InfoCenter Home > 6.6.32: Administering name service support (overview)Domain Name Service (DNS) supportThe application server can act as a Domain Name Service (DNS) client. In some cases, DNS access is required. For applications using enterprise beans, a name service is also provided. WebSphere Application Server clients and DNS resolutionBy default, a WebSphere administrative server or application server uses the IP address of the local host on which it is running in its object references. Thus, clients of these servers do not usually need to have DNS enabled in order to access these object references, nor do they need to be on the same network as the server. However, in cases where DNS is disabled on the client machine, additional steps must be performed for certain clients as follows:
By default, the administrative server name is the short name of the host on which it is running. As shown above, use an argument to specify the administrative server host name, which is required because the clients do name service lookups for names that are qualified by the administrative server name. Usually, if DNS is enabled, they can derive the administrative server name by doing a DNS reverse translation; however, if DNS is disabled, then they have to be explicitly provided with the administrative server name. In some situations, it might be necessary to override the default value for the host information in the object references generated by WebSphere administrative or application servers. To do this, set the system property com.ibm.CORBA.LocalHost as follows: -Dcom.ibm.CORBA.LocalHost=<value>where <value> can be a host name (long or short) or an IP address. Set this property on a per server basis. Some possible reasons for overriding this value are as follows:
Java Remote Method Invocation (RMI) supportApplications can invoke RMI servers, but should not be RMI serversWebSphere Application Server supports servlets that invoke Remote Method Invocation (RMI) servers, but the servlets are not permitted to be RMI servers themselves. They can be RMI clients. The same applies to enterprise beans. If this guideline is violated, a java.rmi.RMISecurityException will result. Do not set security managers in RMI clientsCorrect use of the Java RMI services requires that a security manager (for example, class java.rmi.RMISecurityManager) be set within the RMI server. Typically, a security manager will not be set in the RMI client program. As such, a servet acting as an RMI client should not set a security manager. The same applies to enterprise beans acting as RMI clients. Setting a security manager within a servlet (that is acting as an RMI client) is not only incorrect usage of RMI, but will cause problems for the server. The security manager will be global to the server and will affect server operations. If one of your applications currently sets a security manager when it should not be doing so, stop the application server containing the application, remove the statements that set the security manager, and start the application server again. |
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