I have been working with the Boost C++ Libraries for quite some time. I absolutely love the Boost Asio C++ library for network programming. However I was introduced to two other libraries: POCO and Adaptive Communication Environment (ACE) framework. I would like to know the good and bad of each.
As rdbound said, Boost has a "near STL" status. So if you don't need another library, stick to Boost. However, I use POCO because it has some advantages for my situation. The good things about POCO IMO:
Better thread library, especially a Active Method implementation. I also like the fact that you can set the thread priority.
More comprehensive network library than
boost::asio is also a very good library.
Includes functionality that is not in Boost, like XML and database interface to name a few.
It is more integrated as one library than Boost.
It has clean, modern and understandable C++ code. I find it far easier to understand than most of the Boost libraries (but I am not a template programming expert :)).
It can be used on a lot of platforms.
Some disadvantages of POCO are:
It has limited documentation. This somewhat offset by the fact that the source is easy to understand.
It has a far smaller community and user base than, say, Boost. So if you put a question on Stack Overflow for example, your chances of getting an answer are less than for Boost
It remains to be seen how well it will be integrated with the new C++ standard. You know for sure that it will not be a problem for Boost.
I never used ACE, so I can't really comment on it. From what I've heard, people find POCO more modern and easier to use than ACE.
Some answers to the comments by Rahul:
I don't know about versatile and advanced. The POCO thread library provides some functionality that is not in Boost:
ThreadPool. IMO POCO threads are also easier to use and understand, but this is a subjective matter.
POCO network library also provides support for higher level protocols like HTTP and SSL (possibly also in
boost::asio, but I am not sure?).
Integrated library has the advantage of having consistent coding, documentation and general "look and feel".
Being cross-platform is an important feature of POCO, this is not an advantage in relation to Boost.
Again, you should probably only consider POCO if it provides some functionality you need and that is not in Boost.
I've used all three so here's my $0.02.
I really want to vote for Doug Schmidt and respect all the work he's done, but to be honest I find ACE mildly buggy and hard to use. I think that library needs a reboot. It's hard to say this, but I'd shy away from ACE for now unless there is a compelling reason to use TAO, or you need a single code base to run C++ on both Unix variants and Windows. TAO is fabulous for a number of difficult problems, but the learning curve is intense, and there's a reason CORBA has a number of critics. I guess just do your homework before making a decision to use either.
If you are coding in C++, boost is in my mind a no-brainer. I use a number of the low level libraries and find them essential. A quick grep of my code reveals shared_ptr, program_options, regex, bind, serialization, foreach, property_tree, filesystem, tokenizer, various iterator extensions, alogrithm, and mem_fn. These are mostly low-level functionality that really ought to be in the compiler. Some boost libraries are very generic; it can be work to get them to do what you want, but it's worthwhile.
Poco is a collection of utility classes that provide functionality for some very concrete common tasks. I find the libraries are well-written and intuitive. I don't have to spend much time studying documentation or writing silly test programs. I'm currently using Logger, XML, Zip, and Net/SMTP. I started using Poco when libxml2 irritated me for the last time. There are other classes I could use but haven't tried, e.g. Data::MySQL (I'm happy with mysql++) and Net::HTTP (I'm happy with libCURL). I'll try out the rest of Poco eventually, but that's not a priority at this point.