Shulou(Shulou.com)06/03 Report--

In this issue, Xiaobian will bring you the categories of data flow. The article is rich in content and analyzed and described from a professional perspective. After reading this article, I hope you can gain something.

Data streams are divided into two categories: 1. Input stream [InputStream], input stream can only be read but not written, and output stream can only be written but not read. OutputStream: Usually programs use the input stream to read data and the output stream to write data, as if data were flowing into and out of the program.

A data stream is an ordered sequence of bytes with a beginning and an end. include an input stream and an output stream.

A data stream is a concept originally used in the field of communications, a sequence of digitally encoded signals representing information used in transmission. This concept was first proposed in 1998 by Henzinger in Ref. 87, who defined a data stream as "a sequence of data that can be read only once in a predetermined order."

The development of data stream applications is the result of two factors:

detail data

Has been able to automatically generate large amounts of detailed data on a continuous basis. This type of data first appeared in the traditional banking and stock trading fields, and later appeared in geological surveys, meteorology, astronomical observations, etc. In particular, the advent of the Internet (network traffic monitoring, clickstream) and wireless communication networks (call logs) has generated a large amount of data flow type data. We notice that most of these data are related to geographic information, mainly because geographic information has a large dimension and is easy to generate such a large amount of detailed data.

complex analysis

Complex analysis of the update stream is required in near real-time. Complex analysis of data in these areas (e.g. trend analysis, forecasting) used to be done offline (in a data warehouse), but new applications Time sensitive (especially in cybersecurity and national security fields), such as detecting extreme events, fraud, intrusions, anomalies on the Internet, complex crowd monitoring, track trend monitoring, exploratory analyses, harmonic analysis, etc., all require online analysis.

After that, the academic community basically recognized this definition, and some articles also modified the definition slightly on this basis. For example, S. Guha et al.[88] consider a data stream to be an "ordered sequence of points that can only be read once or a few times," relaxing the "one-pass" restriction in the previous definition.

Why is there an emphasis on limiting the number of data reads in the processing of data streams? S. Muthukrishnan[89] points out that data streams refer to "incoming data coming at a very high speed," so transmission, computation, and storage of data streams become difficult. In this case, there is only a chance to process the data once it initially arrives, and at other times it is difficult to access the data again (because it is not available and cannot be saved).

Category:

The nature and format of the data are different, and the processing method of the stream is also different. Therefore, in Java's input/output class library, there are different stream classes corresponding to different input/output streams. In the java.io package, the basic input/output stream classes can be divided into two types according to the type of data they read or write: byte streams and character streams.

Input and output streams

Data streams are divided into two categories: Input Stream and Output Stream. The input stream can only be read but not written, while the output stream can only be written but not read. Typically, programs use an input stream to read data and an output stream to write data, as if data were flowing into and out of the program. Data streams are used to make the input and output operations of the program independent of the associated devices.

The input stream may obtain data from a keyboard or file, and the output stream may transmit data to a display, printer, or file.

buffered stream

In order to improve the transmission efficiency of data, buffered streams are usually used, that is, a stream is equipped with a buffer, and a buffer is a memory block dedicated to transmitting data. When writing data to a buffered stream, the system does not send it directly to an external device, but sends the data to the buffer. The buffer automatically records data, and when the buffer is full, the system sends all data to the corresponding device.

When reading data from a buffered stream, the system is actually reading data from a buffer. When the buffer is empty, the system automatically reads data from the relevant device and reads as much data as possible to fill the buffer.

The above is what kinds of data streams are shared by Xiaobian. If there are similar doubts, please refer to the above analysis for understanding. If you want to know more about it, please pay attention to the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.