Migration Guides
This chapter contains comprehensive guides that help you to work through migrations such as from CAP Java 1.x to CAP Java 2.x.
CAP Java 2.10 to CAP Java 3.0
Minimum Versions
CAP Java 3.0 increased some minimum required versions:
| Dependency | Minimum Version |
|---|---|
| Cloud SDK | 5.9.0 |
| @sap/cds-dk | ^7 |
| Maven | 3.6.3 |
CAP Java 3.0 no longer supports @sap/cds-dk ^6.
Production Profile cloud
The Production Profile now defaults to cloud. This ensures that various property defaults suited for local development are changed to recommended secure values for production.
One of the effects of the production profile is that the index page is disabled by default. If you are using the root path / for a readiness or liveness probe in Kyma you will need to adjustment them. in this case the recommended approach would be to use the Spring Boot actuator's /actuator/health endpoint instead.
Learn more about the Production Profile.
Removed MTX Classic Support
Support for classic MTX (@sap/cds-mtx) has been removed. Using streamlined MTX (@sap/cds-mtxs) is mandatory for multitenancy. If you're still using MTX Classic refer to the multitenancy migration guide.
In addition, the deprecated MtSubscriptionService API, has been removed. It has now been superseeded by the DeploymentService API. As part of this change the compatibility mode for the MtSubscriptionService API has been removed. Besides the removal of the Java APIs this includes the following behavioural changes:
- During unsubscribe, the tenant's content (like HDI container) is now deleted by default when using the new
DeploymentServiceAPI. - The HTTP-based tenant upgrade APIs provided by the CAP Java app have been removed, use the
Deploymain method instead. This includes the following endpoints:/mt/v1.0/subscriptions/deploy/**(GET & POST)/messaging/v1.0/em/<tenant>(PUT)
Removed feature cds-feature-xsuaa
The feature cds-feature-xsuaa has been removed. Support for XSUAA and IAS has been unified under the umbrella of cds-feature-identity.
It utilizes SAP´s spring-security library instead of the deprecated spring-xsuaa library.
If your application relies on the standard security configuration by CAP Java and depend on one of the CAP starter bundles, it is expected that you won't need to adapt code.
If you have customized the security configuration, you need to adapt it to the new library. If your application had a direct dependency to cds-feature-xsuaa, we recommend using one of our starter bundles cds-starter-cloudfoundry or cds-starter-k8s.
Though CAP does not support multiple XSUAA bindings, it was possible in previous versions to extend the standard security configuration to work with multiple bindings. If you require this, you need to set cds.security.xsuaa.allowMultipleBinding to true so that all XSUAA bindings are available in custom spring auto-configurations. Note: CAP Java still does not process multiple bindings and requires a dedicated spring configuration. In general, applications should refrain from configuring several XSUAA bindings.
Learn more about the security configuration.Learn more about migration to SAP´s spring-security library.
Proof-Of-Possession enforced for IAS-based authentication
In IAS scenarios, the Proof-Of-Possession is now enforced by default for incoming requests for versions starting from 3.5.1 of the SAP BTP Spring Security Client.
Because of this, applications calling a CAP Java application will need to send a valid client certificate in addition to the JWT token. In particular, applications using an Approuter have to set forwardAuthCertificates: true on the Approuter destination pointing to your CAP backend.
Learn more about Proof-Of-Possession.
Lazy Localization by default
EDMX resources served by the OData V4 /$metadata endpoints are now localized lazily by default. This significantly reduces EDMX cache memory consumption when many languages are used. Note, that this requires at least @sap/cds-mtxs in version 1.12.0.
The cds build no longer generates localized EDMX files by default anymore, but instead generates templated EDMX files and a i18n.json containing text bundles. If you need localized EDMX files to be generated, set --opts contentLocalizedEdmx=true when calling cds build.
Star-expand and inline-all are no longer permitted
Previously, you could not use expand or inline without explicit paths on draft-enabled entities. Now they are rejected for all entities on application service level.
For example, following statement will not be executed when submitted to an instance of ApplicationService.
Select.from(BOOKS).columns(b -> b.expand());This does not impact OData where expand=* is transformed into expands for all associations.
Adjusted POJO class generation
Some parameter defaults of the goal generate have been adjusted:
| Parameter | Old Value | New Value | Explanation |
|---|---|---|---|
sharedInterfaces | false | true | Interfaces for global arrayed types with inline anonymous type are now generated exactly once. sharedInterfaces ensures such types are not generated as inline interfaces again, if used in events, actions or functions. |
uniqueEventContexts | false | true | Determines whether the event context interfaces should be unique for bound actions and functions, by prefixing the interfaces with the entity name. |
Both these changes result in the generation of incompatible POJOs. To get the former POJOs, the new defaults can be overwritten by setting the parameters to the old values.
Consider the following example:
service MyService {
entity MyEntity {
key ID: UUID
} actions {
// bound action
action doSomething(values: MyArray);
}
}
// global arrayed type
type MyArray: many {
value: String;
}With the new defaults the generated interface for the doSomething action looks like this:
// uniqueEventContexts: true =>
// interface is prefixed with entity name "MyEntity"
public interface MyEntityDoSomethingContext extends EventContext {
// sharedInterfaces: true => global MyArray type is used
Collection<MyArray.Item> getValues();
void setValues(Collection<MyArray.Item> values);
}Formerly the generated interface looked like this:
// uniqueEventContexts: false =>
// interface is not prefixed with entity name
public interface DoSomethingContext extends EventContext {
// sharedInterfaces: false => global MyArray type is not used,
// instead an additional interface Values is generated inline
Collection<Values> getValues();
void setValues(Collection<Values> values);
interface Values extends CdsData {
// ...
