Sometimes in our application, we need to build custom services that run when Maximo starts. We can extend the psdi.server.AppService class and register it with MXServer by inserting a new entry into the MAXSERVICE table. If the service executes slow-running queries, it is a good idea to cache the data in memory to improve performance. We can implement MaximoCache interface for this purpose. By doing this, we can initialize the service when MXServer starts and pre-load all data required by the service into JVM memory. When the service is called, it will only use cached data to provide instant response which gives a much better user experience. 
 
Below are the steps to create a sample service that loads all Location’s descriptions into memory. The service will provide a function to check if an input string matches a location’s description or not. We will call this check when the user enters an Item’s description and it will throw an error whenever the input matches with the description of any existing Location. This is not a very good use case. But for the sake of simplicity, I hope it gives you an idea of how it can be implemented.

1. Create a LocationCache class, implementing psdi.mbo.MaximoCache
interface:
  • For the getName() function, set a name for the cache, such as “LOCATION_CACHE”.
  • Create method loadData() to query and load all locations’
    description into a HashSet
  • Call the loadData() method in the init(), reload(), reload(String)
    function overridden from the MaximoCache interface
  • Create function isLocationExist(String) to check if an
    input String matches with a description contained in the HashSet

2. Create a LocationCheck class extending the psdi.server.AppService
class. Override the init() method to initialize a new LocationCache object and
add it to the MXServer’s cache.

 
3. Insert a new entry into the MAXSERVICE table to register with MXServer to initialize the service when Maximo starts. Sample SQL statement to insert the record as follows:

4. Extend the LocationSet class to override the fireEventsAfterDBCommit() method. Essentially this method will reload the cache whenever there is a change to location data. This will ensure that the information stored in the cache will always be in sync with the new update.

5. Create a FldDescription class to override the validate()
method, and associate it with the Item.Description field. In the validate()
method, we will check if the description entered is the same as a location’s description stored inside the cache and throw an error dialog if there is a
match.

You can view or download the full sample code from this GitHub repository: link

After deploying the code and associating the LocationSet to
the Location object and the FldDescription class the Description field of the
Item object, to test if the code works, open an Item and enter a description
that matches the description of a location, it should throw an error
message as in the image below:

To check if the cache is reloaded properly, create a new location or update an existing one, enter the description of the updated location to an item’s description, it should also throw an error message. 

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