corda/docs/source/api-vault-query.rst

API: Vault Query

Overview

Corda has been architected from the ground up to encourage usage of industry standard, proven query frameworks and libraries for accessing RDBMS backed transactional stores (including the Vault).

Corda provides a number of flexible query mechanisms for accessing the Vault:

• Vault Query API
• Using a JDBC session (as described in Persistence <jdbc_session_ref>)
• Custom JPA/JPQL queries
• Custom 3rd party Data Access frameworks such as Spring Data

The majority of query requirements can be satisfied by using the Vault Query API, which is exposed via the VaultService for use directly by flows:

../../core/src/main/kotlin/net/corda/core/node/services/VaultService.kt

And via CordaRPCOps for use by RPC client applications:

../../core/src/main/kotlin/net/corda/core/messaging/CordaRPCOps.kt

../../core/src/main/kotlin/net/corda/core/messaging/CordaRPCOps.kt

Helper methods are also provided with default values for arguments:

../../core/src/main/kotlin/net/corda/core/messaging/CordaRPCOps.kt

../../core/src/main/kotlin/net/corda/core/messaging/CordaRPCOps.kt

The API provides both static (snapshot) and dynamic (snapshot with streaming updates) methods for a defined set of filter criteria:

• Use queryBy to obtain a current snapshot of data (for a given QueryCriteria)
• Use trackBy to obtain both a current snapshot and a future stream of updates (for a given QueryCriteria)

Note

Streaming updates are only filtered based on contract type and state status (UNCONSUMED, CONSUMED, ALL)

Simple pagination (page number and size) and sorting (directional ordering using standard or custom property attributes) is also specifiable. Defaults are defined for paging (pageNumber = 1, pageSize = 200) and sorting (direction = ASC).

The QueryCriteria interface provides a flexible mechanism for specifying different filtering criteria, including and/or composition and a rich set of operators to include:

• Binary logical (AND, OR)
• Comparison (LESS_THAN, LESS_THAN_OR_EQUAL, GREATER_THAN, GREATER_THAN_OR_EQUAL)
• Equality (EQUAL, NOT_EQUAL)
• Likeness (LIKE, NOT_LIKE)
• Nullability (IS_NULL, NOT_NULL)
• Collection based (IN, NOT_IN)
• Standard SQL-92 aggregate functions (SUM, AVG, MIN, MAX, COUNT)

There are four implementations of this interface which can be chained together to define advanced filters.

1. VaultQueryCriteria provides filterable criteria on attributes within the Vault states table: status (UNCONSUMED, CONSUMED), state reference(s), contract state type(s), notaries, soft locked states, timestamps (RECORDED, CONSUMED).

   Note

   Sensible defaults are defined for frequently used attributes (status = UNCONSUMED, always include soft locked states).

2. FungibleAssetQueryCriteria provides filterable criteria on attributes defined in the Corda Core FungibleAsset contract state interface, used to represent assets that are fungible, countable and issued by a specific party (eg. Cash.State and CommodityContract.State in the Corda finance module). Filterable attributes include: participants(s), owner(s), quantity, issuer party(s) and issuer reference(s).

   Note

   All contract states that extend the FungibleAsset now automatically persist that interfaces common state attributes to the vault_fungible_states table.

3. LinearStateQueryCriteria provides filterable criteria on attributes defined in the Corda Core LinearState and DealState contract state interfaces, used to represent entities that continuously supersede themselves, all of which share the same linearId (e.g. trade entity states such as the IRSState defined in the SIMM valuation demo). Filterable attributes include: participant(s), linearId(s), uuid(s), and externalId(s).

   Note

   All contract states that extend LinearState or DealState now automatically persist those interfaces common state attributes to the vault_linear_states table.