}
}Adjusted Property Defaults
Some property defaults have been adjusted:
| Property | Old Value | New Value | Explanation |
|---|---|---|---|
cds.remote.services.<key>.http.csrf.enabled | true | false | Most APIs don't require CSRF tokens. |
cds.sql.hana.optimizationMode | legacy | hex | SQL for SAP HANA is optimized for the HEX engine. |
cds.odataV4.lazyI18n.enabled | null | true | Lazy localization is now enabled by default in multitenant scenarios. |
cds.auditLog.personalData.throwOnMissingDataSubject | false | true | Raise errors for incomplete personal data annotations by default. |
cds.messaging.services.<key>.structured | false | true | Enhanced message representation is now enabled by default. |
Adjusted Property Behavior
| Property | New Behavior |
|---|---|
cds.outbox.persistent.enabled | When set to false, all persistent outboxes are disabled regardless of their specific configuration. |
Removed Properties
The following table gives an overview about the removed properties:
| Removed Property | Replacement / Explanation |
|---|---|
cds.auditlog.outbox.persistent.enabled | cds.auditlog.outbox.name |
cds.dataSource.csvFileSuffix | cds.dataSource.csv.fileSuffix |
cds.dataSource.csvInitializationMode | cds.dataSource.csv.initializationMode |
cds.dataSource.csvPaths | cds.dataSource.csv.paths |
cds.dataSource.csvSingleChangeset | cds.dataSource.csv.singleChangeset |
cds.security.identity.authConfig.enabled | cds.security.authentication.authConfig.enabled |
cds.security.xsuaa.authConfig.enabled | cds.security.authentication.authConfig.enabled |
cds.security.mock.users.<key>.unrestricted | Special handling of unrestricted attributes has been removed, in favor of explicit modelling. |
cds.messaging.services.<key>.outbox.persistent.enabled | cds.messaging.services.<key>.outbox.name |
cds.multiTenancy.compatibility.enabled | MtSubscriptionService API has been removed and compatibility mode is no longer available. |
cds.multiTenancy.healthCheck.intervalMillis | cds.multiTenancy.healthCheck.interval |
cds.multiTenancy.mtxs.enabled | MTXS is enabled by default. |
cds.multiTenancy.security.deploymentScope | HTTP-based tenant upgrade endpoints have been removed. |
cds.odataV4.apply.inCqn.enabled | cds.odataV4.apply.transformations.enabled |
cds.odataV4.serializer.enabled | The legacy serializer has been removed. |
cds.outbox.persistent.maxAttempts | cds.outbox.services.<key>.maxAttempts |
cds.outbox.persistent.storeLastError | cds.outbox.services.<key>.storeLastError |
cds.outbox.persistent.ordered | cds.outbox.services.<key>.ordered |
cds.remote.services.<key>.destination.headers | cds.remote.services.<key>.http.headers |
cds.remote.services.<key>.destination.queries | cds.remote.services.<key>.http.queries |
cds.remote.services.<key>.destination.service | cds.remote.services.<key>.http.service |
cds.remote.services.<key>.destination.suffix | cds.remote.services.<key>.http.suffix |
cds.remote.services.<key>.destination.type | cds.remote.services.<key>.type |
cds.sql.search.useLocalizedView | cds.sql.search.model |
cds.sql.supportedLocales | All locales are supported by default for localized entities, as session variables can now be leveraged on all databases. |
Deprecated Session Context Variables
| Old Variable | Replacement |
|---|---|
$user.tenant | $tenant |
$at.from | $valid.from |
$at.to | $valid.to |
Removed Java APIs
Removed deprecated classes:
com.sap.cds.services.environment.ServiceBindingcom.sap.cds.services.environment.ServiceBindingAdaptercom.sap.cds.services.mt.MtAsyncDeployEventContextcom.sap.cds.services.mt.MtAsyncDeployStatusEventContextcom.sap.cds.services.mt.MtAsyncSubscribeEventContextcom.sap.cds.services.mt.MtAsyncSubscribeFinishedEventContextcom.sap.cds.services.mt.MtAsyncUnsubscribeEventContextcom.sap.cds.services.mt.MtAsyncUnsubscribeFinishedEventContextcom.sap.cds.services.mt.MtDeployEventContextcom.sap.cds.services.mt.MtGetDependenciesEventContextcom.sap.cds.services.mt.MtSubscribeEventContextcom.sap.cds.services.mt.MtSubscriptionServicecom.sap.cds.services.mt.MtUnsubscribeEventContext
Removed deprecated methods:
com.sap.cds.services.request.ModifiableUserInfo.addUnrestrictedAttributecom.sap.cds.services.request.ModifiableUserInfo.setUnrestrictedAttributescom.sap.cds.services.request.ModifiableUserInfo.removeUnrestrictedAttributecom.sap.cds.services.request.UserInfo.getUnrestrictedAttributescom.sap.cds.services.request.UserInfo.isUnrestrictedAttributecom.sap.cds.ql.Insert.cqn(String)com.sap.cds.ql.Update.cqn(String)com.sap.cds.ql.Upsert.cqn(String)
Deprecations:
com.sap.cds.ql.cqn.CqnSearchPredicate, instead useCqnSearchTermPredicatecom.sap.cds.ql.cqn.Modifier.search(String), instead usesearchTerm(CqnSearchTermPredicate)com.sap.cds.services.messaging.MessageService.emit(String, String)instead useemit(String, Map)oremit(String, Map, Map)
Removed goals in cds-maven-plugin
The goal addSample from the cds-maven-plugin has been removed. Use the new goal add with the property -Dfeature=TINY_SAMPLE instead.
Cloud SDK 4 to 5
CAP Java 2.6.0 and higher is compatible with Cloud SDK in version 4 and 5. For reasons of backward compatibility, CAP Java assumes Cloud SDK 4 as the default. However, we highly recommend that you use at least version 5.9.0 of Cloud SDK. If you relied on the Cloud SDK integration package (cds-integration-cloud-sdk), you won't need to adapt any code to upgrade your CAP Java application to Cloud SDK 5. In these cases, it's sufficient to add the following maven dependency to your CAP Java application:
<dependency>
<groupId>com.sap.cloud.sdk.cloudplatform</groupId>
<artifactId>connectivity-apache-httpclient4</artifactId>
</dependency>If you are using Cloud SDK APIs explicitly in your code consider the migration guide for Cloud SDK 5 itself: https://sap.github.io/cloud-sdk/docs/java/guides/5.0-upgrade-steps
CAP Java 1.34 to CAP Java 2.0
This section describes the changes in CAP Java between the major versions 1.34 and 2.0. It provides also helpful information how to migrate a CAP Java application to the new major version 2.0.
As preparation, we strongly recommend to firstly upgrade to 1.34.x and then follow this guide to upgrade to 2.0.x.
Spring Boot 3
CAP Java 2 uses Spring Boot 3 as underlying framework. Consult the Spring Boot 3.0 Migration Guide for changes between Spring Boot 2.7 and Spring Boot 3.0. A CAP Java application is typically only affected by Spring Boot 3 incompatibilities if it uses native Spring APIs.
