(4), Geoprocessing library com.esri.arcgis.geoprocessing Geoprocessing is a fundamental part of ArcGIS. Whether you're a new or experienced user, geoprocessing will become an essential part of your daily work routine with ArcGIS Engine and ArcGIS Server for the Java platform. Geoprocessing provides the data analysis, data management, and data conversion tools necessary for all geographic information system (GIS) users. a, Geoprocessing operators and tools Geoprocessing consists of operators (tools) that operate on the data (tables, feature classes, rasters, triangulated irregular networks [TINs], and so on), and perform tasks that are necessary for manipulating and analyzing geographic information across a wide range of disciplines . Each geoprocessing tool performs an essential operation on geographic data, such as projecting datasets from one map projection to another, adding fields to a table, or creating buffer zones around features. ArcGIS includes over 400 geoprocessing tools. A geoprocessing tool takes ArcGIS datasets as inputs (such as feature classes, tables, rasters, and computer-aided design [CAD] files), applies an operation against this data, and creates a dataset as output. See the following illustration: b, Using the geoprocessor A geoprocessing tool is executed by the geoprocessor. The geoprocessor class is the main class that simplifies the task of executing geoprocessing tools. The geoprocessor contains properties and methods that make it possible to execute tools, set global geoprocessor environment settings, and examine the resulting messages . It is the single access point for the execution of any geoprocessing tool in ArcGIS, including extensions. Source.