4. VaultCustomQueryCriteria provides the means to specify one or many arbitrary expressions on attributes defined by a custom contract state that implements its own schema as described in the Persistence </api-persistence> documentation and associated examples. Custom criteria expressions are expressed using one of several type-safe CriteriaExpression: BinaryLogical, Not, ColumnPredicateExpression, AggregateFunctionExpression. The ColumnPredicateExpression allows for specification arbitrary criteria using the previously enumerated operator types. The AggregateFunctionExpression allows for the specification of an aggregate function type (sum, avg, max, min, count) with optional grouping and sorting. Furthermore, a rich DSL is provided to enable simple construction of custom criteria using any combination of ColumnPredicate. See the Builder object in QueryCriteriaUtils for a complete specification of the DSL.

   Note

   Custom contract schemas are automatically registered upon node startup for CorDapps. Please refer to Persistence </api-persistence> for mechanisms of registering custom schemas for different testing purposes.

All QueryCriteria implementations are composable using and and or operators.

All QueryCriteria implementations provide an explicitly specifiable set of common attributes:

1. State status attribute (Vault.StateStatus), which defaults to filtering on UNCONSUMED states. When chaining several criteria using AND / OR, the last value of this attribute will override any previous
2. Contract state types (<Set<Class<out ContractState>>), which will contain at minimum one type (by default this will be ContractState which resolves to all state types). When chaining several criteria using and and or operators, all specified contract state types are combined into a single set

An example of a custom query is illustrated here:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

Custom contract states that implement the Queryable interface may now extend common schemas types FungiblePersistentState or, LinearPersistentState. Previously, all custom contracts extended the root PersistentState class and defined repeated mappings of FungibleAsset and LinearState attributes. See SampleCashSchemaV2 and DummyLinearStateSchemaV2 as examples.

Examples of these QueryCriteria objects are presented below for Kotlin and Java.

Note

When specifying the ContractType as a parameterised type to the QueryCriteria in Kotlin, queries now include all concrete implementations of that type if this is an interface. Previously, it was only possible to query on concrete types (or the universe of all ContractState).

The Vault Query API leverages the rich semantics of the underlying JPA Hibernate based Persistence </api-persistence> framework adopted by Corda.

Note

Permissioning at the database level will be enforced at a later date to ensure authenticated, role-based, read-only access to underlying Corda tables.

Note

API's now provide ease of use calling semantics from both Java and Kotlin. However, it should be noted that Java custom queries are significantly more verbose due to the use of reflection fields to reference schema attribute types.

An example of a custom query in Java is illustrated here:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Note

Queries by Party specify the AbstractParty which may be concrete or anonymous. In the later case, where an anonymous party does not resolve to an X500 name via the IdentityService, no query results will ever be produced. For performance reasons, queries do not use PublicKey as search criteria.

Pagination

The API provides support for paging where large numbers of results are expected (by default, a page size is set to 200 results). Defining a sensible default page size enables efficient checkpointing within flows, and frees the developer from worrying about pagination where result sets are expected to be constrained to 200 or fewer entries. Where large result sets are expected (such as using the RPC API for reporting and/or UI display), it is strongly recommended to define a PageSpecification to correctly process results with efficient memory utilisation. A fail-fast mode is in place to alert API users to the need for pagination where a single query returns more than 200 results and no PageSpecification has been supplied.

Here's a query that extracts every unconsumed ContractState from the vault in pages of size 200, starting from the default page number (page one):

val vaultSnapshot = proxy.vaultQueryBy<ContractState>(
    QueryCriteria.VaultQueryCriteria(Vault.StateStatus.UNCONSUMED),
    PageSpecification(DEFAULT_PAGE_NUM, 200))

Note

A pages maximum size MAX_PAGE_SIZE is defined as Int.MAX_VALUE and should be used with extreme caution as results returned may exceed your JVM's memory footprint.

Example usage

Kotlin

General snapshot queries using VaultQueryCriteria:

Query for all unconsumed states (simplest query possible):

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed states for some state references:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed states for several contract state types:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed states for a given notary:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed states for a given set of participants:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed states recorded between two time intervals:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

This example illustrates usage of a Between ColumnPredicate.

Query for all states with pagination specification (10 results per page):

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

The result set metadata field totalStatesAvailable allows you to further paginate accordingly as demonstrated in the following example.