Java 17
Spring Boot 3 requires Java 17 as minimum version. Maven dependencies, which are not managed by CAP Java, need to be updated to Java 17 compatible versions.
Jakarta EE 10
Spring Boot 3 requires Jakarta EE 10. This includes a switch in package names from javax to jakarta. For example all Servlet-related classes are moved from package javax.servlet to jakarta.servlet.
For instance, replace
import javax.servlet.http.HttpServletResponse;with
import jakarta.servlet.http.HttpServletResponse;Maven dependencies, which are not managed by CAP Java or Spring Boot, need to be updated to Jakarta EE 10 compatible versions.
Spring Security
Since version 1.27 CAP Java is running with Spring Boot 2.7, which uses Spring Security 5.7. Spring Boot 3 uses Spring Security 6. In case you defined custom security configurations you need to follow the guides, which describe the migration from 5.7 to 5.8 and the migration from 5.8 to 6.0.
Minimum Dependency Versions
Make sure that all libraries used in your project are either compatible with Spring Boot 3 / Jakarta EE 10 or alternatively offer a new version which you can adopt.
CAP Java 2.0 itself requires updated dependency versions of:
@sap/cds-dk@sap/cds-compiler- XSUAA library
- SAP Cloud SDK
- Java Logging (replace
cf-java-logging-support-servletwithcf-java-logging-support-servlet-jakarta)
WARNING
The Cloud SDK BOM sdk-bom manages XSUAA until version 2.x, which isn't compatible with CAP Java 2.x. You have two options:
- Replace
sdk-bomwithsdk-modules-bom, which manages all Cloud SDK dependencies but not the transitive dependencies. - Or, add dependency management for XSUAA before Cloud SDK's
sdk-bom.
API Cleanup
Some interfaces, methods, configuration properties and annotations, which had already been deprecated in 1.x, are now removed in version 2.0. Please strictly fix all usage of deprecated APIs by using the recommended replacement.
TIP
In your IDE, enable the compiler warning "Signal overwriting or implementing deprecated method".
Legacy Upsert
Up to cds-services 1.27, upsert always completely replaced pre-existing data with the given data: it was implemented as cascading delete followed by a deep insert. In the insert phase, for all elements that were absent in the data, the initializations were performed: UUID generation, @cds.on.insert handlers, and initialization with default values. Consequently, in the old implementation, an upsert with partial data would have reset absent elements to their initial values! To avoid a reset with the old upsert, data always had to be complete.
Since version 1.28 the upsert is implemented as a deep update that creates data if not existing. An upsert with partial data now leaves the absent elements untouched. In particular, UUID values are not generated with the new upsert implementation.
Application developers upgrading from cds-services <= 1.27 need to be aware of these changes. Check, if the usage of upsert in your code is compatible with the new implementation, especially:
- Ensure that all key values are contained in the data and you don't rely on UUID key generation.
- Check if insert is more appropriate.
WARNING
The global configuration parameter cds.sql.upsert.strategy, as well as the upsert hint to switch back to the legacy upsert behavior are not supported anymore with 2.0. If you rely on the replace behavior of the legacy upsert, use a cascading delete followed by a deep insert.
Representation of Pagination
The interfaces CqnLimit and Limit are removed. Use the methods limit(top) and limit(top, skip) of the Select and Expand to specify the pagination settings. Use the methods top() and skip() of the CqnEntitySelector to introspect the pagination settings of a CqnExpand and CqnSelect.
Statement Modification
Removal of Deprecated CqnModifier
The deprecated CqnModifier, whose default methods make expensive copies of literal values, is removed. Instead, use the Modifier as documented in Modifying CQL Statements.
If your modifier overrides one or more of the CqnModifier:literal methods that take value and cdsType as arguments, override Modifier:literal(CqnLiteral<?> literal) instead. You can create new values using CQL.val(value).type(cdsType);.
Removal of Deprecated Methods in Modifier
The deprecated methods ref(StructuredTypeRef) and ref(ElementRef<?>) are removed, instead implement the new methods ref(CqnStructuredTypeRef) and ref(CqnElementRef). Use CQL.copy(ref) if you require a modifiable copy of the ref.
Modifier modifier = new Modifier() {
@Override
public CqnStructuredTypeRef ref(CqnStructuredTypeRef ref) {
RefBuilder<StructuredTypeRef> copy = CQL.copy(ref); // try to avoid copy
copy.targetSegment().filter(newFilter);
return copy.build();
}
@Override
public CqnValue ref(CqnElementRef ref) {
List<Segment> segments = new ArrayList<>(ref.segments());
segments.add(0, CQL.refSegment(segments.get(0).id(), filter));
return CQL.get(segments).as(alias);
}
};
CqnStatement copy = CQL.copy(statement, modifier);Removed Interfaces and Methods Overview
com.sap.cds
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| ConstraintViolationException | UniqueConstraintException | |
| ResultBuilder | updatedRows | see javadoc |
com.sap.cds.ql
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| CQL | literal | val or constant |
| Select | groupBy | groupBy |
com.sap.cds.ql.cqn
com.sap.cds.reflect
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| CdsAssociationType | keys | refs |
| CdsStructuredType | isInlineDefined | isAnonymous |
com.sap.cds.services
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| ErrorStatus | getCode() | getCodeString() |
| ServiceException | messageTarget(prefix, entity, path) | messageTarget(parameter, path) |
com.sap.cds.services.cds
| Class/Interface | Method | Replacement |
|---|---|---|
| CdsService | CqnService |
com.sap.cds.services.environment
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| ServiceBinding | com.sap.cloud.environment.servicebinding.api.ServiceBinding |
Details
Interface ServiceBinding
The interface com.sap.cds.services.environment.ServiceBinding is deprecated and replaced with interface com.sap.cloud.environment.servicebinding.api.ServiceBinding. For convenience the adapter class com.sap.cds.services.utils.environment.ServiceBindingAdapter is provided, which maps the deprecated interface to the new one.
com.sap.cds.services.handler
| Class/Interface | Method | Replacement |
|---|---|---|
| EventPredicate | n/a |
Details
Interface EventPredicate
The interface com.sap.cds.services.handler.EventPredicate is removed. Consequently, all methods at interface com.sap.cds.services.Service containing this interface as argument are removed. All removed method were marked as deprecated in prior releases.
