A data driven description of software architecture based on UML and the C4 model.
Describe your model as data and specify/generate representations (e.g. diagrams) for your model. All core and supplementary C4 diagrams except code diagrams are supported. Also UML use case, state machine and class diagrams are supported.
Overarch is not so much about how to model your architecture (see C4 Model for that), but about making these models composable and reusable.
- models and views as data
- C4 models and views
- UML use case, state machine and class models and views
- Concept models, concept maps and glossaries
- separation of models and views
- hierarchical models and element references
- view specific customization of model elements
- extensible format
- exports
- JSON if you need to process models with languages without EDN support
- PlantUML
- all C4 views (except code view)
- use case, state machine and class diagrams
- styling and sprite support
- GraphViz
- Concept maps
- Markdown
- Glossary, textual representations of graphical views
- Structurizr experimental
- watch model directory for changes
UML and C4 models are great to vizualize an architecture on different levels of detail with the various diagrams types. The value lies in an expressive description and visualization of an architecture with different views.
But the models used for diagram generation with the existing tools are not models in the sense of generality. Especially if you describe your model in PlantUML files, these descriptions are mere textfiles.
The textfiles don't compose and you can't do anything else with these descriptions other than render them with PlantUML. The parsing process is opaque and you don't have access to the data of the model.
Also the model is complected with the diagrams, as layout and rendering information is part of the model description and vice versa. The model should capture the essence of the architecture and not its representation.
If the model is described as plain data in an open format, it can be transformed into a graphical representation, e.g. into PlantUML textfiles, via the specification of views on the model.
In Overarch the model data is separated from information about these representations. Models can be composed with these views and with other models. By doing so, the model may also be used in other ways, e.g. the generation of documentation, code or infrastructure.
Even if the model is specified as data, the format should be a text file (EDN, JSON) to be easily edited with text editors by the whole team and to be committed to version control, instead of being in some propriatory binary format.
The native format is the Extensible Data Notation (EDN) with representations in other formats like JSON. EDN is a textual format for data, which is human readable. It is also directly readable into data structures in clojure or java code.
The data format is open for extension. E.g. it copes with additional attributes or element types in the data structures.
The model should describe the architecture (the structure) of your system(s). The elements are based on UML and the C4 model and are a hierarchical composition of the elements of the architecture.
Model references are used to refer to model elements from other models and representations (e.g. diagrams). To allow references to elements and relations, they must be given an id.
Model references may be enhanced with additional attributes that are specific to the usage context (e.g. a style attribute in the context of a diagram)
This is an example of the specification of a model and some diagrams based on the Internet Banking System example of Simon Brown at C4 Model.
The complete model and diagram specifications can be found under models/banking.
Further information about modelling with Overarch can be found in Usage.
#{; actors
{:el :person
:id :banking/personal-customer
:name "Personal Banking Customer"
:desc "A customer of the bank, with personal banking accounts."}
; system under design
{:el :system
:id :banking/internet-banking-system
:name "Internet Banking System"
:desc "Allows customers to view information about their bank accounts and make payments."
:ct #{{:el :container
:id :banking/web-app
:name "Web Application"
:desc "Deliveres the static content and the internet banking single page application."
:tech "Clojure and Luminus"}
{:el :container
:id :banking/single-page-app
:name "Single-Page Application"
:desc "Provides all of the internet banking functionality to customers via their web browser."
:tech "ClojureScript and Re-Frame"}
{:el :container
:id :banking/mobile-app
:name "Mobile App"
:desc "Provides a limited subset of the internet banking functionality to customers via their mobile device."
:tech "ClojureScript and Reagent"}
{:el :container
:id :banking/api-application
:name "API Application"
:desc "Provides internet banking functionality via a JSON/HTTPS API."
:tech "Clojure and Liberator"}
{:el :container
:subtype :database
:id :banking/database
:name "Database"
:desc "Stores the user registration information, hashed authentication credentials, access logs, etc."
