= Architecture =

[[Image(Architecture.png)]]

Sahana Eden uses a [wiki:S3XRC/RESTfulAPI WebServices] architecture

API documentation is available in Epydoc format:
 * http://pub.nursix.org/eden/s3/

ER diagrams can be built using MySQL Workbench 

dbwrench could also be used as a E-R diagram modelling tool for Postgres database


== !Key/Value Tables ==
This is a fairly common pattern for storing flexible data models.

If you need massive scale then using a dedicated NoSQL database for this does have it's advantages, however it is rarely useful for normal Eden tables due to performance limitations & the inability to use database constraints here (like Foreign Keys). Another disadvantage is that it is [http://howfuckedismydatabase.com/nosql/ unable to be queried easily].

For these reasons there is currently no support for this model in CRUD, although it would be easy to add if-required.

If there is a strong need for this pattern for the non-foreign keys, then it is best to encode all the key/value pairs into a single text field, e.g. in JSON (like deleted_fk). Then need to add widget to handle the user presentation, validation & encoding/decoding. A Metavalidator could be used for server-side validation, if required.

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DeveloperGuidelines