The paper describes system and program metrics used for load balancing algorithms for Java program execution in the SOAJA (Service Oriented Adaptative Java Applications) executive environment. This environment aims in maintaining design and execution of large scale computing tasks in complex networked Grid environments. SOAJA services provide means for static and dynamic load balancing with the use of special metrics obtained by Java object observation. SOAJA comprises mechanisms and algorithms for automatic placement and adaptation of application objects, in response to evolution of resource availability. Under control of SOAJA, parallel Java objects can be optimally allocated to Grid nodes before execution and next migrated at runtime to less loaded nodes to maintain the balance of loads of constituent JVMs. SOAJA mechanisms employ computation power metrics based on measurements of the idle time of processor nodes and communication bandwidth metrics for network resources based on statistical assessment of the existing traffic. Due to these mechanisms the granularity of computing and distribution of the application elements on the Grid platform can be optimally controlled.