This second tutorial covers the basic of logging the backend calls from within transactions and shows how easy it is to log backend calls of e.g. filesystem, databases, SAP, ....
These logs are stored in the transaction log files and can be analyzed the same way using the E2E Dashboard services.

Building a Simple Example

Start by using the project from Tutorial 1: Logging the Transaction of a Simple HTTP Server.

Adding a backend call

Instead of writing the response directly, you will read it from a file. Create a file named Hello.html and put some HTML data in it. Replace the code of the sayHello function to read the response from this file.

function sayHello(req, res, cb){
    fs.readFile(__dirname + '/Hello.html',function(err, data){
        res.writeHead(200, {'Content-Type': 'text/html'});
        res.end(data);
        cb();
    });
}

Logging the requests

Now use the e2e-transaction-logger to trace the backend call. As you need the trx object, you have to add a parameter.

function sayHello(req, res, trx, cb){
    var io = trx.startIO('Read','FILE','Hello.html');
    fs.readFile(__dirname + '/Hello.html',function(err, data){
        io.end('OK');
        res.writeHead(200, {'Content-Type': 'text/html'});
        res.end(data);
        cb();
    });
}
...
		trx = e2eLogger.startTransaction('Say Hello');
            sayHello(req, res, trx, function(){
                trx.end();
            });

Use the startIO function of the transaction at the beginning to create the backend call. Parameters of these function are the name of the backend call ('Read'), the domain ('FILE') and the backend system ('Hello.html'). Simply call end on the returned object when it is done.

If you run the server and do some '/hello' requests, you will see the IO logs in the transaction log file.

2014-04-22    08:52:48    +0200    64a173f0-b9c4-4adc-b598-28592bd4a1d3    1    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    08:52:48    +0200    64a173f0-b9c4-4adc-b598-28592bd4a1d3    1    Read    2    OK    FILE    IO_ENTER        Hello.html
2014-04-22    08:52:48    +0200    64a173f0-b9c4-4adc-b598-28592bd4a1d3    1    Read    4    OK    FILE    IO_EXIT        Hello.html
2014-04-22    08:52:48    +0200    64a173f0-b9c4-4adc-b598-28592bd4a1d3    1    Say Hello    6    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    08:52:52    +0200    eba414a6-bd61-4b1d-b870-81757f74d54b    2    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    08:52:52    +0200    eba414a6-bd61-4b1d-b870-81757f74d54b    2    Read    1    OK    FILE    IO_ENTER        Hello.html
2014-04-22    08:52:52    +0200    eba414a6-bd61-4b1d-b870-81757f74d54b    2    Read    2    OK    FILE    IO_EXIT        Hello.html
2014-04-22    08:52:52    +0200    eba414a6-bd61-4b1d-b870-81757f74d54b    2    Say Hello    3    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    08:52:56    +0200    ee13c258-e2f9-4a78-ba7f-0071a1e5e81e    3    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    08:52:56    +0200    ee13c258-e2f9-4a78-ba7f-0071a1e5e81e    3    Read    1    OK    FILE    IO_ENTER        Hello.html
2014-04-22    08:52:56    +0200    ee13c258-e2f9-4a78-ba7f-0071a1e5e81e    3    Read    1    OK    FILE    IO_EXIT        Hello.html
2014-04-22    08:52:56    +0200    ee13c258-e2f9-4a78-ba7f-0071a1e5e81e    3    Say Hello    2    OK    INTERFACE    SERVICE_EXIT

Transaction log files: IO entries

The parameters are in the following order:

Parameter	Format	Description
Date	YYYY-MM-DD	The current date.
Time	HH:mm:s	The time.
Timezone	+/-HHMM	The timezone offset.
Transaction ID	string	The transaction id is defined by the developer or uniquely generated.
Request ID	number	This is the unique id of the request on this server. It is automatically generated.
Name	string	The name of this IO, defined by the developer.
Elapsed time	number	The number of milliseconds elapsed since the start of the transaction.
State	string	The state of the entry. Can be 'OK' or 'ERROR'. It is used to differentiate successful operations and failed ones.
Domain	string	The domain indicates which kind of entry it is. In case of IOs, it is defined by the developer.
Log type	string	The log type indicates the type of entry. In case of IOs, it can be 'IO_ENTER' on IO call start and 'IO_EXIT' on IO call end.
Parameter 1		Parameter 1 is not used by IO entries.
Parameter 2	string	For the IO calls, parameter 2 contains the backend system as provided by the developer.

