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• Calculated control on subform based on current record

  - by rtochip

  I have the following: main form "customer" from a "customer" table. subform "invoices" with fields "invoice date", "invoice amount" "customer id" etc. from a table "invoices" whenever user clicks or goes to a record in the "invoices" sub form. I would like a "total so far" control to calculate the sum of the "invoices amount" up until the date of the current record being "clicked" or selected. i.e. for customer microsoft with invoices: 1) may 2 09, $150 2) may 3 09, $200 3) may 4 09, $500 If user clicks on record 2), "total so far" should show $350 If user clicks on record 1), "total so far" should show $150 If user clicks on record 3), "total so far" should show $850 Currently, I am using DSum function on an event "OnCurrent" in the subform "invoices" to set the "total so far" value. Is this method slow, inefficient? Any other simpler,cleaner,more elegant,faster, efficient method using ms access features? I want the "invoices" subform to show ALL the invoices for this customer no matter which record is clicked.

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• A detail question when applying genetic algorithm to traveling salesman

  - by burrough

  I read various stuff on this and understand the principle and concepts involved, however, none of paper mentions the details of how to calculate the fitness of a chromosome (which represents a route) involving adjacent cities (in the chromosome) that are not directly connected by an edge (in the graph). For example, given a chromosome 1|3|2|8|4|5|6|7, in which each gene represents the index of a city on the graph/map, how do we calculate its fitness (i.e. the total sum of distances traveled) if, say, there is no direct edge/link between city 2 and 8. Do we follow some sort of greedy algorithm to work out a route between 2 and 8, and add the distance of this route to the total? This problem seems pretty common when applying GA to TSP. Anyone who's done it before please share your experience. Thanks.

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• Properly handling possible System.NullReferenceException in lambda expressions

  - by Travis Johnson

  Here's the query in question return _projectDetail.ExpenditureDetails .Where(detail => detail.ProgramFund == _programFund && detail.Expenditure.User == _creditCardHolder) .Sum(detail => detail.ExpenditureAmounts.FirstOrDefault( amount => amount.isCurrent && !amount.requiresAudit) .CommittedMonthlyRecord.ProjectedEac); Table Structure ProjectDetails (1 to Many) ExpenditureDetails ExpenditureDetails (1 to Many) ExpenditureAmounts ExpenditureAmounts (1 to 1) CommittedMonthlyRecords ProjectedEac is a decimal field on the CommittedMonthlyRecords. The problem I discovered in a Unit test (albeit an unlikely event), that the following line could be null: detail.ExpenditureAmounts.FirstOrDefault( amount => amount.isCurrent && !amount.requiresAudit) My original query was a nested loop, in where I would be making multiple trips to the database, something I don't want to repeat. I've looked in to what seemed like some similar questions here, but the solution didn't seem to fit. Any ideas?

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• How to retrieve row count of one-to-many relation while also including original entity?

  - by kaa

  Say I have two entities Foo and Bar where Foo has-many Bar's, class Foo { int ImportantNumber { get; set; } IEnumerable<Bar> Bars { get; set; } } class FooDTO { Foo Foo { get; set; } int BarCount { get; set; } } How can I efficiently sum up the number of Bars per Foo in a DTO using a single query, preferrably only with the Criteria interface. I have tried any number of ways to get the original entity out of a query with ´SetProjection´ but no luck. The current theory is to do something like SELECT Foo.*, BarCounts.counts FROM Foo LEFT JOIN ( SELECT fooId, COUNT(*) as counts FROM Bar GROUP BY fooId ) AS BarCounts ON Foo.id=BarCounts.fooId but with Criterias, and I just can't seem to figure out how.

