THE USE OF GRID STORAGE PROTOCOLS FOR
HEALTHCARE APPLICATIONS
Flavia Donno
CERN, CH-1211, Geneva 23, Switzerland
Elisabetta Ronchieri
INFN-CNAF, Viale Berti Pichat 6/2, I-40126 Bologna, Italy
Keywords: HealthGrid, Storage grid Technology.
Abstract: Grid computing has attracted worldwide attention for a variety of domains. Healthcare projects focus on
data mining and standardization techniques, the issue of data accessibility and transparency over the storage
systems on the Grid has seldom been tackled. In this position paper, we identify the key issues and
requirements imposed by Healthcare applications and point out how Grid Storage Technology can be used
to satisfy those requirements. The main contribution of this work is the identification of the characteristics
and protocols that make Grid Storage technology attractive for building a Healthcare data storage
infrastructure.
1 INTRODUCTION
Grid computing aims at the definition of a global
infrastructure able to share geographically
distributed resources (such as data, storage,
computers, software, tools, applications,
instruments, and networks) in a secure context. The
name “Grid” comes from the metaphor of “Electrical
Grids” and the idea to get access to a resource (e.g.,
electricity) by using a plug (Foster, et al., 2001).
The integration of Grid and Healthcare has created a
new area called HealthGrid (Breton, et al., 2005),
which has produced a great impact on almost every
aspect of Healthcare.
Grid builds an infrastructure that provides
resources and distributed information to the medical
personnel. The available resources may include
computational resources, storage, equipment (e.g.,
scanners, lab), or human resources (specialists).
Healthcare specific policies (such as privacy or
authorization) are enforced according to a given
service agreement.
In this paper we focus on Grid Storage
technologies and investigate how these could be
exploited by healthcare applications. In particular, in
Section 2 we describe Healthcare use cases and
requirements. Section 3 reports on related work. In
Section 4 we give an overview of Grid storage
technology. Section 5 elaborates on existing Grid
Storage protocols for data consistency, privacy, and
preservation. A few examples are given for encoding
medical metadata and preserve the information on a
Grid Storage Service for later retrieval. Finally,
Section 6 summarizes our conclusions and describes
future work.
2 HEALTHCARE USE CASES
AND REQUIREMENTS
A medical application can include a check-up, a
specialist consultant exam, bio-signal or genomic
measurements. The patient data are first collected.
Old documentation concerning the patient is
connected to the current patient file. New tests are
performed and medical images or other exams are
acquired. While the data concerning the patient are
strictly protected and must not be exposed to
insecure access, the images produced by the exams
can be made available to several physicians for
further comparative or statistics studies. By using
the Grid, all the exams and measurements can be
made available on geographically distributed
computing resources. Online medical information
can be acquired by connecting to national or
international medical information centres to help the
484
Donno F. and Ronchieri E. (2009).
THE USE OF GRID STORAGE PROTOCOLS FOR HEALTHCARE APPLICATIONS.
In Proceedings of the International Conference on Health Informatics, pages 484-487
DOI: 10.5220/0001553404840487
Copyright
c
 SciTePress

diagnosis. Remote consultation can also be set up
through the network. Cooperation and
interoperability of clinical data is essential.
Algorithms for searching and retrieving data from
knowledge bases have to be properly defined.
Furthermore, data mining is another essential
process. Some of the distributed sources of data may
have strong privacy rules. Therefore, the system
must be proven highly reliable for privacy and
security. Health Grid applications have specific data
distribution and access requirements:
Security. By authentication we intend the process
for which it is possible to know who a user is.
Authorization implies the discovery of what a user is
allowed to do in the system. Auditing is the process
that keeps track of the actions performed by a user.
Privacy and Confidentiality of Data. It can be
achieved by splitting sensitive patient data from the
rest of the data content and using de-identification or
encryption.
Legal and Ethical Enforcements. The legal and
ethical requirements impose obtaining explicit
consensus from the patients and clearance to use
data from ethics’ committees. Local policies must be
enforced over global decisions for data distributed
world-wide.
Interoperability of Data. The interoperability
between data stored in different centres can be
achieved through standardization of data formats,
structures and models.
Data Access Transparency. It is important to
guarantee location independent transparent access to
data. Therefore, a storage infrastructure should allow
for the preservation of metadata (contextual data
about the information being stored) and the
negotiation of supported capabilities. The metadata
information could concern for example the software
that has generated the data, their encoding, their
validity, security and privacy information and other
data logically connected. A framework processing
such a description could allow for the negotiation of
given capabilities with the data access services.
Quality of Service. The quality of service
requirement is related to guarantee for example
adequate access time and storage quality for the type
of data being stored at a site. It is important to
negotiate a Service Level Agreement (SLA) in terms
of access latencies, integrity, etc. for specific
important data stored in a Grid.
