Libraries Initialization and Termination

When an AIMMS application is launched, the initialization procedures are executed before all else. Likewise, when the app is shut down the termination procedures are executed.

See also

If you want some action to happen each time you open the app, such as reading data from a database, you can integrate this functionality into the one of the AIMMS initialization routines. A thoughtful model builder, before coding, may consider the questions:

  1. But which AIMMS initialization procedure (design)?

  2. And what are the consequences of placing such a call in an initialization procedure (evaluate)?

  3. And does it make sense to place a data read procedure in the initialization (evaluate)?

The purpose of this article to give you a better understanding of the initialization and termination of an AIMMS app. With this understanding, you can provide an informed answer to the above questions and to the questions below, in the context of the app being developed:

  1. Which are the initialization procedures available to an application (knowledge)?

  2. When can you rely on a library to be initialized (understanding)?

  3. Does the order in which libraries are declared matter to the initialization and termination of an application (understanding)?

  4. Do initialization and termination depend on the way the application is deployed (knowledge)?

  5. How to stop a running application (knowledge)?

In this article, the above questions are not answered directly. Please use the project below to follow this article’s explanations.

The pr_visit Procedure

The purpose of the procedure pr_visit is to mark the visiting procedures. The procedure pr_visit has the following simple code:

1p_visits += 1 ;
2sp_node := callerNode(1);
3sp_line := formatString("Visit %2i from: %s", p_visits, sp_node);
4pr_log(sp_line);

whereby the procedure pr_log outputs the line either into the session log or to a local file, depending on how the app is called.

Subsequently, a call to pr_visit is placed at every procedure that might be involved in the initialization or termination.

Running the InitTerm Application

To test, please open the application, click on “solve” button and close AIMMS. The visit.txt file will be:

 1Visit  1 from: MainInitialization
 2Visit  2 from: a::LibraryInitialization
 3Visit  3 from: b::LibraryInitialization
 4Visit  4 from: c::LibraryInitialization
 5Visit  5 from: d::LibraryInitialization
 6Visit  6 from: PostMainInitialization
 7Visit  7 from: a::PostLibraryInitialization
 8Visit  8 from: b::PostLibraryInitialization
 9Visit  9 from: c::PostLibraryInitialization
10Visit 10 from: d::PostLibraryInitialization
11Visit 11 from: pr_startup
12Visit 12 from: pr_openPageWebUI
13Visit 13 from: pr_solve
14Visit 14 from: d::PreLibraryTermination
15Visit 15 from: c::PreLibraryTermination
16Visit 16 from: b::PreLibraryTermination
17Visit 17 from: a::PreLibraryTermination
18Visit 18 from: PreMainTermination
19Visit 19 from: d::LibraryTermination
20Visit 20 from: c::LibraryTermination
21Visit 21 from: b::LibraryTermination
22Visit 22 from: a::LibraryTermination
23Visit 23 from: MainTermination

There are several remarks to be made about this log:

  1. The order in which the libraries are initialized is top to bottom, and in which they are terminated is bottom to top.

    Tip

    Consequently, it is practical to put the system libraries AimmsProLibrary and AimmsWebUI at the top of the library list. This permits other libraries to use the functionalities of these libraries even in their LibraryInitialization and LibraryTermination procedures.

  2. On line 13 the procedure pr_solve is visited.

  3. Once closed the application, AIMMS initiates the shutdown of the session (lines 14-23).

Note

If there is a number jump just before PostMainInitialization, this implies that a startup case is loaded when opening AIMMS.

Deployment Dependent Actions Taken

The following lists which actions are taken by application start or application finish:

Developer

WebUI

Solver

AimmsCmd

runonly

MainInitialization

LibraryInitialization

Load of startup case

PostMainInitialization

PostLibraryInitialization

Startup procedure

Page open of WebUI page

Page close of WebUI page

Read input case

Write output case

PreLibraryTermination

PreMainTermination

LibraryTermination

MainTermination

The columns of the above table are:

  1. AIMMS Developer: the actions taken by AIMMS Developer by opening and closing the InitTerm application.

  2. WebUI: the actions taken by a WebUI application published on AIMMS Cloud by opening and closing the InitTerm application.

    Tip

    Many users appreciate a quick start of an application as this will as this will put them at ease knowing that the system is up and running. In addition, they appreciate progress information during a long running data read procedure, perhaps via webui::SetProgressMessage. Please consider placing long running data read procedures as an explicit action to be invoked by the user.

    Note

    A published WebUI app can be closed in two ways:

    1. By running the procedure pro::sessionmanager::FinishSession().

    2. By closing all browser tabs, and waiting a minute.

  3. Solver: A solver session submitted by pro::delegateToServer.

    1. The input case is the case constructed by the data session (WinUI or WebUI) to provide input to the solver session.

    2. The output case is the case constructed by the solver session to pass the results to the data session.

    Tip

    It may be redundant to read in data in an initialization procedure of a solver session when that data is also provided in the input case.

  4. AimmsCmd: Running the InitTerm application via AimmsCmd and just opening and closing it.

  5. runonly: Running aimms.exe with the –run-only command line argument (using AIMMS 4.87.4 or newer).

See also