Creating new layers

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(Restoring database topic map)
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Topic map standard defines a merge operation between identical topics. Merge operation is extremely powerful as it allows incremental knowledge building. Knowledge packets addressing same topics superposition. The only problem with merge rules is that the source of topic is lost. You can't recognize which source assigned which topic element. Backtracking the merge changes is essential not just backtracking errors in knowledge but also to ensure trust between knowledge sources and aggregators. One backtracking method is to allow the aggregator to cancel and redo the merge easily.
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Topic map standard defines a merge operation between identical topics. Merge operation is extremely powerful as it allows incremental knowledge building. Knowledge packets addressing same topics superposition. The only problem with merge rules is that the source of topic is lost. You can't recognize which source assigned which topic element. Backtracking the merge is essential because original topics may contain errors. Backtracking also ensures trust between knowledge sources and aggregators. One backtracking method is to allow the aggregator to cancel and redo the merge easily.
  
 
Wandora supports layered topic maps. Layered topic map contains one or more topic maps stacked into an ordered array. Wandora user can add and delete topic maps in the layer stack. User can also make topic map layer invisible and lock layers.
 
Wandora supports layered topic maps. Layered topic map contains one or more topic maps stacked into an ordered array. Wandora user can add and delete topic maps in the layer stack. User can also make topic map layer invisible and lock layers.
  
The concept of layers and layer stack in Wandora is similar to the layer concept of many graphic creation and manipulation applications such as Adobe's PhotoShop where single image may contain multiple layers and graphics designer manipulates one layer at time. Layer implementation in graphic application ables the designer to isolate finished image parts from unfinished and enables rapid versioning. This is the motivation behind Wandora's layer implementation also. To make designer's life easier.
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The concept of layers and layer stack in Wandora is similar to the layer concept of many graphic creation and manipulation applications such as Adobe's PhotoShop where single image may contain multiple layers and graphics designer manipulates one layer at a time. Layer implementation in graphic application ables the designer to isolate finished image parts from unfinished and enables rapid versioning. This is the motivation behind Wandora's layer implementation also. To make designer's life easier.
  
Wandora's layer stack locates in bottom left corner of Wandora window. When you start Wandora, application reads topic map from '''conf/wandora.xtm''' and creates the layer  '''Base''' for it.
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Wandora's layer stack locates in bottom left corner of Wandora window. When you start Wandora, application reads topic map from '''conf/wandora.xtm''' and creates the layer  '''Base''' for it. Next image views a layer stack with three layers. Layer '''Base''' is active.
  
To create another layer you can
 
  
* Drag and drop XTM, LTM or RDF(S) file to the layer stack. Wandora imports the file and creates a new memory layer for the imported file.
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[[File:layer_stack_and_three_layers.gif|center]]
* Select '''Layers > [[NewLayer|New layer]]''' or press '''ALT+N'''. This opens layer creating window used to define layer type and properties. Current version of Wandora supports memory, database and remote layers.
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== Creating Memory Layer ==
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To create another layer you can
 
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Configuring new memory layer is very easy. Just enter layer's name and choose to import XTM topic map file to created layer, or not. Below is an example of memory layer configuration panel.
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[[Image:new_layer_memory.gif|center]]
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You can also select to import Wandora's mini ontology '''conf/wandora_mini.xtm''' to the created layer. This mini map contains a set of Wandora's fundamental topics and associations. After layer creation you should see new layer at the left bottom of application window.
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[[Image:newLayerExample.gif|center]]
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Letter '''M''' marks for a memory topic map layer. Letter '''D''' marks for a database topic map layer.
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== Creating Database Layer ==
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To create a database layer is more complicated. If you have configured the layer during previous Wandora sessions, you can simply pick up the layer configuration. Below is an example of database layer selection window.
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[[Image:new_layer_database.gif|center]]
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If you have not configured the layer before you need to create a configuration for the layer. Conguration is created clicking '''New''' button in database layer selection window. This opens configuration window shown below
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[[Image:new_layer_database_configuration.gif|center]]
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To define database configuration you have to select database type first. Current version of Wandora supports two specific and one generic database types. Specific types are for '''MySQL''' and '''Microsoft SQL Server'''. Generic database type allows you to create database layer with any JDBC capable SQL database.
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Setting up '''MySQL''' or '''Microsoft SQL Server''' database configuration you need to enter
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* Database configuration name.
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* IP or domain name for the database server.
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* Database's name.
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* Name of valid database user.
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* Password for the database user. Although Wandora suggests that you can enter database password later without remembering it, current Wandora version supports only ''remembered'' passwords. Wandora does not request password separately but layer creation fails if you have decided ''not to remember'' the password.
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'''Wandora's software package does not contain JDBC library for MySQL or Microsoft SQL Server. You need to download libraries separately from producer's own WWW site. See [[Download]] for specific download addresses.'''
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Setting up generic database configuration you need to enter
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* Database configuration name.
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* Database JDBC driver class name.
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* Connection string.
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* Database user.
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* Database user password.
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* SQL clauses used to initialize the database.
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After the initial database configuration the configuration settings are stored to Wandora's preferences and you can recall the configuration whenever you want to reconnect to an existing database topic map.
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=== Creating database tables for the topic map ===
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Database connection can be established to an existing or a new database. If you are configuring fresh database you probably want to create tables for the database. Wandora does not contain tool to create fresh database and you have to use database's native tools. SQL files to create database locate in '''conf/database''' folder. There is separate creation file for '''MySQL''', '''Microsoft SQL Server''', '''HSQL''' and generic SQL database. Detailed database initialization steps are beyond the scope of this chapter but in case of MySQL the steps are
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Log in the MySQL server with
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  mysql --user=<user_name> --password=<password>
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Create empty database for the topic map layer
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  create database mytopicmap;
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Import database creation clauses from '''db_mysql.sql'''
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  source db_mysql.sql;
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Set database user name and password
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  grant all on mytopicmap.* to "username"@"%" identified by "password";
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* Drag and drop XTM, LTM, JTM, RDF(S) or OBO file to the layer stack. Wandora imports the file and creates a new memory layer for the imported file.
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* Select '''Layers > [[NewLayer|New layer]]''' or press '''ALT+N'''. This opens a layer creating dialog used to define layer type and properties.
  