Extending the Logging

Multiple IO calls

Let's do some more calls in the doSomething request as it could be done in a more realistic server.

function doSomething(req, res, trx, cb){
    var io = trx.startIO('GetCustomer', 'SAP', 'http://sap.e2e.ch:3000/');
    sapGetCustomer(1, function(err, customer){
        io.end();

        io = trx.startIO('GetCustomerDetail', 'DB', 'localhost/mongodb/');
        dbGetCustomerDetail(customer, function(err, customer){
            io.end();

            res.writeHead(200, {'Content-Type': 'application/json'});
            res.end(JSON.stringify(customer));

            cb();
        });
    });
}

And you will get some logs looking like this.

2014-04-22    09:29:59    +0200    1b50ca29-febc-4672-a6b9-faac1eceba83    2    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:29:59    +0200    1b50ca29-febc-4672-a6b9-faac1eceba83    2    Read    0    OK    FILE    IO_ENTER        Hello.html
2014-04-22    09:29:59    +0200    1b50ca29-febc-4672-a6b9-faac1eceba83    2    Read    1    OK    FILE    IO_EXIT        Hello.html
2014-04-22    09:29:59    +0200    1b50ca29-febc-4672-a6b9-faac1eceba83    2    Say Hello    2    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:30:07    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    Do Something    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:30:07    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    GetCustomer    0    OK    SAP    IO_ENTER        http://sap.e2e.ch:3000/
2014-04-22    09:30:07    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    GetCustomer    239    OK    SAP    IO_EXIT        http://sap.e2e.ch:3000/
2014-04-22    09:30:07    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    GetCustomerDetail    239    OK    DB    IO_ENTER        localhost/mongodb/
2014-04-22    09:30:08    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    GetCustomerDetail    1014    OK    DB    IO_EXIT        localhost/mongodb/
2014-04-22    09:30:08    +0200    b88f795f-3141-4cf0-9cdc-2dfbd7d612b2    3    Do Something    1015    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:30:13    +0200    79686607-b17e-4a78-982c-22479dc97394    4    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:30:13    +0200    79686607-b17e-4a78-982c-22479dc97394    4    Read    0    OK    FILE    IO_ENTER        Hello.html
2014-04-22    09:30:13    +0200    79686607-b17e-4a78-982c-22479dc97394    4    Read    1    OK    FILE    IO_EXIT        Hello.html
2014-04-22    09:30:13    +0200    79686607-b17e-4a78-982c-22479dc97394    4    Say Hello    2    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:30:17    +0200    f7e554f8-75e1-4bf7-9a9e-f738872d7f84    5    Say Hello    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:30:17    +0200    f7e554f8-75e1-4bf7-9a9e-f738872d7f84    5    Read    1    OK    FILE    IO_ENTER        Hello.html
2014-04-22    09:30:17    +0200    f7e554f8-75e1-4bf7-9a9e-f738872d7f84    5    Read    2    OK    FILE    IO_EXIT        Hello.html
2014-04-22    09:30:17    +0200    f7e554f8-75e1-4bf7-9a9e-f738872d7f84    5    Say Hello    3    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:30:24    +0200    82279774-459a-4326-9045-a1618047f369    6    Do Something    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:30:24    +0200    82279774-459a-4326-9045-a1618047f369    6    GetCustomer    0    OK    SAP    IO_ENTER        http://sap.e2e.ch:3000/
2014-04-22    09:30:26    +0200    82279774-459a-4326-9045-a1618047f369    6    GetCustomer    2024    OK    SAP    IO_EXIT        http://sap.e2e.ch:3000/
2014-04-22    09:30:26    +0200    82279774-459a-4326-9045-a1618047f369    6    GetCustomerDetail    2024    OK    DB    IO_ENTER        localhost/mongodb/
2014-04-22    09:30:26    +0200    82279774-459a-4326-9045-a1618047f369    6    GetCustomerDetail    2218    OK    DB    IO_EXIT        localhost/mongodb/
2014-04-22    09:30:26    +0200    82279774-459a-4326-9045-a1618047f369    6    Do Something    2219    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:30:41    +0200    223717d1-0579-4b75-a372-8e85c120fa23    7    Say Good Bye    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:30:41    +0200    223717d1-0579-4b75-a372-8e85c120fa23    7    Say Good Bye    1    OK    INTERFACE    SERVICE_EXIT

