Single Large Webapp or multiple small webapps? [closed]

Question

I have a website, consisting of about 20 Java Web applications (Servlet/JSP based webapps), of varying sizes, each handling different areas of the site.

The combined size of all 20 war's is 350mb, however by combining them I anticipate being able to ultimately reduce that and realise combined caching benefits.

Is it best to keep them separate, or merge them into a single Uber webapp war file? (and why)

I'm particularly interested in knowing any technical drawbacks of merging them.

Answer 1

I "vote" to combine them.

Pros

• Code sharing: If you combine them, you can share code between them (becase there will be only one).
  This does not apply to just your code, it also applies all the external libraries you use which will be the bigger gain I think.

• Less memory: Combined will also require less memory (might be very significant) because the external libraries used by multiple apps will only have to be loaded once.

• Maintainability: Also if you change something in your code base or database, you only have to change it in one place and re-deploy one app only.

• Easier synchronization: If the separate apps do something critical in the database for example, it's harder to synchronize them compared to the case when everything is in one app.

• Easier collaboration between different parts/modules of the code. If they are combined, you can simply call methods of other modules. If they are in different web apps, you have to do it in a dirty way like HTTP calls, RMI etc.

Cons

• It will be bigger (obviously). If you worry about it being too big, just exclude the libs from the deployment war, place it under the tomcat libs.

• The separate apps might use different versions of the same lib. But it's better to sort them out early when it can be done easier and with less work.

• Another drawback can be the longer deployment time. Again, "outsourcing" the libs can help making it faster.