Data in Cloud are seamlessly stored and presented to the user as if they reside locally. This means that the Cloud repository is presented as a virtual folder and does not provide the features of a database scheme. In order to provide the user with data querying functionality, medical records and related data (images and biosignals) are stored into a SQLite [21] file. SQLite is the database platform supported by Android. The file resides into a specific location at the Cloud and is retrieved on the device every time user needs to query data. The query is performed locally and the actual location of the data in the cloud is revealed to the applications. The database file is updated and uploaded into the Cloud every time user modifies data, respectively.
I. UTILIZING AMAZON S3 CLOUD SERVICE
For the realization of the mobile healthcare information management system the Amazon Simple Storage Service (S3) has been utilized. The main reason for selecting the specific Cloud Computing platform is that it is a commercial service well established and used successfully in several applications ([22]). It provides users with several interoperable web interfaces for managing data (SaaS model) and developers with the ability to create their own applications for accessing the latter (PaaS model) and is suitable for managing healthcare information ([23]).
II. INITIAL EVALUATION FROM THE SYSTEM IN PRACTICE
In order to prove the system’s usability, some initial experiments evaluating the system’s performance have been conducted. Experiments concern the time needed to transmit data to the Amazon S3 Cloud storage service. Due to the fact that textual data like a patient’s health record or a biosignal sequence do not consist of large data files and do not require high bandwidth, the presented results involve the transmission of medical images. The @HealthCloud application as presented in previous sections has been used on a HTC G1 mobile phone running Android OS version 1.6. A number of medical images of different modalities (MR, CT, PET, OT and Ultrasound) and different file sizes have been used. The transmission times are displayed in Table I. As indicated, two different wireless network infrastructure types have been utilized; a WLAN and a commercial 3G Network