Please don’t chase Waterfalls

Posted in Methods, SDN blogger on December 6th, 2007 by dan

There have been a couple of blogs recently about the waterfall method and it’s usefulness: one from The CIO Weblog, which linked to Eugene Nizker at CIO Magazine which points to an IBM article by Dr. Kruchten on the subject.

For some reason none of these blogs comes right out and says the obvious.  Software development methodologies are like religions:  everyone has one and they all hate everyone else’s for no reason except they aren’t their sworn religion.  In real life, this is dangerous, expensive and prone to the types of failures noted in the blogs.

I haven’t worked in industry for 35+ years like Mr. Nizker but after a few projects it became obvious to me when you can use agile methods and when waterfall is the most appropriate.  Let’s try and do what none of the other blogs tried to do and break it down.

“Roll-out”

A very common thing in large companies (this was found via the CIO Weblog right?) is to take a newly developed solution and push it all over the world to standardize a business process.  These systems are the perfect candidate for the waterfall method.  The users can look at a system and see the gaps and let the people in charge of creating their “copy” of the system know about the changes.  This allows the “developers” to take the requirements in advance and while creating this new “copy” of the system add the modifications required for the new location.  Once the system is ready it can be easily tested with prior business cases and be easily validated for the new location.   I guess this is the “deterministic” task talked about by CIO Magazine.

“I think I need…”

Everything else falls into this category.  The category where the person defining the system has only half of a clue about what they need or want.  I do like the way Mr. Nizker classifies these problems, “[there is a] volatile reality, which changes on them every day [and] the systems we develop influence [that] reality.”  It’s sort of the Heisenberg uncertainly principal of IT systems.  Until we start to peel back the layers the people trying to define the system don’t know the extent of their own delusion.  You should think of it like therapy we must slowly work to the actual root of the problem.  You can only do this in an iterative manner until the user has seen the solution they have no clue what their problem even is.

It is all about using the right tool for the job and being able to tell the different before you start.  Just as using the iterative method is overkill for a roll-out style project, the waterfall spells total doom for the iterative project.  I rarely have a hard time deciding which tool to use.

Community Activism

Posted in SDN blogger on November 28th, 2007 by dan

The SDN leadership have done a great thing, they have linked their “points” incentive program to a good world cause, School Feeding.  From Chief Evangelist Mark Finnern’s blog Food for Points:

The whole community collected around 2.5 million points last year.

If we reach the same amount of points next year, we will have 100K Euro. (If we don’t, we will walk in shame.)

If we reach 3.0 million points, SAP will donate 150K Euro.

Now if we even reach 3.5 million points, the amount will rise to the maximum of 200K Euro.

From the World Food Programme’s web site:

It costs just 10 US cents a day to give a child a cup of porridge at school. An additional nine US cents a day provides a child with a nutritional package, including basic health and sanitation support.

1 Pt * ( # of Euros / # of Points ) *  ( 1 USD / .67 EUR ) * ( child / .1 USD ) = Conversion

Roughly translated back to points that means for every point you earn on SDN you will feed between .6 and .85 children for one day.  With the average blog post getting around 50 points, one blog can feed 30-40 children that day.

“One person can make a difference and every person should try.” John Fitzgerald Kennedy

SAP Web Services in Flex Builder

Posted in ABAP, Flex, SDN blogger on November 14th, 2007 by dan

SAP web services are really complex, tables inside rows inside tables inside structures.  I’ve been fielding an increasing number of questions about using these in the forum so, instead of answering everyone separately here are a few examples from simple to complex.

Let’s start off with one of the simpler examples just to get the hang of it.  Use SAPLink and install this function group and generate a web service from the one function in it.  Now, lets write some Flex code to call this.

Import Statements

A few people have asked me to add the import statements to this.  For reference if you go to the object that has the error, move your cursor to the end of the word hold control and press space the import will be added for you automatically, welcome to the wonderful world of a good IDE.  But the following in a <mx:Script> block between the <mx:Application> tags.

import mx.rpc.AbstractOperation; import mx.rpc.events.FaultEvent; import mx.rpc.events.ResultEvent; import mx.rpc.soap.LoadEvent; import mx.rpc.soap.WebService;

Simplest Example

Step 1 – Get your WSDL

1 private function callWebService():void{ 2 fooService = new WebService(); 3 fooService.wsdl = "http://localhost/sap/bc/srt/rfc/sap/Z_TEST_CHANGING_PARAM?sap-client=300&wsdl=1.1"; 4 fooService.addEventListener(LoadEvent.LOAD, loadListener); 5 fooService.addEventListener(ResultEvent.RESULT, resultTrigger); 6 fooService.addEventListener(FaultEvent.FAULT,fault); 7 fooService.loadWSDL(); 8 }

