Easiest way to save data - BOSS by Josiah Mangiameli

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Easiest way to save data - BOSS by Josiah Mangiameli

Introduction

Saving Data can be one of the hardest parts of a smalltalk project.
There are many different options but the easiest is definitely BOSS.
Boss saves data on an external file in a compact binary format.
In the small quantities that you use in this class, the data saves/loads quickly and easily.
Boss is only meant to save data and it cannot save interface (UI)

Steps

1. Load the BOSS Parcel in the Application Development folder

2.Determine what class or classes you want to store your data

Ex. In our case, we stored all of our patient, doctor, treatment, and hospital data in our Hospital class

and we stored all of our login names and passwords in our UserSecurity class

3. Make sure that all classes that you plan to store are regular objects and not UI classes

You can easily do this by checking your class definition, if its superclass is "Core.Object"

then you are ok, if it is "UI.ApplicationModel" then it is not a class you should be saving

4. Save your data using these steps

Create the temporary variables for the dataObject, dataStream, and boss. Must be done at start of method
Set the dataObject to the file you want to save
Create a DataStream on a particular filename
Create a BinaryObject with the data stream as an argument
Store the dataObject using the nextPut message

This may seem confusing so here is an example

dataObject dataStream bos
dataObject := PointExample x: 3 y: 4 z: 5.
dataStream := 'points.b' asFilename writeStream.
bos := BinaryObjectStorage onNew: dataStream.
[bos nextPut: dataObject] valueNowOrOnUnwindDo: [bos close].

This is what our save looked liked. We store an array of the collection of hospitals and security data.

5. Load the data back in using these steps

Create a boss readStream on your particular filename
Read the data out
Set it to the initialized data

bos array
bos := BinaryObjectStorage
onOldNoScan: 'points.b' asFilename readStream.
[array := bos contents] valueNowOrOnUnwindDo: [bos close].

This is what our load looked liked. Load an array of the collection of hospitals and security data.

6. Other Notes

You must implement the save code first. This creates the file that the load code will be looking for.
This PDF is a great reference.

http://coweb.cc.gatech.edu/cs2340/uploads/6598/BOSS.pdf

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Cases last edited on 30 July 2011 at 2:33 am by r59h132.res.gatech.edu