Here are the details of my use case:
What's my data.. There would be user experiences, error report, state info and so on. The data is fragmented and may change in the future. So I plan to use NoSQL, maybe mongodb, to save data in the server.
What are the clients.. They are clients written in different languages, like C#, C++, LabVIEW and so on. Some don't even have an access to a mongodb driver, so of course it's not an option to communicate with database directly. And framework like below is needed.
Clients -> (Some protocol) -> Broker -> Database.
As those clients are not web client, so common web server using http may not suit for my case, right? Is there any suggestion for the protocol, broker and database, Or even a new framework. My goal is to make the clients can send data as convenient as possible.
This is not really new, but a message driven application, which is a well understood pattern.
I did this mostly in Java, so I will stick to this language here.
A broker alone would be not enough here. Let us say you use Apache ActiveMQ as you message broker, you would still need to get your data into the database, since MQ is... ...a message queue. So you need a part which gets the messages out of MQ, processes them according to your business rules and stores them in the (correct) database instance, and the correct collection/bucket/table. Of course you could write this part by hand, but that would be pretty much reinventing the wheel. There is a notion of a "message routing and mediation engine", and the most commonly suggested here is Apache Camel, which has quite some components to communicate with databases and other so called consumers and producers. And that is the key point. In general, if possible, your clients should send their data to the message broker directly. But, if they can't, they can simply send text files or make REST calls – there are actually too many options to list here. This incoming data can be preprocessed and normalized to your standard format by a "route" in Apache Camel (a set of a consumer, conversion rules and a producer, in it's simplest form) and send as an AMQP message to MQ. From there, another Camel route can process the AMQP messages, apply your business rules and store the data in the database... ...or whatever else may come to your mind (for example sending an email).
So this solution supports a multitude of protocols for incoming and outgoing messages (as long as they are supported by Camel) and you have your business rules in a centralized and well defined location.
To implement this, I'd strongly suggest using Apache ServiceMix, which is a distribution of ActiveMQ, Camel and a system to manage the components and business rules.