com.sap.cds.services.messages
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| Message | target(prefix, entity, path) | target(start, path) |
| MessageTarget | getPrefix() | getParameter() |
| getEntity(), getPath() | getRef() |
com.sap.cds.services.persistence
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| PersistenceService | getCdsDataStore() | Use PersistenceService |
com.sap.cds.services.request
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| ParameterInfo | getQueryParameters() | getQueryParams() |
| UserInfo | getAttribute(String) | getAttributeValues(String) |
com.sap.cds.services.runtime
| Class / Interface | Method / Field | Replacement |
|---|---|---|
| CdsModelProvider | get(tenantId) | get(userInfo, features) |
| CdsRuntime | runInChangeSetContext(Consumer) | changeSetContext().run(Consumer) |
| runInChangeSetContext(Function) | changeSetContext().run(Function) | |
| runInRequestContext(Consumer) | requestContext().run(Consumer) | |
| runInRequestContext(Function) | requestContext().run(Function) | |
| Request | CdsRuntime.runInRequestContext(Request, Function|Consumer) | CdsRuntime.requestContext().run(Function) |
| RequestParameters | CdsRuntime.runInRequestContext(Request, Function|Consumer) | CdsRuntime.requestContext().run(Function) |
| RequestUser | CdsRuntime.runInRequestContext(Request, Function|Consumer) | CdsRuntime.requestContext().run(Function) |
Details
Method CdsRuntime.runInRequestContext(Request, Function|Consumer)
The interface Request and its used interfaces RequestParameters and RequestUser are removed. They were still used in the method CdsRuntime.runInRequestContext(Request, Function|Consumer), which was also deprecated and should be replaced by CdsRuntime.requestContext().run(Function)
Overview of Removed CDS Properties
Some CdsProperties were already marked as deprected in CAP Java 1.x and are now removed in 2.x.
| removed | replacement |
|---|---|
| cds.dataSource.serviceName | cds.dataSource.binding |
| cds.drafts.associationsToInactiveEntities | see Lean Draft |
| cds.locales.normalization.whiteList | cds.locales.normalization.includeList |
| cds.messaging.services.<key>.queue.maxFailedAttempts | Use custom error handling |
| cds.messaging.services.<key>.topicNamespace | cds.messaging.services.<key>.subscribePrefix |
| cds.multiTenancy.instanceManager | cds.multiTenancy.serviceManager |
| cds.multiTenancy.dataSource.hanaDatabaseIds | obsolete, information is automatically retrieved from bindings |
| cds.odataV4.indexPage | cds.indexPage |
| cds.security.authenticateUnknownEndpoints | cds.security.authentication.authenticateUnknownEndpoints |
| cds.security.authorizeAutoExposedEntities | if disabled, add auto-exposed entities explicitly into your service definition |
| cds.security.authorization.autoExposedEntities | if disabled, add auto-exposed entities explicitly into your service definition |
| cds.security.defaultRestrictionLevel | cds.security.authentication.mode |
| cds.security.draftProtection | cds.security.authorization.draftProtection |
| cds.security.instanceBasedAuthorization | if disabled, remove @requires / @restrict annotations |
| cds.security.authorization.instanceBasedAuthorization | remove @requires / @restrict annotations |
| cds.security.openMetadataEndpoints | cds.security.authentication.authenticateMetadataEndpoints |
| cds.security.openUnrestrictedEndpoints | cds.security.authentication.mode |
| cds.security.xsuaa.serviceName | cds.security.xsuaa.binding |
| cds.security.xsuaa.normalizeUserNames | obsolete, effectively hard-coded to false |
| cds.services | cds.application.services |
| cds.sql.upsert | See Legacy Upsert |
Removed Annotations Overview
@search.cascadeis no longer supported. It's replaced by @cds.search.
Changed Behavior
Immutable Values
The implementations of Value are now immutable. This change makes copying & modifying CQL statements cheaper, which significantly improves the performance.
Changing the type of a value via Value::type now returns a new (immutable) value or throws an exception if the type change is not supported:
Literal<Number> number = CQL.val(100);
Value<String> string = number.type(CdsBaseType.STRING); // number is unchangedImmutable References
In CDS QL, a reference (ref) identifies an entity set or element of a structured type. References can have multiple segments and ref segments can have filter conditions.
The default implementations of references (ElementRef and StructuredTypeRef), as well as ref segments (RefSegment) are now immutable. This change makes copying & modifying CQL statements much cheaper, which significantly improves the performance.
- Set alias or type
CQL:entity:asRef, CQL:to:asRef and CQL:get create immutable refs. Modifying the ref is not supported. Methods as(alias) and type(cdsType) now return a new (immutable) ref:
ElementRef<?> authorName = CQL.get("name").as("Author");
ElementRef<?> nombre = authorName.as("nombre"); // authorName is unchanged
ElementRef<?> string = authorName.type("cds.String"); // authorName is unchanged- Modify ref segments
Also the segments of an immutable ref can't be modified in-place any longer. Create an immutable ref segment with filter as follows:
Segment seg = CQL.refSegment("title", predicate);The deprecated RefSegment:id and RefSegment:filter methods now throw an UnsupportedOperationException. For in-place modification of ref segments use CQL.copy(ref) to create a RefBuilder, which is a modifiable copy of the original ref. The RefBuilder allows to modify the segments in-place to change the segment ID or set a filter. Finally call the build method to create an immutable ref.
To manipulate a ref in a Modifier, implementations need to override the new ref(CqnStructuredTypeRef ref) and ref(CqnElementRef ref) methods.
Null Values in CDS QL Query Results
With CAP Java 2.0, null values are not removed from the result of CDS QL queries anymore, this needs to be considered when using methods that operate on the key set of Row, such as Row:containsKey, Row:keySet and Row:entrySet.
