System architecture

System architecture#

Znuny is a cross-platform application framework built on open source technologies. The default technology stack used in development is a LAMP stack.

  • Linux

  • Apache

  • MySQL

  • Perl

Other technologies and standards used include (not exclusively):

  • POP(S)

  • IMAP(S/TLS)

  • SMTP(S/TLS)

  • JavaScript

  • HTML

  • JQuery

Application Layers#

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It’s a server-based web application consisting of the following layers:

  • Presentation

  • Program Logic

  • Business Logic

  • External Integration

  • Storage

Application Layers

Application Structure#

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The following text discusses the application structure in great detail, outlining the file system and important files.

Application Directories#

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Directories give a sensible structure to the application and knowing what each directory is used for is essential to programming for, debugging, and maintaining the product.

Directory

Description

bin/

command-line tools

bin/cgi-bin/

web handle

bin/fcgi-bin/

fast cgi web handle

Kernel

application codebase

Kernel/Config/

configuration files

Kernel/Config/Files

configuration files

Kernel/GenericInterface/

the Generic Interface API

Kernel/GenericInterface/Invoker/

invoker modules for Generic Interface

Kernel/GenericInterface/Mapping/

mapping modules for Generic Interface, e.g. Simple

Kernel/GenericInterface/Operation/

operation modules for Generic Interface

Kernel/GenericInterface/Transport/

transport modules for Generic Interface, e.g. “HTTP SOAP”

Kernel/Language

language translation files

Kernel/Scheduler/

Scheduler files

Kernel/Scheduler/TaskHandler

handler modules for scheduler tasks, i.e. GenericInterface

Kernel/System/

core modules, e.g. Log, Ticket, …

Kernel/Modules/

frontend modules, e.g. QueueView…

Kernel/Output/HTML/

html templates

var/

variable data

var/log

logfiles

var/cron/

cron files

var/httpd/htdocs/

htdocs directory with index.html

var/httpd/htdocs/skins/Agent/

available skins for the Agent interface

var/httpd/htdocs/skins/Customer/

available skins for the Customer interface

var/httpd/htdocs/js/

JavaScript files

scripts/

misc files

scripts/test/

unit test files

scripts/test/sample/

unit test sample data files

Files Extensions#

.pl

Perl

.pm

Perl Module

.tt

Template::Toolkit template files

.dist

Default templates of files

.yaml | .yml

YAML files, used for Web Service configuration

Core Modules#

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Core modules are under $OTRS_HOME/Kernel/System/*.

Core modules build program logic and user-programmed business logic. Routines such as locking and creating a ticket or processing a transition for a business processes name just a few tasks performed by core modules.

A few main core modules are:

Module

Description

Kernel::System::Config

Access to configuration options

Kernel::System::Log

Access to logging

Kernel::System::DB

Access to the database

Kernel::System::Auth

User authentication

Kernel::System::User

User management

Kernel::System::Group

Group functions

Kernel::System::Email

Email processing

Note

Module Names and Paths

Above the Perl notation is used. The path to each .pm file is Kernel/System or Custom/Kernel/System as known from Perl.

Front-end Handle#

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Each user interface has a set of handles. The handles call the Action modules, generate the front-end (if applicable), and provide function.

A typical handle looks like this.

http://znuny.example.com/otrs/index.pl?Action=Module

Front-end Modules#

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Front-end modules are composed of an HTML Template and it’s identically named Perl module. Here we are referring to the logic layer.

Front-end modules are under Kernel/Modules/.

There are two public functions per module:

new()

run()

These are use by the front-end handle.

An example:

index.pl new() is used to create a front-end module object. The front-end handle provides the basic framework objects.

These are, for example:

Framework Object

Description

ParamObject

Get form parameters.

DBObject

Use the active database connection.

LayoutObject

Use templates and other html layout functions

ConfigObject

Access system configurations.

LogObject

Access to logging.

UserObject

Access to user functions (current user)

GroupObject

Access to group functions.

Command Frontend (CMD)#

The CMD front-end are used by non-humans and have access to all framework objects except the LayoutObject.

The CMD modules used by core modules for various actions in the system like providing a RPC (SOAP) front-end via the bin/cgi-bin/rpc.pl.

Additional CMD modules are all those contained under the bin` directory. Most notably bin/otrs.Console.pl

Generic Interface Modules#

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Generic interface modules are under Kernel/GenericInterface/*. Different generic interface modules are used to handle each part of a web service provider or consumer request to the system.

The main modules for the Generic Interface are:

Module Name

Description

Kernel::GenericInterface::Transport

(to interact with remote systems)

Kernel::GenericInterface::Mapping

(to transform data into a required format)

Kernel::GenericInterface::Requester

(to use Znuny as a client for the web service)

Kernel::GenericInterface::Provider

(to use Znuny as a server for web service)

Kernel::GenericInterface::Operation

(to execute provider actions)

Kernel::GenericInterface::Invoker

(to execute pequester actions)

Kernel::GenericInterface::Debugger

(to track web service communication, using log entries)

Generic Interface Invoker Modules#

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Generic interface invoker modules are under Kernel/GenericInterface/Invoker. Each Invoker is contained in a folder called Controller.

