I have to design an application which gets requests from multiple sources like Web service (can be SOAP or REST), online system, Message Queue or some batch job. Application needs to interface with 2 more applications for getting results. I understand that this can be done using microservices. This application needs to be built in Java. I am looking for some framework which can help me with accepting input from multiple sources as mentioned above.
If you want to build a lightweight simple layer (single app) to cater all these requirements, I would recommend using Apache Camel. This single app can listen to rest/soap requests, read from file system, JMS store, database etc. You can even embed it into another application and have all sorts of integration with different data source and excellent and easy to configure routing and transformation engine. Plus the documentation and community is awesome.