow it to be used in a wide variety of fields.

An Asset Management Systems’ duty is to hold the data which are created by the users of the system in an organised manner, and let them quickly reach and find their files. A Production Asset Management Systems’ duty is, in addition to the asset management systems’, also handle the production steps or tasks and allow the users of the system to collaborate. If more information about this subject is needed, there are great books about Digital Asset Management (DAM) Systems.

The usage of an asset management system in an animation/vfx studio is a must for the sake of the studio itself. Even the benefits of the system becomes silly to be mentioned when compared to the lack of even a simple system to organise stuff.

Every studio outside establishes and develops their own asset management system. Stalker will try to be the framework that these proprietary asset management systems will be build over. Thus reducing the work repeated on every big projects’ start.

## Concepts¶

There are a couple of design concepts those needs to be clarified before any further explanation of Stalker.

Stalker on itself basically is the Model in an MTV system (where the Stalker Pyramid is the Template and View). So it defines the data and the interaction of the data with itself.

Because the idea behind Stalker was to build an open source library that any studio using it can build their own pipeline on top of it, it is designed to stay simple and solid at the same time. So the UI and other stuff is ripped off from the original Stalker package and moved to another Pyramid web application called Stalker Pyramid.

### Stalker Object Model (SOM)¶

Stalker has a very robust object model, which is called Stalker Object Model or SOM. The idea behind SOM is to create a class hierarchy which is both usable right out of the box and also expandable by the studios’ developers. SOM is actually a little bit more complex than a basic possible model, it is designed in this way just to be able to create a simple pipeline to be able to build the system over it.

Lets look at how a simple studio works and try to create our asset management concepts around it.

An animation/vfx studios duty is to complete a Project. A project, generally is about to create a Sequence of Shots which are a series of images those at the end converts to a movie. So a sequence in general contains Shots. And Shots can use Assets. So basically to complete a project the studio should complete the shots and assets needed by those shots.

Furthermore all the Projects, Sequences, Shots or Assets are divided in to different Tasks those need to be done sequentially or in parallel to complete that project.

A Task relates to a work, a work is a quantity of time spent or going to be spend for that specific task. The time spent on the course of completion of a Task can be recorded with TimeLogs. TimeLogs show the total time spent by an artist for a certain Task. So it holds information about how much effort has been spent to complete a Task.

During the completion of the Task or at the end of the work a User creates Versions for that particular Task. Versions are the different incarnations or the progress of the resultant product, and it is connected to files in the fileserver or in Stalkers term the Repository.

All the names those shown in bold fonts are a class in SOM. and there are a series of other classes to accommodate the needs of a Studio.

The inheritance diagram of the classes in the SOM is shown below:

## Inheritance Diagram¶

Stalker is a configurable and expandable and most importantly it is an open source system. All of these features allows the system to have a flexible structure.

There are two levels of expansion, the first level is the simplest one, by just adding different statuses, different types or these kind of things in which Stalker’s current design is ready to. This is explained in How To Customize Stalker.

The second level of expansion is achieved by expanding the SOM. Expanding the SOM includes creating new classes and database tables, and updating the old ones which are already coming with Stalker. These expansion schemes are further explained in How To Extend SOM.

### Features¶

1. Developed purely in Python (2.6 and over) using TDD (Test Driven Development) practices

2. SQLAlchemy for the database back-end and ORM

3. Uses Jinja2 as the template system for the file and folder naming convention, it is possible to use templates like:

{repository.path}/{project.code}/Assets/{asset.type.name}/{asset.code}/ {asset.name}_{asset.type.name}_v{version.version_number}.{version.extension}

4. File and folders and file sequences can be uploaded to the server as assets, and the server decides where to place the folder or file by using the template system.

5. The event system gives full control for every CRUDL (create/insert, read, update, delete and list) by giving step like before insert, after insert call-backs.

6. The messaging system allows the users collaborate efficiently.

7. Has an embedded Ticket system.

9. Has a predefined workflow for task statuses called Task Status Workflow which manages the statuses of a Task during the project completion.

For usage examples see API Tutorial.

## How To Customize Stalker¶

This part explains the customization of Stalker.

## How To Extend SOM¶

This part explains how to extend Stalker Object Model or SOM.

## Creating Data¶

There are some examples here, to create simple data.

### Creating a Project¶

To create a Project, we need:

1. A Repository
2. A Structure object to define the file structure of the Project:
3. FilenameTemplates for Task, Asset, Shot, Sequence types, to define the placement of the Versions created for them.
4. An ImageFormat to define the output size of the project.
5. A StatusList with enough Statuses that will define the desired Project Statuses. Stalker doesn’t have a Project Status Workflow, yet! so define yours.
6. If desired we can also add a Type for the Project to distinguish commercials from Feature Film projects.
7. We need to create a user as the lead for the project.

Here is the code:

from stalker import (db, Repository, Structure, FilenameTemplate, StatusList,

# first setup the database connection (assuming that you have a config.py
# defined, so we do not need to supply a database address)
db.setup()

# initialize the database just for the first time
db.init()  # run this only for the first time, subsequent runs will not
# create any errors, but it is unnecessary

# re-use Statuses NEW, WIP and CMPL from default statuses
status_new = Status.query.filter_by(code='NEW').first()
status_wip = Status.query.filter_by(code='WIP').first()
status_cmpl = Status.query.filter_by(code='CMPL').first()

# and create a new one
status_on_air = Status(name='On Air', code='OA')

# status list for project
project_status_list = StatusList(
name='Project Statuses',
target_entity_type='Project',
statuses=[
status_new,
status_wip,
status_cmpl,
status_on_air
],
)

image_format_hd = ImageFormat(
name="HD",
width=1920,
height=1080,
)

commercial_type = Type(
name='Commercial',
code='COMM',
target_entity_type='Project'
)

repo = Repository(
name='Commercials Repo',
linux_path='/mnt/T/Commercials/',
windows_path='T:/Commercials/',
osx_path='/Volumes/T/Commercials/'
)

commercial_structure = Structure(
name='Commercial Project Structure',
code=''
)

name='Erkan Ozgur Yilmaz',
email='eoyilmaz@stalker.com',
)

# lets create the Project
proj1 = Project(
name='Test Project',
code='TP',
description="This is the first project",
image_format=image_format_hd,
fps=25,
type=commercial_type,
structure=commercial_structure,
repository=repo,
status_list=project_status_list,
status=status_new
)

# just add the project to the database
from stalker.db.session import DBSession

# and commit the data to database
DBSession.commit()


It may seem too much for just creating a Project, but it is for the first time only. For a second project, we can use the previous Repository, Structure, Lead, StatusList etc.

Because we have a project now lets create a task for this project:

# connect to the database if you have not done yet
db.setup()

# create a new user as the resource for the task
resource1 = User(
name='User1',
email='user@users.com',
)

"something fancy",
resources=[resource1],
schedule_timing=1,
schedule_unit='d',
schedule_model='effort',
project=proj1
)
# we do not need to supply a StatusList for the Task, statuses for tasks are
# created by default when we called db.init() in previous example

# add it to the database

print(task1.status)