This section contains a description of several access technologies with application in healthcare. Since there are a variety of technologies which can be used for construction of telemedical services and since their architectures can vary considerably, this section should only be seen as an outline.
5.1 Web Services
Web Services [8] can be defined as a software construct that exposes business functionality over the Internet. Exposing in this context means identifying
business processes, providing them in loosely-coupled, service-oriented interfaces and describing these interfaces in a standard way. Web Services-based applications are often built using the promising SOA approach described in the previous section. Loose coupling applied when constructing services allows for independent development of small, well-defined pieces of code and minor changes and enhancements in services do not usually require updates in other services (especially client applications). Web Services allow users to organize communication in various ways, best suited to the characteristics of each particular service: traditional request-response synchronous operation invocations and asynchronous or event-driven models, which are especially useful when considering long running transactions (LRT).
Web Services make extensive use of the XML language. Its advantages include simplicity of processing in any software environment, as well as portability – XML documents are strictly formatted text documents. Considerable overhead resulting from verbosity when compared with binary representations is perceived as a disadvantage of XML.
To describe business functionality, Web Services use Web Services Description Language (WSDL), an XML-based language presenting the interface of a service. To publish the interface, WSDL descriptions can be advertised in UDDI (Universal Description, Discovery and Integration) repositories.
Communication in the Web Services environment is performed using messages formatted according to the Simple Object Access Protocol (SOAP) which is an XML-based protocol. SOAP messages are usually sent via HTTP or HTTPS protocols. The benefit of using these particular protocols is that communication can easily pass through firewalls. Upon arriving at the destination, the original message is extracted from its SOAP envelope and delegated to the proper business protocol instance.
Systems built with various technologies such as CORBA, .NET, EJB may be accessible via Web Services interfaces. In this case, Web Services runtime components handle the reception of the message, translation of the XML to another format if necessary and invocation of the back-end business functionality. The advantages of this common approach coincide with Web Services advantages, but the introduced overhead may in some cases prove unacceptable.
Figure 3-5 Web Services architecture.
Web Services are extensively used in medical environments. By hiding the details of implementation of Web Services, this loosely-coupled model helps healthcare information systems overcome integration challenges faced by POC devices, POCIS, LIS and HIS systems.
5.2 Portal Technologies
Many enterprise-scale systems are accessible for their users via portal interfaces. Portal platforms provide numerous ready-to-run mechanisms which enable managing access to the entire system in a convenient and consistent manner. Portals are usually the main entry point to the enterprise, providing users with Web interfaces for virtually any exposable content and integrating their separate systems and functionality into one common interface. Portals can provide access to databases, various services, legacy systems, etc. In the context of e-health environments, access to LIS/HIS systems can be particularly important. Portals can have built-in mechanisms making integration with some systems almost automatic (e.g. with databases and Web Services).
By using portal solutions, access to resources can be efficiently secured — including authentication, authorization and encryption of data transfer with the HTTPS protocol. Portal platforms usually support a single sign-on (SSO) mechanism, not requiring multiple logins when requesting another portal resource within the same session. Users of portals can usually be divided into groups with different interests and permissions; portal technologies support this fact by providing granular authorization to portal content, according to users’ roles or individual needs.
The users themselves can also have influence on the appearance of their workspace. They can customize both the content and the interface in the way they like — creating private workspaces. Moreover, portals are able to support different types of displays allowing users to access portal services from various kinds of devices, e.g. handheld appliances and desktop computers. In each case, the workspace is automatically arranged in such a way as to be properly adjusted to the display dimensions of the system the user logs in from.
There are many mature portal environments available on the market. The most popular ones include [9] the Oracle 9ias Portal, the Sun Java Enterprise Portal System, the IBM WebSphere Portal and Microsoft SharePoint.
Referring to medical systems, portal technologies efficiently facilitate creation of e-health solutions. They can be perceived as the perfect tool to provide modern medical services for medicine professionals and staff as well as for patients. The former group will be supported in everyday work and the latter one can seek information or advice, and can have access to personal data regarding health state.
5.3 Interactive and Multimedia Communication
Portal technologies allow users to access the content of the portal in a client- server manner. One side (typically a Web browser) is the requestor and the other side (portal system) acts as the service provider. As mentioned before, portals encompass various media types but sometimes this model of communication is not appropriate because the Web architecture is not well suited to interactivity. Yet, such communication is often necessary, especially in audio- and videoconferences (although the range of applications is much broader). In the medical context, interactive communication is required e.g. when remote surgery or distributed collaborative consultations take place. In such cases, specialized applications are the preferred solution.
Nowadays the Internet is becoming more and more accessible as a basic, cost- effective communications channel, even for real-time voice and video. Nevertheless, transferring interactive multimedia data (so-called streams) requires a completely different approach than e.g. for file transfer. For example, the preferred transport-level protocol is best-effort UDP instead of reliable TCP because overheads associated with the latter are unacceptable. Moreover, interactive communication is very demanding and many issues regarding it remain unresolved.
The Internet, as a network in which all data get equal treatment, is practically devoid of Quality of Service guarantees so when strong constraints are imposed,
using dedicated connections or signing a Service-Level Agreement with an Internet service provider should be considered, particularly in the area of medical services.
6 Case Studies
The authors have developed a number of systems to address the issues of access to medical data through the Internet for the purpose of reviewing them. Several approaches have been used, although the idea behind all of them was to reduce costs and effort required to perform medical consultations.
In some difficult cases, there is a need to discuss patient documentation with specialists from a referential center. In the past, a physician who needed advice had to drive from their hospital to the center and wait for consultation. Moreover, it was difficult to assess whether the patient should come along with the doctor, or if a diagnosis could be made on the basis of existing medical documentation. Our applications have been positively reviewed and are being put to everyday use at several Polish hospitals.
6.1 Supporting Teleconsultations with
TeleNegatoscope
TeleNegatoscope, one of the deliverables of the Krakow Centre for Telemedicine and Preventive Medicine (KCT) project, is a tool for interactive medical consultations [1]. The name of the tool is connected with its initial aim – remote access to a negatoscope – but it quickly turned out that TeleNegatoscope may be successfully used to transfer not just radiological images, but also other medical documentation, such as ECGs, scanned paper forms, etc. (see Figure 3-6).
Figure 3-6 Sample TeleNegatoscope session.
The tool allows two sides, called peripheral and referential, to work on the same data at the same time and exchange opinions and comments with each other. The data utilized by the application consists of compressed digital images and annotations. The annotations are made using simple shapes: ellipses and rectangles shared between both sides. Consultation is also supported by common pointers, shared by participants, meaning that during consultation only small amounts of data are transferred, conserving network bandwidth.
As an efficient tool for peripheral medical centers with poor connection to the Internet, TeleNegatoscope is limited to medical documentation available in general-purpose graphical formats. Unfortunately, the quality of the acquired pictures is not sufficient for some types of examinations (especially CT or coronarography).