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• SQL Developer Data Modeler: On Notes, Comments, and Comments in RDBMS

  - by thatjeffsmith

  Ah the beautiful data model. They say a picture is worth a 1,000 words. And then we have our diagrams, how many words are they worth? Our friends from the Human Relations sample schema So our models describe how the data ‘works’ – whether that be at a logical-business level, or a technical-physical level. Developers like to say that their code is self-documenting. These would be very lazy or very bad (or both) developers. Models are the same way, you should document your models with comments and notes! I have 3 basic options: Comments Comments in RDBMS Notes So what’s the difference? Comments You’re describing the entity/table or attribute/column. This information will NOT be published in the database. It will only be available to the model, and hence, folks with access to the model. Table Comments (in the design only!) Comments in RDBMS You’re doing the same thing as above, but your words will be stored IN the data dictionary of the database. Oracle allows you to store comments on the table and column definitions. So your awesome documentation is going to be viewable to anyone with access to the database. RDBMS is an acronym for Relational Database Management System – of which Oracle is one of the first commercial examples If the DDL is produced and ran against a database, these comments WILL be stored in the data dictionary. Notes A place for you to add notes, maybe from a design meeting. Or maybe you’re using this as a to-do or requirements list. Basically it’s for anything that doesn’t literally describe the object at hand – that’s what the comments are for. I totally made these up. Now these are free text fields and you can put whatever you want here. Just make sure you put stuff here that’s worth reading. And it will live on…forever.

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• Jetzt geht’s los - speaking in Germany!

  - by Hugo Kornelis

  It feels just like yesterday that I went to Munich for the very first German edition of SQL Saturday – and it was a great event. An agenda that was packed with three tracks of great sessions, and lots of fun with the organization, attendees, and other speakers. That was such a great time that I didn’t have to hesitate long before deciding that I wanted to repeat this event this year. Especially when I heard that it will be held in Rheinland, on July 13 – that is a distance I can travel by car! The...(read more)

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• Is my sequence diagram correct?

  - by Dummy Derp

  NOTE: I am self studying UML so I have nobody to verify my diagrams and hence I am posting here, so please bear with me. This is the problem I got from some PDF available on Google that simply had the following problem statement: Problem Statement: A library contains books and journals. The task is to develop a computer system for borrowing books. In order to borrow a book the borrower must be a member of the library. There is a limit on the number of books that can be borrowed by each member of the library. The library may have several copies of a given book. It is possible to reserve a book. Some books are for short term loans only. Other books may be borrowed for 3 weeks. Users can extend the loans. Draw a use case diagram for a library. I already drew the Use Case diagram and had it checked by a community member. This time I drew sequence diagrams for borrowing a book and extending the date of return. Please let me know if they are correct. I drew them using Visual Paradigm and I dont know how to keep a control of the sequence numbers. If you do, please let me know :) Diagrams

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• SQL Developer Data Modeler v3.3 Early Adopter: Search

