有关进销存管理系统中英文翻译.doc

In traditional supply chain inventory management, orders are the only information firms exchange, but information technology now allows firms to share demand and inventory data quickly and inexpensively. We study the value of sharing these data in a model with one supplier, N identical retailers, and stationary stochastic consumer demand. There are inventory holding costs and back-order penalty costs. We compare a traditional information policy that does not use shared information with a full information policy that does exploit shared information. In a numerical study we find that supply chain costs are 2.2% lower on average with the full information policy than with the traditional information policy, and the maximum difference is 12.1%. We also develop a simulation-based lower bound over all feasible policies. The cost difference between the traditional information policy and the lower bound is an upper bound on the value of information sharing: In the same study, that difference is 3.4% on average, and no more than 13.8%. We contrast the value of information sharing with two other benefits of information technology, faster and cheaper order processing, which lead to shorter lead times and smaller batch sizes, respectively. In our sample, cutting lead times nearly in half reduces costs by 21% on average, and cutting batches in half reduces costs by 22% on average. For the settings we study, we conclude that implementing information technology to accelerate and smooth the physical flow of goods through a supply chain is significantly more valuable than using information technology to expand the flow of information.
Inventory management is a commercial enterprise management of the core areas, Enterprises can also achieve an effective key, if we can achieve from the purchase of stock, Sales then the entire flow of goods and capital flow situation for the unified management and reasonable production, timely sales and inventory is the smallest. reduce the backlog of material, then the business will achieve the best results.

1.session
In my experience, session word is probably second only to the extent of the abuse of transaction, even more interesting is the transaction and the session in the context of the meaning of some of the same.

session, the Chinese often translated into the session, its original meaning refers to the beginnings and ends of a series of action / information, such as a phone call from the dial to pick up the phone to hang up the middle of the process can be described as a series of session. Sometimes we can see that the case "during the session in a browser session ,...", term used here is its original meaning, is open from a browser window to close the period of ①. The most confusing is the "user (client) during the first session," the words, it may refer to a series of user actions (generally with a specific purpose related to a series of actions, such as log on to buy goods from to sign out such an online shopping checkout process, sometimes also called a transaction), but sometimes may be just that a connection could also be that the meaning of ①, the difference can only be inferred by context ②.

However, when the term session is associated with the network protocol when it often implies a "connection-oriented" and / or "on hold" so the two meanings, "connection-oriented" refers to both the communication in the communication prior to first establish a communication channel, such as phone calls, until the other party answered the phone communication can begin, and this is the opposite of writing, before you sent the letter, the time you and can not confirm the other side of the address is correct, communication channels Buyi Ding can be established, but the sender, the communication has already begun. "Keep state" means the communication party is able to associate a series of messages, making messages between each other depends, for example, a waiter can recognize old customers come back and remember the last time the customer still owes a store, dollar . Examples of this type, "a TCP session" or "a POP3 session" ③.

And to the web server flourishing, session in the context of semantic web development has a new expansion, its meaning is mean to the client and server to maintain state between the solution ④. Session is also sometimes used to refer to such solutions, storage structures, such "stored in the session to xxx where" ⑤. For various 用于 web development languages are available to some extent on the support of such a solution, so in the context of a particular language 下, session also used to denote a solution on behalf of the language, such as regular Java in the provision of javax.servlet.http.HttpSession referred to as the session ⑥.

In view of this confusion has been changed, in this article use the term session will have different meanings depending on the context, drew attention to the resolution.
In this article, the use of Chinese "during the browser session," to convey the meaning of ①, use "session mechanism" to convey the meaning ④, use the "session" expression meaning ⑤, use specific "HttpSession" to convey the meaning ⑥
Second, HTTP protocol and the state to maintain
HTTP protocol itself is stateless, HTTP protocol which is consistent with the original purpose of the client only needs a simple request to download some file server, either the client or the server not have been necessary records of past behavior to each other, and each time between the request are independent, like a customer and a vending machine or an ordinary (non-membership) as the relationship between supermarkets.

However, smart (or greedy?) People soon discovered that if they can provide on-demand generation of dynamic web information will become more useful, like a cable TV with on-demand the same function. This demand on the one hand to force gradually add HTML form, script, DOM and other client-side behavior, on the other hand there is the server-side CGI practices to respond to client-side dynamic request, the HTTP protocol as the transport carrier also added a file upload , cookie these characteristics. The role which cookie is to solve the stateless HTTP protocol efforts defects. As for the subsequent emergence of the session mechanism is yet another in between the client and the server state solution.