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• F# Static Member Type Constraints

  - by Stephen Swensen

  I'm trying to define a function, factorize, which uses structural type constraints (requires static members Zero, One, +, and /) similar to Seq.sum so that it can be used with int, long, bigint, etc. I can't seem to get the syntax right, and can't find a lot of resources on the subject. This is what I have, please help. let inline factorize (n:^NUM) = ^NUM : (static member get_Zero: unit->(^NUM)) ^NUM : (static member get_One: unit->(^NUM)) let rec factorize (n:^NUM) (j:^NUM) (flist: ^NUM list) = if n = ^NUM.One then flist elif n % j = ^NUM.Zero then factorize (n/j) (^NUM.One + ^NUM.One) (j::flist) else factorize n (j + ^NUM.One) (flist) factorize n (^NUM.One + ^NUM.One) []

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• Computing MD5SUM of large files in C#

  - by spkhaira

  I am using following code to compute MD5SUM of a file - byte[] b = System.IO.File.ReadAllBytes(file); string sum = BitConverter.ToString(new MD5CryptoServiceProvider().ComputeHash(b)); This works fine normally, but if I encounter a large file (~1GB) - e.g. an iso image or a DVD VOB file - I get an Out of Memory exception. Though, I am able to compute the MD5SUM in cygwin for the same file in about 10secs. Please suggest how can I get this to work for big files in my program. Thanks

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• Flex AdvancedDataGrid - ColumnOrder With Formatter and ItemRenderer Question For Experts

  - by robin1126

  I have a advanceddatagrid that has around 15 columns. Some are string, some are numbers. I have shown 4 columns below. The number columns have formatting done for zero precision and 2 digits precision. The itemRenderer is just to show Blue Color if the number is +ve and Red Color if the number is -ve. It looks something like below ... I am trying to save the users setting of column order when he closes the application and reload with the same order when the user opens the applications. I am using SharedObjects and below is the code. for(var i:int=0; i< adgrid.columns.length;i++){ var columnObject:Object = new Object(); columnObject.columnDataField = adgrid.columns[i].dataField as String; columnObject.columnHeader =adgrid.columns[i].headerText as String; columnObject.width = adgrid.columns[i].width; columnArray.push(columnObject); } and then I save the columnArray to SharedObject. I retrive them using the below code for(var i:int=0;i adgrid.columns[i].dataField =columnArray[i].columnDataField; adgrid.columns[i].headerText =columnArray[i].columnHeader; adgrid.columns[i].width = columnArray[i].width; } How can I save and reload the Formatter and ItemRenderer data . I am having trouble saving the formatter and itemrenderer and reloading it again. I would really appreciate if you can shown the code. How can I reshuffle the columns but can preserve all the properties of it to the sharedobject and recover it again.

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• Hierarchy based aggregation

  - by Ganapathy Subramaniam

  I have a hierarchy table in SQL Server 2005 which contains employees - managers - department - location - state. Sample table for hierarchy table: ID Name ParentID Type 1 PA NULL 0 (group) 2 Pittsburgh 1 1 (subgroup) 3 Accounts 2 1 4 Alex 3 2 (employee) 5 Robin 3 2 6 HR 2 1 7 Robert 6 2 Second one is fact table which contains employee salary details ID and Salary. Sample data for fact table: ID Salary 4 6000 5 5000 7 4000 Is there any good to way to display the hierarchy from hierarchy table with aggregated sum of salary based on employees. Expected result is like Name Salary PA 15000 (Pittsburgh + others(if any)) Pittusburgh 15000 (Accounts + HR) Accounts 11000 (Alex + Robin) Alex 6000 (direct values) Robin 5000 HR 4000 Robert 4000 In my production environment, hierarchy table may contain 23000+ rows and fact table may contain 300,000+ rows. So, I thought of providing any level of groupid to the query to retrieve just its children and its corresponding aggregated value. Any better solution?

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• How to configure maximum number of channels in WCF?

  - by Hemant

  Consider following code which calls a calculator service: static void Main (string[] args) { for (int i = 0; i < 32; i++) { ThreadPool.QueueUserWorkItem (o => { var client = new CalcServiceClient (); client.Open (); while (true) { var sum = client.Add (2, 3); } }); } Console.ReadLine (); } If I use TCP binding then maximum 32 connections are opened but if I use HTTP binding, only 2 TCP connections are opened. How can I configure the maximum number of connections that can be opened using HTTP binding?

