GC 不仅可以管理任何主流的 Oracle 产品、而且还能侦测自定义(比如：路由器)的目标

  OMAs 收集目标的信息（比如：可用性、配置和性能）、然后把这些信息传递给 OMS 
  一个 OMA 只和一个 OMS 对话、但一个 OMS 能服务多个 OMA
  接着、OMS 把所接收的信息再抄送一份给 OMR 
  一个 OMS 只和一个 OMR 对话、然而一个 OMR 可服务多个 OMS

  ㈠ Oracle Management Agent
     
     The OMA is responsible for ：
     ① all active monitoring 
     ② communication between Grid Control and all managed targets.
     
     The OMA:
     
     ● Must be installed on each host server
               
        A single management agent interfaces the OMS with all managed targets on the host server
               
     ● Must be in its own ORACLE_HOME
               
        Management agents are installed in their own ORACLE_HOME、and
        controlled with the emctl utility
               
     ● Communicates with the OMS via HTTP or HTTPS

  ㈡ Oracle Management Service
     
     The OMS is responsible for ：
     ① renders the user interface for Grid Control, works with all OMAs
     ② stores persistent data in the OMR             
     
     The OMS:
     
     ● Includes member components:
        Ⅰ Oracle HTTP Server (OHS)
        Ⅱ Oracle Application Server Containers for J2EE (OC4J)
        Ⅲ OracleAS Web Cache
        
     ● Is a J2EE application deployed on Oracle Application Server 10g
     
     ● Connects to the OMR by using JDBC

     You can connect to the GC via a Web browser through OHS and OracleAS Web Cache：
     
     ① OracleAS Web Cache is configured to listen for DBA\'s connections on port 7777
          and pass the connection through to the OHS on port 7778
        
     ② OMAs connect to the application directly throughOHS, bypassing OracleAS Web Cache
          In most installations, OHS listens for OMA traffic on port 4889
        
        
  ㈢ Oracle Management Repository
  
     The OMR is responsible for ：
     ① organizes the data receiving from OMS so it can be retrieved by OMS and displayed on GC
     
     The OMR:
     
     ● Resides in an Oracle database
     ● Includes schema objects belonging to SYSMAN
        
        The OMR is installed in an Oracle database as a group of approximately 4,000 schema objects
        These schema objects contain information about:
        GC administrators, targets, and applications that are managed by GC
        
     ● Can be installed in a preexisting database
        
        The OMR may be installed either in its own private database orin an existing database