Instance Level Configuration

This chapter describes elements of the AMPS configuration that set parameters for the instance as a whole.

The tabs below describe the options available at the instance level of the AMPS configuration file.

AMPS Process Options

<AMPSConfig>
    ....

    <Name>AMPS</Name>
    <Group>Sample-AMPS</Group>

    ....
   
</AMPSConfig>

Authentication and Entitlements Management

AMPS authentication and entitlements are managed for each Transport. You can set the default to use for all transports at the instance level.

See the Authentication section for the details on setting identity management for the instance. See the Entitlement section for details on setting permissions for the instance.

Slow Client Policies

AMPS includes a set of parameters that specify how the instance should manage slow clients. Sometimes, AMPS can publish messages faster than an individual client can consume messages, particularly in applications where the pattern of messages includes "bursts" of messages. Clients that are unable to consume messages faster or equal to the rate messages are being sent to them are ”slow clients”. By default, AMPS queues messages for a slow client in memory to grant the slow client the opportunity to catch up. However, scenarios may arise where a client can be over-subscribed to the point that the client cannot consume messages as fast as messages are being sent to it. In particular, this can happen with the results of a large SOW query, where AMPS generates all of the messages for the query much faster than the network can transmit the messages.

Slow client management is one of the ways that AMPS prevents slow clients from disrupting service to the instance. 60East recommends enabling slow client management for instances that serve high message volume or are mission critical. Slow client policies for all Transports in the instance are set at the root level of the configuration file. A Transport can override any of these settings, or choose to use the instance-wide settings. Details on slow client handling are available in the AMPS User Guide.

This table describes policies that are applied based on the total resource consumption of clients.

Minidump Settings

AMPS minidumps contain information on the current state of the AMPS program execution, which is useful for support and diagnostics. AMPS will generate a minidump file on any crash event, or a minidump file can be generated at any point in time through the monitoring interface (see the AMPS Monitoring Guide).

AMPS allows you to set the directory in which minidump files will be created and the permissions mask for minidump files.

<AMPSConfig>
    ...

    <MiniDumpDirectory>/var/tmp</MiniDumpDirectory>
    <MiniDumpFileMask>0644</MiniDumpFileMask>

    ...
</AMPSConfig>

Tuning

The Tuning section of the configuration file sets instance-level parameters for tuning the performance of AMPS. In many cases, AMPS self-tunes to take advantage of the hardware and environment. However, explicitly setting tuning parameters is sometimes necessary in cases where an AMPS instance cannot determine the best value. For example, if multiple AMPS servers are running on the same system, 60East recommends disabling NUMA.

Use the Tuning element with care. Options in the Tuning element can affect AMPS performance, and the behavior of Tuning options may be version-specific.

<AMPSConfig>
    ....
    <Tuning>
        <NUMA>
            <Enabled>enabled</Enabled>
        </NUMA>
    </Tuning>
    ....
</AMPSConfig>

Externals

The AMPS server depends on external libraries for some functionality. The Externals configuration item allows you to control the exact shared object loaded for some of these external libraries, particularly those related to security.

<AMPSConfig>
    <Externals>
        <SSL>
            <Library>/opt/audited/libopenssl.so</Library>
        </SSL>
        <Crypto>
            <Library>/opt/audited/libcrypto.so</Library>
        </Crypto>
        <Curl>
            <Library>/opt/resolver/lib/libcurl.so</Library>
        </Curl>
    </Externals>
</AMPSConfig>

Specialized Options

This section describes options that are configured at the instance level for specialized purposes.

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