This approach defines the name space not only for internal classes and controllers but for filenames too.

For example: Kernel/GenericInterface/Invoker/Ticket is the folder for all ticket invokers.

Generic interface invoker modules prepare data for consumers without the need for Znuny API knowledge.

Generic Interface Mapping Modules#

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The generic interface makes use of data mapping technologies.

All generic interface mapping modules are located under Kernel/GenericInterface/Mapping/*. These modules are used to transform data (keys, values pairs) output types.

Default mapping modules are

  • Simple

  • XSLT (Version 1.1)

Special can be performed with

  • Znuny

  • Test

  • OutOfOffice

Generic Interface Operation Modules#

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Generic interface operation modules are under Kernel/GenericInterface/Operation. Each operation is contained in a folder named Controller.

This approach defines the name space not only for internal classes and methods but for filenames too.

For example: Kernel/GenericInterface/Operation/Ticket/ is the Controller for all Ticket-type operations. The associated ticket operations are:

  • TicketGet.pm

  • TicketSearch.pm

  • Ticket*.pm

Generic interface operation modules are the backend logic for consumer requests and provide the consumer a valid response without the need for Znuny API knowledge.

Generic Interface Transport Modules#

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Generic interface network transport modules are under Kernel/GenericInterface/Operation. Each transport module should be placed in a directory named identical to the protocol used.

For example: The “HTTP SOAP” transport module, located in Kernel/GenericInterface/Transport/HTTP/SOAP.pm.

Generic Interface transport modules control the consumer transport options (i.e. end-point, authentication, headers, etc.) required for requests to third party systems.

Process Management#

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Process Management Transition Action Modules#

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Process Management Activities#

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Scheduler Task Handler Modules#

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Scheduler task handler modules are under Kernel/Scheduler/TaskHandler. These modules are used to perform asynchronous tasks. One example of such a task is the GenericInterface (GI) task handler. This performs GI Requests to third-party systems. This helps the system to be more responsive, preventing possible performance issues by scheduling the tasks to be performed individually.

Database Structure#

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Znuny relies on a relational database for persistent storage. The model is moderately large and contains the following tables per default.

Below you is a list of all tables. The relationship model is at GitHub.

  • acl

  • acl_sync

  • acl_ticket_attribute_relations

  • article

  • article_data_mime

  • article_data_mime_attachment

  • article_data_mime_plain

  • article_data_mime_send_error

  • article_data_otrs_chat

  • article_flag

  • article_search_index

  • article_sender_type

  • auto_response

  • auto_response_type

  • calendar

  • calendar_appointment

  • calendar_appointment_ticket

  • cloud_service_config

  • communication_channel

  • communication_log

  • communication_log_object

  • communication_log_object_entry

  • communication_log_obj_lookup

  • customer_company

  • customer_preferences

  • customer_user

  • customer_user_customer

  • dynamic_field

  • dynamic_field_obj_id_name

  • dynamic_field_value

  • follow_up_possible

  • form_draft

  • generic_agent_jobs

  • gi_debugger_entry

  • gi_debugger_entry_content

  • gi_webservice_config

  • gi_webservice_config_history

  • group_customer

  • group_customer_user

  • group_role

  • group_user

  • link_object

  • link_relation

  • link_state

  • link_type

  • mail_account

  • mail_queue

  • notification_event

  • notification_event_item

  • notification_event_message

  • package_repository

  • permission_groups

  • personal_queues

  • personal_services

  • pm_activity

  • pm_activity_dialog

  • pm_entity_sync

  • pm_process

  • pm_transition

  • pm_transition_action

  • postmaster_filter

  • process_id

  • queue

  • queue_auto_response

  • queue_preferences

  • queue_standard_template

  • roles

  • role_user

  • salutation

  • scheduler_future_task

  • scheduler_recurrent_task

  • scheduler_task

  • search_profile

  • service

  • service_customer_user

  • service_preferences

  • service_sla

  • sessions

  • signature

  • sla

  • sla_preferences

  • smime_signer_cert_relations

  • standard_attachment

  • standard_template

  • standard_template_attachment

  • sysconfig_default

  • sysconfig_default_version

  • sysconfig_deployment

  • sysconfig_deployment_lock

  • sysconfig_modified

  • sysconfig_modified_version

  • system_address

  • system_data

  • system_maintenance

  • ticket

  • ticket_flag

  • ticket_history

  • ticket_history_type

  • ticket_index

  • ticket_lock_index

  • ticket_lock_type

  • ticket_loop_protection

  • ticket_number_counter

  • ticket_priority

  • ticket_state

  • ticket_state_type

  • ticket_type

  • ticket_watcher

  • time_accounting

  • user_preferences

  • users

  • valid

  • virtual_fs

  • virtual_fs_db

  • virtual_fs_preferences

  • web_upload_cache

  • xml_storage