Result of Updates Without Matching Entity
The Result rows of CDS QL Updates are not cleared anymore if no entity was updated. To find out if the entity has been updated, check the update count:
CqnUpdate update = Update.entity(BOOKS).entry(book); // w/ book: {ID: 0, stock: 3}
Result result = service.run(update);
long updateCount = result.rowCount(); // 0 matches with ID 0For batch updates use Result::rowCount with the batch index:
// books: [{ID: 251, stock: 11}, {ID: 252, stock: 7}, {ID: 0, stock: 3}]
CqnUpdate update = Update.entity(BOOKS).entries(books);
Result result = service.run(update);
result.batchCount(); // number of batches (3)
result.rowCount(2); // 0 matches with ID 0Provider Tenant Normalization
The default value of CDS Property cds.security.authentication.normalizeProviderTenant is changed to true. With this change, the provider tenant is normalized and set to null in the UserInfo by default. If you have subscribed the provider tenant to your application you need to disable this feature.
Lean Draft
The property cds.drafts.associationsToInactiveEntities has been removed. It enabled a feature, which caused associations to other draft documents to combine active and inactive versions of the association target. This mixing of inactive and active data is no longer supported. In cases where it is still required to connect two independent draft documents through an association, you can annotate this association with @odata.draft.enclosed. Note: This ensures that the active version points to an active target, while the inactive version points to an inactive target. It will not mix active and inactive data into the same association.
The following table summarizes the behaviour of associations between different draft-enabled entities:
| Source Entity | Association Type | Target Entity | Draft Document Boundaries |
|---|---|---|---|
| active1 | composition | active | same document |
| inactive2 | composition | inactive | same document |
| active | backlink association | active | same document |
| inactive | backlink association | inactive | same document |
| active | association | active | independent documents |
| inactive | association | active | independent documents |
| active | association with @odata.draft.enclosed | active | independent documents |
| inactive | association with @odata.draft.enclosed | inactive | independent documents |
1 IsActiveEntity = true
2 IsActiveEntity = false
Changes to Maven Plugins
cds-maven-plugin
The deprecated parameters generateMode and parserMode are removed from the goal generate.
cds4j-maven-plugin
The deprecated Maven plugin cds4j-maven-plugin is removed and no longer available. It's replaced by the cds-maven-plugin which provides the same functionality and more.
Classic MTX to Streamlined MTX
How to migrate from classic MTX to streamlined MTX is described here.
CAP Java Classic to CAP Java 1.x
To make the CAP Java SDK and therefore the applications built on it future-proof, we revamped the CAP Java SDK. Compared the classic CAP Java Runtime (also known as the "Java Gateway stack"), the new CAP Java SDK has numerous benefits:
- Starts up much faster
- Supports local development with SQLite
- Has clean APIs to register event handlers
- Integrates nicely with Spring and Spring Boot
- Supports custom protocol adapters (OData V4 support included)
- Has a modular design: Add features as your application grows
- Enables connecting to advanced SAP BTP services like SAP Event Mesh
We strongly recommend adopting the new CAP Java SDK when starting a new project. Existing projects that currently use the classic CAP Java Runtime can adopt the new CAP Java SDK midterm to take advantage of new features and the superior architecture. In the following sections, we describe the steps to migrate a Java project from the classic CAP Java Runtime to the new CAP Java SDK.
OData Protocol Version
The classic CAP Java Runtime came in several different flavors supporting either the OData V2 or V4 protocols. The new CAP Java SDK streamlines this by providing a common protocol adapter layer, which enables to handle any OData protocol version or even different protocols with one application backend. Hence, if you decide to change the protocol that exposes your domain model, you no longer have to change your business logic.
TIP
By default, the CAP Java Runtime comes with protocol adapters for OData V4 and OData V2 (Beta). Therefore, you can migrate your frontend code to new CAP Java SDK without change. In addition, you have the option to move from SAP Fiori Elements V2 to SAP Fiori Elements V4 at any time.
Migrate the Project Structure
Create a new CAP Java project beside your existing one, which you want to migrate. You can use the CAP Java Maven archetype to create a new CAP Java project:
mvn archetype:generate -DarchetypeArtifactId=cds-services-archetype -DarchetypeGroupId=com.sap.cds -DarchetypeVersion=RELEASEFurther details about creating a new CAP Java project and the project structure itself can be found in section Starting a New Project.
By default, the Java service module goes to the folder srv. If you want to use a different service module folder, you have to adapt it manually. Rename the service module folder to your preferred name and adjust also the <modules> section in the file pom.xml in your projects root folder:
...
<modules>
<module>srv</module> <!-- replace srv with your folder name -->
</modules>
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If you've changed the service module folder name, you have to consider this in the next steps.
Copy the CDS Model
Now, you can start migrating your CDS model from the classic project to the newly created CAP Java project.
Therefore, copy your CDS model and data files (*.cds & *.csv) manually from the classic project to the corresponding locations in the new project, presumably the db folder. If you organize your CDS files within subfolders, also re-create these subfolders in the new project to ensure the same relative path between copied CDS files. Otherwise, compiling your CDS model in the new project would fail.
Usually the CDS files are located in the following folders:
| Usage | Location in classic project | Location in new CAP Java project |
|---|---|---|
| Database Model | <CLASSIC-PROJECT-ROOT>/db/** | <NEW-PROJECT-ROOT>/db/** |
| Service Model | <CLASSIC-PROJECT-ROOT>/srv/** | <NEW-PROJECT-ROOT>/srv/** |
If your CDS model depends on other reusable CDS models, add those dependencies to <NEW-PROJECT-ROOT>/package.json:
...
"dependencies": {
"@sap/cds": "^3.0.0",
... // add your CDS model reuse dependencies here
},
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In your CDS model, ensure that you explicitly define the data type of the elements whenever an aggregate function (max, min, avg etc.) is used, else the build might fail.
In the following example, element createdAt has an explicitly specified datatype (that is timestamp):
view AddressView as select from Employee.Address {
street, apartment, postal_code, MAX(createdAt) AS createdAt: timestamp
};CDS Configuration
The CDS configuration is also part of <PROJECT-ROOT>/package.json and has to be migrated as well from the classic to the new project. Therefore, copy and replace the whole cds section from your classic package.json to the new project:
...
"dependencies": {
"@sap/cds": "^3.0.0",
},
"cds": { // copy this CDS configuration from your classic project
...
}
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If there's also a <CLASSIC-PROJECT-ROOT>/.cdsrc.json in your classic project to configure the CDS build, copy this file to the new project.
You can validate the final CDS configuration by executing a CDS command in the root folder of the new project:
cds envIt prints the effective CDS configuration on the console. Check, that this configuration is valid for your project. Execute this command also in your classic project and compare the results, they should be same.
