[Erlang Systems]

1 Appmon

1.1 Introduction

The application monitor Appmon is a graphical node and application viewer. The tool shows an overview of all applications on all known nodes, and it is possible to view the process tree for an application running on any of the nodes.

1.2 Getting Started with Appmon

Start Appmon by calling appmon:start(). It will start the main window showing a load meter and the applications running at the current node. By clicking on one of the applications a window showing the process tree of the application will be opened, the application window.

The main window is equipped with a menubar from which it is possible to:

The application window shows the process tree for an application with each process displayed as a box. It is possible to view information about the processes, to send messages to them, and to trace and kill them.

1.3 The Main Window

The main window shows a load meter and all applications running at the displayed node. Select which node to display in the window by chosing the node name from the Nodes menu. It is also possible to run Appmon in a many-window mode where a new instance of the main window is opened for each node to be displayed.

main_win
The Main Window.

The load meter shows load measured as processor time, or as the length of the ready queue.

Every application running at the node is shown as a button. Clicking the button will open the application window showing the process tree for the application.

1.3.1 The File Menu

Show List Box...
This will open the listbox window which lists all nodes and applications. This window can be more easy to use than the normal, graphical user interface when the system consists of a large number of nodes and/or applications.
Close
Close the window. If no other instance of the main window exists, Appmon will be stopped.
Exit
Stop Appmon.

1.3.2 The Actions Menu

Reboot
Call init:reboot() at the currently displayed node. This will stop the node. If the -heart system flag was given, the heart program will try to reboot the system.
Restart
Call init:restart() at the currently displayed node. This will restart the node.
Stop
Call init:stop() at the currently displayed node. This will stop the node.
Ping
Call net:ping(Node) where Node is the currently displayed node. This can be useful when the connection to the node has been lost.

1.3.3 The Options Menu

One window/Many windows
Select one of these radio button to run Appmon in one-window or many-window mode. In many-windows mode, a new instance of the main window is opened for each node to be displayed. The default value is one-window mode.
Load: time/queue
Select one of these radio buttons to either calculate load as processor time or as the length of the ready queue, which is the number of processes ready to execute. By default, the load is calculated as processor time.
Load: progressive/linear
Select one of these radio buttons to show load either according to a progressive or a linear scale. By default, the load is shown according to a progressive scale.

1.3.4 The Nodes Menu

The Nodes menu contains all currently and previously known nodes. Selecting a node from the Nodes menu will cause that node to be displayed in either the same window, or in a new window, depending on if Appmon is run in one-window or many-windows mode. If the connection to the node has been lost, this will be shown in the window.

1.3.5 The Help Menu

Help
Selecting Help from the Help menu will cause the HTML version of the Appmon User's Guide (this document) to be displayed. Currently this function requires Netscape to be up and running.

1.4 The Application Window

The application window shows the process tree for an application. The window title contains the application name and the node name. The window also contains a menubar and a toolbar.

The application window can be opened from the main window by clicking on the button denoting the application, or from the listbox window by selecting the application and clicking on the Load button.

app_win
The Application Window.

The application can be shown either as a strict supervision tree, or as a process view with all linked processes. In supervision mode, the tree-gathering and -building algorithm assumes conformance to the OTP design principles.

1.4.1 The File Menu

Close
Close the application window.

1.4.2 The Options Menu

Refresh
Refresh the application window.
Sup. view/ Proc. view
Select one of these radio buttons to show the application as a strict supervision tree, or as a process view with all linked processes. By default, the process view is used.

1.4.3 The Toolbar

The toolbar consists of four buttons: Info, Send, Trace and Kill. First select one of these buttons and then select to which process the action should apply by clicking on a process in the process tree. By default Info is selected which means that clicking on a process, without selecting Send, Trace or Kill first, will open the process information window.

Info
Open the process information window, which displays the information about the process given by process_info(Pid).
Send
Send a message to a process. A window is opened where the message can be specified. Click Ok to send the message or Cancel to cancel.
Trace
Switch on OTP tracing of a process. sys:trace(Pid,true) is called. Selecting Trace a second time for the same process will switch the tracing off instead.
Kill
Kill a process. exit(Pid,kill) is called.

1.5 The Listbox Window

The listbox window lists all nodes and applications. This window can be more easy to use than the normal, graphical user interface when the system consists of a large number of nodes and/or applications.

listbox_win
The Listbox Window.

The window contains three buttons:

Load
First selecting an application and then clicking the Load button will open the application window for that application.
Clear
De-select any selected node or application name.
Close
Close the listbox window.

1.6 The Process Information Window

The process information window shows information about different processes as given by process_info(Pid).

pinfo_win
The Process Information Window.

1.6.1 The File Menu

Close
Close the process information window.

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