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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 
  
Therefore, it is necessary to return some legible or illegible 
attributes according to the user. Three types of access have 
been defined : 
- A reading and writing access, reserved to the 
administrator of information solely; 
- A reading access for groups having a consultation right; 
- No access to information: In this case, one distinguishes 
the case where the user has the right to know that 
information exists even though it cannot consult it, and 
the case where the same existence of information must 
remain confidential. 
4. THESETTING UP OF A LOCAL GIS 
ACCORDING TO THE SRT 
To pass from SRT abstract state to the concrete state, only 
the computer representation can play this role; otherwise to 
pass to the stage of the implementation of the Communal 
GIS. Concretely, the realization of this passage rests on two 
complementary steps. 
The first issue on the development of a flat shape of 
exchange between partners and this to facilitate tasks of 
professions in the setting of the planning and the 
management of the local territory. The material architecture 
of this platform is based on the concept of making in 
relation servers and customers with the mean of 
telecommunication networks (TIC). In technical term, this 
architecture is based on a dedicated server (geographical 
server) that plays the role of a tool facilitating exchanges as 
well between the varied users internal as external to the 
collectivity (Fig. 3). It has functions of storage and 
protection of data, of management of competitor accesses, 
opening on the varied formats and interfaçages with the 
existing applications, data funding geographical or 
alphanumeric. 
One of the major functions of a geographical server is its 
capacity to converse operational and transparent manner, 
exchanges of data with other graphic software and the 
software GIS by interfaces recognizing the main formats of 
the market [ex: DXF, ASCII]. Concerning funding of data 
one of the main functions is to assure the follow-up of the 
differential between the external updatings and the real state 
of data. 
  
  
  
  
  
m [9 
bod m 
Clients 
Figure 3. Client/Server Architecture 
The second gait is about the realization of an environment 
permitting the access, the consultation and the easy 
extraction of data. This environment constitutes a tool of 
research and identification of the following elements : 
- The available data through a definition and a description 
of classes of entities of the local territory and their 
attributes; . 
97 
- Means of consultation and access to data through a 
hierarchical organization of entity classes; 
- The existing projects, under realization or intended; 
-. The available products (national cards, cadastral plans, 
satellites pictures, orthophotos, etc. ); 
- The different servers depositories of data of the 
Communal GIS; 
- The different active partners on the local territory with 
reference to elements that are associated to them (data, 
project, products, servers). 
The different modules of this environment that are 
conceived according to the systemic representation of the 
territory, permit to answer to the following fundamental 
questions: What are the existing data? , Who possesses them 
and manage them? , Where they are localized? , How can 
we reach them? and what are the conditions to get them? 
The different menu organization within the environment of 
the Communal GIS.rests on the SRT. This environment of 
manipulation on the Communal GIS and is thus able to offer 
a common language of description of the local territory after 
their installation on the different servers of partners. 
The development of this language or this interdisciplinary 
model of the local territory that we called SRT in the setting 
of this work, result a gait including the set of partners who 
have for tasks to give a definition and a common description 
of entities and relations that are going to represent all the 
process of the management of the local territory that is 
especially based on the geographical information. 
5. EXAMPLE OF REALIZATION: APPLICATION 
TO THE TOWNSHIP OF ARZEW 
Arzew, is a socio-industrial Algerian township of average 
size, delimited by parallels: 35? 45 ' 38 " and 35° 54 ' 35 " 
North in latitude and the meridian 00?S 15 ' 37 " and 00? 20 
' 27 " West in longitude, situated on the first terrace above 
the wilaya of Mostaganem between the township of 
Béthioua and the township of Gdyel, at less than 45 km of 
the Oran city (Fig. 4). 
  
    
  
Algeria 
Figure 4. Geographical situation of the Arzew township