Design > Architecture

Release Information

Internal Release Number: X.Y.Z
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TODO: Answer the questions below to help you define your system architecture. Some example text is provided.


What are the most important facts that a developer should know about this system architecture?
What software architecture style is being used?
Single-process desktop application (with plug-in extension modules).
Client-server with a custom thick-clients and server.
2-tier web application: webserver/app-server, database.
3-tier web application: webserver, app-server, database.
Single web service: app-server, database.
Network of web services.
Peer-to-peer with/without central server.
Computing grid / distributed servers.
What are the ranked goals of this architecture?
  1. Ease of integration
  2. Extensibility
  3. Capacity matching


What are the components of this system?
The components of this system are clearly defined in this UML Model with Component Diagram.
The components of this system are listed below by type:


How will the components be deployed to processes and machines?
The deployment of components to processes and machines is clearly defined in this UML Model with Deployment Diagram.
The deployment of components to processes and machines is clearly defined below:
The deployment of components to processes and machines is clearly defined below:
What aspects/resources of their environment are shared?
Everything is on one server so all machine resources are shared by all components.
All machines share the same bandwidth to the Internet. All machines access the same file server. So, if one component uses the resources heavily, other components may have to wait.
How are requests allocated to redundant or load-balanced servers?
We are not doing any load-balancing or redundancy for fail-over.
Load-balancing among front-end servers is handled by a load balancing device that we can make very few assumptions about. However, once a user session is established, the same front-end server will be used for all requests during that session.
What alternative deployment configurations are possible?
This is the only possible deployment.
The database could be moved to a different machine with a fairly simple change to a configuration file. Otherwise, nothing can be changed about the deployment.
We have the ability to move the database process to a separate machine. We have the ability to add more front-end servers. The application logic running on the application server cannot be split or load-balanced.


How will components be integrated? Specifically, how will they communicate?
All of our code uses direct procedure calls. The database is accessed through a driver.
Components within the same process use direct procedure call or standard Java events. Plug-ins are also accessed through a API of direct procedure calls and standard events. Communication with the database uses a JDBC driver. Communication between the front end-and back-end servers uses XML-RPC.
What architectural mechanisms are being used to ease future extensions or modifications?
We could change the database by switching drivers. Otherwise, extensions and modifications can only be done at the design level.
New front-end components could be added so long as they access the back-end the same way. New plug-in components can be dynamically loaded, so long as they satisfy the plug-in API. Otherwise, there is no ability to add or exchange components, because this architecture uses direct dependencies between its components rather than implicit invocation. Extensions and modifications can be made at the design-level, but deploying those changes requires recompilation and down-time.

Architectural Scenarios

TODO: Provide architecture scenarios that show how objects will communicate across components, processes, and machines. Focus on scenarios where the architecture itself is changing, e.g., system startup, shutdown, adding or upgrading components, load balancing or fail-over.

The following sequence diagrams give step-by-step descriptions of how components communicate during some important usage scenarios:

Architecture Checklist

TODO: Evaluate your architecture with respect to each of your goals.
Ease of integration: Have mechanisms been provided for all needed types of integration?
Yes. In this system, all of the new components are designed to work together. And, the reused components are integrated via fairly simple interfaces.
Extensibility: What types of components can be added later and how?
See above.
Capacity matching: How has this architecture matched component resource needs to machines?
The database can be on a machine with RAID disks and a hot-swappable power supply, while the web front-end components can be on cheaper machines that could fail individually without causing system downtime. The front-end web servers and application server are both CPU-intensive, so they are deployed to different CPUs. The database is disk-intensive, so it can be deployed to the same machine as the CPU-intensive application server, with only moderate competition for resources.
Has the architecture been communicated to the development team and other stakeholders?
Yes, everyone understands. Feedback is welcome.
No, this is a risk that is noted in the Risk Management section.
TODO: Check for words of wisdom and discuss ways to improve this template. Or, evaluate the ReadySET Pro professional architectural design template.
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Copyright © 2003-2004 Jason Robbins. All rights reserved. License terms. Retain this copyright statement whenever this file is used as a template.