  - by thatjeffsmith

  photo: Stuck in Customs via photopin cc The next version of Oracle SQL Developer Data Modeler is now available as an Early Adopter (read, beta) release. There are many new major feature enhancements to talk about, but today’s focus will be on the brand new Search mechanism. Data, data, data – SO MUCH data Google has made countless billions of dollars around a very efficient and intelligent search business. People have become accustomed to having their data accessible AND searchable. Data models can have thousands of entities or tables, each having dozens of attributes or columns. Imagine how hard it could be to find what you’re looking for here. This is the challenge we have tackled head-on in v3.3. Same location as the Search toolbar in Oracle SQL Developer (and most web browsers) Here’s how it works: Search as you type – wicked fast as the entire model is loaded into memory Supports regular expressions (regex) Results loaded to a new panel below Search across designs, models Search EVERYTHING, or filter by type Save your frequent searches Save your search results as a report Open common properties of object in search results and edit basic properties on-the-fly Want to just watch the video? We have a new Oracle Learning Library resource available now which introduces the new and improved Search mechanism in SQL Developer Data Modeler. Go watch the video and then come back. Some Screenshots This will be a pretty easy feature to pick up. Search is intuitive – we’ve already learned how to do search. Now we just have a better interface for it in SQL Developer Data Modeler. But just in case you need a couple of pointers… The SYS data dictionary in model form with Search Results If I type ‘translation’ in the search dialog, then the results will come up as hits are ‘resolved.’ By default, everything is searched, although I can filter the results after-the-fact. You can see where the search finds a match in the ‘Content’ column Save the Results as a Report If you limit the search results to a category and a model, then you can save the results as a report. All of the usual suspects You can optionally include the search string, which displays in the top of of the report as ‘PATTERN.’ You can save you common reporting setups as a template and reuse those as well. Here’s a sample HTML report: Yes, I like to search my search results report! Two More Ways to Search You can search ‘in context’ by opening the ‘Find’ dialog from an active design. You can do this using the ‘Search’ toolbar button or from a model context menu. Searching a specific model Instead of bringing up the old modal Find dialog, you now get to use the new and improved Search panel. Notice there’s no ‘Model’ drop-down to select and that the active Search form is now in the Search panel versus the search toolbar up top. What else is new in SQL Developer Data Modeler version 3.3? All kinds of goodies. You can send your model to Excel for quick edits/reviews and suck the changes back into your model, you can share objects between models, and much much more. You’ll find new videos and blog posts on the subject in the new few days and weeks. Enjoy! If you have any feedback or want to report bugs, please visit our forums.

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• Is there a way communicate or measure levels of abstraction?

  - by hydroparadise

  I'll be the first to say that this question is a bit... out there. But here are a couple questions I bear in mind : Is abstraction continuous or discrete? Is there a single unit of abstraction? But I'm not sure those questions are truly answerable or even really makes sence. My naive answer would be something along the lines of abitrarily discrete but not necescarily having a single unit measure. Here's what I mean... Take a Black Labrador; an abstraction that could be made is that a Black Lab is a type of animal. [Animal]<--[Black Lab] A Black Lab is also a type of Dog. [Dog]<--[Black Lab] One way to establish a degree of abstraction is by comparing the two the abstractions. We could say that [Animal] is more abstract than [Dog] in respect to a Black Lab. It just so happens [Animal] can also be used as an abstraction of [Dog] So, we might end up with something like [Animal]<--[Dog]<--[Black Lab] With the model above, one might be inclined to say that there's two hops of abstraction to get from [Black Lab] to [Animal]. But you can't exactly tell somebody they need one level abstraction and reasonalby expect they will come up with [Dog] given they aren't explicity given the options above. If I needed to tell someobody in a single email that they needed an abstract class with out knowing what that abstract class is, is there a way to communaticate a degree of abstraction such that they might end up on Dog instead of Animal? As a side note, what area of study might this type of analysis fall under?

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• Tools for modelling data and workflows using structured text files

  - by Alexey

  Consider a case when I want to try some idea of an application. But I want to avoid investing a lot of effort in coding UI/work flows/database schema etc before I see that it's going to be useful to me (as example of potential user). My idea is stay lightweight and put all the data in text files. So the components could be following: Domain objects are represented by text files or their fragments Domain objects are grouped by their type using directories Structure the files using some both human- and machine-friendly format, e.g. YAML Use some smart text editor (e.g. vim, emacs, rubymine) to edit and navigate those files Use color schemes and macros/custom commands of the text editor to effectively manipulate those files Use scripts (or a lightweight web framework like Sinatra) to try some business logic ideas on top of the data model The question is: Are there tools or toolkits that support or can be adopted to this approach? Also any ideas, links to articles/other knowledge sources are very welcome. And more specific question: What is the simplest way to index and update index of files with YAML files?

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• Model Driven Architecture Approach in programming / modelling

  - by yak

  I know the basics of the model driven architecture: it is all about model the system which I want to create and create the core code afterwards. I used CORBA a while ago. First thing that I needed to do was to create an abstract interface (some kind of model of the system I want to build) and generate core code later. But I have a different question: is model driven architecture a broad approach or not? I mean, let's say, that I have the language (modelling language) in which I want to model EXISTING system (opposite to the system I want to CREATE), and then analyze the model of the created system and different facts about that modeled abstraction. In this case, can the process I described above be considered the model driven architecture approach? I mean, I have the model, but this is the model of the existing system, not the system to be created.