:tech "Datomic"}}}
; external systems
{:el :system
:id :banking/mainframe-banking-system
:external true
:name "Mainframe Banking System"
:desc "Stores all the core banking information about customers, accounts, transactions, etc."}
{:el :system
:id :banking/email-system
:external true
:name "E-mail System"
:desc "The internal Microsoft Exchange email system."}
; Context view relations
{:el :rel
:id :banking/personal-customer-uses-internet-banking-system
:from :banking/personal-customer
:to :banking/internet-banking-system
:name "Views account balances and makes payments using"}
{:el :rel
:id :banking/internet-banking-system-uses-email-system
:from :banking/internet-banking-system
:to :banking/email-system
:name "Sends e-mail using"}
{:el :rel
:id :banking/internet-banking-system-using-mainframe-banking-system
:from :banking/internet-banking-system
:to :banking/mainframe-banking-system
:name "Gets account information from, and makes payments using"}
{:el :rel
:id :banking/email-system-sends-mail-to-personal-customer
:from :banking/email-system
:to :banking/personal-customer
:name "Sends e-mail to"}} #{{:el :context-view
:id :banking/system-context-view
:title "System Context View of the Internet Banking System"
:ct [; model elements
{:ref :banking/personal-customer}
{:ref :banking/email-system}
{:ref :banking/mainframe-banking-system}
{:ref :banking/internet-banking-system}
; relations
{:ref :banking/personal-customer-uses-internet-banking-system :direction :down}
{:ref :banking/internet-banking-system-uses-email-system :direction :right}
{:ref :banking/internet-banking-system-using-mainframe-banking-system}
{:ref :banking/email-system-sends-mail-to-personal-customer :direction :up}]}
{:el :container-view
:id :banking/container-view
:title "Container View of the Internet Banking System"
:ct [; model elements
{:ref :banking/personal-customer}
{:ref :banking/internet-banking-system}
{:ref :banking/email-system}
{:ref :banking/mainframe-banking-system}
; relations
{:ref :banking/email-system-sends-mail-to-personal-customer :direction :up}
{:ref :banking/personal-customer-uses-web-app}
{:ref :banking/personal-customer-uses-single-page-app}
{:ref :banking/personal-customer-uses-mobile-app}
{:ref :banking/web-app-deliveres-single-page-app :direction :right}
{:ref :banking/single-page-app-calls-api-application}
{:ref :banking/mobile-app-calls-api-application}
{:ref :banking/api-application-uses-database :direction :left}
{:ref :banking/api-application-uses-email-system :direction :right}
{:ref :banking/api-application-uses-mainframe-banking-system}
]}
}@startuml banking_systemContextView
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Context.puml
title System Context View of the Internet Banking System
Person(banking_personalCustomer, "Personal Banking Customer", $descr="A customer of the bank, with personal banking accounts.")
System_Ext(banking_emailSystem, "E-mail System", $descr="The internal Microsoft Exchange email system.")
System_Ext(banking_mainframeBankingSystem, "Mainframe Banking System", $descr="Stores all the core banking information about customers, accounts, transactions, etc.")
System(banking_internetBankingSystem, "Internet Banking System", $descr="Allows customers to view information about their bank accounts and make payments.")
Rel_Down(banking_personalCustomer, banking_internetBankingSystem, "Views account balances and makes payments using")
Rel_Right(banking_internetBankingSystem, banking_emailSystem, "Sends e-mail using")
Rel(banking_internetBankingSystem, banking_mainframeBankingSystem, "Gets account information from, and makes payments using")
Rel_Up(banking_emailSystem, banking_personalCustomer, "Sends e-mail to")
SHOW_LEGEND()
@enduml
Overarch is written in Clojure and gets built with leiningen. To build it, you need to have Java 11 or higher and leiningen installed.
In the cloned overarch repository, run
lein uberjar
to build a JAR file with all dependencies. This JAR file is created in the target folder and is named overarch.jar
If you have a clojure environment in some editor or IDE, just use it. Maybe a PlantUML plugin exists for this environment too.
If not, try Visual Studio Code with the Calva and PlantUML extensions.
With this setup you get an editor for the EDN files with code completion, syntax check and syntax highlighting.
You also get integrated previews of the exported PlantUML diagrams and the ability to generate image files in different formats (e.g. PNG, SVG, PDF, ...) directly from within Visual Studio Code.
PlantUML also needs an installation of graphviz. Please read the installation instructions in the PlantUML extension on how to install graphviz for your operating system.
To get support for icons (PlantUML sprites) from the PlantUML standard library, a recent plantuml.jar is highly recommended. Please download it from PlantUML Releases and reference it in the PlantUML extension settings.
Use a folder for all the data (e.g. models, view specifications) of a project. Add EDN files for the model and the view specifications. All the EDN files in the folder will be loaded.
Start the the Overarch CLI tool with java.
java -jar overarch.jar [options]
Overarch currently supports these options
Overarch CLI Exporter
Reads your model and view specifications and renders or exports
into the specified formats.
Usage:
java -jar overarch.jar [options].
Options:
-m, --model-dir PATH models Model directory or path
-r, --render-format FORMAT Render format (all, graphviz, markdown, plantuml)
-R, --render-dir DIRNAME export Export directory
-x, --export-format FORMAT Export format (json, structurizr)
-X, --export-dir DIRNAME export Export directory
-w, --watch Watch model dir for changes and trigger action
--model-warnings Returns warnings for the loaded model (default true)
--model-info Returns infos for the loaded model (default false)
--plantuml-list-sprites Lists the loaded PlantUML sprites
-h, --help Print help
--debug Print debug messages
If you use Visual Studio Code as described above, you can start Overarch in watch mode from a terminal inside VS Code. Every time you save some changes in the EDN files, the views will be updated and previews can be rendered with the PlantUML extension.
See Usage for additional information on modelling and usage of the Overarch CLI tool.
See Design for information about the design of Overarch.
Here are my current plans to enhance overarch in the next releases.
- enhanced conveniance in view specifications
- automatic includes of elements e.g.
- include relations for referenced elements
- includes based on selection criteria
- automatic includes of elements e.g.
- provide relations between elements of the different models to model traceability information (e.g. from use cases to the containers implementing them or from domain concepts to domain model elements)
© 2023 Ludger Solbach
Eclipse Public License 1.0 (EPL1.0)