International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
transactional WFS (Web Feature Service) and GML 
(Geography Markup Language). MapServer is not a stand-alone 
system; it basically needs to be run on web server such as 
Apache WebServer. MapServer consists of three different 
components 
" The CGI program 
=" The template files 
= The Mapfile 
CGI program provide standard protocol to interfacing browser 
and web server, it reads and processes both the map file settings 
and the template file, user defined variables and returns the 
processed outputs as maps, variables or values and query results 
shown in the template files. Every CGI output is a temporary 
image or value updated at each CGI work session. 
The Mapfile is the heart of MapServer. It defines the 
relationships between objects, points MapServer to where data 
are located and defines how things are to be drawn. This is a 
built-in object oriented scripting language in MapServer, which 
defines how to create and use the maps and their layers. OGR 
connection (by OGR library) is used to connect the database in 
MySQL and web GIS. 
Template files are used to define the look of a MapServer CGI 
application interface and to provide the results of the query. 
They guide the presentation of results, either as a text or as map, 
to the user. Common HTML page tags are provided by the 
MapServer and can thus be viewed in web browser. 
OpenLayers is a free JavaScript which makes it easy to put a 
dynamic map in any web page. Capable to display map tiles and 
markers loaded from different source/servers. OpenLayers has 
been developed to further the use of geographic information of 
all kinds. 
5. MYSQL & DATA PROCESSING 
Database in MySQL is designed to support geo-referenced data 
from HF Radar in a tabular format. Database is segregated into 
different tables based on station and year indexed by 
observation time for faster response. The basic naming 
convention for tables are t TOTL [station] [year], eg. 
t TOTL Anco 2010; and the table description is given in the 
following table. 
  
  
  
  
  
  
  
  
  
  
  
  
  
Field Type Null | Key | Default 
station id varchar(10) YES | MUL | NULL 
observation time 
i datetime YES | MUL | NULL 
longitude decimal(12,7) | YES NULL 
latitude decimal(12,7) | YES NULL 
speed decimal(8,3) YES NULL 
direction decimal(8,3) YES NULL 
  
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Along with this main table maintains all the raw data received 
from HF Radar with following description: 
  
  
  
  
  
  
  
  
  
  
Field Type Null | Key Default 
station id varchar(10) | YES | MUL | NULL 
observation time | datetime YES | MUL | NULL 
datafile longblob YES NULL 
  
The data extraction tool developed using Java, organizes and 
stores the location and currents information into database from 
the data received through scheduled FTP at hourly intervals 
Similar procedure has been adopted for the data received from 
wave rider buoys and tide gauges. 
MySQL interaction with MapServer 
Mapfile LAYER object of MapServer plays the important role 
to interact with MySQL database. Layer is a combination of 
data and styling, in the form of attributes and geometry using 
CLASS and STYLE derivatives. To read data from MySQL 
database the MapServer should be compiled using OGR 
support. The following parameters have to be specified with 
CONNECTIONTYPE OGR derivatives to read vector data from 
database. 
e the connection parameters, viz name of the database, 
user name and password. 
e the name of table and its geometry column 
e the filter with the syntax user for a SQL query 
WHERE clause. 
The other important derivatives used in layers are CLASS, 
STYLE, SIZE, COLOR, ANGLE and EXPRESSION 
e CLASS is used to classify the vector data based on 
speed of currents, where EXPRESSION specifies to 
which CLASS the feature belongs to. 
e STYLE with SIZE to map the data with specified size 
depends on speed, COLOR to map data with specified 
color and ANGLE to map symbol “Arrow” in the 
direction of currents. 
e ANGLE rotates the symbol in counter clockwise. 
Thus angle attribute is adjusted to specify angles in 
compass direction. 
OpenLayers interaction with MapServer 
OpenLayers.Layer.MapServer instances are used to display data 
from MapServer CGI instance. Whereas MapServer also 
exposes its CGI functionalities in WMS mode. Thus 
OpenLayers.Layer. WMS instance is preferred over 
OpenLayers.Layer.MapServer, since MapServer layer can lead 
maps to not work properly due to mis-configurations and 
projection issues [3]. 
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