MFP 8.0 adapter cache

Question

I am using MFP 8.0, and there are requirements that we want implement cache on the adapter level.

Whenever MFP server starts we want to dump all the database in cache till the server restart again.

Now whenever user hit some transaction or adapter procedure which call database so instead of calling database it must read from cache.

Answer 1

Adapters support read-only and transactional access modes to back-end systems.

Adapters are Maven projects that contain server-side code implemented in either Java or JavaScript. Adapters are used perform any necessary server-side logic, and to transfer and retrieve information from back-end systems to client applications and cloud services.

JSONStore is an optional client-side API providing a lightweight, document-oriented storage system. JSONStore enables persistent storage of JSON documents. Documents in an application are available in JSONStore even when the device that is running the application is offline. This persistent, always-available storage can be useful to give users access to documents when, for example, there is no network connection available in the device.

Answer 2

From your description, assuming you are talking about some custom DB where you have data stored, then you need to implement the logic of caching the data.

Adapter's have two classes <AdapterName>Application.java and <AdapterName>Resource.java. <>Application.java contains the lifecycle methods - init() and destroy().

You should put your custom code of loading data from your DB into cache in the init() method. And also take care of removing it in the destroy().

Now during transactional access (which hits <>Resource.java), you refer to the cache you have already created.

Your requirement, however may not be ideal for heavily loaded systems. You need to consider that:

a) Your adapter initialization is delayed. Any wrongly written code can also break the adapter initialization. An adapter isn't available to service your request until it has been initialized. In case of a clustered environment, the adapter load in all cluster members will delayed depending on the amount of data your are loading. Any client request intended for this adapter will get a runtime exception until the initialization is complete.

b) Holding the cache in memory means, so much space in the heap is used up. If your DB keeps growing, this adversely affects adapter initialization and also heap usage.

c) You are in charge maintaining the data at the latest level and also cleaning it up after use.

To summarize, while it is possible, it is not recommended. While this may work in case of very small data set, this cannot scale well. The design of adapters is to provide you transactional access to data/backend systems. You should use the adapter the way it was designed to.