3 Tier Application Architecture

[JAMES KHOR]

Hi there,

Does Atlassian Service Desk server edition follow 3 tiers application architecture?

I went through the documentation and believe there are 3 tiers application architecture. For security requirements, i can install the client on a virtual machine in the web zone, application server on a virtual machine in the app zone and database server on a virtual machine in the DB zone.

Thanks.

[Nic Brough _Adaptavist_]

You'll need to explain what you thnk "3 tiers architecture" is here, google gives me four widely differing definitions.

If you really mean the standard 7 tier architecture for web applications, then yes, it does that - OS (user) + client + OS (server side) + application server + application + OS (database) + database.  Each layer is independent in itself and could be swapped for something else. 

[JAMES KHOR]

Hi Nic, can it be confirmed that Atlassian does not have a 3 tier application architecture?

jira application is a web application server that connects to the database in the DB zone.

There is no client application that connects to the JIRA application. To comply to the 3 tier application architecture, I will need to set up a reverse proxy in the web tier in order to access the JIRA application.

Is my understanding correct?

[Nic Brough _Adaptavist_]

No, because you have not explained what you think a 3 tier architecture is.  It clearly means something different to me.  What do you mean by "tier" in this?

You say "There is no client application that connects to the JIRA application."

That is completely and utterly wrong.  You can't use Jira without one.  Whether it's a browser, a script or a dedicated program on a phone, desktop, tablet, car, spaceship or or or, you are using a client application.

I can't tell you about "compliance to 3 tier architecture" as you've not explained what you think it is.

[JAMES KHOR]

Hello Nic,

The 3-tier application architecture refers to the following.

1. Presentation tier which is the front-end layer that is accessible through a web-based application that displays content to the user. It is often built on web technologies such as javascript, HTML5 and others.

2. Application tier which contains the functional business logic that is written in Java, .NET and others.

3. Database tier comprises of the data storage layer such as mySQL, postgresql.

I understand JIRA service desk as the web application in the application tier that contains the functional business logic. It connects to a DB server in the database tier.

What i don't understand is whether there is a separate web-based application in the presentation tier that connects to JIRA web application in the application tier.

Hope this is clear to you.

[Nic Brough _Adaptavist_]

Thank you for explaining that.  It really does help frame the question a lot.

The 3-tier architecture you have here is an idealised reductionist model of software that can be useful for analysis, but has not been a good representation of most software for a couple of decades.

Applying it to Jira:

Tier 3 is mostly right.  There's a database.  Jira does not use it as a database, it is only a data store, but the tier idea works there.

Tier 2 and Tier 1 fail totally.  There is a "tier 2 application" but you have not recognised that there is a difference between the application, the application server, and the applications that are layered on top of the application. 

What you call "the presentation layer" is mostly done in the application side, not the front end.

TLDR: No.  Jira is not 3 tier, that model cannot explain it usefully.

[JAMES KHOR]

Thanks Nic. You have answered my question!

[JAMES KHOR]

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