Web EUM works in the following way:
- An end user requests a first page from your web application.
- Your web application executes whatever business logic that the particular page requires.
- Your web application creates the response page to return to the end user. The response page includes:
- application specific information.
- As the page is being constructed in the browser, the script collects relevant information about the page's performance.
- At approximately the same time as the
- This second script packages the collected performance information and sends it to the EUM Cloud collector for processing using a web beacon.
- Working together the two scripts continue to collect and send performance information as the end user navigates through the instrumented pages of your application.
Not all types of injection are supported on all frameworks and platforms. See the Script Injection columns in the Supported Platform Matrix for Web EUM matrices to find out what types are supported for your application.
Manual injection is supported on all platforms and frameworks. To set up a manually injected page, you:
- Manually configure each page you wish to instrument to find the script where you stored it so that it can be executed as the page is constructed by the browser.
For detailed instructions on using manual injection in your application, see Manual Injection.
If you are using a Java or .Net app agent on the server-side, and your application is running in an environment that supports the Apache Jasper JSP compiler (for Java) or ASP.NET or ASPX (for .NET), you may be able to use automatic injection, where the server-side app agent completely manages injecting the code at runtime. For detailed instructions on using automatic injection in your application, see Automatic Injection.
Assisted injection is available in two variants. In both cases some of the work is done manually by you and some of the work is done by the server-side Java or .Net app agent.
Assisted Injection using Injection Rules (Java only)
For detailed information on using this form of assisted injection, see Assisted Injection-Using Injection Rules - Java Only.
Assisted Injection using Attribute Injection
In this type of assisted injection you copy small code snippets appropriate to your framework into your page templates or other code that creates your pages. This snippet contains two variables, JS_HEADER and JS_FOOTER, which the app agent replaces with the appropriate information in the response object at runtime.
For detailed information on using this form of assisted injection, see Assisted Injection-Using Attribute Injection.
Choosing an Injection Method
If you are uncertain which procedure to use to inject the agent into your web pages, follow these guidelines, in this order:
- If you want to use Web EUM and do not have any app agents on the server side, use manual injection. See Manual Injection.
- If automatic injection is available and works for your framework, use automatic injection.
Automatic injection requires the least amount of effort because you do not have to manually instrument every page. Check the matrices at End User Monitoring (EUM) Compatibility to see if automatic injection has been tested in your environment. Also see Automatic Injection.
- If you cannot use automatic injection, and you can edit the source code of your web pages, use manual injection. See Manual Injection.
- If you cannot use automatic injection, and you can edit the source code of your web application, use one of the kinds of assisted injection. See Assisted Injection-Using Injection Rules (Java Only) or Assisted Injection-Using Attribute Injection.
Verifying Injection with Manual Injection
If after two attempts you still do not see EUM metrics, try one of the other injection schemes if they are available for your platform, or call AppDynamics Support.
If you try one way to inject and it does not work, AppDynamics recommends that you undo the current injection configuration before implementing another one.
- To undo assisted injection using injection rules, clear the Enable check box for each injection rule in the injection rules list.
If multiple copies of the agent exist on a page, the second copy does not execute.
Getting Full Timing Data for Associated Business Transactions
To get the full real execution time for correlated business transactions your injection method must write the JS_FOOTER data variable to your page. Manual injection gives the server-side agent the ability to write data only to the header of the page as it is being constructed by your web application. It is possible that complete business-transaction timing information is not available at the moment that the header data is written. Using the footer allows the server-side agent to write timing data at the footer of the page, by which time a fuller picture of business transaction timing is available.
You can write the JS_FOOTER data variable into the footer of a web page using the following techniques:
- If you use automatic injection for the injecting into the head section, you automatically get injection into the footer as well.
- If you use manual injection for the head section, for applications built on Java platforms you can use assisted injection-using injection rules to inject into the footer. Or for applications built on Java servlet or ASP.NET platforms, you can use assisted injection-using attribute injection.
If you cannot add the JS_FOOTER variable to your page, the timing shown for associated business transactions is the average response time for that transaction rather than the real execution time for that specific page.
- Manual Injection
- Automatic Injection
- Assisted Injection-Using Attribute Injection
- Assisted Injection-Using Injection Rules - Java Only