Success or fail

The end function of a IO takes a parameter which allow you to set the success or fail of the transaction. The valid values are true or 'OK' for success and false or 'ERROR' for fail. A failed backend call doesn't always mean a failed transaction - this is up to the developer.

function doSomething(req, res, trx, cb){Tutorial2.zip
    var io = trx.startIO('GetCustomer', 'SAP', 'http://sap.e2e.ch:3000/');
    sapGetCustomer(1, function(err, customer){
        if(err){
            io.end(false);
            res.writeHead(500, {'Content-Type': 'application/json'});
            res.end(JSON.stringify(err));

            cb(false);
            return;
        }
        io.end();

        io = trx.startIO('GetCustomerDetail', 'DB', 'localhost/mongodb/');
        dbGetCustomerDetail(customer, function(err, customerWithDetail){
            if(err){
                io.end(false);
                res.writeHead(200, {'Content-Type': 'application/json'});
                res.end(JSON.stringify(customer));

                cb();
                return;
            }
            io.end();

            res.writeHead(200, {'Content-Type': 'application/json'});
            res.end(JSON.stringify(customerWithDetail));

            cb();

        });
    });
}

Now, you can see the state of the end entries.

2014-04-22    09:47:30    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    Do Something    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:47:30    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    GetCustomer    0    OK    SAP    IO_ENTER        http://sap.e2e.ch:3000/
2014-04-22    09:47:32    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    GetCustomer    1169    OK    SAP    IO_EXIT        http://sap.e2e.ch:3000/
2014-04-22    09:47:32    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    GetCustomerDetail    1169    OK    DB    IO_ENTER        localhost/mongodb/
2014-04-22    09:47:33    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    GetCustomerDetail    2057    OK    DB    IO_EXIT        localhost/mongodb/
2014-04-22    09:47:33    +0200    23662f11-1012-40cd-97ed-883ee72f9bb5    5    Do Something    2058    OK    INTERFACE    SERVICE_EXIT        
2014-04-22    09:47:39    +0200    9098b116-0fe1-49d5-94fe-994acb7630e0    6    Do Something    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:47:39    +0200    9098b116-0fe1-49d5-94fe-994acb7630e0    6    GetCustomer    0    OK    SAP    IO_ENTER        http://sap.e2e.ch:3000/
2014-04-22    09:47:39    +0200    9098b116-0fe1-49d5-94fe-994acb7630e0    6    GetCustomer    206    ERROR    SAP    IO_EXIT        http://sap.e2e.ch:3000/
2014-04-22    09:47:39    +0200    9098b116-0fe1-49d5-94fe-994acb7630e0    6    Do Something    207    ERROR    INTERFACE    SERVICE_EXIT        
2014-04-22    09:47:44    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    Do Something    0    OK    INTERFACE    SERVICE_ENTER        
2014-04-22    09:47:44    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    GetCustomer    0    OK    SAP    IO_ENTER        http://sap.e2e.ch:3000/
2014-04-22    09:47:46    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    GetCustomer    2314    OK    SAP    IO_EXIT        http://sap.e2e.ch:3000/
2014-04-22    09:47:46    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    GetCustomerDetail    2314    OK    DB    IO_ENTER        localhost/mongodb/
2014-04-22    09:47:47    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    GetCustomerDetail    3268    ERROR    DB    IO_EXIT        localhost/mongodb/
2014-04-22    09:47:47    +0200    b86575fc-025a-4ce8-afbc-7257eddf4fc1    7    Do Something    3269    OK    INTERFACE    SERVICE_EXIT

You can download the complete example project of tutorial 2.

Dashboards

These log files are fully compatible with the E2E Dashboards services, so they can be loaded into the database and used with the dashboards to analyze the performance of your services.

Find below some examples of the views you would get with this enhanced HTTP server.

Figure: Table View of the E2E Service Dashboard

BRIDGE > Tutorial 2: Backend Access > service_dashboard_table_view.PNG

Figure: Graphical View of the E2E Service Dashboard

BRIDGE > Tutorial 2: Backend Access > service_dashboard_graph_view.PNG

Dashboards

Download Example Project