## 3 Design of Maritime Data Security Management Platform
### Data Layer  
The data layer is mainly a big data storage system, which is connected to the upper layer through a unified data access interface, including basic maritime databases, dynamic databases and special databases. It can carry out the extraction and cleaning, organization and management, quality management, sharing management and other services of maritime spatiotemporal data. The existing navigation support system still has problems regarding difficult integration of heterogeneous data from multiple sources and low efficiency of data management. Therefore, the maritime data security management platform integrates the information resources of the maritime department, adopts the dynamic class loading technology to realize the unified management of the data from different interfaces and multiple sources, establishes a database that can store information effectively and realizes the configuration and management of the navigation data collection and storage. In order to meet the needs of various user applications, this paper has been optimized from the following four aspects. 1. Use a reasonable database optimization strategy to improve the speed and performance of database applications. First, use as simple an integer or short string as possible to simplify and avoid sorting. Then, when a large number of data are sorted, the relevant data are put into a temporary table operation. Index during a multi-table query, multi-joint query and data filtering to reduce I/O. Use more \"And\" concatenation and less \"Or\" concatenation when using a \"where\" clause, and avoid complex expressions, non-initial substrings and long strings. 2. Using Ehcache data caching technology, such as ship dynamic data, real-time data of buoys and real-time hydrometeorological data are cached by the distributed cache. Ehcache provides an Application Programming Interface (API) that is easy to use, easy to configure and easy to deploy and run. In large memory situations, all processes can support hundreds of gigabytes of throughput. The lifetime, free time, memory and maximum number of caches for each Cache can be flexibly set and can be changed at run time. The user first accesses the cache to obtain data when requesting data, and only accesses the database to obtain data when the data do not exist, to reduce the access to the database. 3. The establishment of a separate physical database is conducive to the promotion of the system in the future. When the number of users increases and the system needs to be expanded, the number of virtual or physical servers can be easily increased to achieve diversion and reduce the pressure of the system without changing the system structure. 4. The Oracle Real Application Cluster (RAC) is used to improve system performance, reliability and balance server load pressure through RAC cluster configuration. In order to solve the problem of compatibility between the data required by the application system and the data collected by hardware devices in standards and formats, the platform designs a unified data management process, establishes a data warehouse management system, analyzes and processes all data and provides services for all users. As shown in Figure 3, the management process of this system mainly includes data collection, data conversion, data fusion, log management and the acquisition state, which constitute the database management system. 1. Data collection. The sources of data mainly include maritime departments and observation equipment acquisition. For example, hydrometeorological data are partly from the National Marine Environmental Forecast Center, which mainly includes historical data and forecast data of a certain sea area. The other part comes from  
Figure 3: The process of data management. the data collected by the ship's equipment, mainly the real-time data of the sea area near the route. The basic data of the electronic navigation chart are mainly from the Navy Press, and updated data are obtained by processing satellite remote sensing images.