UVM Virtual Sequence Example.

// Base Virtual Sequence Class
class base_vseq extends uvm_sequence #(uvm_sequence_item);
   `uvm_object_utils(base_vseq)
 
   // Target Agent Sequencers
   uvm_sequencer #(ahb_txn) SQR_AHB;
   uvm_sequencer #(axi_txn) SQR_AXI;
 
   // Constructor
   function new (string name = "base_vseq");
      super.new(name);
   endfunction: new
 
endclass: vseq_base

// Virtual Sequence Class
class my_vseq extends base_vseq;
   `uvm_object_utils(my_vseq)
 
   // Constructor
   function new (string name = "my_vseq");
      super.new(name);
   endfunction: new
 
   // Sequence Body Task
   task body();
 
      ahb_seqeunce ahb_seq;
      axi_sequence axi_seq;
 
      ahb_seq = ahb_sequence::type_id::create("ahb_seq");
      axi_seq = axi_sequence::type_id::create("axi_seq");
 
      fork
         abh_seq.start(SQR_AHB);
         axi_seq.start(SQR_AXI);
     join
   endtask
 
endclass: my_vseq

// Base Test Class
class base_test extends uvm_test;
   `uvm_component_utils(base_test);
 
   // Environment Class Instantiation
   top_env Env;
 
   // Constructor
   function new (string name = "base_test", uvm_component parent = null);
      super.new(name, parent);
   endfunction: new
 
   // Build Phase
   function void build_phase (uvm_phase phase);
      Env = top_env::type_id::create("Env");
   endfunction: build_phase
 
   // Method to Connect Sequencer Handles in VSEQ
   function void init_vseq (base_vseq vseq);
      vseq.SQR_AHB = test.env.ahb_agent.SQR_AHB;
      vseq.SQR_AXI = test.env.axi_agent.SQR_AXI;
   endfunction: init_vseq
 
endclass: base_test

// Main Test
class test extends base_test;
   `uvm_component_utils(test)
 
   // Constructor
   function new (string name = "test", uvm_component parent = null);
      super.new(name, parent);
   endfunction: new
 
   // Run Phase
   task run_phase (uvm_phase phase);
      // Create the Virtual Sequence
      my_vseq vseq = my_vseq::type_id::create("vseq");
      phase.raise_objection(this);
      // Virtual Sequence Initialization
      init_vseq(vseq);
      // Start the Virtual Sequence
      vseq.start(null);
      phase.drop_objection(this);
   endtask: run_phase
 
endclass: test