Line by Line:

  1. Declare a function that will start the whole process
  2. Create a WebService object, this should be global or at least visible to the other methods ( you’ll need it later )
  3. Point the WS to the location of the WSDL
  4. Add an EventListener for when the Loading of the WSDL is complete
  5. Add an EventListener for the results coming back from the call
  6. Add an EventListener for any errors that occur
  7. Tell the WS to load the WSDL

Step 2 – Set Some Parameters

1 private function loadListener(event:LoadEvent):void{ 2 var op:AbstractOperation = fooService.getOperation("Z_DOUBLE_ROWS"); 3 var input:Object = new Object(); 4 input.TEST = new Array(); 5 input.TEST.push("foo"); 6 input.TEST.push("bar"); 7 op.arguments = input; 8 op.send(); 9 }

Line by Line:

  1. Declare a function who handles the event you subscribed to in the Step 1 line 4.
  2. Get the Operation from the WSDL file.  This is one of those “standard” ways of doing things.  If you look at your WSDL file you will see that it could have more then one operation in it, this gets the particular operation you want to call.
  3. Create a dynamic object that will hold the inbound parameters to your WS.  In this case the parameter TEST is a table of strings.
  4. Here we create what Flex builder thinks is how to hold  a table, an Array.
  5. Then we push each “row” of the table into the array again, in this case it’s just one string at a time.
  6. See Line 5
  7. We then map the input object to the arguments of the WS.
  8. Send our request including all the input data to the server

Step 3 – Look at the Output

1 private function resultTrigger(event:ResultEvent):void{ 2 var item:String; 3 for each(item in event.result){ 4 trace(item); 5 } 6 }

Line by Line

  1. Define a function to handle the event from section 1 line 5
  2. Declare on object to hold each result
  3. Loop at each item in the result list, which happen to be strings.
  4. Print them out to the debug console

I will talk about more advanced parsing of the result set later on.

Inbound Table Parameter

First, get your WSDL, in this case I will be using the FM BAPI_FLIGHT_GETLIST from the SFLIGHTS example we are all so fond of.  You should run this FM a few times to make sure you have data on the ABAP side, I will be passing in a date range to this FM so, you might want to find two dates that return some data for you. ( I named my WebService “Z_GET_FLIGHT_LIST” )

Step 1 – Get Your WSDL

This is the same exact thing you did before, just with a different WSDL.

Step 2 – Set some Parameters

There is a strange behavior with ABAP WebServices where if you have a table that is both Input and Output you must pass it as part request to get it filled.  You’ll see in a second:

1 private function loadListener(event:LoadEvent):void{ 2 var op:AbstractOperation = fooService.getOperation("BAPI_FLIGHT_GETLIST"); 3 var input:Object = new Object(); 4 input.FLIGHT_LIST = new Array(); 5 input.RETURN = new Array(); 6 op.arguments = input; 7 op.send(); 8 }

Line by Line

  1. Define a function that handles the event
  2. Get the right operation
  3. Dynamic input object
  4. You have to pass blank parameters to the WS so that the Web Application Server will fill them
  5. See line 4
  6. Same as last time
  7. Same here

Set Table Parameters

1 var dateRangeRow:Object = new Object(); 2 input.DATE_RANGE = new Array(); 3 dateRangeRow.SIGN = "I"; 4 dateRangeRow.OPTION = "EQ"; 5 dateRangeRow.LOW = "2002-12-20"; 6 dateRangeRow.HIGH = ""; 7 input.DATE_RANGE.push(dateRangeRow);

Line by Line ( add this between lines 5 and 6 from the prior example )

  1. Create a new dynamic object that holds a Row of the DATE_RANGE table
  2. Create an array called DATE_RANGE which will map to the DATE_RANGE input parameter
  3. Set each field dynamically
  4. More fields
  5. More fields
  6. More fields ( don’t need to pass this one because it’s blank )
  7. Push this row into the array

Step 3 – Look at the Output

1 private function resultTrigger(event:ResultEvent):void{ 2 var row:Object; 3 for each (row in event.result.FLIGHT_LIST){ 4 trace(row.AIRLINE + " " + row.CITYFROM); 5 } 6 }

Line by Line

  1. Function, again.
  2. Use a place holder dynamic object
  3. Loop at the table called FLIGHT_LIST ( looks like ABAP doesn’t it? )
  4. Print to the console the fields you want ( looks like ABAP doesn’t it? )

Disclaimer: There are a number of ways to call WebServices in Flex, I believe this is the most complete and “standard” way to call them, if not someone please point me to Adobe docs that show the most correct way.