Query for all states using a pagination specification and iterate using the totalStatesAvailable field until no further pages available:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

LinearState and DealState queries using LinearStateQueryCriteria:

Query for unconsumed linear states for given linear ids:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for all linear states associated with a linear id:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed deal states with deals references:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for unconsumed deal states with deals parties:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

FungibleAsset and DealState queries using FungibleAssetQueryCriteria:

Query for fungible assets for a given currency:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Query for fungible assets for a minimum quantity:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

This example uses the builder DSL.

Query for fungible assets for a specific issuer party:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Aggregate Function queries using VaultCustomQueryCriteria:

Note

Query results for aggregate functions are contained in the otherResults attribute of a results Page.

Aggregations on cash using various functions:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

otherResults will contain 5 items, one per calculated aggregate function.

Aggregations on cash grouped by currency for various functions:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

otherResults will contain 24 items, one result per calculated aggregate function per currency (the grouping attribute - currency in this case - is returned per aggregate result).

Sum aggregation on cash grouped by issuer party and currency and sorted by sum:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

otherResults will contain 12 items sorted from largest summed cash amount to smallest, one result per calculated aggregate function per issuer party and currency (grouping attributes are returned per aggregate result).

Dynamic queries (also using VaultQueryCriteria) are an extension to the snapshot queries by returning an additional QueryResults return type in the form of an Observable<Vault.Update>. Refer to ReactiveX Observable for a detailed understanding and usage of this type.

Track unconsumed cash states:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Track unconsumed linear states:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

This will return both DealState and LinearState states.

Track unconsumed deal states:

../../node/src/test/kotlin/net/corda/node/services/vault/VaultQueryTests.kt

Note

This will return only DealState states.

Java examples

Query for all unconsumed linear states:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Query for all consumed cash states:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Query for consumed deal states or linear ids, specify a paging specification and sort by unique identifier:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Query for all states using a pagination specification and iterate using the totalStatesAvailable field until no further pages available:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Aggregate Function queries using VaultCustomQueryCriteria:

Aggregations on cash using various functions:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Aggregations on cash grouped by currency for various functions:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Sum aggregation on cash grouped by issuer party and currency and sorted by sum:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Track unconsumed cash states:

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Track unconsumed deal states or linear states (with snapshot including specification of paging and sorting by unique identifier):

../../node/src/test/java/net/corda/node/services/vault/VaultQueryJavaTests.java

Troubleshooting

If the results your were expecting do not match actual returned query results we recommend you add an entry to your log4j2.xml configuration file to enable display of executed SQL statements:

<Logger name="org.hibernate.SQL" level="debug" additivity="false">

    <AppenderRef ref="Console-Appender"/>

</Logger>

Behavioural notes

1. TrackBy updates do not take into account the full criteria specification due to different and more restrictive syntax in observables filtering (vs full SQL-92 JDBC filtering as used in snapshot views). Specifically, dynamic updates are filtered by contractStateType and stateType (UNCONSUMED, CONSUMED, ALL) only
2. QueryBy and TrackBy snapshot views using pagination may return different result sets as each paging request is a separate SQL query on the underlying database, and it is entirely conceivable that state modifications are taking place in between and/or in parallel to paging requests. When using pagination, always check the value of the totalStatesAvailable (from the Vault.Page result) and adjust further paging requests appropriately.

Other use case scenarios

For advanced use cases that require sophisticated pagination, sorting, grouping, and aggregation functions, it is recommended that the CorDapp developer utilise one of the many proven frameworks that ship with this capability out of the box. Namely, implementations of JPQL (JPA Query Language) such as Hibernate for advanced SQL access, and Spring Data for advanced pagination and ordering constructs.

The Corda Tutorials provide examples satisfying these additional Use Cases:

1. Example CorDapp service using Vault API Custom Query to access attributes of IOU State
2. Example CorDapp service query extension executing Named Queries via JPQL
3. Advanced pagination queries using Spring Data JPA