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Mature Data Model
◆ Full support for various spatial object model
SuperMap SDX+ fully supports various spatial object models, including simple spatial objects (E.g. point, line, and polygon) and complex spatial data model (Such as text, composite object, network, route, TIN, DEM, GRID and image.
◆ Sequential data model
SuperMap SDX+ provides historical data tracing and storing so that the data modified at any time slice can be retrospected. Namely, the change of the historical data can be rewinded just like rewinding the movie.
It is very easy to access the sequential data. When the registration Option of the dataset is set to "scoSequence", any data modification will be recorded automatically. When retrospecting the historical data with setting the display filter (the DisplayFilterEx property) of the layer (the soLayer object) to the desired historical time, then the data at that specified time will be shown on the map after refreshing.
The sequential data management is further enhanced in the latest SuperMap SDX+. The function of managing data at different historical time is added for users' setting different time to take the snap-shot of the data. Therefore, the data at any particular time can be located, deleted, or retrospected quickly.
◆ Topological relationship storing
The topological model is further enhanced by implementing a complete topology models and topology validation rules in the latest SuperMap products.
The SDX+ of SuperMap GIS 2008 redefines topological model. The point, line, region and other types of data can be integrated and managed in a unified model; The user can set the topology rules between datasets and run topology validation. The validation include checking whether the points in one point dataset are covered by the endpoints of the arcs in another line dataset, whether the lines in one line dataset can be covered by the boundaries in another line dataset, whether the lines in two line datasets overlap and so on. The violation results are stored in a system table so that the user can correct the topology relationships. After correction, the user can perform topology validation in the "dirty areas" where the modifications have been made or the user-specified areas. Some common topological rules are listed below:
Topological Rules |
Dataset Type |
Description |
| (Must Not Overlap) |
Region |
The regions should not overlap each other in the dataset. |
| (Must Not Have Gaps) |
Region |
No gap is allowed between adjacent regions. |
| (Must Not Overlap With) |
Region |
The regions in one region dataset cannot overlap with the regions in anther region dataset. |
| (Must Be Covered By Dataset Of) |
Region |
A region in one region dataset must be covered by at least one region in another region dataset. |
| (Must Cover Each Other) |
Region |
The regions in one region dataset must be contained within the regions of another region dataset. |
| (Must Be Covered By) |
Region |
The regions in one region dataset must be covered by at least one region in another region datasets. |
| (Boundary Must Be Covered By) |
Region
Line |
The boundaries of the regions must be covered by the line objects from a line dataset. |
| (Area Boundary Must Be Covered By Boundary Of) |
Region
Region |
The boundaries of regions in one region dataset must be covered by the boundaries of regions in another region dataset. |
| (Contains Point) |
Region
Point |
A polygon in one region dataset must contain at least one point from another point dataset. |
| (Must Not Overlap) |
Line |
The lines must not overlap each other in a line dataset. |
| (Must Not Intersect) |
Line |
The lines in the same line dataset must not cross or intersect each other. |
| (Must Not Have Dangles) |
Line |
The lines must touch each other in the same line dataset at both ends, namely there must be no dangles in the line dataset. |
| (Must Not Have Pseudo-nodes) |
Line |
A line must not have pseudo-nodes, that is to say, a line connect to more than one line at each endpoint. |
| (Must Not Intersect Or Touch Interior) |
Line |
The lines must touch the other lines in the same dataset at endpoints only. |
| (Must Not Overlap With) |
Line
Line |
The line from one dataset must not overlap with the line in another dataset. |
| (Must Be Covered By Feature Class Of) |
Line
Line |
The lines in the first dataset must be covered by the lines in the second dataset. |
| (Must Be Covered By Boundary Of) |
Line
Polygon |
The lines must be covered by the boundaries of regions. |
| (Endpoint Must Be Covered By) |
Line
Point |
The endpoints of lines must be covered by points in point dataset. |
| (Must Not Self Overlap) |
Line |
The lines must not self-overlap. |
| (Must Not Self Intersect) |
Line |
The lines must not intersect or overlap themselves. |
| (Must Be Single Part) |
Line |
The lines must only have one part. |
| (Must Covered By Boundary Of) |
Point
Region |
The points must fall on the boundary of the regions. |
| (Must Be Properly Inside Polygons) |
Point
Region |
The points must be properly inside polygons |
| (Must Be Covered By Endpoint Of) |
Point
Line |
The points must be covered by endpoint of the lines in anther dataset. |
| (Must Be Covered By Line) |
Point
Line |
The points must be covered by lines in another dataset. |
| (Must be larger than cluster tolerance) |
Line
Region |
The distance between nodes of Line or polygon must be larger than the cluster tolerance. |
 Version Management and Long Transaction
Version Management
It is recommended that data editing should be paid more attention in GIS application. It'd better save every version of modified data so that the rollback or restoration can be performed.
