The Process Facet
An activation service, such as an IceGrid node, needs a reliable way to gracefully deactivate a server. One approach is to use a platform-specific mechanism, such as POSIX signals. This works well on POSIX platforms when the server is prepared to intercept signals and react appropriately. On Windows platforms, it works less reliably for C++ servers, and not at all for Java servers. For these reasons, the Process facet provides an alternative that is both portable and reliable.
Be aware of the security considerations associated with enabling the Process facet.
The Process Interface
The Slice interface Ice::Process allows an activation service to request a graceful shutdown of the program:
module Ice
{
interface Process
{
void shutdown();
void writeMessage(string message, int fd);
}
}When shutdown is invoked, the object implementing this interface is expected to initiate the termination of its process. The activation service may expect the program to terminate within a certain period of time, after which it may terminate the program abruptly.
The writeMessage operation allows remote clients to print a message to the program's standard output (fd == 1) or standard error (fd == 2) channels.
Integrating the Process Facet with an Activation Service
If the Ice.Admin.ServerId and Ice.Default.Locator properties are defined, the communicator performs the following steps after creating the admin object:
Obtains proxies for the
Processfacet and the default locatorInvokes
getRegistryon the locator proxy to obtain a proxy for the locator registryInvokes
setServerProcessProxyon the locator registry and supplies the value ofIce.Admin.ServerIdalong with a proxy for theProcessfacet
The identifier specified by Ice.Admin.ServerId must uniquely identify the process within the locator registry.
In the case of IceGrid, IceGrid defines the Ice.Admin.ServerId and Ice.Default.Locator properties for each deployed server. IceGrid also supplies a value for Ice.Admin.Endpoints if neither this property nor Ice.Admin.Enabled are defined by the server.