I have developed an crawler in c++ with curl library and as it is developed in c++ it does not has an GUI and i am planning to implement the GUI using java .I have a question how to develop an API to access it in java…
for example
Mongo db is written in c++ and it has API for all languages..how it access the c++ do it uses socket to communicate…
You will need to write/wrap the crawler as a service and host it on a server that is listening on a port. You might want to create a text or binary protocol whereby the clients can then talk to this service. Once thats established, you can write the clients in any language including Java.