Let us use some examples to describe the session cookie and the differences and similarities between the mechanisms. I once frequented a coffee shop with free gifts to drink five cups of coffee offers a cup of coffee, but a onetime consumption of five cups of coffee is remote, then need a way to record a customer's consumption. Imagine that in fact nothing less than the following several options:
1, the store's staff is very powerful, able to remember each customer's consumption, as long as customers entered the cafe, shop assistants know how to deal with the. This approach is the agreement itself to support the state.
2, issue customers a card recording the number of consumers in general have a validity period. Each consumer, if this card is produced, then the consumer will be with the consumer before or after linking up. This approach is maintained in the client state.
3, a membership card issued to customers, in addition to any information outside the card number is not recorded, each consumer, if the card is produced, then the records clerk in the store to find the card number corresponds to the record to add some consumer information. This approach is maintained in the server-side state.
As the HTTP protocol is stateless, but due to various considerations do not want to become a state, therefore, the last two programs has become a realistic option. Specifically cookie mechanism is used to maintain state of the client program, which uses a session mechanism to maintain state in the server-side program. We also see that, thanks to server-side maintain state of the program in customer client but also Xuyaobaocun a logo, so mechanisms may need the help of session cookie mechanism to identify the purpose of Da Dao saved, it actually alternatives are available.
Third, the cookie mechanism
The basic principle cookie mechanism as simple as the above example, but there are several issues to resolve: "membership card" how to distribute; "membership card" of the content; and customers how to use the "Member Card."
Orthodox cookie distribution is by extending the HTTP protocol to achieve, and the server through the HTTP response header with a line of special instructions to prompt the browser in accordance with the instructions generates the corresponding cookie. But pure client-side scripting such as JavaScript or VBScript can also generate the cookie.
The cookie used by the browser in the background according to certain principles automatically sent to the server. Check all stored browser cookie, if a cookie is greater than or equal scope statement will be the location of the requested resources, put the resources of the HTTP request cookie attached to the head sent the request to the server. Means that McDonald's membership card can only be produced in the McDonald's store, if a store has also issued its own membership card, then enter the store when the addition to produce McDonald's membership card, but also to produce a member of the store card.

cookie's contents include: name, values, expiration time, path and domain.
You can specify a domain in which a domain such as. G, the equivalent of main store signs, such as Procter & Gamble, you can also specify a specific domain of a machine under such or , can float Flexibility to do than.
Path is the name behind the URL with the path, such as / or / foo, etc., can do more than a counter Rejoice.
Path together with the domain constitutes a cookie's scope.
If you do not set the expiration time, then the lifetime of this cookie to the browser during the session, simply close the browser window, cookie disappears. This period of life of the cookie browser session is called session cookie. Session cookie is generally not stored on the hard disk but kept in memory, of course, provided that it is not standardized. If you set the expiration time, the browser the cookie will be saved to the hard disk, open again after closing the browser, the cookie is still valid until the expiration time exceeds a set.

Stored in a cookie on your hard disk in a different browser, shared between processes, such as the two IE windows. And stored in memory for the cookie, different browsers have different approaches. For IE, open windows in a press Ctrl-N (or from the File menu) to open the window can be shared with the original window while using other means to open the IE process will not have to open the windows shared memory cookie; for Mozilla Firefox0.8, all of the process and can share the same tab the cookie. In general is the window.open javascript window will open with the original windows shared memory cookie. Browser, this cookie for the session cookie does not believe that people only recognize the approach to the use of the regular session of web application development mechanism causing great distress.

Here is a goolge set cookie response header example
HTTP/1.1 302 Found
Location:
Set-Cookie: PREF = ID = 0565f77e132de138: NW = 1: TM = 1098082649: LM = 1098082649: S = KaeaCFPo49RiA_d8; expires = Sun, 17-Jan-2038 19:14:07 GMT; path = /; domain =. google . com
Content-Type: text / html

This is the use of HTTPLook the HTTP Sniffer HTTP communications software to capture the part of the record
Goolge browser to access the resources again, automatically send out cookie
Use Firefox can easily observe the current value of cookie
Use HTTPLook with Firefox cookie can easily understand the working principle.
IE can be set to ask before accepting cookie
This is a dialog box asking to accept cookie.

Fourth, understand the session mechanism
mechanism is a server-side session mechanism, the server uses a hash table is similar to the structure (and probably is to use a hash table) to save the information.

When the program needs for a client's request to create a session when the server first checks the client's request is included in a session ID - known as the session id, if the description contains a session id for this client previously Create over session, the server in accordance with the session id to retrieve the session out of the use (if not retrieved, may be the new one), if the client request does not include session id, then create a session for this client and generate a session with this associated with the session id, session id value should be a not only will not repeat, not easy to find the law to copy the string, the session id to be returned in this response to the client saved.

Save the session id of the ways to use cookie, so the interaction of the browser can automatically identify this play by the rules to the server. The name of this cookie are generally similar to SEEESIONID, and. For example, web applications weblogic generated cookie, JSESSIONID = ByOK3vjFD75aPnrF7C2HmdnV6QZcEbzWoWiBYEnLerjQ99zWpBng! -145788764, Its name is JSESSIONID.

As the cookie can be artificially prohibited, there must be other mechanisms to be banned in the cookie when the session id still be able to pass back to the server. Often use a technique called URL rewriting, the session id is attached to the URL path directly behind, there are two additional ways, one is the URL path as additional information, showing the form of http:// ... .. / xxx; jsessionid = ByOK3vjFD75aPnrF7C2HmdnV6QZcEbzWoWiBYEnLerjQ99zWpBng! -145788764
The other is as a URL query string appended to the back, showing the form of http://...../xxx?jsessionid=ByOK3vjFD75aPnrF7C2HmdnV6QZcEbzWoWiBYEnLerjQ99zWpBng!-145788764
Both ways is no different for users, and only a server parsing the time to deal with the different ways, using the first ways are conducive to turning one kind of session id's information and to distinguish normal program parameters.
Wei Liao Zai the interaction always maintain state, we must each client may request a path to the rear of containing this session id.

Another technique known as hidden form fields. Is that the server will automatically modify the form, add a hidden field, so when the form is submitted to the session id passed back to the server. Example, the following form