write-hash <hash> \
    key <key> \
    value <value> \
    [ status [ define ] <status> ] \
    [ old-value [ define ] <old value> ]
    [ old-key [ define ] <old key> ]
    [ process-key ]
    [ process-value ]

new-hash define h size 1000
write-hash h key "mykey" value "some data"

write-hash h key "mykey" value "new data" status define st old-value define od
if (st == VV_ERR_EXIST) {
    @Previous value for this key is <<p-out od>>
}

%% /hashsrv
    out-header default

    do-once
    new-hash define h size 1024 process-scope
    end-do-once

    // Get input parameters
    task-param op
    input-param key
    input-param data

    if-task "add" // Add data to hash, make a copy as input params are request-scoped
        copy-string key to define c_key
        copy-string data to define c_data
        write-hash h key c_key value c_data old-value define old_data old-key define old_key status define st
        if (st == VV_ERR_EXIST) {
            delete-mem old_key
            delete-mem old_data
        }
        @Added [<<p-out key>>]
    else-task "delete" // Delete data and obtain the value deleted
        read-hash h key (key) value define val old-key define okey delete status define st
        if (st == VV_ERR_EXIST) {
            @Not found [<<p-out key>>]
        } else {
            // If found, then delete key and value
            @Deleted [<<p-out val>>]
            delete-mem val
            delete-mem okey
        }
    else-task "query" // Query hash based on key value
        read-hash h key (key) value define val status define st
        if (st == VV_ERR_EXIST) {
            @Not found, queried [<<p-out key>>]
        } else {
            @Value [<<p-out val>>]
        }
    end-task
%%