Using Magik on Java

You can access the Magik on Java runtime either though the limited Magik on Java console, or by using GNU Emacs with the standard Smallworld extensions.

Using the console

Run start_magik_console.bat to start the console. This console has limited functionality, but it does:

• provide a command history
• allow you to enter commands over multiple lines (and will tell you what closing keyword it expects to see next in the window’s title bar)
• provide standard cut-and-paste functionality

Using Emacs

It is possible to use Magik on Java via the standard Emacs GIS mode. Type F2 Z and then run start_magik_cli.bat in the correct directory:

[<installation directory>] <installation directory>/start_magik_cli.bat

A few things to note for using Emacs are:

• You might need to select Java installation—ensure that Emacs starts with PATH which points to the correct version of Java. See Troubleshooting your Java installation.
• The Class Browser is not supported.

Executing Magik code

You can execute Magik (but there are some limitations).

You can add products and load modules in the standard Magik way. Here’s how you use Magik on Java to load all code in the base_image module using an existing Core 4.3.0 installation (other modules and TSB versions of Core 4.3.0 may not work):

sw_module_manager.load_module(:base_image)

You will not always be expected to load the base_image module yourself from source: later releases will ship with precompiled versions of all Core code, and provide mechanisms for you to compile your own application code. The functionality in this release is just the first step towards being able to load all Core product and application modules, and also developing support for replacements for closed and open images.

In the meantime, feel free to try loading more modules on top of base, but do expect things to fall over in places. As always, we would appreciate your feedback and bug reports to help us determine the areas that we should work over the next few releases.

Note At this release, we claim to load the source for some modules which aren’t actually loaded. This is needed to work round some outstanding language or low-level library limitations in Magik on Java. See Limitations for a list of these modules.

Troubleshooting out of memory errors

In case you get an out of memory error while loading more modules, you can work around it for now by increasing the Java permGen memory in the <installation directory>/start_magik_console.bat when using the console, or <installation directory>/start_magik_cli.bat when using Emacs.

You can do it by changing the value of the -XX:MaxPermSize parameter to say something greater than the current 256M.

set ALCHEMY_ARGS=%javaOptions% -Xmx1g -XX:MaxPermSize=256M 

-Dmagik.readClasses=true -jar libs/org.eclipse.osgi_3.8.0.v20111025-1330.jar 

-configuration libs/magikConsoleConfig %1

Datastore support

Magik on Java provides access to datastore functionality via low-level exemplars such as ds_version_view or database_view, and to whole databases via gis_program_manager.open_database().

Datastore files can be accessed using the Smallworld Datastore Server, swmfs, or in single-user mode by passing :concurrency_mode, :single_user to, for example, ds_version_view.add_file().

For example, to open the Cambridge Database and access the sector of an object, such as min_road, execute the following in the console:

gis_program_manager.open_database("C:<path_to_cambridge_db>\ds\ds_admin")
min_road << gis_program_manager.cached_dataset(:gis).collection(:min_road)
centre_line_sector_rope << min_road.an_element().centre_line.sectors

The majority of non-administrative functions are working. This functionality has been extensively tested by in-house automated functionality and stress tests and so is ready for detailed experimentation.

Alternatives and checkpoints are supported.

Graphics support

Magik on Java provides some graphics support. The following example displays a window containing a diagonal line, and the line adjusts when the window is resized (although the drawing canvas will not).

def_slotted_exemplar(:graphics_base,
	{
        {:canvas1,     _unset },
        {:background?, _false },
        {:bg_style,    _unset },
        {:styles,      _unset }
	},
	{:model} )
$
graphics_base.define_slot_access(:background?, :writable)
$

graphics_base.define_shared_constant(:canvas_width, 600, _false )
$

graphics_base.define_shared_constant(:canvas_height, 450, _false )
$

_private _method graphics_base.activate_in(f)
	## create the user interface. Simply creates a canvas on which
	## to install the popup menu.
	
	a << canvas_agent.new(_unset)
	.canvas1 << canvas.new(f,_self.canvas_width,_self.canvas_height,a)	
	a.define_redraw(:|redraw()|, _self)
_endmethod
$

_method graphics_base.redraw(window, _optional bnds)
	## This method is the default redraw method, it tests the
	## damage area as specified in the BNDS argument. The indicated
	## area should match the occluding window.
	##
	endPts << short_integer_vector.new_with(0,0, window.width, window.height)
	style << line_style.new(colour.called("green"), 4)
	
	window.clear()
	window.draw_rline(style, 10, 10, endPts)
_endmethod
$

g << graphics_base.new()
g.open()

We support mouse events and more and more drawing surface primitives. Please try it and if it doesn’t work let us know.