A service extraction and application composition system comprising: at least one processor; and a preprocessor, executed by the at least one processor, to preprocess and instrument an existing application that is to be converted to a service-oriented application by injecting instrumentation code into the existing application by identifying a code signature where a service of the services related to the existing application is initiated to preprocess and instrument the existing application, the existing application containing the entire source code package, test cases to test the existing application, and a running environment where the existing application may be executed, wherein the code signature represents a code point where the service is initiated, wherein identifying the code signature comprises scanning for the code signature, and wherein injecting the instrumentation code comprises injecting the instrumentation code into the existing application at appropriate locations for extraction of functionality of the existing application; a trace generator to execute the preprocessed and instrumented existing application to generate traces related to a runtime behavior of services related to the existing application; a calling code generator to utilize the traces related to the runtime behavior of the services related to the existing application to generate calling code related to the services related to the existing application; a code generator to generate representational state transfer, REST, application programming interfaces, APIs, that include the calling code to call the services related to the existing application; a refactored code generator to generate refactored code for the existing application by modifying the source code of the existing application and/or adding new code to the existing application code for invocation of the services related to the existing application by the REST APIs; and a package generator to utilize the REST APIs and the refactored code for the existing application to generate the service-oriented application by wrapping the refactored code for the existing application in a facade layer, the facade layer including the REST APIs and exposing the REST APIs to a client, wherein the calling code includes an existing application invocation code for invoking a specified part of the existing application that is related to invocation of a REST API of the REST APIs. at least one processor; and a preprocessor, executed by the at least one processor, to preprocess and instrument an existing application that is to be converted to a service-oriented application by injecting instrumentation code into the existing application by identifying a code signature where a service of the services related to the existing application is initiated to preprocess and instrument the existing application, the existing application containing the entire source code package, test cases to test the existing application, and a running environment where the existing application may be executed, wherein the code signature represents a code point where the service is initiated, wherein identifying the code signature comprises scanning for the code signature, and wherein injecting the instrumentation code comprises injecting the instrumentation code into the existing application at appropriate locations for extraction of functionality of the existing application; a trace generator to execute the preprocessed and instrumented existing application to generate traces related to a runtime behavior of services related to the existing application; a calling code generator to utilize the traces related to the runtime behavior of the services related to the existing application to generate calling code related to the services related to the existing application; a code generator to generate representational state transfer, REST, application programming interfaces, APIs, that include the calling code to call the services related to the existing application; a refactored code generator to generate refactored code for the existing application by modifying the source code of the existing application and/or adding new code to the existing application code for invocation of the services related to the existing application by the REST APIs; and a package generator to utilize the REST APIs and the refactored code for the existing application to generate the service-oriented application by wrapping the refactored code for the existing application in a facade layer, the facade layer including the REST APIs and exposing the REST APIs to a client, wherein the calling code includes an existing application invocation code for invoking a specified part of the existing application that is related to invocation of a REST API of the REST APIs.