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• Django: Summing values of records grouped by foreign key

  - by Dan0

  Hi there In django, given the following models (slightly simplified), I'm struggling to work out how I would get a view including sums of groups class Client(models.Model): api_key = models.CharField(unique=True, max_length=250, primary_key=True) name = models.CharField(unique=True, max_length=250) class Purchase(models.Model): purchase_date = models.DateTimeField() client = models.ForeignKey(SavedClient, to_field='api_key') amount_to_invoice = models.FloatField(null=True) For a given month, I'd like to see e.g. April 2010 For Each Client that purchased this month: * CLient: Name * Total amount of Purchases for this month * Total cost of purchases for this month For each Purchase made by client: * Date * Amount * Etc I've been looking into django annotation, but can't get my head around how to sum values of a field for a particular group over a particular month and send the information to a template as a variable/tag. Any info would be appreciated

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• Question with R. Element wise multiplication, addition, and division with 2 data.frames with varying

  - by Michael

  I have a various data.frames with columns of the same length where I am trying to multiple 2 rows together element-wise and then sum this up. For example, below are two vectors I would like to perform this operation with. > a.1[186,] q01_a q01_b q01_c q01_d q01_e q01_f q01_g q01_h q01_i q01_j q01_k q01_l q01_m 3 3 3 3 2 2 2 3 1 NA NA 2 2 and > u.1[186,] q04_avl_a q04_avl_b q04_avl_c q04_avl_d q04_avl_e q04_avl_f q04_avl_g q04_avl_h q04_avl_i q04_avl_j q04_avl_k q04_avl_l q04_avl_m 4 2 3 4 3 4 4 4 3 4 3 3 3` The issue is that various rows have varying numbers of NA's. What I would like to do is skip the multiplication with any missing values ( the 10th and 11th position from my above example), and then after the addition divide by the number of elements that were multiplied (11 from the above example). Most rows are complete and would just be multiplied by 13. Thank you!

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• _mask and Rails

  - by Eric Koslow

  So I am trying to get the cancan gem to work with my rails 3 app and I've hit a problem. I tried to copy the code that Ryan Bates (the creator of the gem) used in his screen cast, but I get an error saying that roles_mask is not a method. I figure that the _mask method was removed from Ruby/Rails at some point, and I'm now wondering what is the replacement. Here's the code in my user.rb model: named_scope :with_role, lambda { |role| {:conditions => "roles_mask & #{2**ROLES.index(role.to_s)} > 0 "} } ROLES = %w[admin student principal admissions] def roles=(roles) self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum end def roles ROLES.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? } end def role? roles.include? role.to_s end def role_symbols roles.map(&:to_sym) end I'm using Rails 3 and Ruby 1.9.2dev Thank you

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• how to group by over anonymous type with vb.net linq to object

  - by smoothdeveloper

  I'm trying to write a linq to object query in vb.net, here is the c# version of what I'm trying to achieve (I'm running this in linqpad): void Main() { var items = GetArray( new {a="a",b="a",c=1} , new {a="a",b="a",c=2} , new {a="a",b="b",c=1} ); ( from i in items group i by new {i.a, i.b} into g let p = new{ k = g, v = g.Sum((i)=>i.c)} where p.v > 1 select p ).Dump(); } // because vb.net doesn't support anonymous type array initializer, it will ease the translation T[] GetArray<T>(params T[] values){ return values; } I'm having hard time with either the group by syntax which is not the same (vb require 'identifier = expression' at some places, as well as with the summing functor with 'expression required' ) Thanks so much for your help!

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• Parsing a file in C

  - by sfactor

  I need parse through a file and do some processing into it. The file is a text file and the data is a variable length data of the form "PP1004181350D001002003..........". So there will be timestamps if there is PP so 1004181350 is 2010-04-08 13:50. The ones where there are D are the data points that are three separate data each three digits long, so D001002003 has three coordonates of 001, 002 and 003. Now I need to parse this data from a file for which I need to store each timestamp into a array and the corresponding datas into arrays that has as many rows as the number of data and three rows for each co-ordinate. The end array might be like TimeStamp[1] = "135000", low[1] = "001", medium[1] = "002", high[1] = "003" TimeStamp[2] = "135015", low[2] = "010", medium[2] = "012", high[2] = "013" TimeStamp[3] = "135030", low[3] = "051", medium[3] = "052", high[3] = "043" .... The question is how do I go about doing this in C? How do I go through this string looking for these patterns? Note: Here the seconds value in timestamp is added on our own as it is known at each data comes after 15 seconds.

