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Inquire Channel Status

 

Compaq NonStop Kernel	HP OpenVMS	i5/OS	UNIX systems	Windows	z/OS
X	X	X	X	X	X

The Inquire Channel Status (MQCMD_INQUIRE_CHANNEL_STATUS) command inquires about the status of one or more channel instances.

You must specify the name of the channel for which you want to inquire status information. This can be a specific channel name or a generic channel name. By using a generic channel name, we can inquire either:

• Status information for all channels, or

• Status information for one or more channels that match the specified name.

You must also specify whether you want:

• The current status data (of current channels only), or

• The saved status data of all channels, or

• On z/OS only, the short status data of the channel.

  Status for all channels that meet the selection criteria is given, whether the channels were defined manually or automatically.

There are three classes of data available for channel status. These are saved, current, and short. The status fields available for saved data are a subset of the fields available for current data and are called common status fields. Note that although the common data fields are the same, the data values might be different for saved and current status. The rest of the fields available for current data are called current-only status fields.

• Saved data consists of the common status fields. This data is reset at the following times:

  • For all channels:

    • When the channel enters or leaves STOPPED or RETRY state

  • For a sending channel:

    • Before requesting confirmation that a batch of messages has been received

    • When confirmation has been received

  • For a receiving channel:

    • Just before confirming that a batch of messages has been received

  • For a server connection channel:

    • No data is saved

  Therefore, a channel which has never been current will not have any saved status.

• Current data consists of the common status fields and current-only status fields. The data fields are continually updated as messages are sent or received.

• Short data consists of the queue manager name that owns the channel instance. This class of data is available only on z/OS.

This method of operation has the following consequences:

• An inactive channel might not have any saved status –if it has never been current or has not yet reached a point where saved status is reset.

• The "common" data fields might have different values for saved and current status.

• A current channel always has current status and might have saved status.

Channels can be current or inactive:

Current channels

These are channels that have been started, or on which a client has connected, and that have not finished or disconnected normally. They may not yet have reached the point of transferring messages, or data, or even of establishing contact with the partner. Current channels have current status and can also have saved or shortstatus.

The term Active is used to describe the set of current channels which are not stopped.

Inactive channels

These are channels that have either not been started or on which a client has not connected, or that have finished or disconnected normally. (Note that if a channel is stopped, it is not yet considered to have finished normally – and is, therefore, still current.) Inactive channels have either saved status or no status at all.

There can be more than one instance of a receiver, requester, cluster-sender, cluster-receiver, or server-connection channel current at the same time (the requester is acting as a receiver). This occurs if several senders, at different queue managers, each initiate a session with this receiver, using the same channel name. For channels of other types, there can only be one instance current at any time.

For all channel types, however, there can be more than one set of saved status information available for a given channel name. At most one of these sets relates to a current instance of the channel, the rest relate to previously current instances. Multiple instances arise if different transmission queue names or connection names have been used in connection with the same channel. This can happen in the following cases:

• At a sender or server:

  • If the same channel has been connected to by different requesters (servers only),

  • If the transmission queue name has been changed in the definition, or

  • If the connection name has been changed in the definition.

• At a receiver or requester:

  • If the same channel has been connected to by different senders or servers, or

  • If the connection name has been changed in the definition (for requester channels initiating connection).

The number of sets returned for a given channel can be limited by using the XmitQName, ConnectionName and ChannelInstanceType parameters.

Required parameters:

ChannelName

Optional parameters:

ChannelDisposition, ChannelInstanceAttrs, ChannelInstanceType, CommandScope, ConnectionName, IntegerFilterCommand, StringFilterCommand, XmitQName

• Required parameters
  

• Optional parameters
  

• Error codes
  

 

Parent topic:

Definitions of the Programmable Command Formats

pc12430_

 

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