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Overview of Invocation Timeouts

Invocation timeouts let an application specify the maximum amount of time it's willing to wait for invocations to complete. If the timeout expires, the application receives InvocationTimeoutException as the result of an invocation. The Ice runtime starts the timer for the invocation timeout after the marshalling of the invocation input parameters and before its starts any network activity (connection establishment and sending of the request over the network connection). For a twoway invocation, it stops the timer as soon as the response is received from the server and before the invocation output parameters are un-marshalled. For a oneway invocation, it stops the timer as soon as the invocation is sent.

Configuring the Default Invocation Timeout

The property Ice.Default.InvocationTimeout establishes the default timeout value for invocations. This property has a default value of -1, which means invocations do not time out by default. If defined to -2, invocation timeouts are disabled and the Ice run time behaves like Ice versions < 3.6: it uses connection timeouts (defined on the endpoints) to wait for the response of the invocation. This setting is provided only for backward compatibility and might be deprecated in a future Ice major release.

Consider this setting:

Ice.Default.InvocationTimeout=5000

This configuration causes all invocations to time out if they do not complete within five seconds. Generally speaking however, it's unlikely that a single timeout value will be appropriate for all of the operations that an application invokes. It's more common for applications to configure invocation timeouts on a per-proxy basis, as we describe in the next section.

Configuring Invocation Timeouts for Proxies

You have a couple of options for configuring invocation timeouts at the proxy level:

• Use a proxy property
• Call ice_invocationTimeout

Assuming you've defined a configuration property containing a proxy that your application reads using propertyToProxy, you can statically configure an invocation timeout as follows:

# Assumes the application calls propertyToProxy("MyProxy")
MyProxy=theIdentity:tcp -p 5000
MyProxy.InvocationTimeout=2500  # 2.5 seconds

The InvocationTimeout proxy property specifies the invocation timeout that will be used for all invocations made via the proxy returned by propertyToProxy.

To configure an invocation timeout at run time, use the ice_invocationTimeout factory method to obtain a new proxy with the desired timeout:

shared_ptr<Filesystem::FilePrx> myFile = ...;
auto timeoutFile = myFile->ice_invocationTimeout(2500);  // 2.5 seconds

Filesystem::FilePrx myFile = ...;
FileSystem::FilePrx timeoutFile = myFile->ice_invocationTimeout(2500);  // 2.5 seconds

Invocation Timeout Failures

An application that configures invocation timeouts must be prepared to catch InvocationTimeoutException:

shared_ptr<Filesystem::FilePrx> myFile = ...;
auto timeoutFile = myFile->ice_invocationTimeout(2500);

try 
{
    auto text = timeoutFile->read();   // Read with timeout
} 
catch(const Ice::InvocationTimeoutException&)
{
    cerr << "invocation timed out" << endl;
}

auto text = myFile->read();            // Read without timeout

Filesystem::FilePrx myFile = ...;
FileSystem::FilePrx timeoutFile = myFile->ice_invocationTimeout(2500);

try 
{
    Lines text = timeoutFile->read();   // Read with timeout
} 
catch(const Ice::InvocationTimeoutException&)
{
    cerr << "invocation timed out" << endl;
}

Lines text = myFile->read();            // Read without timeout

The effects of an invocation timeout are limited to the client; no indication is sent to the server, which may still be busy dispatching the request. The Ice run time in the client ignores a reply for this request if the server eventually sends one.

See Also

• Proxy Methods
• Proxy Properties
• Ice.Default.*
• Connection Timeouts
• Obtaining Proxies