gvSIG blog

One of the most important characteristics of the gvSIG Desktop 2.0 version is the Add-ons Manager, from which the different packages (extensions, add-ons…, and translation files later) can be installed directly from the application. This version is totally oriented to this, it won’t be necessary to download the extensions independently and install them from gvSIG after that. For this reason, it become necessary to have several download servers available, several mirrors for downloading the packages.

Until now, the download servers have been provided by the gis-lab.info Russian Community, the gvSIG Russian Community, LAPIG (Laboratório de Processamento de Imagens e Geoprocessamento, Universidade Federal de Goiás, Brazil), the i3Geo Project (Edmar Moretti, Brazil), Geocuba (Cuba), ELOGeo (E-learning for Open Geospatial Community, University of Nottingham, United Kingdom), and the Open Source Geospatial Foundation (OSGeo).

This new infrastructure will allow to download the packages of the different extensions, add-ons, etc., from the Add-ons Manager in gvSIG (Tools->Addons Manager menu). For this reason the different servers URL have been included in a pull-down menu at the home window.

In addition, it will allow to download the application binaries (the All-included version) from the downloads table at the gvSIG website, where the user will be able to choose the server which they will be downloaded from.

From the gvSIG Project we want to thank all the people and entities that have provided these download servers.

One of the most new and useful functionalities in gvSIG 2.0 would be the Add-ons manager, even though a first version was already available in gvSIG 1.12. The main advantages of the new Add-ons manager are:

• Add-ons can be updated without waiting for the upcoming release of gvSIG.
• Installation of gvSIG can be customized.
• Add-ons such as symbols, languages and script can be easily shared.

Before explaining how this tool works, it is important to know the exact version of the downloaded gvSIG software, because depending on the version, different add-on options can be selected:

• Standard version. It contains the packages of the default setup plus a reduced number of add-ons. It corresponds to the release “All included version” of the download table.
• Online version. It contains basic and minimum gvSIG setup without any add-ons. To finalize the setup, an internet connection is needed. It corresponds to the release “with no extra software” of the download table.

The Add-ons manager allows to modify the default setup by adding or deleting the default add-ons and to install or update add-ons later on. In this article we are going to explain how this tool works, assuming that gvSIG has already been installed.

The Add-ons manager is available in the menu Tools/Add-ons manager in gvSIG 2.0. When launched, a dialog window appears, showing three options as shown in the following picture:

• Standard installation (install addons contained in the gvSIG standard distribution)
• Installation from file (install addons contained in a .gvspki or .gvspks file)
• Installation from URL (install addons from a remote repository)

Details for each option:

Standard installation

This option is available only if gvSIG has been setup from standard distribution, which allows to install only the add-ons already included; usually the most diffuse and stable add-ons are included. This option, thus, is the safer one because it should guarantee add-ons without fatal errors.

No internet connection is needed during the installation procedure.

Installation from file

The most evident advantage of this distribution is the possibility to install shared add-ons with another person even if they are not in the official gvSIG repository. It is useful even if you want to install an official add-on downloaded previously and individually. All the available add-ons for gvSIG version 2.0 can be browsed through this link [1].

Installation from URL

Through this option it is possible to view all the add-ons available in different repositories. The URL suggested by default refers to the repository of the installed distribution, containing all the release compatible add-ons, including the ones in development.

Other URLs relate to generic official repository mirrors of the installed release (gvSIG 2.0 in this case) through which all the add-ons compatible with all the distributions of a given release we can download.

This option is suggested if you want to test add-ons under development since all add-ons are shown without any indication of the state of development. For the same reason it is not indicated to install to many add-ons all together, since one out of them could cause fatal errors. If add-ons are installed one by one, it is easier to identify and remove the add-ons causing problems.

After selecting one of these three options, a list of add-ons appears containing both the ones already installed and the ones that can be installed according to the selected option.

The first three columns of the list provide the following information:

• If the add-on is already installed (green), or not (white). The already installed add-ons can be installed again except if they are checked with the white symbol.
• If the add-on is official or suggested.
• The compatible operating system in case the add-on is only compatible with one specific.

Other information relate to:

• Name
• Release. Useful if there is more than one available release of the same add-on.
• Type. Only two types exist so far (plug-in and symbols) but other, such as languages, icons and so on, will be added in the future.