3 RELATED WORK
In 2002, the European Community has funded
projects specifically on Healthcare. They are
MammoGrid (Warren, et al., 2007), and GEMSS
(Grid-Enabled Medical Simulation Services Project,
http://www.it.neclab.eu/gemss/). The UK e-Science
program made funds available between 2001 and
2004 in Healthcare. These were used to sponsor
projects such as eDiaMonND (UK e-Science
eDiaMoND Project,
http://www.ediamond.ox.ac.uk/), CLEF (CLEF –
integrating information for the clinical e-Scientist,
http://www.clinical-escience.org/start.html) and
CareGrid (Liu, et al., 2007).
The MammoGrid (European Federated
Mammogram Database Implemented on a GRID
Structure) project aimed to develop a pan-European
distributed database of mammography images using
Grid technologies. The GEMSS (Grid-Enabled
Medical Simulation Services) project aimed at
providing an innovative Grid middleware to support
several medical service applications including
maxillofacial surgery simulation, neuro-surgery
support, radio-surgery simulation, inhaled drug
delivery simulation, cardio-vascular system
simulation and advanced medical image
reconstruction. The eDiaMoND (on digital
mammography) project aimed at delivering a
prototype which could support breast screening in
the UK through screening tests, computer-based
training, epidemiology studies and computer aided
detection of breast cancer. It gave patients,
physicians and hospitals fast access to a vast
database of digital mammogram images. The
database was also used for image analysis
algorithms research, for data mining and imaging
standardization techniques. The CLEF (CLinical E-
science Framework) project aimed at creating a
generic scalable architecture based on Grid
technology for capturing, integrating, interpreting
and using clinical data with genomic data and
images within practical clinical systems. The
CareGrid project focuses on developing software for
supporting decisions based on trust, privacy, security
and context models in Healthcare application
domain.
One topic not yet covered is how to provide
support to Healthcare applications through the Grid
Storage Technology.
THE USE OF GRID STORAGE PROTOCOLS FOR HEALTHCARE APPLICATIONS
485

4 GRID STORAGE
TECHNOLOGY
A Grid Storage Element (SE) is the set of
hardware and software solutions adopted in order to
realize a storage Grid service. It hides the difference
among specific solutions and allows users for
consistently and securely storing files at a Grid site.
An SE provides a set of useful functionalities.
Grid users and applications migrate across multiple
administrative domains. Both a transparent
interface for specific, very frequent operations and a
set of different communication protocols are
supported. Security protocols used across domains
might differ and are equally and transparently
supported. In particular, authentication and
authorization mechanisms valid across domains are
honored. Reliable and high performing data
transfers protocols across domains are available.
Local policies and priorities have priority over
global ones. A set of storage classes is advertised so
that application and services can take advantage of
them. A storage class is a type of storage space with
specific attributes such as reliable, persistent storage
or unreliable scratch space for temporary usage only
with very low access latency. Grid users also need to
have available a set of operations for managing and
reserving storage space and for filesystem-like
operations (such as ls, mkdir, ln, and file locks).
Grid Storage services differentiate between valuable
and expendable data (volatile vs. permanent data).
Operations such as transparent, automatic or
forced migration to tertiary storage (tapes) are
available. Mechanisms for transparently locating
data on any storage device are provided for
debugging, disaster recovery, and security reasons.
Storage systems also provide a mechanism to
advertise capacity, status, availability and content
to an information system. Management and
monitoring functions for Grid global control of
service behavior and functionality are available.
Data integrity mechanisms allow through the
usage of checksum and location independent
information to ensure correctness of data even after
replication or reprocessing. Data privacy
mechanisms is ensured with the support of side
services that allow for instance the storage of
encryption keys on distributed servers so to protect
also from malicious attempts at a specific site.
The Storage Resource Manager (SRM)
specification (Shoshani, et al., 2004) is used today
by many Grid storage services. Other emerging
protocols are available and could be used in the
context of healthcare. In the next section, we provide
an overview of the most common protocols used
today in the Grid environment for storage services
together with some Healthcare application examples.
5 GRID STORAGE PROTOCOLS
A Storage Resource Manager (Sim, et al., 2008) is
a middleware component whose function is to
provide dynamic space allocation and file
management on shared storage components on the
Grid. It satisfies most of the requirements explained
in the previous section. Data sets and metadata
information can be packaged in a file that SRM can
manage.
Let us illustrate the functionality of an SRM
through a typical healthcare use case. A physician
would like to make available a set of files through
the Grid. The application used checks that the
amount of space needed for storing the data is.
Therefore, after authentication and authorization are
performed, the application can issue an SRM request
to reserve the space to store the data on an SE with a
certain quality (magnetic device/online disks/fast
access) to allow for security and preservation
policies to be applied. Additionally, the application
is enabled to only use a certain set of file protocols,
as in the case of DICOM (http://medical.nema.org)
images. Therefore, it can negotiate the provision of
an area of space where the requested protocol can be
used. As a result, the SRM provides a protocol
dependent file handle that the application can use to
store the data. The application initiates the store
session that includes data encryption and storage of
encryption keys on specific servers, like Hydra
Keyserver (Gilliam, 2002). Metadata information
can also be stored through interfaces such as the
SNIA XAM (Storage Networking Industry
Association, Information Management – Extensible
Access Method (XAM) – Part 1: Architecture,
Version 1.0, 2 April 2008,
http://www.snia.org/forums/xam/technology/specs/
XAM_Arch_v1.0_Apr6.pdf
.) described later. Access
Control Lists can be defined on both the data
namespace and the storage space to control access.
