Monitoring HTTP Client Calls with ITCAM for Transactions V7.3 and ITCAM for Applications Diagnostics 7.1

Overview

While not strictly a true Java 2 Enterprise Edition (J2EE) interface, many customers have resorted to using an Apache HTTP client to connect their enterprise applications with a variety of web-based HTTP sources. In the absence of true Web Services, these applications use an HTTP client to connect directly to web pages and parse the HTML to retrieve the data they need. HTTP providers may include other web servers within the enterprise; web-enabled CICS transaction servers; or even external public web sites. Some customers may even have used Apache HTTP client to build their own SOAP-based Web Services clients. Until now, it has not been possible to track transactions that use HTTP client code to connect to a CICS HTTP server with ITCAM for Transactions. ITCAM for Transactions V7.3 FP1 together with ITCAM AD 7.1 FP3 LA2 provides this capability.

There are actually two versions of the Apache HTTP client API in common use. The original client was distributed as part of the Apache Commons project, Commons HttpClient 3.x is now end of life and has been superseded by the richer featured Apache HttpComponents client. Both versions of Http Client are supported by ITCAM AD 7.1 FP3 LA2.

Configuration

Configuration is simple. By default, HTTP client calls are not instrumented by ITCAM for AD. To enable instrumentation, locate file toolkit_custom.properties in the ITCAM custom directory for the server you wish to be monitored. The runtime server custom directory is identified by the application server name, version, node and server name, for example <itcam_home>/runtime/was80.nodea.server1/custom

Add the following line to toolkit_custom.properties
com.ibm.tivoli.itcam.toolkit.dc.enable.apache.httpclient=true

Instrumentation Options

By default, the HTTP client instrumentation adds an HTTP ARM header to every HTTP request that the client makes. The ITCAM for CICS Transactions 7.3 FP1 Data Collector supports HTTP requests to a CICS Transaction Server with Web Support. It is also possible to track SOAP Web Services invoked by HTTP Client code in WebSphere connecting to CICS Web Services. In order to allow SOAP traffic to be tracked from WebSphere it is necessary to add another property to the toolkit_custom.properties file in the ITCAM AD 7.1 server runtime custom directory.
com.ibm.tivoli.itcam.dc.http.token.to=body

It is not possible to track HTTP Clients using both ARM HTTP Header instrumentation and SOAP body instrumentation at the same time.

Using 128-bit ITCAM Transaction Tracking Tokens

Another advanced feature of ITCAM for Transactions 7.3 FP1 is support for consolidated, 128-bit UUID tokens. Until now, only 32-bit ITCAM Managing Server GPS tokens or ITCAM for SOA 64-bit tokens could be used to track remote Web Services. Enterprises attempting to track extremely high volumes of requests run the risk of tracking token collision when using 32-bit (and even with 64-bit) tokens. Since a portion of the tracking token is used to identify the source of a request (typically 10-bits), leaving fewer bits available for incremental transaction identification. Once the counter reaches its maximum value, it wraps back to zero. A long-running transaction response may be mis-identified as a result. The new consolidated 128-bit UUID tokens available in ITCAM for Transactions V 7.3 FP1 completely eliminate this possibility. ITCAM for AD 7.1.0.3 LA2 supports 128-bit UUID tokens for both HTTP header and SOAP body instrumentation by specifying property:
com.ibm.tivoli.itcam.dc.ttapi.httpclient.token128bit=true

Limitations

Note that HTTP client instrumentation is only used by ITCAM for Transactions V7.3 FP1. There is no support for HTTP Client composite application tracking or Nested Request Analysis in the ITCAM AD Managing Server or ITM user interfaces.