Normally, the data size is very large. Single person will take hours to do the editing job. Therefore, it is necessary to allow multiple users to simultaneously operate the data without interfering with each other. This requires that the spatial data engine provides the versioning functionality.
To cater to the centralized data management and asynchronous maintenance, the version management model is introduced in SuperMap SDX+ so that one or more versions of the target dataset can be created. Once the version is created, all editing operations on the data will be differentially recorded in that new version branch. The version branches are independent from the base version data as well as each other version data, therefore, every editor can access and lock the data. On the other hand, the multiple editors can perform editing on the same dataset at the same time while their versions will not interfere with each other.
The version confliction will be happened when the same data is edited by different users simultaneously. A convenient solution is available in SuperMap SDX+. When merging the branch versions data back to the base version, the modified data will be checked to see if it has been modified by the other users. If not, then commit the modification; otherwise, a warning message will be shown up and the different modifications will be displayed visually. This will be easy for users to decide which branch version should be saved as the final result.
Long Transaction
A transaction in database management systems is defined as a series of operations executed by a single logical working unit; it refers to one or more database access operations (i.e. insertion, deletion, modification or retrieval of data). A single logical working unit should have the following properties: Atomicity, Consistency, Isolation, and Durability known as ACID. Only with these properties is it able to be a transaction.
The atomicity ensures that every procedure must be completed successfully in a group of procedure. If one step fails, the other steps will not be started. This transaction mechanism, called short transaction mode, is provided by DBMS and supported by SuperMap. But the data edit processing could take hours, days, or longer in GIS application, therefore, it require GIS applications with a specialized long transaction mechanism so that the processing will not affect users' data viewing and querying. SuperMap provide a long transaction mechanism by taking the merits of the short transaction (ACID) to avoid its limitations. Below is a list of characteristics:
◆ A part of a layer can be locked for editing so that the other uses can browse only that part of base version data and cannot edit the locked data;
◆ Long transaction can last for several days, months, or even longer;
◆ Even the power failure, system crash or the other unforeseen accidents will not lost or damage the data;
◆ Be able to roll back all changes to original if it is necessary;
◆ Once the changes are committed, the other users will be able to view the updated data immediately;
◆ Only after the updating is committed or rolled back, the other users can modify the locked data.
The Development of SuperMap SDX+
Spatial database engine is the core component of GIS platform software. Previously SuperMap SDX+ focused on the implementation of a database engine and file engine. SuperMap GIS 2008, the latest version of SDX+ has provided more functional extensions, including adding web service data engine and spatial engine.
The database engine is useed for the relational databases, such as Oracle, SQL Server, Sybase, DB2, and Kingbase; the file engine is for SDB and SIT; the web service engine is for getting direct access to the data provided by the standard web service, such as WFS, WMS and etc. With the web service engine, the map and data published by web service can be treated as a SuperMap’s datasource. SuperMap SDX+ supports data formats of Oracle Spatial, ESRI ArcSDE Geodatabase, and so on. If a spatial database is built with the other format, this format of data can be directly accessed by SuperMap SDX+.
Through these engine extensions, industry-leading spatial information storage solutions can be integrated with SuperMap to simplify users’ operations as well as increase integrity and flexibility of GIS applications.
Figure 3 Datasource supported by SuperMap SDX+
The new SuperMap SDX+, released with SuperMap GIS 2008 has been able to support WMS, WFS, and Oracle Spatial. More engines for the OGC standard datasources and ESRI ArcSDE Geodatabase will be available in the next releases. Further more, MySQL will be supported also.
Through the severe competition and continuous development, SuperMap SDX+ has become a key technology in SuperMap GIS products. It will be improved consistently with the rapid pace of IT development. The Version Management will be enhanced to improve implementation of long transaction and unit the two lock modes of long transaction and version management. The offline editing and distributed updating functions will be provided soom. |
What's SuperMap SDX+?