Odysseus provides a simply feature for storing, retrieving and removing of values from a key value store.

Out of the box, odysseus provides

• MemoryStore: A key value store that keep the values in memory only
• FileStore: A key value store that keeps the data in main memory and stores it additionally to disk

Creating a store

A store can be created with the Odysseus Script command: #CREATE_KV_STORE name type (PARAM_1_KEY=PARAM_1_VALUE,..., PARAM_N_KEY=PARAM_N_VALUE)

To create a Memory Store simply use:

#CREATE_KV_STORE test MemoryStore

Some stores have parameters, e.g. the FileStore (with the paramter filename):

#CREATE_KV_STORE test FileStore (filename=c:/temp/tmp.store)

For all stores, the normal behavior is to allow creation only if there exists no store with the desired name. But with the parameter "createOnlyIfNotExists", one can change that behavior:

#CREATE_KV_STORE test MemoryStore(createOnlyIfNotExists=false) /// default is true

Access a store

MEP functions can be used to read an write from the store. So this can be used in all operators that contain expressions or predicates (e.g. Map operator or Select operator)

• kvwrite(String StoreName, String KeyName, Object Value): (Overwrites) a value in the give store and key
• kvread(String StoreName, String KeyName): reads the value from the store with the key
• kvremove(String StoreName, String KeyName): remove the value from the store

The following code block shows an example

#PARSER PQL
#RUNQUERY
timer = TIMER({
            period = 1000,
            source = 'timersource'
          }
        )

Map1 = MAP({EXPRESSIONS = ['time','kvwrite("test2","Time",time)','kvread("test2", "Time")']}, timer)

You could also use an operator to write to an existing store:

StoreWriter

#PARSER PQL
#RUNQUERY
timer = TIMER({
            period = 1000,
            source = 'timersource'
          }
        )

out = StoreWriter({IdAttribute='time', store="test2")},timer)