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• Is my use case diagram correct?

  - by Dummy Derp

  NOTE: I am self studying UML so I have nobody to verify my diagrams and hence I am posting here, so please bear with me. This is the problem I got from some PDF available on Google that simply had the following problem statement: Problem Statement: A library contains books and journals. The task is to develop a computer system for borrowing books. In order to borrow a book the borrower must be a member of the library. There is a limit on the number of books that can be borrowed by each member of the library. The library may have several copies of a given book. It is possible to reserve a book. Some books are for short term loans only. Other books may be borrowed for 3 weeks. Users can extend the loans. 1. Draw a use case diagram for a library. 2. Give a use case description for two use cases: • Borrow copy of book • Extend loan Diagram: Use case description: 1. Borrow a copy of the book: If the person wishes to borrow a book from Derpville Public Library, he/she must be a member of the library in which case they will be allowed to issue a certain number of books. If the person is not a member, the book will not be issued to them for taking away, rather they will have to sit and read in the library. 2. Extending loan: Some books will be lent for 3 weeks while others will be lent for more than 3 weeks in which case the person borrowing has to come to the library and get the date extended. There is a limit on how much the user can extend the date of a particular book.

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• Telecomunication SID model and resources [on hold]

  - by andygluk

  There is a SID model well-known in telecom industry. Following this model you define resources as resources owned by your enterprise, and then you build resource-oriented services on top of it and then customer-oriented services and so on... So everything is based on enterprise-owned resources, which you have to identify first. What I am looking for and what I am asking is some alternative to this model, build not on enterprise-owned resources, but on resources sell by enterprise. Say, you are selling licenses for using your products. So instead of building model on top of enterprise resources you may be interested to build it on top of licenses you are selling.

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• SQL Developer Data Modeler v3.3 Early Adopter: Link Model Objects Across Designs

  - by thatjeffsmith

  The third post in our “What’s New in SQL Developer Data Modeler v3.3” series, SQL Developer Data Modeler now allows you to link objects across models. If you need to catch up on the earlier posts, here are the first two: New and Improved Search Collaborative Design via Excel Today’s post is a very simple and straightforward discussion on how to share objects across models and designs. In previous releases you could easily copy and paste objects between models and designs. Simply select your object, right-click and select ‘Copy’ Once copied, paste it into your other designs and then make changes as required. Once you paste the object, it is no longer associated with the source it was copied from. You are free to make any changes you want in the new location without affecting the source material. And it works the other way as well – make any changes to the source material and the new object is also unaffected. However. What if you want to LINK a model object instead of COPYING it? In version 3.3, you can now do this. Simply drag and drop the object instead of copy and pasting it. Select the object, in this case a relational model table, and drag it to your other model. It’s as simple as it sounds, here’s a little animated GIF to show you what I’m talking about. Drag and drop between models/designs to LINK an object Notes The ‘linked’ object cannot be modified from the destination space Updating the source object will propagate the changes forward to wherever it’s been linked You can drag a linked object to another design, so dragging from A - B and then from B - C will work Linked objects are annotated in the model with a ‘Chain’ bitmap, see below This object has been linked from another design/model and cannot be modified. A very simple feature, but I like the flexibility here. Copy and paste = new independent object. Drag and drop = linked object.

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• Merge two different API calls into One

  - by dhilipsiva

  I have two different apps in my django project. One is "comment" and an other one is "files". A comment might save some file attached to it. The current way of creating a comment with attachments is by making two API calls. First one creates an actual comment and replies with the comment ID which serves as foreign key for the Files. Then for each file, a new request is made with the comment ID. Please note that file is a generic app, that can be used with other apps too. What is the cleanest way of making this into one API call? I want to have this as a single API call because I am in a situation where I need to send user an email with all the files as attachment when a comment is made. I know Queueing is the ideal way to do it. But I don't have the liberty to add queing to our stack now. So this was the only way I could think of.

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• Should a Parent with Children have a DefaultChild, or should a Child have a Default property?