Further details about effective CDS configuration can be found in section Effective Configuration.
First Build and Deployment
After you've copied all your CDS files, maintained additional dependencies and configured the CDS build, you can try to build your new CAP Java project the first time. Therefore, execute the following Maven command in the root folder of your new CAP Java project:
mvn clean installIf this Maven build finishes successfully, you can optionally try to deploy your CDS model to an SAP HANA database by executing the following CDS command:
cds deploy --to hanaSee section SAP HANA Cloud for more details about deploying to SAP HANA.
Migrate Java Business Logic
Migrate Dependencies
Now, it's time to migrate your Java business logic. If your event handlers require additional libraries that go beyond the already provided Java Runtime API, add those dependencies manually to section dependencies in file <NEW-PROJECT-ROOT>/srv/pom.xml, for example:
...
<dependencies>
<!-- add your additional dependencies here -->
...
<dependency>
<groupId>com.sap.cds</groupId>
<artifactId>cds-starter-spring-boot-odata</artifactId>
</dependency>
<dependency>
<groupId>org.xerial</groupId>
<artifactId>sqlite-jdbc</artifactId>
</dependency>
...
</dependencies>
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Don't add any dependencies of the classic Java Runtime to the new project. Those dependencies are already replaced with the corresponding version of the new CAP Java SDK.
Migrate Event Handlers
In the next steps, you have to adapt your Java classes to be compatible with the new Java Runtime API. That means, you'll copy and migrate your event handler classes from the classic to the new project. It will be required to modify and adapt your Java source code to be compatible with the new Java SDK.
Usually the event handler classes and tests are located in these folders:
| Usage | Location in classic project | Location in new CAP Java project |
|---|---|---|
| Handler classes | <CLASSIC-PROJECT-ROOT>/srv/src/main/java/** | <NEW-PROJECT-ROOT>/srv/src/main/java/** |
| Test classes | <CLASSIC-PROJECT-ROOT>/srv/src/test/java/** | <NEW-PROJECT-ROOT>/srv/src/test/java/** |
Copy your Java class files (*.java) manually from the classic project to corresponding locations in the new project. It's important that you re-create the same subfolder structure in the new project as it is in the classic project. The subfolder structure reflects the Java package names of your Java classes.
Annotations
Annotate all of your event handler classes with the following annotations and ensure a unique service name:
@org.springframework.stereotype.Component
@com.sap.cds.services.handler.annotations.ServiceName("serviceName")TIP
All event handler classes also have to implement the marker interface com.sap.cds.services.handler.EventHandler. Otherwise, the event handlers defined in the class won't get called.
Finally, your event handler class has to look similar to this example:
import org.springframework.stereotype.Component;
import com.sap.cds.services.handler.EventHandler;
import com.sap.cds.services.handler.annotations.ServiceName;
@Component
@ServiceName("AdminService")
public class AdminServiceHandler implements EventHandler {
// ...
}The new CAP Java SDK introduces new annotations for event handlers. Replace event annotations at event handler methods according to this table:
| Classic Java Runtime | CAP Java SDK |
|---|---|
@BeforeCreate(entity = "yourEntityName") | @Before(event = CqnService.EVENT_CREATE, entity = "yourEntityName") |
@BeforeDelete(entity = "yourEntityName") | @Before(event = CqnService.EVENT_DELETE, entity = "yourEntityName") |
@BeforeRead(entity = "yourEntityName") | @Before(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@BeforeQuery(entity = "yourEntityName") | @Before(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@BeforeUpdate(entity = "yourEntityName") | @Before(event = CqnService.EVENT_UPDATE, entity = "yourEntityName") |
@Create(entity = "yourEntityName") | @On(event = CqnService.EVENT_CREATE, entity = "yourEntityName") |
@Delete(entity = "yourEntityName") | @On(event = CqnService.EVENT_DELETE, entity = "yourEntityName") |
@Query(entity = "yourEntityName") | @On(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@Read(entity = "yourEntityName") | @On(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@Update(entity = "yourEntityName") | @On(event = CqnService.EVENT_UPDATE, entity = "yourEntityName") |
@AfterCreate(entity = "yourEntityName") | @After(event = CqnService.EVENT_CREATE, entity = "yourEntityName") |
@AfterRead(entity = "yourEntityName") | @After(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@AfterQuery(entity = "yourEntityName") | @After(event = CqnService.EVENT_READ, entity = "yourEntityName") |
@AfterUpdate(entity = "yourEntityName") | @After(event = CqnService.EVENT_UPDATE, entity = "yourEntityName") |
@AfterDelete(entity = "yourEntityName") | @After(event = CqnService.EVENT_DELETE, entity = "yourEntityName") |
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The sourceEntity annotation field doesn't exist in the new CAP Java SDK. In case your event handler should only be called for specific source entities you need to achieve this by analyzing the CQN in custom code.
Event Handler Signatures
The basic signature of an event handler method is void process(EventContext context). However, it doesn't provide the highest level of comfort. Event handler signatures can vary on three levels:
- EventContext arguments
- POJO-based arguments
- Return type
Replace types from package com.sap.cloud.sdk.service.prov.api.request in the classic Java Runtime by types from package com.sap.cds.services.cds as described by the following table:
| Classic Java Runtime | New CAP Java SDK |
|---|---|
CreateRequest | CdsCreateEventContext |
DeleteRequest | CdsDeleteEventContext |
QueryRequest | CdsReadEventContext |
ReadRequest | CdsReadEventContext |
UpdateRequest | CdsUpdateEventContext |
ExtensionHelper | Use dependency injection provided by Spring |
You can also get your entities injected by adding an additional argument with one of the following types:
java.util.stream.Stream<yourEntityType>java.util.List<yourEntityType>
See section Event Handler Method Signatures for more details.
