Tìm hiểu về Session, ViewState, ControlState, HttpContext.Current, Shared/Static Object.

Đối tượng có vòng đời ngắn nhất là HttpContext.Current chỉ tồn tại trên Request, sẽ kết thúc khi Server trả về một Response.

Đối tượng ViewState nằm trên cả Request và Response. Đối tượng này được lưu trên Client thông qua biến ẩn HiddenField và được mã hóa để tránh nhòm ngó.

Một đối tượng khác tương đương ViewState là ControlState. ControlState được sử dụng để lưu lại hành vi của Control và cũng được lưu trên Client thông qua biến ấn Hidden Field. Khi tắt ViewState trên Client thì các thuộc tính được lưu trong ViewState sẽ “chết”, trong khi ControlState vẫn tồn tại vì được bảo vệ trong Control.

Đối tượng Session có mức độ phủ rộng hơn ViewState, nó tồn tại trên bất cứ postback nào ở bất cứ trang nào. Đối tượng Session chỉ kết thúc vòng đời của nó khi shutdown server hoặc tắt trình duyệt. Khác với đối tượng ViewState, đối tượng Session được lưu trên Server nên bảo mật hơn. Nhược điểm là đối tượng Session chiếm nhiều tài nguyên Server. Server sẽ quá tải nếu có nhiều Client gửi Request cùng một lúc.

Why do most Vietnamese developers usually retire after 30 years old?

Quite a few years ago, most developers choose IT as a good start to grow up, earn money and become a boss soon after. That's a reason why many IT developers retire after 30 years old. Even worst, if they haven't promoted to a post of manager in that age, they prepare to drop out of his company, burn their bridges behind them with the hope to change their life, such as Stock Exchange, Trading... Some developers take a Master course in another field like MBA just after graduation or join the first company not long ago. This is very common in Vietnam.

Vietnamese people has strength in Math background, one of important factors to make a good developer. However, it’s not enough. Hard-working, persistence, good attitudes, passion, energy… are all that sum up to good performing developer. In the developing countries like Vietnam, China…, people has tendency to choose the less hard working job but high earning professional. Having worked for IT industry for a couple of years, people will feel the stress in doing software with pretty tightening schedule. Normally, developers have to work more than 8 hours a day to get the job done, especially the projects that usually go down the drain.

Most developers do not notice that if they don't have the so-called "passion" to work on something, they cannot success in any area of business, not in addition to IT only. People of all kinds run into same problem as they think that they come to work for earning money mostly. In fact, in any kinds of job, people always find the fun in it to get the job done.

20 typical answer from developers to tester

20. "That’s weird…"
　19. "It’s never done that before."

　18. "It worked yesterday."

17. "How is that possible?"
　16. "It must be a hardware problem."
　15. "What did you type in wrong to get it to crash?"
　14. "There is something funky in your data."
　13. "I haven’t touched that module in weeks!"
　12. "You must have the wrong version."
　11. "It’s just some unlucky coincidence."
　10. "I can’t test everything!"
　09. "THIS can’t be the source of THAT."
　08. "It works, but it hasn’t been tested."
　07. "Somebody must have changed my code."
　06. "Did you check for a virus on your system?"
　05. "Even though it doesn’t work, how does it feel?
　04. "You can’t use that version on your system."
　03. "Why do you want to do it that way?"
　02. "Where were you when the program blew up?"
　01. "It works on my machine"