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1. Application attributes - an associative array of Strings specified on an application side. Business logic might depend on such attributes - application language, application name, date/time formats, debug tokens, etc ([2], [4]).
2. SecuritySubject can be used to provide fine-grained access control to cache data. For example, CacheInterceptor saves the subject id it along with data and it can be used for filtering.

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Application context mechanism exists in Oracle [1] and it's widely used [6]. Support similar mechanisms (custom session variables) exist in multiple DBMS (e.g. SQLServer [8], Snowflake [7], MySQL [9]).

Description

Accessing application attributes

1. ApplicationContext is an entrypoint for accessing all non-tabular data.
2. The access requires static methods, because objects injection isn't possible for user functions (QuerySqlFunction are static, CacheInterceptor is a cache singleton).
3. User can easily create own QuerySqlFunction  to get access to the attribute from attributes in SQL queries if needed (see example below).

/** ApplicationContext interface. It's an entrypoint for all non-tabular data. */
public class ApplicationContext {
    /** @return Application attributes set for current thread. */
    public static @Nullable Map<String, String> getAttributes();

    /** @return Current SecuritySubject. */
	public static @Nullable SecuritySubject getSecuritySubject();
 }
 
/** Example, use it in QuerySqlFunction. */
public static class UserDefinedFunctions {
    /** @return Session ID set with application attributes. */
    @QuerySqlFunction
    public static @Nullable String sessionId() {
        Map<String, String> appAttrs = ApplicationContext.getAttributes();
 
        return appAttrs == null ? null : appAttr.get("SESSION_ID");
    }
}

Setting application attributes

IgniteClient (Java)

...

. 

1. Users set attributes with ClientCache#withApplicationAttributes  and must clean it by selfClient should mirror the logic of Ignite node.
2. New feature is needed in the ClientBitmaskFeature protocol.

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// Example of usage.
try (IgniteClient cln = Ignition.startClient(clnCfg)) {
    Map<String, String> appAttrs = F.asMap("SESSION_ID", "1234");

	ClientCache<?,    try (ClientTransaction tx?> cache = cln.transactionscache("CACHE").withApplicationAttributes(appAttrs).txStart(;	

 	...
}

JDBC

IgniteClient (Java). 

1. Users set attributes with ClientCache#withApplicationAttributes  and must clean it by self.
2. New feature is needed in the ClientBitmaskFeature protocol.

// Example of usage.
try (IgniteClient cln = Ignition.startClient(clnCfg)) {
    Map<String, String> appAttrs = ...
    }F.asMap("SESSION_ID", "1234");

	ClientCache<?, ?> cache = cln.cache("CACHE").withApplicationAttributes(appAttrs);	

 	...
}

JDBC

The standard jdbc protocol describes the methods Connection#setClientInfo, which allow changing the values ​​of client attributes during the life of the connection [3]. Implementation features:

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