Also replace the classic handler return types with the corresponding new implementation:
| Classic Java Runtime | New CAP Java SDK |
|---|---|
return BeforeCreateResponse | call CdsCreateEventContext::setResult(..) or return Result |
return BeforeDeleteResponse | call CdsDeleteEventContext::setResult(..) or return Result |
return BeforeQueryResponse | call CdsReadEventContext::setResult(..) or return Result |
return BeforeReadResponse | call CdsReadEventContext::setResult(..) or return Result |
return BeforeUpdateResponse | call CdsUpdateEventContext::setResult(..) or return Result |
Delete Obsolete Files
There are numerous files in your classic project, which aren't required and supported anymore in the new project. Don't copy any of the following files to the new project:
<PROJECT-ROOT>/
├─ db/
│ ├─ .build.js
│ └─ package.json
└─ srv/src/main/
├─ resources/
│ ├─ application.properties
│ └─ connection.properties
└─ webapp/
├─ META-INF/
│ ├─ sap_java_buildpack/config/resources_configuration.xml
│ └─ context.xml
└─ WEB-INF/
├─ resources.xml
├─ spring-security.xml
└─ web.xmlTransaction Hooks
In the Classic Java Runtime, it was possible to hook into the transaction initialization and end phase by adding the annotations @InitTransaction or @EndTransaction to a public method. The method annotated with @InitTransaction was invoked just after the transaction started and before any operation executed. Usually this hook was used to validate incoming data across an OData batch request.
See section InitTransaction Hook for more details about init transaction hook in classic CAP Java.
The method annotated with @EndTransaction was invoked after all the operations in the transaction were completed and before the transaction was committed.
See section EndTransaction Hook for more details about end transactions hook in classic CAP Java.
The new CAP Java SDK doesn't support these annotations anymore. Instead, it supports registering a ChangeSetListener at the ChangeSetContext supporting hooks for beforeClose and afterClose.
See section Reacting on ChangeSets for more details.
To replace the @InitTransaction handler, you can use the beforeClose method, instead. This method is called at the end of the transaction and can be used, for example, to validate incoming data across multiple requests in an OData batch before the transaction is committed. It's possible to cancel the transaction in this phase by throwing an ServiceException.
The CAP Java SDK sample application shows how such a validation using the ChangeSetListener approach can be implemented. See here for the example code.
Note that to validate incoming data for single requests, we recommend to use a simple @Before handler, instead.
See section Introduction to Event Handlers for a detailed description about Before handler.
Security Settings
For applications based on Spring Boot, the new CAP Java SDK simplifies configuring authentication significantly: Using the classic CAP Java Runtime, you had to configure authentication for all application endpoints (including the endpoints exposed by your CDS model) explicitly. The new CAP Java SDK configures authentication for all exposed endpoints automatically, based on the security declarations in your CDS model.
Authorization can be accomplished in both runtimes with CDS model annotations @requires and @restrict as described in section Authorization and Access Control. Making use of the declarative approach in the CDS model is highly recommended.
In addition, the new CAP Java SDK enables using additional authentication methods. For instance, you can use basic authentication for mock users, which are useful for local development and testing. See section Mock Users for more details.
An overview about the general security configuration in the new CAP Java SDK can be found in section Security.
Configuration and Dependencies
To make use of authentication and authorization with JWT tokens issued by XSUAA on the SAP BTP, add the following dependency to your pom.xml:
<dependency>
<groupId>com.sap.cds</groupId>
<artifactId>cds-feature-xsuaa</artifactId>
</dependency>This feature provides utilities to access information in JWT tokens, but doesn't activate authentication by default. Therefore, as in the classic CAP Java Runtime, activate authentication by adding a variant of the XSUAA library suitable for your application (depending on if you use Spring, Spring Boot, plain Java) as described in the following sections.
Spring Boot
Activate Spring security with XSUAA authentication by adding the following Maven dependency:
<dependency>
<groupId>com.sap.cloud.security.xsuaa</groupId>
<artifactId>xsuaa-spring-boot-starter</artifactId>
<version>${xsuaa.version}</version>
</dependency>Maintaining a spring-security.xml file or a custom WebSecurityConfigurerAdapter or SecurityFilterChain isn't necessary anymore because the new CAP Java SDK runtime autoconfigures authentication in the Spring context according to your CDS model:
Endpoints exposed by the CDS model annotated with
@restrictare automatically authenticated.Endpoints exposed by the CDS model not annotated with
@restrictare public by definition and hence not authenticated.All other endpoints the application exposes manually through Spring are authenticated. If you need to change this default behavior either manually configure these endpoints or turn off auto configuration of custom endpoints by means of the following application configuration parameter:
yamlcds.security.authentication.authenticate-unknown-endpoints: false
Plain Java
The existing authentication configuration stays unchanged. No autoconfiguration is provided.
Enforcement API & Custom Handlers
The new CAP Java SDK offers a technical service called AuthorizationService, which serves as a replacement for the former Enforcement APIs. Obtain a reference to this service just like for all other services, either explicitly through a ServiceCatalog lookup or per dependency injection in Spring:
@Autowire
AuthorizationService authService;Information of the request user is passed in the current RequestContext:
EventContext context;
UserInfo user = context.getUserInfo();or through dependency injection within a handler bean:
@Autowire
UserInfo user;With the help of these interfaces, the classic enforcement API can be mapped to the new API as listed in the following table:
| classic API | new API | Remarks |
|---|---|---|
isAuthenticatedUser(String serviceName) | authService.hasServiceAccess(serviceName, event) | |
isRegisteredUser(String serviceName) | no substitution required | |
hasEntityAccess(String entityName, String event) | authService.hasEntityAccess(entityName, event) | |
getWhereCondition() | authService.calcWhereCondition(entityName, event) | |
getUserName() | user.getName() | The user's name is also referenced with $user and used for managed aspect. |
getUserId() | user.getId() | |
hasUserRole(String roleName) | user.hasRole(roleName) | |
getUserAttribute(String attributeName) | user.getAttribute(attributeName) | |
isContainerSecurityEnabled() | no substitution required |
See section Enforcement API & Custom Handlers in Java for more details.
Data Access and Manipulation
There are several ways of accessing data. The first and most secure way is to use the Application Service through an CqnService instance. The second is to use PersistenceService, in that case the query execution is done directly against underlying datasource, bypassing all authority checks available on service layer. The third one is to use CDS4J component called CdsDataStore, which also executes queries directly.
Access Application Service in Custom Handler and Query Execution
To access an Application Service in custom handler and to execute queries, perform the following steps:
- Inject the instance of
CqnServicein your custom handler class:
@Resource(name = "CatalogService")
private CqnService catalogService;See section Services Accepting CQN Queries for more details.
In each custom handler, replace instance of
DataSourceHandleras well asCDSDataSourceHandlerwith theCqnServiceinstance.Rewrite and execute the query (if any).
