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Administration Console Online Help

Server --> Connections --> jCOM

Overview

This tab defines configuration attributes for controlling various aspects of communication between COM applications and WebLogic Server, such as authentication, timeouts and packet sizes. Use the attribute fields on this tab to:

- Configure the server's listen port to listen for COM calls

- Limit the number of seconds WebLogic Server will wait for a complete COM message

- Limit how large a COM message packet WebLogic Server accepts

- Set the primary domain controller to be used for authentication

- Allow or disallow COM clients and WebLogic Servers to communicate in jCOM's native mode

- Enable the logging of memory usage

- Allow prefetching of elements

- Allow or disallow apartment-threaded COM initialization in native mode

Tasks

Tasks are divided into two categories: those that require a server restart for the attribute change to take effect and those that don't. All but two require a server restart. We describe those two tasks first.

Limiting the Size of a COM Message Packet WebLogic Server Accepts

Limiting the Number of Seconds WLS Waits for a Complete COM Message

Allowing or Disallowing COM Calls on the Server's Listen Port

Setting the Primary Domain Controller to be Used for Authentication

Allowing or Disallowing Native Mode Communication

Enabling or Disabling the Logging of Memory Usage

Allowing Prefetching of Elements

Allowing or Disallowing Apartment Threaded COM Initialization in Native Mode

Additional Documentation

(Requires an Internet connection.)

Programming WebLogic jCOM.

Attributes

Attribute Label | Description | Value Constraints
--- | --- | ---
Enable COM | Whether or not COM support is enabled on the plaintext port. (COM is not supported on the SSL port.) MBean: weblogic.management. configuration.ServerMBean Attribute: COMEnabled | Default: false Readable: yes Writable: yes
COM Max Message Size | Specify the maximum COM message size allowable in a message header. This attribute attempts to prevent a denial of service attack whereby a caller attempts to force the server to allocate more memory than is available thereby keeping the server from responding quickly to other requests. This setting only applies to connections that are initiated using one of the default ports (ServerMBean setListenPort and setAdministrationPort or SSLMBean setListenPort). Connections on additional ports are tuned via the NetworkChannelMBean. MBean: weblogic.management. configuration.ServerMBean Attribute: MaxCOMMessageSize | Units: bytes Minimum: 4096 Maximum: 2000000000 Default: 10000000 Configurable: yes Dynamic: yes Readable: yes Writable: yes
COM Message Timeout | Specify the maximum number of seconds spent waiting for a complete COM message to be received. This attribute helps guard against denial of service attacks in which a caller indicates that they will be sending a message of a certain size which they never finish sending. This setting only applies to connections that are initiated using one of the default ports (ServerMBean setListenPort and setAdministrationPort or SSLMBean setListenPort). Connections on additional ports are tuned via the NetworkChannelMBean. MBean: weblogic.management. configuration.ServerMBean Attribute: CompleteCOMMessageTimeout | Units: seconds Minimum: 0 Maximum: 480 Default: 60 Configurable: yes Dynamic: yes Readable: yes Writable: yes
NTAuth Host | The address of the primary domain controller to be used for authenticating clients. If this property is not set, COM clients will not be authenticated. MBean: weblogic.management. configuration.COMMBean Attribute: NTAuthHost | Configurable: yes Readable: yes Writable: yes
Native Mode Enabled | Use native DLLs to allow Java objects to interact with COM Objects. Only supported on Windows. MBean: weblogic.management. configuration.COMMBean Attribute: NativeModeEnabled | Default: false Readable: yes Writable: yes
Memory Logging Enabled | Enables logging of memory usage MBean: weblogic.management. configuration.COMMBean Attribute: MemoryLoggingEnabled | Default: false Readable: yes Writable: yes
Prefetch Enums | Some COM methods return a COM VariantEnumeration type. The java2com tool automatically converts the returned type into a java.lang.Enumeration. This is not a perfect match since COM enumerations have no equivalent to the hasMoreElements() call. The client must continue to call nextElement until a NoSuchElementExceptionoccurs. Setting this property will cause jCOM to prefetch the next element in behind the scenes and return the correct value when hasMoreElements is called. MBean: weblogic.management. configuration.COMMBean Attribute: PrefetchEnums | Readable: yes Writable: yes
Apartment Threaded | Controls the flag that is used to initialize COM in native mode. By default, jCOM initializes COM using the COINIT_MULTITHREADED_FLAG. If the server logs a Class Not Registered Message when using native mode, try setting this property. (COINIT_APARTMENTTHREADED) MBean: weblogic.management. configuration.COMMBean Attribute: ApartmentThreaded | Default: false Readable: yes Writable: yes