TapSchemaInterrogator (Starjava VO API)

java.lang.Object
- uk.ac.starlink.vo.TapSchemaInterrogator

```
public class TapSchemaInterrogator
extends java.lang.Object
```
Interrogates the TAP_SCHEMA tables from a TAP service to acquire table metadata information. In the current implementation, synchronous queries are used.

Since:

6 Jun 2011

Author:

Mark Taylor

See Also:

TAP standard

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`static class`	`TapSchemaInterrogator.MetaQuerier<T>`	Object that can read a certain type of TAP metadata object from a table of a TAP_SCHEMA database table.

Field Summary

Fields
Modifier and Type	Field	Description
`static TapSchemaInterrogator.MetaQuerier<ColumnMeta>`	`COLUMN_QUERIER`	Acquires ColumnMeta objects from TAP_SCHEMA.columns.
`static TapSchemaInterrogator.MetaQuerier<ForeignMeta>`	`FKEY_QUERIER`	Acquires ForeignMeta objects from TAP_SCHEMA.keys.
`static TapSchemaInterrogator.MetaQuerier<ForeignMeta.Link>`	`LINK_QUERIER`	Acquires ForeignMeta.Link objects from TAP_SCHEMA.key_columns.
`static TapSchemaInterrogator.MetaQuerier<SchemaMeta>`	`SCHEMA_QUERIER`	Acquires SchemaMeta objects from TAP_SCHEMA.schemas.
`static TapSchemaInterrogator.MetaQuerier<TableMeta>`	`TABLE_QUERIER`	Acquires TableMeta objects from TAP_SCHEMA.tables.

Constructor Summary

Constructors
Constructor	Description
`TapSchemaInterrogator(EndpointSet endpointSet, int maxrec, uk.ac.starlink.util.ContentCoding coding)`	Constructs an interrogator with explicit configuration.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected TapQuery`	`createTapQuery(java.lang.String adql)`	Constructs a TAP query for a given ADQL string.
`protected uk.ac.starlink.table.StarTable`	`executeQuery(TapQuery tq)`	Performs an ADQL TAP query to this interrogator's service.
`EndpointSet`	`getEndpointSet()`	Returns the TAP endpoint locations used by this interrogator.
`static void`	`main(java.lang.String[] args)`	Prints out metadata content of a given TAP service.
`void`	`populateForeignKey(ForeignMeta fmeta, java.util.Map<java.lang.String,java.util.List<ForeignMeta.Link>> lMap)`	Fills in link information for a ForeignMeta object.
`void`	`populateSchema(SchemaMeta smeta, java.util.Map<java.lang.String,java.util.List<TableMeta>> tMap)`	Fills in table information for a SchemaMeta object.
`void`	`populateTable(TableMeta tmeta, java.util.Map<java.lang.String,java.util.List<ForeignMeta>> fMap, java.util.Map<java.lang.String,java.util.List<ColumnMeta>> cMap)`	Fills in foreign key and column information for a TableMeta object, Any relevant entries are removed from the supplied maps.
`SchemaMeta[]`	`queryMetadata()`	This convenience method returns an array of fully filled in SchemaMeta objects describing the tables available from the service.
`<T> java.util.List<T>`	`readList(TapSchemaInterrogator.MetaQuerier<T> mq, java.lang.String moreAdql)`	Reads a list of metadata items using a given MetaQuerier object.
`<T> java.util.Map<java.lang.String,java.util.List<T>>`	`readMap(TapSchemaInterrogator.MetaQuerier<T> mq, java.lang.String moreAdql)`	Reads a map of metadata items using a given MetaQuerier object.
`SchemaMeta[]`	`readSchemas(boolean populateSchemas, boolean populateTables, boolean addOrphanTables)`	Reads all schemas.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LINK_QUERIER
```
public static final TapSchemaInterrogator.MetaQuerier<ForeignMeta.Link> LINK_QUERIER
```
    Acquires ForeignMeta.Link objects from TAP_SCHEMA.key_columns. When reading a map, it is keyed by key_id.
  - FKEY_QUERIER
```
public static final TapSchemaInterrogator.MetaQuerier<ForeignMeta> FKEY_QUERIER
```
    Acquires ForeignMeta objects from TAP_SCHEMA.keys. When reading a map, it is keyed by from_table.
  - COLUMN_QUERIER
```
public static final TapSchemaInterrogator.MetaQuerier<ColumnMeta> COLUMN_QUERIER
```
    Acquires ColumnMeta objects from TAP_SCHEMA.columns. When reading a map, it is keyed by table_name.
  - TABLE_QUERIER
```
public static final TapSchemaInterrogator.MetaQuerier<TableMeta> TABLE_QUERIER
```
    Acquires TableMeta objects from TAP_SCHEMA.tables. When reading a map, it is keyed by schema_name.
  - SCHEMA_QUERIER
```
public static final TapSchemaInterrogator.MetaQuerier<SchemaMeta> SCHEMA_QUERIER
```
    Acquires SchemaMeta objects from TAP_SCHEMA.schemas. It doesn't read maps.
- Constructor Detail
  - TapSchemaInterrogator
```
public TapSchemaInterrogator(EndpointSet endpointSet,
                             int maxrec,
                             uk.ac.starlink.util.ContentCoding coding)
```
    Constructs an interrogator with explicit configuration.
    