Example of query execution in Classic Java Runtime:
CDSDataSourceHandler cdsHandler = DataSourceHandlerFactory
.getInstance()
.getCDSHandler(getConnection(), queryRequest.getEntityMetadata().getNamespace());
CDSQuery cdsQuery = new CDSSelectQueryBuilder("CatalogService.Books")
.selectColumns("id", "title")
.where(new ConditionBuilder().columnName("title").IN("Spring", "Java"))
.orderBy("title", true)
.build();
cdsHandler.executeQuery(cdsQuery);See section CDS Data Source for more details.
The corresponding query and its execution in New CAP Java SDK looks as follows:
Select query = Select.from("CatalogService.Books")
.columns("id", "title")
.where(p -> p.get("title")
.in("Spring", "Java"))
.orderBy("title");
catalogService.run(query);See section Query Builder API for more details.
- Rewrite and execute the CRUD operations (if any).
| Action | Classic Java Runtime | New CAP Java SDK |
|---|---|---|
| Create | dsHandler.executeInsert(request.getData(), true) | catalogService.run(event.getCqn()) or catalogService.run(Insert.into("Books").entry(book)) |
| Read | dsHandler.executeRead(request.getEntityMetadata().getName(), request.getKeys(), request.getEntityMetadata().getElementNames()); | catalogService.run(event.getCqn()) or catalogService.run(Select.from("Books").where(b->b.get("ID").eq(42))) |
| Update | dsHandler.executeUpdate(request.getData(), request.getKeys(), true) | catalogService.run(event.getCqn()) or catalogService.run(Update.entity("Books").data(book)) |
| Delete | dsHandler.executeDelete(request.getEntityMetadata().getName(), request.getKeys()) | catalogService.run(event.getCqn()) or catalogService.run(Delete.from("Books").where(b -> b.get("ID").eq(42))) |
As you can see in New CAP Java SDK it's possible to either directly execute a CQN of the event, or you can construct and execute your own custom query.
See section Query Builder API for more details.
Accessing PersistenceService
If for any reason you decided to use PersistenceService instead of CqnService in your custom handler, you need to inject the instance of PersistenceService in your custom handler class:
@Autowired
private PersistenceService persistence;See section Persistence API for more details.
Example of Query execution in Classic Java Runtime:
CDSDataSourceHandler cdsHandler = ...;
CDSQuery cdsQuery = new CDSSelectQueryBuilder("CatalogService.Books")
.selectColumns("id", "title")
.where(new ConditionBuilder().columnName("title").IN("Spring", "Java"))
.orderBy("title", true)
.build();
cdsHandler.executeQuery(cdsQuery);The corresponding query execution in New CAP Java SDK looks as follows:
Select query = Select.from("CatalogService.Books")
.columns("id", "title")
.where(p -> p.get("title")
.in("Spring", "Java"))
.orderBy("title");
persistence.run(query);Accessing CdsDataStore
If you want to use CdsDataStore in your custom handler, you first need to do the steps described in section Accessing PersistenceService. After that you can get the instance of CdsDataStore using persistence.getCdsDataStore() method:
Select query = ...; // construct the query
CdsDataStore cdsDataStore = persistence.getCdsDataStore();
cdsDataStore.execute(query);CDS OData V2 Adapter
When you generate a new project using the CAP Java Maven Archetype, OData V4 is enabled by default.
To be able to migrate the backend from the Classic Java Runtime without making changes in your frontend code, you can activate the OData V2 Adapter as follows:
Add the following dependency to the
pom.xmlof yoursrvmodule:xml<dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-adapter-odata-v2</artifactId> <scope>runtime</scope> </dependency>In addition, turn off the OData V4 adapter by replacing the following dependency:
xml<dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-starter-spring-boot-odata</artifactId> </dependency>with
xml<dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-starter-spring-boot</artifactId> </dependency>if present. Additionally, remove the dependency
xml<dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-adapter-odata-v4</artifactId> </dependency>if present.
To make the CDS Compiler generate EDMX for OData V2, add or adapt the following property in the .cdsrc.json file:
json{ ... "odata": { "version": "v2" } }TIP
In case you're using multitenancy, keep in mind to make the same change in the .cdsrc.json of the mtx-sidecar.
After rerunning the Maven build and starting the CAP Java application, Application Services are served as OData V2. By default, the endpoints will be available under <host:port>/odata/v2/<Service>. The default response format is xml, to request json use $format=json or Accept: application/json header.
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The index page available at <host:port> lists service endpoints of all protocol adapters.
Enabling OData V2 and V4 in Parallel
You can also use OData V2 and V4 in parallel. However, by default the Maven build generates EDMX files for one OData version, only. Therefore, you've to add an extra compile step for the missing OData version to the Maven build of your application:
In .cdsrc, choose
v4forodata.versionAdd an extra compile command to the subsection
commandsof the section with IDcds.buildin the pom.xml file in the srv folder of your project:xml<command>compile ${project.basedir} -s all -l all -2 edmx-v2 -o ${project.basedir}/src/main/resources/edmx/v2</command>This command picks up all service definitions in the Java project base directory (
srvby default) and generates EDMX for OData V2. It also localizes the generated EDMX files with all available translations. For more information on the previous command, callcds help compileon the command line. If your service definitions are located in a different directory, adopt the previous command. If your service definitions are contained in multiple directories, add the previous command for each directory separately. Make sure to use at leastcds-dk 3.2.0for this step. If you are using feature toggles in your CAP Java project, the list of models must also contain the features' root folder:xml<command>compile ${project.basedir} ${session.executionRootDirectory}/fts/* -s all -l all -2 edmx-v2 -o ${project.basedir}/src/main/resources/edmx/v2</command>This command includes the folder /fts and all sub-folders into the CDS model.
Make sure that the dependencies to the OData V2 and V4 adapters are present in your pom.xml file:
xml<dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-starter-spring-boot</artifactId> </dependency> <dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-adapter-odata-v2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>com.sap.cds</groupId> <artifactId>cds-adapter-odata-v4</artifactId> <scope>runtime</scope> </dependency>Optionally it's possible to configure different serve paths for the application services for different protocols. See Serve configuration for more details.
After rebuilding and restarting your application, your Application Services are exposed as OData V2 and OData V4 in parallel. This way, you can migrate your frontend code iteratively to OData V4.