---
last_review: "2025-01-01"
last_reviewer: "-"
documented_code: [ ]
---

```{tags} developer, explanation
```

# HTTP Resources

:::{note}
This page has been migrated from the old documentation, and has not yet been fully revised.
There might be inconsistencies or errors when using with current LinkAhead versions.
:::
% TODO: Issue: https://gitlab.indiscale.com/caosdb/src/linkahead-docs/-/issues/113

HTTP resources are implemented in the [resource](/reference/server/api/org/caosdb/server/resource/package-index.rst)
package, in classes inheriting from [AbstractCaosDBServerResource](/reference/server/api/org/caosdb/server/resource/AbstractCaosDBServerResource.rst)  (
which inherits Restlet's [Resource](https://javadocs.restlet.talend.com/2.4/jee/api/org/restlet/resource/Resource.html)
class). The main [CaosDBServer](/reference/server/api/org/caosdb/server/CaosDBServer.rst) class
defines which HTTP resource (for example `/Entity/{specifier}`) will be handled by which class
([EntityResource](/reference/server/api/org/caosdb/server/resource/transaction/EntityResource.rst)
in this case).

Implementing classes need to overwrite for example the `httpGetInChildClass()` method (or methods
corresponding to other HTTP request methods such as POST, PUT, ...). Typically, they might call the
`execute()` method of a [Transaction](/reference/server/api/org/caosdb/server/transaction/Transaction.rst)
object. Transactions are explained in detail in the [Transactions and Schedules](./transaction.md#transactions-and-schedules)
section.

```{eval-rst}
.. uml::

  @startuml
  abstract AbstractCaosDBServerResource {
    {abstract} httpGetInChildClass()
    {abstract} httpPostInChildClass()
    {abstract} ...InChildClass()
  }
  abstract RetrieveEntityResource
  class EntityResource
  AbstractCaosDBServerResource <|-- RetrieveEntityResource
  RetrieveEntityResource <|-- EntityResource
  @enduml
```