The Design And Implementation Of Restful Data Access Service In Data-as-a-service Of IBM Private Cloud

With cloud computing technology developing more and more mature in thecompanies of the Internet, more and more acceptable to enterprise users, thetraditional IT companies are also beginning to enter into this field. Data-as-a-Service(DaaS) is a solution of cloud storage service, made and implemented by IBM in itsprivate cloud platform, BlueMix, under this background. The result of this paper isone of the core sub-services of DaaS, based on Java. It provides RESTful, whichstands for “REpresentational State Transfer”, APIs for DaaS to access databases suchas MySQL or MongoDB, in order to complete persistence operations of data models,data objects or references between objects.The implementation of the web framework and RESTful APIs of the targetservice of this paper are based on Spring Web MVC, and the persistence operationsare based on Spring Data. This service can be divided functionally into three layers:the application layer handles RESTful requests and invokes logic layer; the logiclayer handles data models for meta data management, handles data objects for accessadaptors or dynamically generates Java bytecode files for code generators; theinteraction layer provides Spring-Data-based entity classes and repository interfaces.These three layers are an object-oriented abstraction above the cloud databases,which provides an access with RESTful APIs, instead of standard query languages.The result of this paper provides three kinds of data access functions: datamodel functions, operations for data structure, include the definition, deletion andquery of how data should be organised; data object functions, operations for dataitself, include the creation, deletion, modification, simple query and query withcomplex conditions of what data really is; data reference functions, operations forthe references between different data objects, include add or remove of references,and query data objects according some certain reference.The requirement of accuracy and extendibility is high in the work of this paper.As for accuracy, every request, no matter it is valid or not, must get a response; asfor extendibility, several design patterns, such as factory method pattern, strategypattern and so on, are used to decouple in order to make each module as separate aspossible.The work of this paper is a part of an enterprise incubation project of IBM. Thisproject has already been completed and transferred to Mobile-Backend-as-a-Serviceteam for further development to become an official product eventually.