The original set of data together with its metadata
bundle can be automatically replicated at different
sites for better availability and preservation or to
optimize data access. Other physicians at a different
location on the Grid can check for the availability of
the data in order to start further processing. Data
integrity methods guarantee the correctness and
authenticity of the data and the associated metadata.
Once done, the space reserved by the can be
HEALTHINF 2009 - International Conference on Health Informatics
486

recollected by the system and reused to satisfy other
requests. Files can be removed automatically by the
system for further security, allowing only a specific
time window for given operations. SRM offers a
namespace similar to the one of a UNIX filesystem.
The Grid Security Infrastructure (Campana, et al.,
2004) is also used.
Another emerging protocol that is acquiring
popularity is NFS v4 (http://www.nfsv4.org/).
Among the features of NFS v4 we can list: improved
access and good performance on the Internet; strong
security, with security negotiation built into the
protocol; enhanced cross-platform interoperability;
extensibility of the protocol. Furthermore, NFS v4.1
provides support for metadata encapsulation.
SRM and NFS v4 address the problem of
providing control and access uniform interfaces to
world-wide distributed Grid Storage Services. The
Storage Networking Industry Association (SNIA) is
promoting the definition of the eXtensible Access
Method (XAM). This protocol proposes a way to
handle reference information (metadata) at the level
of a storage device. Such metadata provide a way to
relocate data across diverse local hardware
platforms, without compromising data integrity.
Based on the XAM-retrieved metadata content, the
storage service can trigger automatic data operation
before serving the data to a user for access or
manipulation. XAM provides: a Global location
independent unique name associated with
reference information, that allows for
implementing data integrity practices; metadata
strictly coupled with its data, facilitating the data
management, access and manipulation together with
data interoperability; storage systems accessed via
a standard, pluggable architecture. XAM also
provides a standardized set of management
disciplines and semantics for fixed content.
Retention and expiration policies can be enforced.
An example of application of the XAM technology
to HealthCare application is for instance the
encoding of the Clinical Document Architecture
(CDA) in XAM objects. CDA is a schema for
recording clinical events in documents. The schema
is composed of two entities: a header that contains
information like global-unique identifiers, document
type code, timestamp, confidentiality code, patient,
author and custodian; a body that contains tables,
lists, sounds, and video clips. CDA schema can be
translated in XAM, simply abstracting data and
metadata into XSet contained into a logical
XSystem. Therefore it is possible to represent for
example a mock up patient data by using an
XSystem characterized by several XSets one for
each CDA entity.
6 CONCLUSIONS
In this work we have identified the Grid storage
services and protocols that could facilitate the
integration and interoperation of Healthcare data and
frameworks world-wide. While many of the current
Healthcare Grid projects address issues such as
simulation, data location and description on the Grid
and security, the problems connected to data storage,
integrity, preservation and distribution have been
neglected. We are planning to make available a
prototype infrastructure using EGEE gLite that
integrates all protocols mentioned as a proof of
concept for distribution and sharing of medical data.
REFERENCES
Breton, V., et al., 2005, “The HealthGrid White paper,” In
Proceedings of HealthGrid 2005 (From Grid to
HealthGrid), IOS Press, vol. 112, pp. 249-321.
Campana, S., et al., 2004, “Toward a Grid Technology
Independent Programming Interface for HEP
Applications,” In Proceedings of CHEP2004, Sept. 27
- Oct. 1, 2004 Interlaken, Switzerland.
Foster, I., et al., 2001, “The Anatomy of the Grid:
Enabling Scalable Virtual Organizations,” In
International Journal of Supercomputer Applications,
vol. 15, no. 3, pp. 200-222,
http://www.globus.org/research/papers/anatomy.pdf.
Gilliam, D., 2002, “Summary report on enterprise security
workshop,” In Proceedings of the Eleventh IEEE
International Workshops on Enabling Technologies:
Infrastructure for Collaborative Enterprises, pp. 43-
46.
Liu, Y., et al., 2007, “On smart-care services: Studies of
visually impaired users in living context,” In
Proceedings of the First International Conference on
the Digital Society (ICDS’07), pp. 32-40, IEEE Press,
January 2007.
Shoshani, A., et al., 2004, “Storage Resource
Management: Concepts, Functionality, and Interface
Specification,” GGF 10, The Future of Grid Data
Environment, 9-13 March 2004, Humboldt University,
Berlin Germany.
Sim, A., et al., 2008, “The Storage Resource Manager
Interface Specification Version 2.2,” OGF-GSM, 24
May 2008.
Warren, R., et. al., 2007, “MammoGrid - A Prototype
Distributed Mammographic Database for Europe,” In
Clinical Radiology, vol. 62, no. 11, pp. 1044-1051,
June 2007.
THE USE OF GRID STORAGE PROTOCOLS FOR HEALTHCARE APPLICATIONS
487