  - by Stijn

  Which of the following two models makes more sense? I'm leaning towards the first one because there can only be one default child. The examples are in C# but I think it can apply to other languages too. Here DefaultChild holds one of the items in Children. class Parent { int ID { get; set; } Child DefaultChild { get; set; } IEnumerable<Child> Children { get; set; } } class Child { int ID { get; set; } } Here one of the items in Children has Default set to true while the others have it set to false. class Parent { int ID { get; set; } IEnumerable<Child> Children { get; set; } } class Child { int ID { get; set; } bool Default { get; set; } } A concrete situation: a User in our system has one or more Customers attached. When logging in, if said User has a default Customer, they are immediately working under this Customer. If they don't, they have to select a Customer to work under. While logged in, they can switch between Customers.

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• How to show or direct a business analyst to a data modelling subject?

  - by AaronLS

  Our business analysts pushed hard to collect data through a spreadsheet. I am the programmer responsible for importing that data. Usually when they push hard for something like this, I never know how well it will work out until a few weeks later when I have time assigned to work on the task of programming the import of the data. I have tried to do as much as possible along the way, named ranges, data validations, etc. But I usually don't have time to take a detailed look at all the data and compare to the destination in the database to determine how well it matches up. A lot of times there will be maybe a little table of items that somehow I have to relate to something else in the database, but there are not natural or business keys present that would allow me to do so. Make the best of this, trying to write something that can compare strings and make a best guess at it and then go through the effort of creating interfaces for a user to match the imported data to the destination. I feel like if the business analyst was actually creating a data model, they would be forced to think about these relationships, and have an appreciation for the need of natural or business keys to be part of the spreadsheet for the purposes of smoothly importing the data. The closest they come to business analysis is a big flat list of fields, and that would be fine if it were like any other data dictionary and include data types+relationships, but it isn't. They are just a bunch of names. No indication of what type of data they might hold, and it is up to me to guess. When I have pushed for more detail, they say that it is just busy work. How can I explain the importance of data modelling? How can I tell them what it is and how to do it? It feels impossible, because they don't have an appreciation for its importance. They do however, usually have an interest in helping out in whatever way they can, it's just this in particular has never gotten a motivated response.

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• Relationships in a Chen ERD

  - by Nibroc A Rehpotsirhc

  I am working on a Chen ERD to model our organizations merchandise. Our central entity is a Style. We have supplemental entities of Color and Season. I am defining our assortment as the relationship between these three entities, and this relationship itself will have attributes and is defined by the three entities which participate in the mandatory relationship. The rules are; Many Styles can be offered in a Season, and a Style can be offered in many Seasons. Within a Season, a Style can be offered in Many Colors. I then have 2 other entities, one of which I believe is a weak entity, Climate, and the other may be weak, but I am not sure, this being Transaction Channel. I am thinking of these as relationships off of a relationship? Meaning, for a given Style/Color combination offered in a Season, it can be available through 1 or more Transaction Channels. Additionally, within a season, a given Style/Color combination can be intended for 1 or more Climates. Is it valid to have relationships off of relationships? Or does this requirement dictate that I should think of this Style/Color/Season relationship as an entity itself, and define the relationships to Climate and Transaction Channel off of this entity?

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• What schema documentation tools exist for PostgreSQL

  - by Brad Koch

  MySQL has MySQL Workbench for designing and documenting your schema, and generates CREATE and ALTER scripts based on your design. We're looking at migrating to PostgreSQL in the near future, and we do need a practical way of documenting and modifying the schema structure. What similar tools exist for Postgres (that are OS X/Linux compatible)? Alternatively, what equivalent conventions would be followed for designing and documenting the structure of your Postgres database?

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• How to show or direct a business analyst to do data modelling?