And the database is ready to be used as a layer in Wandora. Wandora database contains 8 different database tables. Below is an illustration of database structure.
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Wandora supports multiple different data storage options for topic maps. Usually memory stored topic map, i.e. Memory topic map is sufficient. However, the amount of memory limits also the size of potential topic maps. Database storage option is available for large topic maps with millions of topics and associations. Wandora also introduces special topic map constructs used to stack multiple topic maps into a single topic map, to filter and to mirror existing topic maps. Current version of Wandora supports next layer types:
  
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* [[Layered topic map]]s
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* [[Memory topic map]]s
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* [[Database topic map]]s
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* [[Query topic map]]s
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* [[Linked topic map]]s
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* [[Remote topic map]]s
  
[[Image:Database.gif|center]]
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Next image views a Create new layer dialog window used to create memory layer.
  
=== Restoring database topic map ===
 
  
It may be more convenient to handle SQL dumps instead of XTM exports when using database topic maps. Wandora features a '''[[SQLTopicMapImport|SQL topic map import...]]''' tool used to restore existing SQL database dump. Of cource you can import SQL dump directly to database but sometimes it is difficult to access the database directly and optional method is required. To restore existing database dump you need empty database and wandora connected to the database. Select the database topic map layer and choose '''File > Import > [[SQLTopicMapImport|SQL topic map import...]]'''. Tool requests the database dump file. Note that '''SQL topic map import...''' requires a valid database topic map dump. Invalid SQL dump makes Wandora easily unstable.
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[[File:new_layer_memory.gif|center]]
  
Note also that Wandora features '''Database extractor''' tool used to transform any SQL database into a topic map. Do not mix up '''SQL topic map import...''' and '''Database extractor'''. First is used to restore Wandora topic map database dumps as the latter is used to transform SQL databases to topic maps.
 
  
== Creating Remote Layer ==
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== See also ==
  
Remote layers are memory topic maps that locate in a remote Wandora server application. Remote layers are currently very experimental and unfinished. You should not use remote layers in current Wandora version.
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* [[Introduction to Layered Topic Maps]]
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* [[Layer order and arranging layers]]
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* [[Topic's layer distribution]]

Latest revision as of 19:45, 3 December 2013

Topic map standard defines a merge operation between identical topics. Merge operation is extremely powerful as it allows incremental knowledge building. Knowledge packets addressing same topics superposition. The only problem with merge rules is that the source of topic is lost. You can't recognize which source assigned which topic element. Backtracking the merge is essential because original topics may contain errors. Backtracking also ensures trust between knowledge sources and aggregators. One backtracking method is to allow the aggregator to cancel and redo the merge easily.

Wandora supports layered topic maps. Layered topic map contains one or more topic maps stacked into an ordered array. Wandora user can add and delete topic maps in the layer stack. User can also make topic map layer invisible and lock layers.

The concept of layers and layer stack in Wandora is similar to the layer concept of many graphic creation and manipulation applications such as Adobe's PhotoShop where single image may contain multiple layers and graphics designer manipulates one layer at a time. Layer implementation in graphic application ables the designer to isolate finished image parts from unfinished and enables rapid versioning. This is the motivation behind Wandora's layer implementation also. To make designer's life easier.

Wandora's layer stack locates in bottom left corner of Wandora window. When you start Wandora, application reads topic map from conf/wandora.xtm and creates the layer Base for it. Next image views a layer stack with three layers. Layer Base is active.


Layer stack and three layers.gif


To create another layer you can

  • Drag and drop XTM, LTM, JTM, RDF(S) or OBO file to the layer stack. Wandora imports the file and creates a new memory layer for the imported file.
  • Select Layers > New layer or press ALT+N. This opens a layer creating dialog used to define layer type and properties.

Wandora supports multiple different data storage options for topic maps. Usually memory stored topic map, i.e. Memory topic map is sufficient. However, the amount of memory limits also the size of potential topic maps. Database storage option is available for large topic maps with millions of topics and associations. Wandora also introduces special topic map constructs used to stack multiple topic maps into a single topic map, to filter and to mirror existing topic maps. Current version of Wandora supports next layer types:

Next image views a Create new layer dialog window used to create memory layer.


New layer memory.gif


[edit] See also

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