com.im.df.api
Interface DFSchemaProvider

public interface DFSchemaProvider

This interface should be used as primary source of connected and activated DFSchema objects and all its subelements (DFEntity/DFField/...). The typical usage is to get somewhere instance of DFSchemaProvider (perhaps through some factory) and then do these steps:

        DFSchemaProvider schemaProvider = new SomeSchemaProviderImpl();
        DFLock lock = schemaProvider.getLockable().obtainLock("Connect to schema");
        DFEnvironmentRW env = EnvUtils.createDefaultEnvironmentRW(lock, "Connecting to schema", true);
        for (;;) {
            SchemaProvider.State state = schemaProvider.getState();
            if (state.isSchemaReady())
                break;
            Object options = state.getOptions();
            if (options != null) {
                // customize options: find customizer and present to user.
                // The dialog with customizer should have cancel button to stop connecting anytime
            }

            schemaProvider.proceedToNextState(env);
        }

        // Close the environment and release the lock - the best approach is to do this in finally block
        // => and return the activated schema instance
        DFSchema schema = schemaProvider.getState().isSchemaReady() ? schemaProvider.getSchema() : null;

 

Notes about events:

• the PROP_STATE is fired whenever the state changes. When the Provider will start to return DFSchema instance, the schema initialization has completed.
• the PROP_LOCKED is fired on getLockable() when the lock is released. This should happen either after the initialization completes successfully (DFSchema is returned from the provider) or fails (no Schema is returned).

Nested Class Summary

static interface	DFSchemaProvider.State State description
static interface	DFSchemaProvider.StepInfo Return code of "Proceed to next state".

Field Summary

static String

PROP_STATE This property is fired whenever state changes

Method Summary

void	addPropertyChangeListener(PropertyChangeListener listener)
void	closeSchema(DFEnvironmentRW env) Closes the schema and invalidates DFSchema and all its subitems (property "valid" of DFItem).
void	deleteSchema(DFEnvironmentRW env, boolean deleteMetaDataTables) Deletes the schema metadata items from the database.
Map<String,String>	getAllSchemas(DFEnvironmentRO env) Retrieves all schemas available at the database connection.
DFLockable	getLockable() Provides lockable for state operations.
SchemaType	getSchemaType() Provides a schema type.
DFSchemaProvider.State	getState() Get current state
void	proceedToNextState(DFEnvironmentRW env) Continue to next phase.
void	removePropertyChangeListener(PropertyChangeListener listener)

Field Detail

PROP_STATE

static final String PROP_STATE

This property is fired whenever state changes

See Also:

Constant Field Values

Method Detail

getState

DFSchemaProvider.State getState()

Get current state

getLockable

DFLockable getLockable()

Provides lockable for state operations. This prevents more threads or components to start connecting at the same moment.

getSchemaType

SchemaType getSchemaType()

Provides a schema type. Returned value never change during DFSchemaProvider life time.

Returns:

The type of schema provided by this DFSchemaProvider. Never returns null

proceedToNextState

void proceedToNextState(DFEnvironmentRW env)

Continue to next phase. Options should be customised before calling this method. This method should not throw exception. If there are any problems it should be presented in next state description or

closeSchema

void closeSchema(DFEnvironmentRW env)

Closes the schema and invalidates DFSchema and all its subitems (property "valid" of DFItem).

deleteSchema

void deleteSchema(DFEnvironmentRW env,
                  boolean deleteMetaDataTables)
                  throws IOException

Deletes the schema metadata items from the database. If deleteSystemTables is set, it will also delete the IJC_ system tables; that is ALL schemas, users, views etc. The system tables can be deleted only if this is the last schema.

Parameters:

env - The f eedback environment

deleteMetaDataTables - Whether IJC_* tables should be deleted as well.

Throws:

IOException - if the schema is not open, or on schema-manipulation error.

getAllSchemas

Map<String,String> getAllSchemas(DFEnvironmentRO env)

Retrieves all schemas available at the database connection. The returned Map is indexed by schema IDs. Values are schema names. Note: schemaIDs served by the provider are always unique.

Returns:

The map of schemaID -> schema name

addPropertyChangeListener

void addPropertyChangeListener(PropertyChangeListener listener)

removePropertyChangeListener

void removePropertyChangeListener(PropertyChangeListener listener)