Server Load balancer troubleshooting guide (2)

1.1 HTTP protocol analysis tool-HttpWatch and HttpFox
Most of the actually deployed Server Load balancer applications perform Server Load balancer on Web applications, and the core of Web applications is HTTP. Therefore, we need a powerful tool that can analyze the HTTP protocol in detail. Although Wireshark can parse and analyze the HTTP protocol to some extent, I would like to recommend HttpWatch and HttpFox, a super weapon dedicated for HTTP protocol analysis.
HttpWatch can be integrated with IE and Firefox to analyze HTTP/HTTPS protocols. It helps us analyze the interaction details between browsers and Web servers. It not only helps us troubleshoot HTTP problems, but also helps us optimize the performance of Web websites. However, HttpWatch is a commercial software that is expensive and requires $395 for individual user authorization.
After HttpWatch is installed, it is automatically integrated with the IE and Firefox browsers installed in the system. Please note that HttpWatch cannot automatically support the latest browsers. For example, the latest Firefox5.0 must be supported by HttpWatch 7.2 or later.
For more information about HttpWatch, visit the following websites:
Http://www.httpwatch.com
HttpFox can be viewed as a lite version of HttpWatch, which is a plug-in of Firefox and has some of the most common basic functions of HttpWatch.
1) HttpFox supports Firefox. If you need to analyze and compare the differences between different browsers in processing certain behaviors, HttpFox cannot help you.

2) HttpFox is free of charge. Compared with the high price of HttpWatch, HttpFox is cost-effective.

 

1.1.1 record the webpage access process and content
HttpWatch integrates with IE and Firefox browsers as plug-ins. The following uses HttpWatch in Firefox as an example. Click "Tools> HttpWatch" in the Firefox browser to start HttpWatch. The capture window of HttpWatch will appear below the browser. Click "Record" in the label bar above to start the capture program. Then, you enter the Domain Name of the website you want to capture in your browser to start capturing HTTP requests.

 
The capture page of HttpWatch is divided into three parts:
The top menu is the function menu. You can start the capture (Record), Stop the capture (Stop), Clear the current capture window (Clear), and Filter the captured content) query, Save, or Print.
The middle part is divided into the HTTP request list, which displays the list of all HTTP requests executed to open a page recorded by HttpWatch. For example, the request processing time, request size, response size, request method, request result code, type, URL, and so on.
The following is the HTTP request details. By selecting different tags, you can learn about the details of HTTP headers, request processing timelines, Cookie information, and response content.
 
1.1.2 analyze HTTP request details
In the debugging process of the actual problem, we can get a lot of details about the HTTP request through HttpWatch.

 
For example, we can get the following information:
1) It takes 4.376seconds to open http://www.httpwatch.com;

2) a total of 13 valid HTTP requests (Network Round Trips;

3) a total of 7725 Bytes are sent for requests and 198294 Bytes are received for requests. Because compression is enabled, transmission data of 43567Bytes is saved.

4) Five DNS queries are initiated and six TCP connections are established.

 
Select an HTTP request. Let's take a look at the details of the request.

 
Shows the details of HTTP requests and responses: the HTTP Protocol version, browser type, compression mode, Request Host Name, and Cookie information supported by the client. The HTTP Response shows the server type, supported HTTP versions, response length, cache availability, and cache expiration time.
In addition, you can select the Time Chart label to query the Time of each part in the request processing process. For example, the request sending and receiving time is very short, and most of the time is spent waiting for the response process. This may indicate the possibility of Optimization in server processing.

 
Through other tags, we can also learn the Cookie information, cache information, and specific response content of the current request.

 

E.S.

This article is from the "ADC technology blog ".