  - by AaronLS

  Our business analysts pushed hard to collect data through a spreadsheet. I am the programmer responsible for importing that data. Usually when they push hard for something like this, I never know how well it will work out until a few weeks later when I have time assigned to work on the task of programming the import of the data. I have tried to do as much as possible along the way, named ranges, data validations, etc. But I usually don't have time to take a detailed look at all the data and compare to the destination in the database to determine how well it matches up. A lot of times there will be maybe a little table of items that somehow I have to relate to something else in the database, but there are not natural or business keys present that would allow me to do so. Make the best of this, trying to write something that can compare strings and make a best guess at it and then go through the effort of creating interfaces for a user to match the imported data to the destination. I feel like if the business analyst was actually creating a data model, they would be forced to think about these relationships, and have an appreciation for the need of natural or business keys to be part of the spreadsheet for the purposes of smoothly importing the data. The closest they come to business analysis is a big flat list of fields, and that would be fine if it were like any other data dictionary and include data types+relationships, but it isn't. They are just a bunch of names. No indication of what type of data they might hold, and it is up to me to guess. When I have pushed for more detail, they say that it is just busy work. How can I explain the importance of data modelling? How can I tell them what it is and how to do it? It feels impossible, because they don't have an appreciation for its importance. They do however, usually have an interest in helping out in whatever way they can, it's just this in particular has never gotten a motivated response.

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• Modelling work-flow plus interaction with a database - quick and accessible options

  - by cjmUK

  I'm wanting to model a (proposed) manufacturing line, with specific emphasis on interaction with a traceability database. That is, various process engineers have already mapped the manufacturing process - I'm only interested in the various stations along the line that have to talk to the DB. The intended audience is a mixture of project managers, engineers and IT people - the purpose is to identify: points at which the line interacts with the DB (perhaps going so far as indicating the Store Procs called at each point, perhaps even which parameters are passed.) the communication source (PC/Handheld device/PLC) the communication medium (wireless/fibre/copper) control flow (if leak test fails, unit is diverted to repair station) Basically, the model will be used as a focus different groups on outstanding tasks; for example, I'm interested in the DB and any front-end app needed, process engineers need to be thinking about the workflow and liaising with the PLC suppliers, the other IT guys need to make sure we have the hardware and comms in place. Obviously I could just improvise in Visio, but I was wondering if there was a particular modelling technique that might particularly suit my needs or my audience. I'm thinking of a visual model with supporting documentation (as little as possible, as much as is necessary). Clearly, I don't want something that will take me ages to (effectively) learn, nor one that will alienate non-technical members of the project team. So far I've had brief looks at BPMN, EPC Diagrams, standard Flow Diagrams... and I've forgotten most of what I used to know about UML... And I'm not against picking and mixing... as long as it is quick, clear and effective. Conclusion: In the end, I opted for a quasi-workflow/dataflow diagram. I mapped out the parts of the manufacturing process that interact with the traceability DB, and indicated in a significantly-simplified form, the data flows and DB activity. Alongside which, I have a supporting document which outlines each process, the data being transacted for each process (a 'data dictionary' of sorts) and details of hardware and connectivity required. I can't decide whether is a product of genius or a crime against established software development practices, but I do think that is will hit the mark for this particular audience.

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• What modelling technique do you use for your continuous design?

  - by d3prok

  Together with my teammates, I'm trying to self-learn XP and apply its principles. We're successfully working in TDD and happily refactoring our code and design. However we're having problems with the overall view of the design of the project. Lately we were wondering what would be the "good" practices for an effective continuous design of the code. We're not strictly seeking the right model, like CRC cards, communication diagrams, etc., instead we're looking for a technique to constantly collaborate on the high level view of the system (not too high though). I'll try to explain myself better: I'm actually interested in the way CRC cards are used to brainstorm a model and I would mix them with some very rough UML diagrams (that we already use). However, what we're looking for are some principles for deciding when, how and how much to model during our iterations. Have you any suggestion on this matter? For example, when your teammates and you know you need a design session and how your meetings work?

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• UML Receptions and AcceptEventActions

  - by Silli

  What shall be the relationship between the receptions of a class (was classifier before Aadaam correction) and the AcceptEventActions in the activity describing the behavior of its instances? I understand the former is related to signals reception of the type while the latter is related to runtime ReceiveSignalEvent events of the class instances (objects). But it is not totally clear to me how to express consistency among these constructs.

