This document is a section of the Installation Guide. It provides the user with an overview of services provided by the installed LexEVS runtime.

Overview of LexEVS Services

The LexEVS package represents a comprehensive set of software and services to author, publish, and access vocabulary (and to some extent, do so in a variety of web-enabled and grid environments.) Cancer Centers can use the LexEVS package set to install the NCI Thesaurus, NCI Metathesaurus content as well as other terminologies, and provide query access via a rich application programming interface (API). LexEVS services can be used in numerous applications wherever vocabulary content is needed. Content can be loaded from a number of formats including but not limited to OWL, OBO, and RRF.

LexEVS is intended to address the needs of the following groups:

Overview of LexEVS Local Runtime

LexEVS Local Runtime Installed components

  1. Service Management consists of an API and example programs to load, index, publish, and manage both vocabulary content and service metadata for the vocabulary server. Examples are found in the admin directory of the LexEVS root installation directory.
  2. LexEVS Application Programming Interface (API) is comprised of methods to support Lexical Operations, Graph Operations, Value Set Operations, Authoring Operations, and History Operations. Examples are found in the examples directory of the LexEVS root installation directory.
  3. Documentation consists of detailed JavaDocs and the LexEVS 6.0 Programmer's Guide and LexEVS 6.x Administration Guide.
  4. Automated Test Suite is provided to validate the LexEVS installation. It includes relatively small sample vocabularies that can be loaded by the user. These can be found in the test directory and its sub-directory, testData.
  5. Configuration and Resource Files provide custom configuration of the LexEVS runtime to users.

Service Management comprises the following components:

LexEVS API comprises the following components:

The following figure shows the installed services and API.

This graphic shows the installed services and API comprising of the components described above.

Additional information about the LexEVS API is provided in the LexEVS 6.0 Programmer's Guide. Information related to Service Management of a LexEVS Terminology Service can be found in the LexEVS 6.x Administration Guide.

LexEVS Components (Detailed)

The LexEVS installation includes the following components:

Service Management

Administrative Programs for managing LexEVS service and available in the admin directory:


Including Program Examples for common vocabulary functions using sample vocabulary and Coded Node functions found in the examples directory


Automated Test Suite

A shell script providing verification of a correct installation of LexEVS.

Configuration and Resource Files

Contain configuration files and post terminology load indexes servicing LexEVS terminologies – located in the resource_ directory.

Other Installed Components

Deployment Alternatives

Earlier versions of the LexEVS local Runtime package offered flexible database deployment alternatives depending on the underlying data base management systems(DBMS's). Single database configurations allow the user to manage databases more effectively so LexEVS no longer offers the option of loading each terminology as a separate database.

Deploying using single table or multiple table mode are the current options. Data is either collated to a single schema table or broken up by terminologies for a table of each kind for each terminology. Single table modes can be very resource intensive when deleting a large terminology such as the NCI Metathesaurus.

Overview of LexEVS Distributed

(No longer available to the public as a service from NIH/NCI)  It is still possible to run and install this service yourself, but it is being sunsetted as an application and will eventually be deprecated.  See the CTS2 service below.  

The Distributed LexEVS environment is distributed as a single WAR archive designed to be installed in a web application container.

Distributed Installed Components

The following figure shows Distributed Remote LexEVS JAVA API with Coded Node Set Operations, Coded Node Graph Operations, Mappings, and History.

Overview of LexEVS Graph-Resolve REST Service and NodeGraphResolutionExtension

Provides a graphing database REST Service wrapped by a LexEVS extension compatible API in java.  

A SpringBoot enabled REST service queries an Arangodb instance for graph resolutions originally loaded from the LexEVS associations tables.  


A set of methods designed to allow high speed resolution of larger graphs insuring a knowledge of graph resolution result sizes in a timely manner. 

Graph-Resolve Service

A REST service for Non-LexEVS users that provides a platform independent format for resolved graph elements.  

Overview of LexEVS Grid Services (No longer available or Supported – Removed in 6.3)

Separate Analytical and Data Services are distributed in war archives for installation in web application containers.

Analytical Grid Service (Deprecated - Removed in 6.3)

Provides the same subset of the LexEVS APIs as the Distributed environment but is ISO 21090 compliant. The following figure shows the LexEVS Grid Service Java API with Coded Node Set Operations, Coded Node Graph Operations, Mappings, and History.

Data Grid Service (Deprecated - Removed in 6.3)

Allows users to make federated queries, using the CQL XML based query language, of LexGrid model elements hosted at LexEVS grid service nodes. The following figure shows a Federated CQL Queries element.

LexEVS 6.x CTS2 Specific Installations

LexEVS 6.1 features a CTS2 Compatible REST API. The REST server and an accompanying URI resolution service are installed to support this service.

LexEVS 6.1 diagram