= Presentation Layer SPI

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The persistence layer SPIs influence how the framework persists domain objects, for example controlling how to create an audit log of changes to domain objects.


.Presentation Layer SPI
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|===

|SPI
|Description


|xref:refguide:applib:index/services/conmap/ContentMappingService.adoc[ContentMappingService]
|(Attempt to) map the returned data into the representation required by the client's HTTP `Accept` header.

The framework will call all available implementations until a mapping is made (chain of responsibility pattern).
The framework itself provides a couple of implementations:

* xref:refguide:applib:index/services/commanddto/conmap/ContentMappingServiceForCommandDto.adoc[ContentMappingServiceForCommandDto]
* xref:refguide:applib:index/services/commanddto/conmap/ContentMappingServiceForCommandsDto.adoc[ContentMappingServiceForCommandsDto]



|xref:refguide:applib:index/services/userreg/EmailNotificationService.adoc[EmailNotificationService]
|Notify a user during xref:refguide:applib:index/services/userreg/UserRegistrationService.adoc[self-registration] of users.


|xref:refguide:applib:index/services/error/ErrorReportingService.adoc[ErrorReportingService]
|Record details of an error occurring in the system (eg in an external incident recording system such as JIRA), and return a more friendly (jargon-free) message to display to the end user, with optional reference (eg `XXX-1234`).


|xref:refguide:applib:index/services/exceprecog/ExceptionRecognizerService.adoc[ExceptionRecognizerService]
|Convert certain exceptions (eg foreign or unique key violation in the database) into a format that can be rendered to the end-user.

All available implementations are called (chain of responsibility pattern).



|xref:refguide:applib:index/services/hint/HintIdProvider.adoc[HintIdProvider]
|Provide a "logical" identity for view models such that UI hints can be stored for them.


|xref:refguide:applib:index/services/hint/HintStore.adoc[HintStore]
|Stores UI hints on a per-object basis.
For example, the viewer remembers which tabs are selected, and for collections which view is selected (eg table or hidden), which page of a table to render, or whether "show all" (rows) is toggled.



|xref:refguide:applib:index/services/routing/RoutingService.adoc[RoutingService]
|Return an alternative object than that returned by an action.



|xref:refguide:applib:index/services/tablecol/TableColumnOrderService.adoc[TableColumnOrderService]
|Allows the columns of a parented or standalone table to be reordered, based upon the parent object, collection id and type of object in the collection.

|xref:refguide:applib:index/services/tablecol/TableColumnVisibilityService.adoc[TableColumnVisibilityService]
|Filters the columns of a parented or standalone tables.

xref:security:secman:about.adoc[SecMan] provides an implementation of this service that filters out columns based on security permissions.



|xref:refguide:applib:index/services/i18n/TranslationService.adoc[TranslationService]
|Translate an app's UI, messages and exceptions for the current user (as per the language provided by xref:refguide:applib:index/services/i18n/LanguageProvider.adoc[LanguageProvider].


|xref:refguide:applib:index/services/urlencoding/UrlEncodingService.adoc[UrlEncodingService]
|Converts strings into a form safe for use within a URL.
Used to convert view models mementos into usable URL form.


|xref:refguide:viewer:index/commons/applib/services/userprof/UserProfileUiService.adoc[UserProfileUiService]
|Obtain an alternative (usually enriched/customized) name for the current user, to render in the UI.

|===