    Parameters:
    
    endpointSet - TAP service locations
    
    maxrec - maximum number of records to retrieve per query
    
    coding - configures HTTP compression
- Method Detail
  - getEndpointSet
```
public EndpointSet getEndpointSet()
```
    Returns the TAP endpoint locations used by this interrogator.
    
    Returns:
    
    TAP endpoints
  - queryMetadata
```
public SchemaMeta[] queryMetadata()
                           throws java.io.IOException
```
    This convenience method returns an array of fully filled in SchemaMeta objects describing the tables available from the service.
    
    Returns:
    
    fully populated array of known schemas
    
    Throws:
    
    java.io.IOException
  - readSchemas
```
public SchemaMeta[] readSchemas(boolean populateSchemas,
                                boolean populateTables,
                                boolean addOrphanTables)
                         throws java.io.IOException
```
    Reads all schemas. According to the options, the schemas may or may not have their tables filled in, and those tables may or may not have their columns and foreign key information filled in.
    
    Parameters:
    
    populateSchemas - if true, schemas will contain non-null table lists
    
    populateTables - if true, tables will contain non-null column/key lists (ignored if populateSchemas is false)
    
    addOrphanTables - if true include tables whose schemas are not explicitly declared
    
    Returns:
    
    schema list
    
    Throws:
    
    java.io.IOException
  - readMap
```
public <T> java.util.Map<java.lang.String,java.util.List<T>> readMap(TapSchemaInterrogator.MetaQuerier<T> mq,
                                                                     java.lang.String moreAdql)
                                                              throws java.io.IOException
```
    Reads a map of metadata items using a given MetaQuerier object. The key of the map is the name of the parent object of the map value list type. See the documentation of the specific querier object for details.
    The form of the basic SELECT statement generated by this call is "SELECT <columns≫ FROM <table>". If non-null the text of the moreAdql parameter is appended (after a space), so it may be used to qualify the query further.
    
    Parameters:
    
    mq - type-specific querier
    
    moreAdql - additional ADQL text to append after the FROM clause (for example a WHERE clause); may be null
    
    Returns:
    
    map from parent metadata item name to list of metadata items
    
    Throws:
    
    java.io.IOException
  - readList
```
public <T> java.util.List<T> readList(TapSchemaInterrogator.MetaQuerier<T> mq,
                                      java.lang.String moreAdql)
                               throws java.io.IOException
```
    Reads a list of metadata items using a given MetaQuerier object.
    The form of the basic SELECT statement generated by this call is "SELECT <columns≫ FROM <table>". If non-null the text of the moreAdql parameter is appended (after a space), so it may be used to qualify the query further.
    
    Parameters:
    
    mq - type-specific querier
    
    moreAdql - additional ADQL text to append after the FROM clause (for example a WHERE clause); may be null
    
    Returns:
    
    list of metadata items
    
    Throws:
    
    java.io.IOException
  - populateForeignKey
```
public void populateForeignKey(ForeignMeta fmeta,
                               java.util.Map<java.lang.String,java.util.List<ForeignMeta.Link>> lMap)
```
    Fills in link information for a ForeignMeta object. Any relevant entries are removed from the supplied map. If the map contains no relevant entries, an empty list is filled in.
    
    Parameters:
    
    fmeta - unpopulated foreign key item
    
    lMap - map acquired using LINK_QUERIER
  - populateTable
```
public void populateTable(TableMeta tmeta,
                          java.util.Map<java.lang.String,java.util.List<ForeignMeta>> fMap,
                          java.util.Map<java.lang.String,java.util.List<ColumnMeta>> cMap)
```
    Fills in foreign key and column information for a TableMeta object, Any relevant entries are removed from the supplied maps. Where the maps contain no relevant entries, an empty list is filled in.
    
    Parameters:
    
    tmeta - unpopulated table metadata item
    
    fMap - map acquired using FKEY_QUERIER
    
    cMap - map acquired using COLUMN_QUERIER
  - populateSchema
```
public void populateSchema(SchemaMeta smeta,
                           java.util.Map<java.lang.String,java.util.List<TableMeta>> tMap)
```
    Fills in table information for a SchemaMeta object. Any relevant entries are removed from the supplied map. If the map contains no relevant entries, an empty list is filled in.
    
    Parameters:
    
    smeta - unpopulated schema metadata item
    
    tMap - map acquired using TABLE_QUERIER
  - createTapQuery
```
protected TapQuery createTapQuery(java.lang.String adql)
```
    Constructs a TAP query for a given ADQL string. May be overridden.
    
    Parameters:
    
    adql - query text
    
    Returns:
    
    query to execute
  - executeQuery
```
protected uk.ac.starlink.table.StarTable executeQuery(TapQuery tq)
                                               throws java.io.IOException
```
    Performs an ADQL TAP query to this interrogator's service. May be overridden.
    
    Parameters:
    
    tq - tap query
    
    Returns:
    
    output table
    
    Throws:
    
    java.io.IOException
  - main
```
public static void main(java.lang.String[] args)
                 throws java.io.IOException
```
    Prints out metadata content of a given TAP service.
    
    Parameters:
    
    args - first element is TAP service URL
    
    Throws:
    
    java.io.IOException

Class TapSchemaInterrogator

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LINK_QUERIER

FKEY_QUERIER

COLUMN_QUERIER

TABLE_QUERIER

SCHEMA_QUERIER

Constructor Detail

TapSchemaInterrogator

Method Detail

getEndpointSet

queryMetadata

readSchemas

readMap

readList

populateForeignKey

populateTable

populateSchema

createTapQuery

executeQuery

main