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plurals

PODocument Server: Handling Concurrent Saves
primarykey
Id
9675
data
AcceptedAnswerId
9692
AnswerCount
3
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2008-08-13T11:49:14.250
FavoriteCount
0
LastActivityDate
2014-02-14T16:37:17.100
LastEditDate
2014-02-14T16:37:17.100
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2126792
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1182
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0
PostTypeId
1
Score
2
ViewCount
248
LastEditorDisplayName
Outlaw Programmer
text
Body
I'm implementing a document server. Currently, if two users open the same document, then modify it and save the changes, the document's state will be undefined (either the first user's changes are saved permanently, or the second's). This is entirely unsatisfactory. I considered two possibilities to solve this problem: The first is to lock the document when it is opened by someone the first time, and unlock it when it is closed. But if the network connection to the server is suddenly interrupted, the document would stay in a forever-locked state. The obvious solution is to send regular pings to the server. If the server doesn't receive K pings in a row (K > 1) from a particular client, documents locked by this client are unlocked. If that client re-appears, documents are locked again, if someone hadn't already locked them. This could also help if the client application (running in web browser) is terminated unexpectedly, making it impossible to send a 'quitting, unlock my documents' signal to the server. The second is to store multiple versions of the same document saved by different users. If changes to the document are made in rapid succession, the system would offer either to merge versions or to select a preferred version. To optimize storage space, only document diffs should be kept (just like source control software). What method should I choose, taking into consideration that the connection to the server might sometimes be slow and unresponsive? How should the parameters (ping interval, rapid succession interval) be determined? P.S. Unfortunately, I can't store the documents in a database.
Tags
<concurrency><locking><versioning>
Title
Document Server: Handling Concurrent Saves
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PostAcceptedAnswerId
1. PO
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 PostTypePostTypeId
 PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USpschueller
UserOwnerUserId
1. USentropia
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PostsAcceptedAnswerId
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PostsParentIdCreationDate
1. PO
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 PostTypePostTypeId
 PTAnswer
2. PO
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 PostTypePostTypeId
 PTAnswer
3. PO
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 PostTypePostTypeId
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 PODocument Server: Handling Concurrent Saves
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 VTUpMod
2. VO
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 PODocument Server: Handling Concurrent Saves
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CommentsPostId
1. This table or related slice is empty.

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