hubert-heijkers / tm1-log-tracker

TM1 REST API example, written in Go, showing how to process message logs.

tm1-log-tracker

The tm1-log-tracker is a sample application, of hopefully many soon, written against TM1 server's OData v4.0 compliant REST API. Its purpose is to demonstrate how you can retrieve and listen to, and subsequently process, new messages written into the server's message log by using the TM1 Server's REST API.

Getting Started

This sample application was written in Go, a.k.a. Go-lang. Please make sure that you have at least Go version 1.7.5 to use to build this sample. If you don't know what Go is and want to learn more or if you don't have it installed just yet please go to the golang.org site for more information.

Presuming you have Go up and running, you can grab the code for this sample and build the app. To do so, perform the following steps:

1. Open a console/command box
2. Grab the tm1-log-tracker source: go get github.com/hubert-heijkers/tm1-log-tracker
3. Navigate to the tm1-log-tracker source folder: cd %GOPATH%\src\github.com\hubert-heijkers\tm1-log-tracker

Now that you have the code of the sample you can take a closer look at the files. The important files are:

• main.go

  This is, as the name suggests, the main file containing the bulk of the sample code. The main function does the initialization,
  makes an initial request to the TM1 Server requesting its version number, which has the nice side effect of getting authenticated at the same time,
  and, last but not least, calls the TrackCollection utility as in:

  client.TrackCollection(tm1ServiceRootURL, "MessageLogEntries", time.Duration(interval)*time.Second, processMessageLogEntries)

  This is what kick-starts what the sample is all about, retrieving whatever is in the MessageLog, by iterating the MessageLogEntries, and subsequently,
  after waiting a number of seconds defined by the interval, requesting any new message log entries, the delta, since the last request. After every request
  the processMessageLogEntries function is being called. This is the function that gets the chance to process any message log entries returned by the
  server and the function you most likely end up editing later.

• utils/odata.go

  This file introduces some extensions to the standard HTTP client, which makes interaction with an OData compliant service easier in general.
  It also implements the logic, as defined by the OData protocol specification, to iterate a collection and to iterate and track a collection,
  TrackCollection, as used by this sample.

  If you inspect the TrackCollection function, you will notice that the only real difference with just iterating a collection is the additional
  prefer header that is being passed on to the request, set to the value odata.track-changes. This causes the service, the TM1 Server in this case, to return
  a so called delta link at the end of the response, which the application then subsequently can use to find out if any changes have been made to the collection.
  TM1 Server, to date, only supports track-changes on the message and transaction logs which, due to the nature of these collections, only receive new entries
  that are being appended to the log. The delta responses are therefore of exactly the same shape as the initial response containing the complete collection.

• .env

  This sample make use of the godotenv package, which makes grabbing and setting of environment variables using a .env file for
  the application very easy. In the application itself, we make use of the following environment variables:

  • TM1_SERVICE_ROOT_URL

    The service root URL of the TM1 Server you are planning to track the message log for, typically: http[s]://tm1server:port/api/v1/

  • TM1_USER

    The user name of the user to be used to log in to the TM1 Server specified using the service root URL.

  • TM1_PASSWORD

    The password of the user.

  • TM1_TRACKER_INTERVAL

    The interval, in seconds, between requests to the server (if not specified, or a invalid value is specified, defaults to 5)

Editing the Code

Now that you know where everything is, and perhaps even had a peek at the implementation of the processMessageLogEntries function, you likely want to define some specific processing of message log entries to help you achieve your goals. The bare skeleton of the processMessageLogEntries function is:

func processMessageLogEntries(responseBody []byte) (string, string) {

    // Unmarshal the JSON response
    res := MessageLogEntriesResponse{}
    err := json.Unmarshal(responseBody, &res)
    if err != nil {
        log.Fatal(err)
    }

    // Iterate over the message log entries retrieved from the server
    for _, entry := range res.MessageLogEntries {

        // YOUR CODE TO DO ANYTHING WITH A SINGLE MESSAGE LOG ENTRY GOES HERE!

    }

    // Return the nextLink and deltaLink, if there any
    return res.NextLink, res.DeltaLink
}

In the sample as provided, we are only interested in MDX queries that are being processed by the server. This implementation keeps track of the begin and end times of the MDXViewCreate and dumps those time stamps, including the duration (time it took to create the view), into comma-separated output and writes it out to the console.

Building the Code

Now that you have your code ready, the last step is to build it. Luckily for you we are using Go, so simply type go build in your console window and Go will do the rest for you, grabbing dependencies, building any dependencies if so required, and building your application.

After it is done building, you have a tm1-log-tracker executable in your source folder. If you'd rather have the executable installed into the bin folder of your go path instead, then use go install. Keep in mind that to be able to run the executable in that case you'll have to move/copy your .env file to that bin folder as well.

Running the application

Running the application is, after you have correctly set up your environment variables in the .env file, as easy as simply running the executable. The application will run forever unless it runs into a communication issue with the server, the server no longer returns a delta link (which shouldn't happen), or if you hit Ctrl-C to terminate the application.

Enjoy!