Question

I am in the process of writing a web-app that uses multiple web APIs.
For a single request of a single user, my app may need to perform up to 30 HTTP requests to other sites. The site housing the web-app can have hundreds of concurrent users.

I’ve been looking around trying to figure out which library should I use. I’m looking for a mature project that has detailed documentation and tested code, one that will still be around in years to come. Not sure if something like that exists (!)

Couple of questions :

1. In a case such as described above, should I be using an asynchronous HTTP client (without threading), or a regular (possibly pooled) HTTP client (with threading)? Asynchronicity relieves my app from using threads, but makes the code more scattered – will the above mentioned number of requests burden my server too much? (it says here that asynchronous is more scalable)

2. Which library is the common one to use? Is it Apache HttpComponenets HttpClient or its asynch couterpart HttpAsynchClient – which is in Alpha…)? How about jfarcand’s AsyncHttpClient?

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Okay, let’s say I will use threads.
After digging around I realize that spawning threads from within a servlet (in my case – a Struts action), may be a big No No :

related questions:

What is recommended way for spawning threads from a servlet in Tomcat

Need help with java web app design to perform background tasks

Can i spawn a thread from a servlet ?

The way I see it, these are my options:

1. use my own thread pool (container doesn’t manage my threads)
2. use a WorkManager such as CommonJ (seems like an inactive product)
3. use a 3rd party scheduler such as Quartz (may be an overkill … ?)

I would appreciate any recommendations for this specific use case – aggregating lotsa data from different web services (this aggregation is invoked by a single user’s single request).

Answer 1

Good question. I would try an asynchronous solution first to see how everything works. The asynchronous solution would be the simplest to implement.

If that doesn’t work, try a more threaded model.

I would use HttpClient for making your requests. I’ve worked with it a lot and use it for any http work that I have to do.