To make the add-ons search easier, it is possible to filter by category or type (on the left of the window) and by text (upper part of the window).

Once the desired add-on has been selected, a new window appears, where the setup procedure can be monitored. At the end, the system will ask a restart to apply the changes.

The following videos give an example for each setup type:

The gvSIG Desktop 2.0 version must work correctly on 64 bits systems, the problems of the previous versions don’t have to appear now.

gvSIG is developed on Java, and some parts of the application have been developed on C (raster management and reprojections). The parts of the source code developed on Java are multiplatform, and they work on 32 bits as well as on 64 bits. On the other hand, the part developed on C must be run in a 32 bits environment.

The 64 bits Windows systems as well as the Linux ones support a running mode where a 32 bits environment is simulated in a 64 bits machine when they detect that it’s trying to be run a 32 bits application. The problem that can happen is that the application that is really run by the Operative System is the Java Virtual Machine (JVM), and then it run the Java application.

In gvSIG 2.0 this problem has been solved, making gvSIG to run with a 32 bits Java Machine, in Windows as well as in Linux.

The only problem can appear in Linux, if the “Online installation” binary has been downloaded, where if it detects that the installed Java Machine is not the correct one, this message will appear:

Packages are installed that are not compatible with your system.

org.gvsig.raster.tilecache.app (linux/x86)
org.gvsig.crs.extension (linux/x86)
org.gvsig.raster.ermapper.app (linux/x86)
org.gvsig.raster.lizardtech.app (linux/x86)
...

Some are not specific to your system or architecture.

You may need to configure a 32-bit Java environment for the proper functioning of gvSIG.

If it happens, it’s recommended to install the “All included” binary, that will fix the problem.

On the other hand, some problems had been detected in some functionalities in the 1.x gvSIG versions when gvSIG run on a Java 1.7 Machine. The gvSIG 2.0 version is supported on this Java version.

In early versions of gvSIG a support of CRS (Coordinate Reference System) was developed with basic functions and definitions. This implementation allows the user to select the reference system based on the datum, projection and time zone.

However it has some limitations when applying transformations. Besides it doesn’t support, for instance, the time zones from the southern hemisphere.

Then a new version was developed based on GeoTools and Proj4 libraries, with many more features, CRS definitions, even with the option to allow users to create their own CRS.

However, the new extension had two problems:

• While gvSIG is developed in Java language to allow the execution in multiple platforms, the usage of Proj4 which is a native library, lost that platform independence. Although Proj4 is available on multiple architectures and operating systems, it requires to generate different gvSIG installable for each of them. This increases the complexity and the maintenance of the gvSIG binaries.

• That new support uses a local database to query the CRS supported, and require the installation of the library Proj4, along with their dependencies. This involves higher resource requirements (memory and hard disk) than in the previous support.

gvSIG Association has also recently developed a new project focused on educational environments: gvSIG Educa. Within this project includes gvSIG Batoví, which is the distribution that gives rise to gvSIG Educa. This distribution is driven by the Ministry of Transport and Public Works (MTOP) of the República Oriental del Uruguay and developed by the gvSIG Association and the Faculty of Engineering of the Universidad de la República (UdelaR), and focuses on the use of a Geographic Information System in educational environments for the PlanCeibal (Uruguay).
It is a gvSIG 2.0 desktop distribution to be installed on computers OLPC. These computers have limited resources, so it is not viable to use the CRS-based on Proj4. On the other hand the use of basic support is not possible, lacking to manage the time zones from the southern hemisphere.
Alternatively it was developed a new CRS support, using for that purpose the Proj4J library, which is a partial implementation of Proj4 in Java language, and it is independent of the operative system in which gvSIG is installed.
Functionally it allows to choose the CRS based on the authority and code, providing support for large number of definitions.

This new support will be included on gvSIG Batoví distributions, as well as being available for  installing on gvSIG Desktop 2.0 through the add-ons manager plugin.
In gvSIG Desktop 2.0 the three CRS implementations will be available. The basic implementation is included on gvSIG, and the other two can be installed as plugins. If the user install the three of them, the available one from the user interface will be Proj4. But if that one is not installed, the one that will be activated is the Proj4J one.