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• Possible applications of algorithm devised for differentiating between structured vs random text

  - by rooznom

  I have written a program that can rapidly (within 5 sec on a 2GB RAM desktop, 2.33 Ghz CPU) differentiate between structured text (e.g english text) and random alphanumeric strings. It can also provide a probability score for the prediction. Are there any practical applications/uses of such a program. Note that the program is based on entropy models and does not have any dictionary comparisons in its workflow. Thanks in advance for your responses

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• Advice on reconciling discordant data

  - by Justin

  Let me support my question with a quick scenario. We're writing an app for family meal planning. We'll produce daily plans with a target calorie goal and meals to achieve it for our nuclear family. Our calorie goal will be calculated for each person from their attributes (gender, age, weight, activity level). The weight attribute is the simplest example here. When Dad (the fascist nerd who is inflicting this on his family) first uses the application he throws approximate values into it for Daughter. He thinks she is 5'2" (157 cm) and 125 lbs (56kg). The next day Mom sits down to generate the menu and looks back over what the bumbling Dad did, quietly fumes that he can never recall anything about the family, and says the value is really 118 lbs! This is the first introduction of the discord. It seems, in this scenario, Mom is probably more correct that Dad. Though both are only an approximation of the actual value. The next day the dear Daughter decides to use the program and sees her weight listed. With the vanity only a teenager could muster she changes the weight to 110 lbs. Later that day the Mom returns home from a doctor's visit the Daughter needed and decides that it would be a good idea to update her Daughter's weight in the program. Hooray, another value, this time 117 lbs. Now how do you reconcile these data points? Measurement error, confidence in parties, bias, and more all confound the data. In some idealized world we'd have a weight authority of some nature providing the one and only truth. How about in our world though? And the icing on the cake is that this single data point changes over time. How have you guys solved or managed this conflict?

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• How do you handle domain logic that spans multiple model objects in an ORM?

  - by duality_

  So I know that business logic should be placed in the model. But using an ORM it is not as clear where I should place code that handles multiple objects. E.g. let's say we have a Customer model which has a type of either sporty or posh and we wanted to customer.add_bonus() to every posh customer. Where would we do this? Do we create a new class to handle all this? If yes, where do we put it (alongside all the other model classes, but not subclass it from the ORM?)? I'm currently using django framework in python, so specific suggestions are even more wanted.

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• How would you model an objects representing different phases of an entity life cycle?

  - by Ophir Yoktan

  I believe the scenario is common mostly in business workflows - for example: loan management the process starts with a loan application, then there's the loan offer, the 'live' loan, and maybe also finished loans. all these objects are related, and share many fields all these objects have also many fields that are unique for each entity the variety of objects maybe large, and the transformation between the may not be linear (for example: a single loan application may end up as several loans of different types) How would you model this? some options: an entity for each type, each containing the relevant fields (possibly grouping related fields as sub entities) - leads to duplication of data. an entity for each object, but instead of duplicating data, each object has a reference to it's predecessor (the loan doesn't contain the loaner details, but a reference to the loan application) - this causes coupling between the object structure, and the way it was created. if we change the loan application, it shouldn't effect the structure of the loan entity. one large entity, with fields for the whole life cycle - this can create 'mega objects' with many fields. it also doesn't work well when there's a one to many or many to many relation between the phases.

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• Testing my model for hybrid scheduling in Embedded Systems

  - by markusian

  I am working on a project for school, where I have to analyze the performances of a few fixed-priority servers algorithms (polling server, deferrable server, priority exchange) using a simulator in the case of hybrid scheduling, where we have both hard periodic tasks and soft aperiodic tasks. In my model I consider that: the hard tasks have a period equal to their deadline, with a known worst case execution time (wcet). The actual execution time could be smaller than the wcet. the soft tasks have a known wcet and random interarrival times. The actual execution time could be smaller than the wcet. In order to test those algorithms I need realistic case studies. For this reason I'm digging in the scientific literature but I am facing different problems: Sometimes I find a list of hard tasks with wcet, but it is not specified how the soft tasks parameters are found. Given the wcet of a task, how can I model its actual execution time? This means, what random distribution should I use considering the wcet? How can I model the random interarrival times of soft aperiodic tasks?

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• Any tools out there that will EXECUTE BPMN 2.0 xml code yet?

  - by processimprover

  Business Process Modeling Notation with version 2.0, an international standard formally approved by OMG, creates XML code that is generated when a person creates a process model in a process modeling tool...like Visio with ITP-Commerce BPM 2.0 add-in. I would like to know if any of you gurus out there have or can create a tool that will take the XML code and EXECUTE it. Anyone? Thanks very much, Randy

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