The API Gateway has a default mediation flow, which you can extend by adding custom mediation sequences. You create a custom mediation sequences either manually or using WSO2 tooling support (i.e., WSO2 Developer Studio), and then engage it per API or globally to all APIs of a specific tenant.
Creating per-API extensions
The recommended way to engage a mediation extension sequence per API is to upload an XML file through the registry and then engage it using the API Publisher. The following tutorial shows how to do this: Change the Default Mediation Flow of API Requests.
Alternatively, you can name the mediation XML file in the pattern <API_NAME>:v<VERSION>--<DIRECTION> and save it directly in the following location:
- In the single-tenant mode, save the XML file in the
<APIM_HOME>/repository/deployment/server/synapse-configs/default/sequencesdirectory. - In the multi-tenant mode, save the XML file in the tenant's synapse sequence folder. For example, if tenant id is 1, then save it in
<API_Gateway>/repository/tenants/1/synapse-configs/default/sequencesfolder.
In the naming pattern, the <DIRECTION> can be In or Out. When it is In, the extension is triggered on the in-flow (request path) and when it is Out, the extension is triggered on the out-flow (response path). To change the default fault sequence, you can either modify the default sequence or write a custom fault sequence and engage it to APIs through the API Publisher.
Creating global extensions
You can also engage mediation extension sequences to all APIs of a specific tenant at once. To do that, simply create the XML with the naming pattern WSO2AM--Ext--<DIRECTION> and save it in the <APIM_HOME>/repository/deployment/server/synapse-configs/default/sequences directory.