Filtering Mainframe Messages

This chapter explains how you can filter unwanted messages in the Task Manager's VTAM and MVS messages windows. SNA View lets you limit the VTAM and MVS messages at three levels:

• Server Level Filtering--At this level, you can define whether or not a specific VTAM or MVS message is to be forwarded to registered clients. (The VTAM or MVS servers maintain a system filter table that applies to all clients.) A client is any process that successfully registers with SNA View server for services. An example of a registered client is the VTAM Message window.

• System Level Filtering--Filtering at the mainframe.

• Client Level Filtering--At client level filtering, you can filter specific VTAM or MVS messages from the server to each individual client. (The VTAM server maintains a filter table for each registered client.)

The following topics are covered in this chapter:

• MVS and VTAM MVS and VTAM Message Filters

• Filter Statements

• Defining Varying Token Positions

Filtering can also be done at the mainframe and the workstation never sees it.

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Note For procedure information on how to access the Filters window and enter the commands described in this chapter, view the online help.

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MVS and VTAM Message Filters

SNA View maintains separate filters for MVS and VTAM messages. Each filter is really a collection of filter statements in a filter file. Each filter statement states a rule by which a VTAM or MVS message is allowed through the filter or is filtered out. You can create and edit filter statements in the filter files in these ways:

• You can use an editor to add and change filter statements in the MVS and VTAM Filter Files. Filters in these filter files are permanent until you delete them or change them. SNA View provides you with two default system filter parameter files that you can customize by adding and editing filter statements:

  • $SVHOME/parm/svvtamsysfilter.tabl for VTAM messages

  • $SVHOME/parm/svmvssysfilter.tbl for MVS messages

• You can use the SNA View Task Manager to enter filter statements. When you activate the VTAM or MVS Message Client and Server, as described in "Viewing VTAM and MVS Messages," you can select Filter from the Message Window menu bar and select Add Filter. Filters entered in the Add Filter window are temporary, and last only until you stop SNA View.

Filter Statements

Each filter file contains a series of filter statements. Each filter statement defines a rule by which a specific MVS or VTAM message will pass through the filter, or be filtered out. There are two kinds of filter statements:

• Use a default filter statement to define what happens to all messages that do not satisfy any of the conditions defined by the standard filter statements.

• Use user-defined filter statements to define a lengthy series of conditions for filtering messages based on their content.

Default Filter Statement

A default filter statement defines what will happen to all the MVS and VTAM messages that are not specifically included or excluded by the standard filter statements. Each filter file can have one default filter statement. The default filter statement has these two parts:

Filter_Type  DEFAULT

and looks like this sample filter statement:

X DEFAULT

where:

• X--is the filter type, in this case type Exclude. This means that if a message is not specifically included or excluded by a standard filter statement, this default filter statement excludes the message.

• DEFAULT--specifies that this is the default filter condition for all messages not filtered by one of the standard filter statements.

User-Defined Filter Statements

Each user-defined filter statement defines a single condition, based on the presence or absence of one message token, by which a message is either passed through the filter, or screened out. A filter file will contain many user-defined filter statements, each defining a single filter condition. A user-defined filter statement contains these three parts:

Filter_Action  Filter_Token  Token_Position

and looks like this sample filter statement:

I IST105I 1

where:

• I--is the filter action, in this case type Include.

• IST105I--is the token, in this case the message ID.

• 1--is the token's position in the message, in this case position 1.

Filter Statement Actions

There are two filter statement actions:

• I (for include)--Use include filter statements (combined with an X DEFAULT statement) to specify VTAM or MVS messages that are to be included or passed through the filter.

• X (for exclude)--Use exclude filter statements (combined with an I DEFAULT statement) to specify VTAM or MVS messages that are to be excluded when going through the filter.

Filter Tokens

A filter token is a continuous string of alphanumeric characters, with no spaces, that can occur in a VTAM or MVS message. A VTAM or MVS message contains a series of tokens delimited by spaces. A typical VTAM message displayed by SNA View contains a time/date stamp, followed by the actual message. The time/date stamp is not part of the message, it is added by SNA View.

Mon Mar 27 10:09:52 1996 IST105I NT555 NODE NOW INACTIVE

The example VTAM message, following the SNA View header, contains these five tokens:

Token Position	Token
1	IST105I
2	NT555
3	NODE
4	NOW
5	INACTIVE

Filter Token Position

SNA View prefixes VTAM or MVS messages with a time/date stamp. The first actual token position is always the message ID (for example, IST105I). SNA View lets you filter on any token in a message. The filter token position of a filter statement is a number that refers to the position within a VTAM or MVS message where the specific token is listed.

Examples

This Include filter statement for VTAM messages specifies that any VTAM message with the token IST105I in position 1 is to be included (passed through the filter):

I IST105I 1

If you combine this sample filter statement with a default filter statement that excludes all other messages, the system filter table file would contain these filter statements:

I IST105I 1 X DEFAULT

If these filter statements existed when the VTAM server was started, only VTAM messages with message ID IST105I (indicating nodes going inactive) would be passed through the system filter and forwarded to clients. If you wanted clients to receive all VTAM messages indicating an SNA node going into an active state, you could modify the svvtamsysfilter.tbl file to contain the following entries:

I IST105I 1 I IST093I 1 X DEFAULT

If you want clients to receive all VTAM messages except for IST105I and IST093I messages, you would modify the system filter table parameter file to contain the following entries:

X IST105I 1 X IST093I 1 I DEFAULT

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Note New system filter table modifications are effective after the VTAM server is restarted in the Task Manager window.

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Defining Varying Token Positions

When defining a filter table, you are not limited to the VTAM message ID (which is token position 1). Although the VTAM message ID is probably the most useful token, you can specify any token position in the message. For example, if you wanted the clients to receive only messages pertaining to specific resources, you could modify the filter table file to contain the following entries:

I SNARSC1 2 I SNARSC1 3 I SNARSC1 4 I SNARSC2 2 I SNARSC2 3 I SNARSC2 4 X DEFAULT

If you determined that the VTAM messages the clients need to see are those pertaining to the SNA resources SNARSC1 and SNARSC2, and you wanted these names to appear in the VTAM messages only in token positions 2, 3, or 4. The above filter entries would cause only the desired messages to be passed through the system filter and on to any registered clients.