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• crystal report problem

  - by Baharanji

  Dear all, I have a Table which Contains items and its prices and those prices some in Dollars and the rest in pounds and the items are divided into sections and I want to use a modified Sum function in the Crystal Report so as to show at the end of each group the total in pounds like that in C# int price=0; foreach (item it in items) { if (it.curr=="$") { price+=it.price*DollarPrice } else price+=it.price; } return price; That's exactly what i want to do in crystal reports but i dont have any clue how to do so So if you have any Idea please help me, Regards, Baher.

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• Does anyone really understand how HFSC scheduling in Linux/BSD works?

  - by Mecki

  I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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• Help me finish this Python 3.x self-challenge.

  - by Hamish Grubijan

  This is not a homework. I saw this article praising Linq library and how great it is for doing combinatorics stuff, and I thought to myself: Python can do it in a more readable fashion. After half hour of dabbing with Python I failed. Please finish where I left off. Also, do it in the most Pythonic and efficient way possible please. from itertools import permutations from operator import mul from functools import reduce glob_lst = [] def divisible(n): return (sum(j*10^i for i,j in enumerate(reversed(glob_lst))) % n == 0) oneToNine = list(range(1, 10)) twoToNine = oneToNine[1:] for perm in permutations(oneToNine, 9): for n in twoToNine: glob_lst = perm[1:n] #print(glob_lst) if not divisible(n): continue else: # Is invoked if the loop succeeds # So, we found the number print(perm) Thanks!

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• Help me finish this Python self-challenge.

  - by Hamish Grubijan

  This is not a homework. I saw this article praising Linq library and how great it is for doing combinatorics stuff, and I thought to myself: Python can do it in a more readable fashion. After half hour of dabbing with Python I failed. Please finish where I left off. Also, do it in the most Pythonic and efficient way possible please. from itertools import permutations from operator import mul from functools import reduce glob_lst = [] def divisible(n): return (sum(j*10^i for i,j in enumerate(reversed(glob_lst))) % n == 0) oneToNine = list(range(1, 10)) twoToNine = oneToNine[1:] for perm in permutations(oneToNine, 9): for n in twoToNine: glob_lst = perm[1:n] #print(glob_lst) if not divisible(n): continue else: # Is invoked if the loop succeeds # So, we found the number print(perm) Thanks!

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• Compare date from database using parameters

  - by Simon

  string queryString = "SELECT SUM(skupaj_kalorij)as Skupaj_Kalorij " + "FROM (obroki_save LEFT JOIN users ON obroki_save.ID_uporabnika=users.ID)" + "WHERE (users.ID= " + a.ToString() + ") AND (obroki_save.datum= @datum)"; using (OleDbCommand cmd = new OleDbCommand(queryString,database)) { DateTime datum = DateTime.Today; cmd.Parameters.AddWithValue("@datum", datum); } loadDataGrid2(queryString); I tried now with parameters. But i don't really know how to do it correctly. I tried like this, but the parameter datum doesn't get any value(according to c#).

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• Three coworkers Riddle Problem

  - by John S

  This isn't homework, I've got a solution, however it doesn't protect against cheaters. Three coworkers would like to know their average salary. However, they are self-conscious and don't want to tell each other their own salaries, for fear of either being ridiculed or getting their houses robbed. How can they find their average salary, without disclosing their own salaries? Now, a solution that requires the last person to tell the group the sum isn't allowed because that person could cheat. Solution: http://karavi.wordpress.com/2009/12/18/solutions-to-wu%E2%80%99s-puzzles-and-riddles-ghetto-encryption-2-medium/

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• Stack overflow in OCaml and F# but not in Haskell

  - by Fernand Pajot

  I've been comparing for fun different languages for speed in execution of the following program: for i from 1 to 1000000 sum the product i*(sqrt i) One of my implementations (not the only one) is constructing a list [1..1000000] and then folding with a specific funtion. The program works fine and fast in Haskell (even when using foldl and not foldl') but stack overflows in OCaml and F#. Here is the Haskell code: test = foldl (\ a b -> a + b * (sqrt b)) 0 create 0 = [] create n = n:(create (n-1)) main = print (test (create 1000000)) And here is the OCaml one: let test = List.fold_left (fun a b -> a +. (float_of_int b) *. (sqrt (float_of_int b))) 0. ;; let rec create = function | 0 -> [] | n -> n::(create (n-1)) ;; print_float (test (create 1000000));; Why does the OCaml/F# implementation stack overflows?

