Cache Update Policy

Fine-tune device application and Unwired Server performance by defining a cache update policy for mobile business object operations.

Setting a cache update policy for mobile business object (MBO) operations gives you more control of both Unwired Server interactions with the enterprise information system (EIS) to which the MBO is bound, and Unwired Server cache database (CDB) updates. Fine-tuning these interactions and updates improves both Unwired Server and device application performance.

MBO operations perform specific functions based on their definition:
- Read operation – the EIS operation used to define and initially populate the CDB (from the EIS) for the MBO.
- Create, update, delete (CUD operations) – modify EIS data depending on the definition of the operation. Unwired Server maintains a cache (CDB) of back-end EIS data to provide differential synchronization and to minimize EIS interaction. When an operation is submitted from a device application to the EIS, the cache must be refreshed.
  While this type of bulk-fetch and CDB caching are effective in reducing the number of interactions required with the back-end EIS, and work well in some other cases (where MBO data is occasionally updated in the back-end), performance suffers if changes are initiated from Unwired Server (by way of MBO operations), or if changes are frequent.
  
  A cache update policy provides alternative methods of updating the cache at finer granularity, which improves performance.
Cache update policy – determines how the CDB is updated after an operation. You can set the cache update policy for operations, with these exceptions:
- "Other" operations do not support a cache update policy.
- Delete operations always use the Apply results to cache policy, which cannot be unselected.
The cache update policies from which to choose to associate with MBO CUD operations:
- Invalidate the cache
- Apply results to the cache
- No effect – if a cache update policy is not selected, the operation results are not applied to the cache.
When an MBO operation is called, its cache update policy determines how operation results are applied to the CDB.

Note: Other methods used to update the CDB that are external to MBO operations, and not associated with cache update policies include:

EIS-initiated DCN – an HTTP request to Unwired Server, in which the DCN request contains information about the changed data, or the changed data itself.
Scheduled data refresh – Unwired Server polls the EIS for changes at specified intervals.
MBO cache group – every MBO belongs to a cache group that specifies a cache refresh policy for every MBO in that group. Plan carefully to maximize cache group and cache update policy efficiency. Examples include:
- A poorly designed MBO might have an operation with a cache update policy that updates only the operation results to the CDB, but the MBO belongs to a cache group with an interval that refreshes the entire MBO on too short a schedule, minimizing the value of the cache update policy.
- This same MBO properly designed might have a cache group that refreshes the MBO nightly, increasing Unwired Server performance by differing load from peak usage hours.