# An Interoperable UMLS Terminology Service Using FHIR
## 6 Results  
This section will discuss the UMLS FHIR API endpoints and the returned FHIR resources. The base URL for the UMLS FHIR API is [[http://umls.it.ilstu.edu/umlsfhir/fhir](http://umls.it.ilstu.edu/umlsfhir/fhir)]([http://umls.it.ilstu.edu/umlsfhir/fhir](http://umls.it.ilstu.edu/umlsfhir/fhir)). There are two endpoints. * Description: Searches for all UMLS concepts whose name (Figure 3) begins with the user input string, captured by the parameter \"searchString\" and returns the result as an FHIR Bundle resource. A Bundle is a container for the collection of resources, and a search operation on any FHIR resource returns a Bundle [10]. In this case, the bundle contains a collection of CodeSystem. * Example: [[http://umls.it.ilstu.edu/umlsfhir/fhir/CodeSystem?search=malaria](http://umls.it.ilstu.edu/umlsfhir/fhir/CodeSystem?search=malaria)]([http://umls.it.ilstu.edu/umlsfhir/fhir/CodeSystem?search=malaria](http://umls.it.ilstu.edu/umlsfhir/fhir/CodeSystem?search=malaria)) returns all the concepts in whose name starts with \"malaria\". * Responses: Table 3 lists the response codes, its description, and resources for this endpoint. For the user search string \"malaria\", the service returns all concepts whose name starts with \"malaria\" structured as an FHIR CodeSystem and wrapped in an FHIR Bundle. Figure 9 shows the output Bundle with CodeSystem in JSON format. The web application parses this JSON response to display the search results. If there are no results, the service will still return a Bundle resource, where the concept attribute within the CodeSystem resource will be empty. * Description: Searches for the UMLS concept using the user-provided identifier, captured by the \"concept_cui\" parameter, and returns the concept knowledge as a ConceptMap (Figure 7). * Example: [[http://umls.it.ilstu.edu/umlsfhir/fhir/ConceptMap/C0004238](http://umls.it.ilstu.edu/umlsfhir/fhir/ConceptMap/C0004238)]([http://umls.it.ilstu.edu/umlsfhir/fhir/ConceptMap/C0004238](http://umls.it.ilstu.edu/umlsfhir/fhir/ConceptMap/C0004238)) returns knowledge related to the concept identified by CUI C0004238 as ConceptMap. * Response: Table 4 lists the response codes, its description, and resources for this endpoint. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Code** & **Status** & **Description** & **Resource** \\ \hline
200 & OK &
\begin{tabular}{c} Returns all UMLS concepts whose name \\ begins with the search string. \\ \end{tabular} & Bundle \\ \hline
400 & Bad Request &
\begin{tabular}{c} Invalid request. The endpoint does not \\ know how to handle the request. \\ \end{tabular} & None \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Response codes and resources for the search endpoint. In the above example link, the CUI C0004238 identifies the UMLS concept, Atrial Fibrillation, and the knowledge on this concept is returned as a ConceptMap, the profiled ConceptMap (Figure 7). For explanation purposes, the output ConceptMap, in the JSON format, is divided into two figures. Figure 10 shows all the atoms from diverse semantic sources equivalent to the CUI C0004238, and Figure 11 shows its relationships. The table (left) in Figure 10 shows all atoms (63 of them) equivalent to Atrial Fibrillation and the respective ConceptMap representation (right). All the atoms  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Code** & **Status** & **Description** & **Resource (FHIR Resource)** \\ \hline
200 & OK & \begin{tabular}{c} Returns knowledge of the UMLS concept \\ identified by the concept\_Cui \\ \end{tabular}  & ConceptMap \\ \hline
400 & Bad Request & \begin{tabular}{c} Invalid request. The endpoint does not \\ know how to handle the request \\ \end{tabular}