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• C# Textbox validation should only accept integer values, but allows letters as well

  - by sonny5

  if (textBox1.Text != "") // this forces user to enter something { // next line is supposed to allow only 0-9 to be entered but should block all... // ...characters and should block a backspace and a decimal point from being entered.... // ...but it is also allowing characters to be typed in textBox1 if(!IsNumberInRange(KeyCode,48,57) && KeyCode!=8 && KeyCode!=46) // 46 is a "." { e.Handled=true; } else { e.Handled=false; } if (KeyCode == 13) // enter key { TBI1 = System.Convert.ToInt32(var1); // converts to an int Console.WriteLine("TBI1 (var1 INT)= {0}", var1); Console.WriteLine("TBI1= {0}", TBI1); } if (KeyCode == 46) { MessageBox.Show("Only digits...no dots please!"); e.Handled = !char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar); } } else { Console.WriteLine("Cannot be empty!"); } // If I remove the outer if statement and skip checking for an empty string, then // it prevents letters from being entered in the textbox. I need to do both, prevent an // empty textbox AND prevent letters from being entered. // thanks, Sonny5

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• R - find and calculate with unique combinations of values

  - by lecodesportif

  I would like to work with unique combinations of var1 and var2. foo <- data.frame(var1= c(1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4), var2=c(1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 3, 3)) As has been noted (+1 for answers), unique(foo) results in this: var1 var2 1 1 1 2 2 1 3 2 2 4 3 1 5 3 2 6 4 2 7 4 3 Based on the unique combinations, how do I get the number of occurrences of a var1 value and the sum (bla) of each var1 value's var2 values. The output could look like this: var1 n bla 1 1 1 1 2 2 2 3 3 3 2 3 4 4 2 5 edit: The question was too basic and probably duplicate so I extended it.

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• What does the C compiler error "looks like a function definition, but there is no parameter list;" m

  - by user312309

  #include <iostream> #include <fstream> using namespace std; int main { int num1, num2; ifstream infile; ostream outfile; infile.open("input.dat"); outfile.open("output.dat"); infile >> num 1 >> num 2; outfile << "Sum = " << num1 + num2 << endl; infile.close() outfile.close() return 0; } this is what i did and when i compile it, i got this error that said error C2470: 'main' : looks like a function definition, but there is no parameter list; skipping apperent body please dont hate me :( i am new at this computer science....

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• java distributed cache for low latency, high availability

  - by Shahbaz

  I've never used distributed caches/DHTs like memcached, jboss cache, ehcache, etc. I'm wondering which, if any, is appropriate for my use. First, I'm not doing web applications (as most of these project seem to be geared towards web apps). I write servers (Order Management Systems actually) for financial trading firms. The servers themselves are not too complicated. They need to receive information (market data, orders, executions, etc.) rout them to their destination while possibly transforming some of these messages. I am looking at these products to solve the following problems: * Safe repository of the state of the server. I'd rather build the logic of my application as a bunch of transformers (similar to Apache Camel) and store the state in a 'safe' place * This repository should be distributed: in case one of these data stores crashes, one or two more should be up and I should be able to switch to them seamlessly * This repository should be fast. Single digits milliseconds count here, in other words, systems which consume/process this data are automated systems, not humans clicking on links. This system needs to have high-throughput and low latency. By sending my data outside the process, I am necessarily slowing performance, but I am trying to balance absolute raw speed and absolute protection of data. * This repository should be safe. Similar to the point about several on-line backups, this system needs to write data to disk (potentially more than one disk). I'd really like to stop writing my own 'transaction servers.' Am I correct to be looking into projects such as jboss cache, ehcache, etc.? Thanks

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