The following table describes the event IDs, trace collection points, and PRF trace collection levels of the trace concerning the session trace. Note that the information about the global session is also output at points 0x8203, 0x8202, 0x8207, 0x8206, and 0x8300.

Table 8-12 Details of trace collection points in a Web container (session trace)

Event ID	No. in the figure#1	Trace acquisition points	Level#2
0x8200	1	Immediately after a request is acquired, or when the request header analysis is complete (via the Web server)	A/B
0x8202	4, 9	Immediately before a servlet or JSP is invoked	A/B
0x8203	2, 3	Immediately before the filter that is executed before the execution of the servlet or JSP that receives the request is invoked (when the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is omitted, or when a filter for which REQUEST is specified in the [[dispatcher]] tag is invoked)	B
0x8206	7	Immediately before a servlet or JSP is invoked via RequestDispatcher	B
0x8207	4, 9	Immediately before the static contents are invoked (DefaultServlet)	B
0x8208	5	After a session is generated	B
0x8209	6	After a session is discarded	B
0x8210	17	After the session times out	B
0x8211	1	Immediately after a request is acquired, or when the request header analysis is complete (via the in-process HTTP server)	A/B
0x8214	8	Immediately before the filter executed during Forward is invoked (when the filter for which FORWARD is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is invoked)	B
0x8215	8	Immediately before the filter executed during Include is invoked (when the filter for which INCLUDE is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is invoked)	B
0x8216	2	Immediately before the filter that is executed during transfer to the error page is invoked (when the filter for which ERROR is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is invoked)	B
0x8300	16	Immediately after the completion of request processing (via the Web server)	A/B
0x8302	10, 13	Immediately after the completion of processing of the servlet or JSP	A/B
0x8303	14, 15	Immediately after the completion of processing of the filter that is executed before the execution of the servlet or JSP that receives the request (when the processing of the filter for which REQUEST is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is complete)	B
0x8306	12	Immediately after the completion of the processing of the servlet or JSP via RequestDispatcher	B
0x8307	10, 13	Immediately after the completion of the processing of the static contents (DefaultServlet)	B
0x8311	16	Immediately after the completion of the request processing (via the in-process HTTP server)	A/B
0x8314	11	Immediately after the completion of the processing of the filter executed during Forward (when the processing of the filter for which FORWARD is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is complete)	B
0x8315	11	Immediately after the completion of the processing of the filter executed during Include (when the processing of the filter for which INCLUDE is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is complete)	B
0x8316	15	Immediately after the completion of the processing of the filter executed during transfer to the error page (when the processing of the filter for which ERROR is specified in the [[dispatcher]] tag of the [[filter-mapping]] tag of web.xml is complete)	B

Legend:

A: Standard

B: Advanced

A/B: Different information is collected for the Standard and Advanced levels.

#1

Corresponds to the numbers in Figure 8-12.

#2

The information about the session trace is output only when the level is Advanced.

The following figure shows the trace collection points of the session trace in a Web container.

Figure 8-12 Trace collection points of a Web container (session trace)

The session ID that can be acquired at each point is as follows:

Point 1

The session ID can be acquired. However, an invalid session ID (the ID of an HttpSession discarded in a J2EE application, or the ID of an HttpSession discarded due to the expiry of the valid period) might be acquired because the session ID is acquired from the Cookie or URL of the request header.

Even when a valid session ID is acquired, the session might be discarded in the J2EE application.

Points 2, 3, 4, 7, 8, and 9

A valid session ID can be acquired at the trace collection points. However, the session might be discarded in the J2EE application.

Furthermore, the global session ID can also be acquired at these points. The contents of the global session ID that can be acquired are different for each trace collection point.

• Point 2 is the trace collection point at which the event ID 0x8203 is output initially for one request. At this trace collection point, the global session ID sent as a request from the Web client can be acquired. However, at this point, a global session ID that has already become invalid might also be output.
• Valid global session IDs can be acquired from the trace with event IDs 0x8216, 0x8202, 0x8203, 0x8206, 0x8207, 0x8214, and 0x8215 output at points 3, 4, 7, 8, and 9.

Point 5

A valid session ID can be acquired at the trace collection point only when a session is generated in the J2EE application. However, the session might be discarded in the J2EE application.

Point 6

An invalid session ID can be acquired at the trace collection point only when a session is discarded in the J2EE application. However, the session might be discarded in the J2EE application.

Points 10, 11, 12, and 13

A valid session ID can be acquired at the trace collection points. However, the session might be discarded in the J2EE application.

Points 14 and 15

A valid session ID can be acquired at the trace collection points. When the request processing finishes at these trace collection points, the session is not discarded in the J2EE application thereafter.

Point 16

A valid session ID can be acquired at the trace collection point. When the request processing finishes at this trace collection point, the session is not discarded in the J2EE application thereafter.

Furthermore, when a global session is generated, a valid global session ID can be acquired when the request processing ends.

Point 17

An invalid session ID can be acquired only when a session that has exceeded the valid period is discarded.