How to implement online securities trading system through WebMan technology

@RestController
@RequestMapping("/securities")
public class SecuritiesController {

    @Autowired
    private SecuritiesService securitiesService;

    @RequestMapping(method = RequestMethod.GET)
    public List<Security> getAllSecurities() {
        return securitiesService.getAllSecurities();
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    public Security getSecurityById(@PathVariable int id) {
        return securitiesService.getSecurityById(id);
    }

    @RequestMapping(method = RequestMethod.POST)
    public void addSecurity(@RequestBody Security security) {
        securitiesService.addSecurity(security);
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.PUT)
    public void updateSecurity(@PathVariable int id, @RequestBody Security security) {
        securitiesService.updateSecurity(id, security);
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.DELETE)
    public void deleteSecurity(@PathVariable int id) {
        securitiesService.deleteSecurity(id);
    }
}


@Service
public class SecuritiesService {

    private List<Security> securities;

    public SecuritiesService() {
        securities = new ArrayList<>();
        securities.add(new Security(1, "Apple Inc.", "AAPL", "Technology"));
        securities.add(new Security(2, "Microsoft Corporation", "MSFT", "Technology"));
        securities.add(new Security(3, "Alphabet Inc.", "GOOGL", "Technology"));
    }

    public List<Security> getAllSecurities() {
        return securities;
    }

    public Security getSecurityById(int id) {
        return securities.stream().filter(s -> s.getId() == id).findFirst().orElse(null);
    }

    public void addSecurity(Security security) {
        securities.add(security);
    }

    public void updateSecurity(int id, Security security) {
        Security existingSecurity = getSecurityById(id);
        if (existingSecurity != null) {
            existingSecurity.setName(security.getName());
            existingSecurity.setCode(security.getCode());
            existingSecurity.setCategory(security.getCategory());
        }
    }

    public void deleteSecurity(int id) {
        Security existingSecurity = getSecurityById(id);
        if (existingSecurity != null) {
            securities.remove(existingSecurity);
        }
    }
}


public class Security {

    private int id;
    private String name;
    private String code;
    private String category;

    public Security(int id, String name, String code, String category) {
        this.id = id;
        this.name = name;
        this.code = code;
        this.category = category;
    }

    // getters and setters omitted for brevity
}