12 
art Bl, pp. 
| T. Fuchs, 
R for DSM 
B, Vol. 38, 
xin, 201l. 
'rived from 
ukee, WI. 
    
HIERARCHICAL OPTIMIZATION MODEL ON GEONETWORK 
ZHA Zhuhua"" , JIANG Jie", ZHOU Xu“ 
? National Geomatics Center of China, 28 Lianhuachi West Road, 100830, Beijing, China - (zhazh, jjie, 
zhouxu )@nsdi.gov.cn 
Commission IV, IV/5 
KEY WORDS: GeoNetwork, HOM, Performance, Metadata; Web based; Performance; 
ABSTRACT: 
In existing construction experience of Spatial Data Infrastructure (SDI), GeoNetwork, as the geographical information integrated 
solution, is an effective way of building SDI. During GeoNetwork serving as an internet application, several shortcomings are 
exposed. The first one is that the time consuming of data loading has been considerately increasing with the growth of metadata 
count. Consequently, the efficiency of query and search service becomes lower. Another problem is that stability and robustness are 
both ruined since huge amount of metadata. The final flaw is that the requirements of multi-user concurrent accessing based on 
massive data are not effectively satisfied on the internet. A novel approach, Hierarchical Optimization Model (HOM), is presented to 
solve the incapability of GeoNetwork working with massive data in this paper. HOM optimizes the GeoNetwork from these aspects: 
internal procedure, external deployment strategies, etc. This model builds an efficient index for accessing huge metadata and 
supporting concurrent processes. In this way, the services based on GeoNetwork can maintain stable while running massive metadata. 
As an experiment, we deployed more than 30 GeoNetwork nodes, and harvest nearly 1.1 million metadata. From the contrast 
between the HOM-improved software and the original one, the model makes indexing and retrieval processes more quickly and 
keeps the speed stable on metadata amount increasing. It also shows stable on multi-user concurrent accessing to system services, the 
experiment achieved good results and proved that our optimization model is efficient and reliable. 
1. INTRODUCTION 
In Spatial Data Infrastruture(NSDI) implementation fields, 
metadata service is an important part , it can be used to build 
geographic information data sharing service system, and a 
specific pattern of geographic information network distribution 
service (Jin et al, 2008). Europe, United States and other 
developed countries establish geographic information 
distribution service web portal through the integrating 
geographic information metadata input, query, management and 
switching nodes, to provide one-stop geographic information 
query, browse and access services for user(Gong Jianya,2009). 
1.1 GeoNetwork 
GeoNetwork is an open source project for geographical 
spatial metadata service, and it is used widely in the fields. It 
is an OSGeo incubation project, supporting OGC CSW 2.0.2.1t 
is a standard based and decentralized spatial information 
management system, designed to enable access to geo- 
referenced databases and cartographic products from a variety 
of data providers through metadata query and access, enhancing 
the spatial information exchange and sharing between 
organizations and their audience. It can provide access service 
for customers with a convenient and variety of source spatial 
data and thematic maps. The main goal of the software is to 
increase collaboration within and between organizations for 
reducing duplication and enhancing information consistency 
and quality and to improve the accessibility of a wide variety of 
geographic information along with the associated information, 
organized and documented in a standard and consistent way 
(Jeroen Tichler,2007). It is used widely as spatial information 
management system in the United Nations system such as 
UNSDI and other international organizations like NSDI, 
INSPIRE and GEO, etc. Its technical features are: Java 
architecture, Web Service and Servlet technology, using JDBC 
to connect database, using XML technology for metadata, using 
XSLT technology to convert XML, supporting remote access 
and internationalization. 
There are some shortcomings are exposed when using it as a 
web application which has huge users. During GeoNetwork 
serving as an internet application, several shortcomings are 
exposed. The first one is that the time consuming of data 
loading has been considerately increasing with the growth of 
metadata count. Consequently, the efficiency of query and 
search service becomes lower. Another problem is that stability 
and robustness are both ruined since huge amount of metadata. 
The final flaw is that the requirements of multi-user concurrent 
accessing based on massive data are not effectively satisfied on 
the internet. 
1.2 Aims 
A metadata service system need be constructed as SDI part, It is 
running on internet, has more than 30 nodes, the size of 
metadata for loading is more than 1,000,000, publishing and 
searching, We use system to harvest metadata of surveying and 
mapping results in China, and serves for people. Users can 
search results of surveying and mapping which they interested 
on this system, they can know how to get the result, where it is 
and call the number showed in the metadata. We use 
GeoNetwork to build our metadata service system as our system 
prototype. 
GeoNetwork has some shortcomings when using as an 
internet application. The first one is that the time consuming 
of data loading has been considerately increasing with the 
growth of metadata count, because it loads metadata and builds 
index one by one, as building and optimization index may take