# META-GLARE: A Computer-Interpretable Guideline System Shell
## 7 Related Work and Comparisons
### The Advantages of META-GLARE's \"Meta\"-Approach  
In the following, we highlight the advantages provided by the adoption of META-GLARE with respect to (1) \"traditional\" CIG systems (e.g., Asbru [30], EON [53], GLIF [12], GPROVE [54], GUIDE [55], PRODIGY [56], PROforma [29]), and (2) Protege [20] and DeGeL [21]).  
First of all, it is important to emphasize commonalities: META-GLARE, Protege, and DeGeL can be used in different ways to define a new CIG system based on a specific CIG formalism. However, the behavior of such systems, as well as the \"traditional\" systems, in terms of how to acquire and execute a specific guideline, is basically the same.  
On the other hand, META-GLARE is clearly different from the other approaches in case (i) a new CIG system has to be defined on the basis of a new CIG representation formalism, or (ii) an existing system has to be modified in order to update its representation formalism.  
(1) **\"traditional\" CIG approaches.** Traditional CIG systems are based on a specific CIG representation formalism. The software code of the acquisition and execution tools provided by such a system has been specifically developed to manage the chosen representation formalism. Such systems do not provide any facility to change the representation formalism. Therefore, if some change to the formalism is required(e.g., in order to face new phenomena that had not been considered in the original formalism), the system designer has to operate directly on the software code of the acquisition and the execution tools, inspecting it and identifying where changes have to be performed before appropriately changing/extending such a code. Notably, such an approach may be quite difficult and time-consuming in real CIG systems, whose code dimensions and complexities are quite high, even in the case of limited changes in the formalism.
2. **Protege** and **DeGeL approaches**. Protege and DeGeL support a mechanism for the acquisition and management of multiple ontologies, which can be exploited to acquire different CIG representation formalisms. For each acquired CIG formalism, they automatically provide a tool to acquire CIG instances expressed in such a formalism. As a consequence, Protege and DeGeL facilitate designers in the definition of a new CIG system based on a new formalism, or in the update of an existing one to update its formalism: the designer can use their formalism acquisition tool to define the new/updated formalism and gets the tool to acquire CIG instances automatically. However, Protege and DeGeL do not support the system designer with regard to the execution tool. When changing the CIG formalism or defining a new formalism, the system designer has to operate directly on the software code of the execution tool, inspecting it, identifying where changes have to be performed, and appropriately changing/extending such a code.
3. **META-GLARE approach**. As shown by Experiments 1-3 above, META-GLARE further generalizes the support provided by Protege and DeGeL to also consider the execution tool. The META-GLARE DEFINITION_EDITOR module supports system designers in the definition of a new CIG formalism, or in the update of an already acquired one. Since both META-GLARE's tool to acquire specific CIG instances (HG_ACQUISITION module; see Figure 1) and the tool to execute them (HG_EXECUTION module; see Figure 1) are _parametric_ with respect to the input formalism, the definition/update of a CIG formalism does not require any modification to them. No inspection of their code and no modifications are needed at all. Therefore, programming is needed only in case a new component has to be added to the component library (see Experiment 3 above). Notably, our approach is fully modular, since the system designer has only to program the additional component without taking care of the rest of the system. Therefore, META-GLARE supports fast prototyping of the new or extended system.